Startin' with Scuba

August 11, 2008

Dogs, tanks, suits and Nitrox

Sometimes you go diving and it's just for fun. Other times you learn a bunch of new things as I found out this past weekend at Lake Tahoe. Instead of Meeks Bay which is usually overrun with certification classes, we went back to the D. L. Bliss State Park just a few miles away from Meeks. That's the site of the (in)famous Rubicon Wall that plunges down from 60 feet or so to a depth of 1,500 feet within just a quarter mile. Unfortunately, the trail from the Callawee Cove parking lot is a plunge all by itself, and quite a pain with scuba gear on. Still, the lure of the secluded beach and the wall were enough to make us go back.

Parking at D.L. Bliss is just six bucks a day, a real bargain when you consider the giant size of the park (it takes a mile on a narrow, winding forest road to even get to the park entrance gate) and the gorgeous vistas. It's a bit like Big Sur with lots of woods and nature. We arrived at the smallish Callawee Cove lot at 9:30AM when you can still pick your spot. As always with diving, the closer to the beach you can get the better.

This time, with the memory of lugging those giant 104-cubic foot steel tanks down (and up!) the steep trail, we brought comparatively tiny high pressure steel-80s. They don't look very manly, those tanks, but on this trip I certainly got to appreciate them. Sure, I only had 80 cubic-foot of air instead of 104, but that was enough, and the big difference in size and weight made this trip about diving and not about scaling what seems like 700 steps up a vertical cliff.

I never really realized before how important picking the right tank is. As much as I had read about tanks, when I bought my own first tanks I got my two used low-pressure steel-95s because Robert at Diver's Cove in Folsom recommended them, and my metallic-blue anodized aluminum 80 because it looked great. The steel 95s are good but I don't think I ever got a full 2,400 psi charge, and when you begin with 2,100 psi or so, there just isn't all that much air in them. The blue alu tank does look great, but it's actually even longer than the steel-95s, so it's quite a handful for just 80 cubic feet of air, and that's before the annoying buoyancy issues of aluminum tanks (I'll get into that!). So I think I'll relegate the pretty blue tank to pool duty, sell the steel 95s, and invest in high pressure steel 100s if we can find them at a reasonable price. High pressure tanks have their own issues (filling time, availability of high pressure fills, etc.) but at this point weight and length of a tank have become important to me. If you routinely have to carry tanks by the valve, having one that you can carry without it dragging the ground makes things so much easier.

But it's not only tanks where there is no substitute for practical experience. The same goes for wetsuits. While I liked the first wetsuit I ever bought, a 7mm Telos, the thing was so difficult to get into that I started all my dives already exhausted. And pulling the recalcitrant material up your arms and legs practically guarantees sore fingertips as the side of the nails dig into the soft parts. The answer there is to get a suit that really fits. My Telos, for example, was a "medium," which meant it fit my 6-foot, 155 pound frame snugly, but arms and legs were too short. No fun.

Well, Carol pointed out that some wetsuits come in "medium-long," though dive shops don't usually carry the size. My new 7mm Scubapro "Form" wetsuit does come in that size and it fits great. It's also made from a material that is super-stretchy and therefore goes on a whole lot easier. Nothing is ever perfect, though. Somehow it must have escaped Scubapro that Velcro grabs this material like crazy. When you pull the velcro off, it rips the surface layer of the wetsuit material. Scuba gear uses lots of velcro, and so it won't be long before suits made of this material look all chewed up. Anyway, I love the suit and we'll see how it holds up.

The water temperature at Tahoe was 68 degrees as it usually is in the summer. However, I knew from prior dives that it gets colder quickly as you go down and so I used my hood and gloves. I had some concerns about the gloves as we took a test camera along, the new DC800 from SeaLife. The folks at SeaLife have this amazing ability to retrofit ordinary digital camera equipment for underwater duty by tweaking the software and adding special underwater modes that go well beyond what consumer cameras with an underwater setting or two offer. A lot of their magic comes from special white balance modes that correct for the way water filters out different colors as you go deeper. They also know that divers do wear gloves on occasion, and so the buttons on their underwater housings are always spaced to accommodate gloves. It may have escaped them, however, that older divers need reading glasses to see fine print and tiny icons, and so that can be an issue.

I had used Nitrox at the quarry in Tennessee, but this was the first time at altitude. I had contemplated the impacts of altitude on diving before, taken the PADI altitude diver class (twice, really), and read up on the subject. It's hard enough to wrap your mind around the logic of altitude diving on air (it's the ratio of the pressure differences between surface and a certain depth underwater that determines nitrogen absorption, and not the absolute pressure!), and it's worse for Nitrox where you essentially have to determine equivalent air depths twice. From talking to various people and also reading bulletin board posts on the matter, it seems that very few really know how it works. It makes no difference, of course, as everyone relies on their dive computer.

It's interesting to see just how much dive tables and dive computers differ when it comes to the real world. NAUI, for example, sells tables for diving at altitude with 32 and 36% Nitrox as well as for air dives. There are two sets of tables, one for altitudes between 6,000 and 10,000 feet and one for 1,000 to 6,000 feet. My dive eventually took me to 64 feet. Rounded up to 70 feet, the NAUI sea level tables would allow for a maximum dive time (MDT) of 45 minutes. The altitude air table cuts that to 21 minutes. That's because diving 64 feet at 10,000 feet of altitude is more like diving 100 feet or so at sea level as far as nitrogen uptake goes. This is where Nitrox comes in handy. Its lesser percentage of nitrogen increases maximum dive time from 21 to 32 minutes with 32% Nitrox, and 37 minutes with 36% Nitrox. So when diving at altitude, using Nitrox increases maximum bottom times when compared to air, just as it does at sea level.

Now how does all that theory translate into what the dive computer shows during an actual dive? Well, at no time did my no-decompression time fall below 60 minutes. And once set to 36% Nitrox, my Uwatec SmartZ also correctly showed an altitude-adjusted maximum oxygen depth of 100 feet. That's about six feet more than at sea level. Most people would expect less, but as far as oxygen goes, absolute pressure matters and so you reach the recommended 1.4 atmosphere partial pressure of oxygen a few feet deeper at Tahoe altitudes.

It's definitely a good thing to plan one's altitude dives, but once you're down there, the dive computer takes over. And at least in my case, maximum allowable dive time was a lot longer than my air would have lasted. I am getting better with my air consumption, but I am still sucking it up at an alarming rate when I get tense, and diving that wall at Rubicon point is still a somewhat scary experience for me.

The beach at Callawee Cove is shallow. You can dive along the rock cliffs and never reach more than 15-18 feet or so. However, swim away from the beach at the point, and there's the wall. Part of it is just a sheer wall, stark and forbidding. Other parts are giant boulders. All in all, it goes from 60 feet or so down to a 1,500 foot abyss within just a quarter mile. Visibility was far less than when we dove the wall last year. We had at least a hundred feet then, but this time it was just 50 or so, as we had already noticed during other Tahoe dives this year. I am not sure why that is; it must be some sort of local phenomenon as I cannot imagine clarity going down by that much within a single year. Tahoe is totally clean and clear, and pollution simply cannot be a sizable problem. Maybe it was ash and dust from all the California wildfires, and that may also account for the lower water temperatures.

Anyway, I never like low visibility, and its worse when there are severe thermoclines. This time we hit two, each gripping one's entire body. At 65 feet it was already down to 50 degrees. I wasn't uncomfortably cold with the hood and gloves, but between the relatively low visibility, the cold, and the menacing face of the wall, I was breathing hard. By now I know that I do not fall when I cannot see the bottom, but it is still a weird feeling. I did not want for it to overcome me, and so when I saw the wall slowly came into view, I swallowed hard and decided to swim along the sheer and near vertical face of the wall. Last time I had gone over it from the top, following Carol. This time, Carol had gone up to the top and peeked over it, feeling "like the Lion King" as she later told me. I swam along the face, breathing hard and hoping I'd soon come to something other than the sheer face. During those two or three minutes it instantly became clear to me why "blue holes" that often have walls that recede as you go down are considered so dangerous. It's easy to freak when there is nothing below you and rock above. Also, at just 65 feet I didn't feel what I suppose was the calming (to me) influence of a bit of narcosis that I probably had felt at 110 feet. In any case, I am very glad I went back to Rubicon Wall. I love those rock faces and giant boulders, but I'd like them that much better in clearer, warmer water.

Nitrox worked well for me, but then again I'd never had a problem with just air. So for now I know that Nitrox doesn't make me feel weird or anything. There's psychology in that. You need to find out for yourself how something makes you feel.

After a two-hour surface interval on the beautiful beach of the cove we did a second dive. This one was just for fun, poking around the rocks and boulders along the shallow shore. It rarely got to be more than 15 feet deep. We took movies with the SeaLife (once in its case, you cannot switch between still pictures and movies, so you need to decide what mode to use beforehand), watched whole colonies of feisty crawdads do their thing, marveled at how warm the fine sand at the bottom was when you stick your hands in it, and just played around.

This second dive was also a lecture in what an impact different types of tanks can have, and how even the same tank can behave differently when it gets empty. On the first dive I had used the high-pressure steel-80 tank and used 16 pounds of weight in the two pockets of my Scubapro Knighthawk BC. For the second dive I switched to my electric-blue Aluminum-80 tank, this time using 18 pounds to make up for the aluminum tank's higher buoyancy. Carol, who generally barely uses any weights at all, had on her new 7mm wetsuit and was on her second dive with the same tank. She doesn't like a lot of weight and dropped two pounds for this dive. As a result of the different buoyancy she now had trouble going down with eight pounds instead of the ten she'd used on the first dive, and so we switched things around again. Having less weight came back to haunt me after I'd used up about 900 psi of air. As we were returning to the beach and I found myself increasingly unable to stay at the shallow depths as my aluminum bottle was getting more and more buoyant, until I signaled it was no use and I had to surface, and so I did. Note to self: tanks that switch from negative to positive buoyancy are a pain.

I listed dogs in the title of this entry. Where do they come in? Well, we had fun watching some Retrievers and Labs play in the water during our dives. But that wasn't why I mentioned it. Like everyone else, I had learned to look up before surfacing so as not to collide with a boat. I did that and none were in sight. But when I came up I bumped into .... a dog. It was a chocolate Lab, and he'd probably been investigating my bubbles. He was just as surprised as I was and quickly doggie-paddled off. Me, I couldn't stop laughing.

Posted by conradb212 at 04:07 PM | Comments (0)

July 24, 2008

Altitude diving class at Meeks Bay, Lake Tahoe

Almost two years ago I wrote how I got certified as an altitude diver at Lake Tahoe. I thought I had been, I really did. But it turned out that I never got my card and my old instructor vanished. So it seemed like a good idea to do the whole thing over again, and I signed up for the PADI altitude diver class with Fisheye Scuba in Folsom.

There really is no separate altitude class in the PADI system. Altitude is part of "Adventures in Diving" and the concepts and things to know are described in one big instruction manual. I bought the 375-page tome, studied, answered the quiz questions and did the knowledge review. I also attended the altitude portion of the class at Fisheye Scuba which took about an hour.

Instructor Kate Fuquay, who is also part-owner of Fisheye Scuba, wanted students to go up to Lake Tahoe the night before the class so our bodies could properly acclimate to the much higher altitude. A bit of research and calling around yielded a reasonably priced motel room, a rare commodity at Tahoe in just about any season. The motel did not have air conditioning and the room was baking hot despite open windows and night time temperatures dropping into the mid-40s. No big deal as thanks to a big fan I managed to sleep anyway.

Meeks Bay is on the other side of the lake and so it was a bit of a drive to get to the camping and resort area by 8AM. The Fisheye crew was already there and so was an assortment of students taking various classes. Meeks Bay actually has two beaches, a small one north of a marina entrance and a larger one south of it. Both have adequate parking close to the sandy beach and both have rest rooms. The larger resort area beach we used also has a nice store for campers and beachgoers, so that's a plus for when you want a drink, snack or a souvenir (I got a handy nautical map of the lake and surrounding waterways).

My new 6-1/2mm ScubaPro wetsuit went on a lot easier than the recalcitrant 7mm Telos I'd become used to fighting with, but it still took me time to don my gear and make sure all was well. We did the buddy check, then gathered around instructor Kate who spent time going through the special considerations of altitude diving as well as the plans for the dives. One advantage of a group this big (there were probably 20 of us all in all) was that we had a couple of non-divers, and so I had someone to look after my 12-year-old son Morgan who'd come along for the experience. He'd brought his snorkeling gear and I was sure he'd have a great time, but he's still only 12 and I wanted an adult to keep an eye on him.

The water was a nice, refreshing 68 degrees Fahrenheit but I had put on my hood anyway, knowing that Lake Tahoe can get quite chilly during a dive. We swam out to one of the buoys so we could descend on its line to the bottom where we'd compare and record the depths shown on our depth gauges or dive computers. That was on the agenda to see if all were altitude-adjusted and whether readings differed or not. I had my Uwatec SmartZ computer on my left wrist and the Timex Helix on my right. At the bottom the SmartZ showed 42 feet and the Timex 41. Close enough.

Lake Tahoe is wonderfully clear and generally has great viz, but a group of mostly novice divers all gathered at the bottom can fix that in a hurry and so we'd soon kicked up enough sand and silt to make it advisable to move on. The bottom at Meeks Bay is sandy and shallow until it slopes away into the abyss at a 45 degree angle. There isn't a whole lot to see and so we swam along the slope at 50 feet or so. Visibility remained marginal for Tahoe and so our initial convoy soon lost sight of each other and split into smaller groups of twos and fours. It's amazing how quickly you can lose sight of other divers underwater. There weren't any boulders here or schools of fish, and so I mostly concentrated on buoyancy, checking my gear and instruments, and watching the occasional crawdad do its thing. Later I noticed that the temperature had actually dropped all the way to 50 degrees at some point and I never even noticed.

Morgan greeted us on the surface, clearly having a good time. We parked the gear at the shore and debriefed. Our assignment for the second altitude dive was to do a full dive plan, adjusted for altitude, pressure groups and all. Here's what Carol and I came up with:

Our first dive had been to 50 feet at Tahoe altitude of 6,230 feet. The 50 feet translates to a theoretical depth of 65 feet at sea level, so we round up to 70 feet. Our first dive was 29 minutes, so after that first dive we were PADI "N" divers. We then had a surface interval of 2:20 hours, and that brought us down to "A" diver status.

Our dive plan for the second dive was to go to 50 feet again. That again translated to a theoretical depth of 65 feet at sea level. We rounded that up to 70 feet, and found that as "A" divers with a residual nitrogen time of five minutes, that left us with an adjusted bottom time of 35 minutes.

That was that, and we conducted the dive in accordance with the plan. On the second dive I used my compass to navigate to the northern edge of the beach where the underwater scenery was more interesting. We saw some of the huge boulders that had fascinated me on prior dives at Meeks. We swam around and between them, all at non-intimidating depths of just 30 to 40 feet or so. It was a fairly long underwater swim back to the beach, and I used that to once again practice buoyancy at shallow depths where staying level is most difficult. Once you reach eight or ten feet or so, it's all too easy to pop up like a cork and you don't want for that to happen. Constantly correcting by adding air to the BC and then discharging it again is no good; you need to learn to achieve buoyancy by changing the average volume of air in your lungs. Carol barely ever needs her ScubaPro Ladyhawk BC's assistance to maintain buoyancy, and I am getting better at it myself.

We were done diving by two o'clock in the afternoon or so, then headed for lunch/dinner at Rosie's Cafe in Tahoe City. Rosie's alone would have been worth the trip with some of the best Key Lime pie ever, but we also needed to let the residual nitrogen escape from our systems before we tackled the 7,400 feet summit on our way back.

This wasn't the greatest diving ever, but it was fun and I finally have that altitude card in the bag. Not that the card matters. Diving matters, the preparation and anticipation, the people you meet, everything about it. I love it.

Posted by conradb212 at 03:40 PM | Comments (0)

July 23, 2008

Diving at altitude revisited

As we've all been taught in Scuba class, the laws of messieurs Boyle and Dalton describe how air pressure and density, respectively, vary when we dive, and that of Mr. Henry how gasses get absorbed in liquids and tissues under pressure. Nitrogen absorption and release rates directly affect the no-decompression bottom times and are therefore extremely important to divers. The whole pressure picture changes at higher elevations because the air is thinner at altitude.

What we learn in Scuba class always assumes that the pressure at the surface is one atmosphere, or 14.7 pounds per square inch. Course materials then show how a certain volume of air is compressed to half at a depth of 33 feet because the additional pressure of the water on top of us adds another atmosphere, or 14.7 pounds per square inch, for a total of two atmospheres, or 29.4 pounds per square inch. At 66 feet the same volume of air is subjected to three atmospheres and has shrunk to one third of its original surface volume. Conversely, if you blow a certain amount of air into a balloon at a depth of 66 feet, that volume will double once you get back up to 33 feet, and triple at the surface. This is an essential part of understanding diving physics.

However, does this still hold true at altitude? Let's think this through with the example of Lake Tahoe, which is at 6,230 feet above sea level.

At first sight, it would seem that once you are fully acclimated to the Lake Tahoe altitude level, theoretical and actual depth should be the same. At Tahoe you start out at a surface air pressure of roughly 0.8 atmospheres. If you then dive down to 99 feet you'd add another atmosphere's worth of pressure each 33 feet, for a total of 3.8 atmospheres. Then you go back up to the surface where the pressure is once again 0.8 atmospheres. So the pressure difference betwen surface and 99 feet is three atmospheres. At sea level you'd go from 1.0 atmosphere at the surface to 4.0 atmospheres at a depth of 99 feet, and then back up to 1.0 atmospheres, for the same pressure difference of three atmospheres. If anything, when diving in Lake Tahoe you have less total pressure on top of you at 99 feet than at sea level (3.8 ata instead of 4.0 ata) where you'd reach 3.8 ata already at 93 feet. So why then do the altitude tables show that 99 feet at Tahoe corresponds to an ocean depth of about 125 feet and not 93?

The answer is that while the math in the above paragraph is correct, it does not address the problem we're trying to solve. The problem is the uptake of nitrogen, and that means we need to think in terms of pressure ratios and not pressure differences. At sea level, the pressure doubles at 33 feet compared to the surface, triples at 66 feet, and quadruples at 99 feet. Now look at Lake Tahoe where the surface pressure is only 0.8 atmospheres. That corresponds to 26.4 feet of water. So when you dive Lake Tahoe, the pressure doubles at 26.4 feet, triples at 52.8 feet, and quadruples at 79.2 feet. This means that as far as nitrogen ongassing and offgassing goes, you need to divide actual depth by surface pressure to arrive at theoretical depth.

That's because in Lake Tahoe, four times surface pressure is reached at 79.2 feet whereas at sea level four times surface pressure is reached at 99 feet. Henry's law says, "At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid." The way gasses dissolve and expand in liquids and tissues in the body is very complex, but if for simplicity's sake we assume that nitrogen bubbles expand as we ascend to the surface, those bubbles will expand to four times their size from a 79.2 feet dive in Lake Tahoe and from a 99 feet dive at sea level. That is why we need altitude conversion tables (click here for an example of such a chart.)

Below is a table that shows what I call "altitude nitrogen atmospheres." The colored lines show what depth surface pressure multiples correspond to at various altitudes. If you look at the purple line you see that as far as dive tables go, a 132 feet dive at sea level corresponds to a 110 feet dive at 5000 feet altitude and a 98 feet dive at 8000 feet altitude.

It should be obvious by now that altitude conversion tables are used to stay within safe decompression limits. So they handle the nitrogen side of things. But what about oxygen? That's an entirely different ballgame. As anyone who has taken an Enriched Air Diving, or Nitrox, class knows, high oxygen partial pressure can become a problem. Oxygen toxicity can occur when oxygen partial pressure exceeds certain values. This can lead to convulsions and loss of consciousness, and thus quite possibly drowning. The recommended oxygen partial pressure limit is 1.4 ata. The 1.4 ata limit is used by Nitrox divers to compute the "MOD," or "Maximum Operating Depth" of a Nitrox mix. The formula used to compute the MOD is:

MOD = (1.4 / oxygen percentage x 33 ) - surface pressure in feet of water.

If we dive EANx32 (32% Nitrox) at sea level, the MOD is 111.38 feet. But what would the MOD be if we dive 32% Nitrox at Lake Tahoe where the surface pressure is only about 0.8 ata? The answer is 118 feet! Yes, the MOD for diving EANx32 at that altitude is actually 6.4 feet deeper than at sea level. In fact, those 6.4 feet apply to all Nitrox percentages. That's because oxygen toxicity depends on pressure and not on pressure ratio.

That creates an interesting situation: As far as pressure goes, 99 feet in Tahoe is only as much as 93 feet in the ocean. But as far as nitrogen uptake goes those same 99 feet are like 125 in the ocean.

If we dive air, oxygen toxicity is rarely an issue. At Lake Tahoe levels, an air diver would not reach the 1.4 ata partial oxygen pressure level until a depth of almost 200 feet, far deeper than the recommended recreational diving depth limit. For Nitrox divers, however, the MOD can become an issue. At Lake Tahoe altitude, the MOD for a diver using 36% Nitrox is about 103 feet, and that is actual feet, not altitude adjusted feet.

The table below shows altitude-adjusted MOD levels for air as well as Nitrox with oxygen percentages between 30 and 40 percent. Again, the MOD at altitude gets deeper because the surface pressure, converted to the equivalent of feet of water, gets less and less.

But what about altitude adjustment for Nitrox divers? Can they use the same altitude tables? Not directly. Nitrox divers know that in order to use regular dive tables, we need to first calculate the equivalent air depth, or EAD. The formula to compute EAD is:

EAD = (( Partial Pressure Nitrogen / 0.79 ) * (depth + 33 feet)) - 33 feet

You can generate Nitrox Equivalent Air Depth tables in a spreadsheet program with this formula, then use those values to generate a second table that shows Equivalent Air Depth for a given percentage Nitrox at a given altitude, and then use those twice adjusted depths to look up maximum no-decompression bottom times in standard dive tables. What you'll find is that using Nitrox at altitude almost cancels out the effect of altitude: At altitude the equivalent ocean depth is deeper than the actual depth as far as nitrogen goes. But with diving Nitrox the equivalent air depth is always shallower than the actual depth as far as nitrogen goes. Depending on the altitude, diving a certain mix of Nitrox means you can use the standard no-decompression sea level air tables. For diving Lake Tahoe, for example, using 34% Nitrox gives you about the same bottom times as diving air at sea level.

I should also mention that NAUI has plastic dive tables for EAN32 and EAN36 both for altitudes between 2,000 and 6,000 feet and 6,000 and 10,000 feet. The tables are based on the Reduced Gradient Bubble Model and show maximum dive times for the initial dive and a second dive. They are fairly basic and probably include a good deal of safety.

Finally, it's essentially all moot as no one is using dive tables anymore anyway. The dive computer does it all, and almost no one knows how theirs works. That's why I felt a need to figure out how it all fits together. It's still good to know these things. Thanks also to Brian at diverssupport.com for helping me understand all these concepts.

Disclaimer: Although I am fairly confident in my math and checked my findings and results against a number of authoritative sources I do not claim all of this is correct and no one should base their dive plans on what I wrote here.

Posted by conradb212 at 04:01 PM | Comments (0)

June 29, 2008

Full face mask and saltwater

Yesterday I got to experience a new piece of scuba equipment, a full-face mask - and also do my first dive in saltwater. Unfortunately, this all sounds much grander than it was. It all took place at a party at the wonderful home and pool of diving friends. One of the group had brought her full-face mask together with BC and a full tank of air so anyone could check it out. And the gorgeous pool was a saltwater pool, so at least technically I can now say I have been diving in salt water. I know the particulars of this initiation into salt water will only add to the teasing I must endure for having done all of my dives so far in sweet water.

Anyway, the full-face mask was interesting. I had always viewed them as professional equipment beyond the reach and realm of recreational diving. In the "masks" section of our scubadiverinfo.com website I described full-face masks as follows:

"Full face masks protect professional and advanced recreational divers in polluted water and from stings, also allow verbal communication, and alleviate cramps from having to bite on a mouthpiece for long periods of time. They are also warmer in very cold water, and the chance of the mask getting knocked off accidentally is much lower. Full face masks are also referred to as "Jack Browne" masks in recognition of the Desco engineer who came up with the protytpe design of a full face mask with an integrated air supply attachment."

In practice, the full-face mask first looks a bit intimidating. It's large and it has a fairly elaborate strap system. The second stage is built into the mask, so there is no separate mouthpiece. You don't bite on one either. You simply put the mask on, get your hair out of the way, and you're all set. You still breathe through your mouth. The nose is kind of blocked with a rubber piece. BC inflation works the same, with the usual up and down buttons and there was the usual backup second stage, though I am not sure how you'd use it with a full-face mask.

Go under and it's an entirely different experience.

The view is panoramic, and much more so than with any conventional mask I've tried, and by now I've tried quite a view different designs. I wish I could remember the make and model of the mask as, from the looks of it, not all full-face masks offer this panoramic view. As is, this one certainly stood out.

Breathing feels totally natural. It's through the mouth, but not having a mouthpiece to bite on is a huge advantage in my book. Most mouthpieces chafe on my gums or my jaw gets tired from the mouthpiece forever pulling this way or that.

Equalizing your ears is a bit different. The mask did not have the separate nosepiece I use to pinch my nose and blow against it to equalize. The advice was to either move your jaw from side to side or some variation of that, or to move the mask up to block the nose inside as it pushes against that rubber piece in the mask, and then blow against it. I can't remember exactly how I did it, but it was no big deal and certainly not a problem.

Since air flows inside the mask, there is no mask squeeze and you do never have to equalize pressure inside the mask. That's never been a problem for me, but some people forget to do it, sometimes with annoying consequences. All in all, not having to worry about it is nice.

Another big issue for me is mask fogging. I've tried just about every trick to keep my mask from fogging and it does it anyway. This is a real drag. I mean, you don't go diving to see a wondrous underwater world only to see it from behind a fogged-up mask. Sure, you can let some water in and swirl it around the lens occasionally, but that's hardly a satisfying solution. The full-face mask -- at least the one I tried -- did not fog up at all. I suppose it's because of the airflow. It's wonderful not to have to worry about that.

And then there is mask leaking. I was wondering how such a large mask would do. After all, the perimeter of the seal is a lot longer than that of a conventional mask. Amazingly, not as much as a single drop came in. Maybe that's again because of the positive air pressure. If the pressure inside and outside of the mask is the same, water won't come in.

As listed above, there are other reasons to wear a full-face mask. One is to be able to communicate with dive buddies who also wear a full face mask with communications gear, and with the surface. Since you don't have anything in your mouth you can talk, and an integrated microphone then picks it up. I didn't have the battery pack that powers the comms gear and so could not see how well it works.

As for the saltwater pool, it wasn't nearly as salty as I expected. It was also absolutely crystal clear and clean. I'll have to look into it for my own pool.

Posted by conradb212 at 04:38 PM | Comments (0)

June 20, 2008

Quarry Diving

I finally got to dive again and this time it was in a quarry.

Quarries start out as open-pit mines where rocks and other materials are extracted. Once the quarry is no longer used it may fill with water and become a great place for diving. The place I went to is Loch Low-Minn near Athens, Tennessee, a 10-acre lake in the midst of 100 acres of wooded land. Check the web and you find it listed as a McMinn County Highway Department quarry that yielded crushed limestone for concrete and roads in the early 1960s. Its use as a scuba facility came about when a couple by the name of Rick and Stacy Low purchased the quarry in 1996. They named the place Loch (Scottish for Lake) Low (for their last name) Minn (for McMinn County). This quarry is quite popular and has been featured in Dive Training Magazine a couple of times. The owners live on site and take good care of the grounds and the facility. Unlike many quarries, this one has a good number of scuba-related attractions. There are two wooden diving platforms, floating gates for buoyancy training, a navigation course, and any number of sunken artifacts ranging from statues to a Lock Ness monster to funky items like a toilet and such. There is also a large diameter tube to swim through.

Depending on the water level, Loch Low Minn can be as deep as just over 80 feet at the center of the lake. I'd been told that visibility is quite good for a quarry, resulting from the three springs that seep into the lake and all the vegetation that filters run-off from around the lake.

We went there mid-week with a couple of students that had to complete their open water certification. The quarry owners were not there, but had left the big rolling entrance gate unlocked for us. The quarry itself is completely hidden. You don't see it until you drive over an incline and then there it is, a still body of water nestled into rocks and woods. There's a beach and a wooden deck with benches for divers to prepare. A bunch of catfish and a few bass swam around, obviously expecting to be fed.

It was quite hot and humid and I dreaded donning the wetsuit, but my new 7mm Scubapro went on a lot easier than my old 7mm Telos. For one thing, the Scubapro is a medium-long and a better fit than the medium Telos with its short arms and legs. For another, the Scubapro's material is stretchier and softer. It'd been a while since my last real dive and I didn't want to embarrass myself in front of two students, so I prepped my gear slowly and methodically, making sure I didn't forget anything or do anything stupid.

The water felt wonderful, with a surface temperature in the 70s. Carol spent some time talking to her students about the dives ahead and the tasks they had to complete: buoyancy control, emergency free ascents and diver rescue. Then we went down, heading for one of the diving platforms.

As almost always, I had a few minutes of nervousness. Visibility was somewhat less than I expected, and there were rather dramatic thermoclines. The quarry bottom slopes away steeply from the beach and so we soon found ourselves in fairly deep water. I saw the bottom below me disappear, making me feel as if I hovered over nothingness. Then we hit one of the thermoclines that gripped and chilled my body. There was a minute or two when I had to fight a sense of panic ('what if I something went wrong with me?' 'what if I faint?') that urged me to head for the surface. It was over soon and I felt okay again, but the thought of something happening while underwater is not pleasant and I hope I'll never find myself in such a situation.

We soon reached one of the platforms and Carol went through the checkout dive drills with her students. I had the Olympus 770 with me and took pictures of them. Then I saw some of the sunken artifacts I had been told about. I went exploring but the visibility was such that the dive platform quickly disappeared from view. I did not want to get separated from the group and returned before I completely lost sight of it.

Exercises done, we all resurfaced. Carol debriefed the guys and then we set course to the far end of the quarry where we hoped we'd spot some of paddlefish that had been released into the quarry a couple of years ago. This gave the guys an opportunity to learn about compass settings. When asked how they'd reverse the course once we were there, they promptly made the beginners' mistake of trying to visualize what was opposite the original compass reading instead of simply adding 180 degrees. That explained, off we went.

Even though there wasn't anyone else in the quarry to stir up silt, visibility remained fairly low and I realized the value of Carol's bright-yellow fins that made her harder to loose than had she worn standard black ones. As we approached the other end we began seeing slender horizontal shapes in the water -- paddlefish. They seem to be curious enough to check out divers but they don't come close, so I never saw one clear enough to take a picture. While Carol and the guys hovered to look at the paddlefish I decided to drop down to see where the bottom was but at around 40 feet it already got pretty cold dark and I lost sight of the group, and so I ascended until I was at their level again.

Carol then took the lead again and guided us close to the rock wall at the far end. For all practical purposes, it looked like a wall dive. It may have only gone down to 60 or 70 feet, but with the limited visibility it was easy to imagine being in a much larger setting. On we went and back into open water where we swam through a series of hovering PVC pipe shapes. It felt like being in a video game where you got points for flying through a series of gates. The shapes, of course, had been deployed to practice buoyancy. I had hoped we'd also be able to swim through the corrugated metal pipe laying near one of the diving platforms. I had seen it on video and felt it was a clever simulation of an overhead environment without actually being one, but it was on the other side of where we emerged and by now we were at the end of the checkout dives.

We checked remaining air with Carol, needless to say, having used barely more than half of us heavy breathers. Oh, this was also my first time on Nitrox. Since I hadn't brought any scuba gear except my trusted Scubapro Frameless mask I was using borrowed gear. The BC, fins and gauges all worked fine for me, except some chafing on my gums from the different second stage mouthpiece, but I was wondering whether I'd feel a difference diving 40% Nitrox. I didn't. A couple of times I felt a bit like one does after hyperventilating on purpose but I could be wrong. I felt no different after surfacing than I usually feel after a dive, but we'd never gone deeper than 40 feet and total dive time had been just under an hour, so I'll reserve judgement until a longer, deeper dive.

Diving the quarry was fun. It's a very peaceful place with nothing but nature. Before we left we fed the very tame catfish and the pesky bass that always darted between the catfish and snapped away the food from them. I want to go back and have some more time exploring the various stuff placed on the bottom, and also the rock wall on the far end. I am pretty sure I'll get a chance.

Posted by conradb212 at 02:37 PM | Comments (0)

May 06, 2008

Warm-up in the pool

A pool does come in handy for checking out gear and seeing if you still remember how it all works. Once the water had reached 68 degrees Fahrenheit at Dim Cove (the name I have given my pool), I felt it was high time to get wet again after so long. So I pulled the whole setup out of the closet, hoped I had not stashed away some vital part of the gear in some place I now would not remember, and wondered just how I had managed to collect so many masks that in all likelihood I'd never use on a real dive.

Getting the gear out reminded me once again that scuba is equipment-intensive. And almost all of it is needed for a dive. Another good reason to keep it all in one place. A complete set of my stuff is in a large travel bag that I bought at CostCo for just this purpose. It's not a scuba bag, but perfect for the task. I hope it'll hold up to the abuse of many more airplane trips. Things are already beginning to fray a bit here and there. That's probably the difference between a $40 bag and one that costs hundreds.

I was also reminded again just how heavy those tanks are as I shlepped one from my garage through the house and into the backyard. Sure, my steel 95s are monsters and Carol forever advocates the use of smaller and handier tanks for regular dives, but there's just a huge difference between the effortless way happy, smiling divers carry their tanks around in movies and commercials, and how heavy the beasts are in real life. Every time I pick one up I think of cave divers with their doubles, or the deep divers who carry and clip on five or more. Maybe sometime in the future materials science has advanced to a point where compressed air containers, if they are necessary at all, will weigh a fraction of what they do today and people will look at today's gear with the same mix of awe, reverence and amusement we peruse a medieval Knight's suit of armor.

I was pleased that I still remembered how to get the gear assembled. No mistakes there. I know, this must seem trivial to seasoned divers but -- alas -- I am not yet one of them. And I swear, one of these days I'll even learn how to put on my fins more or less elegantly. As is, watching me put them on must be comic relief and raise doubts in onlookers' minds as to my suitability to go under.

But go under I did, and it was great to blow bubbles again. Everything worked fine and, as always, my 12-year-old son had fun looking down with his mask and snorkel and playing with my bubbles. He also practiced his underwater photographer's skills with a Casio in an underwater case. I let him breathe through my regulator just below the surface while I used my AIR2 backup. That's when I noticed a minor annoyance: the nylon tie that secures the mouthpiece of the AIR2 stuck out in the wrong position, poking me in the lip. No big deal, but I always get a bad feeling when factory-authorized service on a potentially life-saving piece of equipment is not done quite right. I mean, if the tie is put on wrong, am I totally sure everything else works okay?

After the 35 minute dive (if you can call practicing in a backyard pool a dive) I was reminded that the end of a dive is really not the end of a dive. That comes only after everything has been taken off, rinsed, put somewhere to dry, and then finally stowed away in its proper place.

Now that my son is old enough to take a scuba class himself, I find myself wondering if I think he's ready for it, and whether I'd be scared letting him dive. I know it's a parent thing to worry, and I'll let him decide if he wants to and when he is ready.

Posted by conradb212 at 02:53 PM | Comments (0)

March 31, 2008

Free diving

When I think of diving, I think of breathing underwater. But most of us dive long before we learn how to use Scuba. When I was a kid, diving to me meant getting to the ten-foot bottom of the public pool, and it made my ears hurt. For a while I practiced breathholding and timed myself. I can't remember how long I managed to go without taking a breath, but it seemed respectable to me back then. I never did learn how to equalize my ears free diving. At Three Sisters in Crystal River, Florida, a sharp pain in my ears kept me from going deeper than eight or ten feet or so. Yet, free divers go much, much deeper than that.

I just finished reading "The Dive -- A Story of Love and Obsession" by Pipin Ferreras. It's the story of a Cuban free diver who set record after record together with his wife, Audrey. A fatal accident killed Audrey during a dive to 170 meters (558 feet) and the book recalls Ferreras life and is also a tribute to his wife. Earlier I had read "The Blue Edge" by Carlos Eyles, also a man who pretty much dedicated his life to free diving, albeit for different reasons. But whether it is records, spear fishing, or just being one with the sea, it is hard for me to imagine how it is done.

Scuba and free diving both take place in the water, but beyond that everything seems different. Scuba dives can take an hour or more. Free dives a couple of minutes or maybe three for accomplished free divers. Scuba is slow and measured movement; free diving means darting down and back to the surface. Scuba means dealing with the gas laws so as to avoid embolisms, narcosis, the bends; free diving has none of that as no additional nitrogen is introduced into the body.

Competitive free diving, of course, has its own rules and governing bodies. There are different categories. In "Constant Weight" the diver follows a line to a certain depth and then swims back up, all on his or her own power. In "Variable Weight" the diver uses a weighted sled to go down, then swims back up. In "No Limit," the diver uses a sled to go down, then inflates an airbag at the bottom and holds on to that to get back to the surface. The depths reached are almost unimaginable. How can they do that?

Apparently, in free diving the rules are all different. With no compressed air to counter-balance the enormous water pressure, the lungs and other air cavities inside the body compress enormously. Conventional equalization of the ears and sinus only goes that far; beyond a certain depth the divers do "water equalization, " i.e. they let salt water into the sinus system in a practice that is described as entirely unpleasant. And another phenomenon takes place when a "blood shift" keeps the lungs from collapsing. It's a residual from ancient times perhaps, from our genetic past, but it works (not that I'd ever want to experience it).

The kind of free diving described in "The Dive" requires extensive planning and preparation. Safety divers on scuba are deployed at regular depth intervals, including the bottom. In those extreme record attempts, that means a diver has to wait at almost 600 feet on Trimix. Breathing gas goes very fast at that depth and it's clear that timing is everything. Once the safety divers are down, the free diving attempt must be made exactly on time. And even so, the deeper safety divers won't be back on the surface to partake in the celebrations as there are hours of decompression time.

Wherever there are records and titles, there are politics and competing agencies and bodies, and apparently that's no different in free diving. In his book, Ferreras describes his life and career, and his intense personality that more or less made him an outcast. Already relying on his own certifying agency, after his wife died in her record attempt he came under intense criticism. One of his own crew wrote a book accusing Ferreras of negligence and wrongdoing.

Knowing my tendency to get deeply involved in topics that interest me, I promised myself not to start research on free diving after I finished the book. But in this day and age that's hard to do. Wiki provides an overview, and Audrey Mestre's final dive is right there on YouTube. Yes, the sled's camera recorded how she is trying to inflate the lift bag at a depth of 558 feet, and it won't inflate. You can watch the whole thing.

Posted by conradb212 at 03:37 PM | Comments (0)

March 26, 2008

Mark Fyvie (1972-2008)

People die every day, by the thousands. From natural causes and from accidents. Unless a death happens in our families or we are confronted with it in some other way, we barely notice. Even the gruesome stuff we see on television or read in the newspapers doesn't really affect us. This only happens to other people, not us. But every once in a while a death does affect us. It can be a celebrity, like Princess Di or Steve Irwin, the Crocodile Hunter. And sometimes a death affects us just because we can somehow relate, through some connection. That's what happened to me when I read about the death of Mark Fyvie. He died on March 10, 2008 inside the Ginnie Springs cave system in Florida.

Running the scubadiverinfo.com site, I get almost every diving-related accident notice via Google news. I don't post them but file them away. It makes no sense to highlight just the danger and the bad things that can happen. Life is dangerous, even one's bathroom where most domestic fatalities occur. I don't see Better Homes & Gardens Magazine report on that very often. It's not necessary.

I first heard of this accident after Carol's certification trip to Ginnie Springs. A cave diver had died the week prior. He had been deep inside the cave system. There had been silting of the system as a result, it was said, and apparently the diver had gone in there by himself with experimental rebreather equipment. I looked it up on Google News and found just three references to it. Compared to the international coverage of the shark-related death during a shark feeding trip, that's a virtual news blackout. In fact, it was just the Gainesville Sun and the local High Springs Heralds that reported at all, or at least that is what Google picked up.

The reports were brief, but what caught my eye was that this was a diver from my native Switzerland. His name was Mark Fyvie, and the paper reported he'd been diving alone, entering the Ginnie Springs underground and underwater caves through the Devil's Eye entry just past noon. When he had not returned by 9pm, another diver by the name of Corey Mearns went looking for him, and Mark Fyvie was found 3,800 feet into the system. The IUCRR (International Underwater Cave Rescue and Recovery) non-profit posted a new thread on the cavediver.net forum entitled "Fatality beyond the Hinkel" in the afternoon of March 11. The report said the diver had used a side mount/no mount rig for passage through a suspected new lead. It was reported that an IUCRR recovery team brought out the body at 9AM on March 11.

I then searched through Tages Anzeiger, the big local newspaper in Zurich, Switzerland but did not find a mention. However, I quickly found Mark Fyvie's website and this is where everything became very emotional. Zurich is my hometown. I grew up there. Zurich Divers, which he started and ran, was Mark Fyvie's diving homebase. His personal site was not in German but in flawless English, which surprised me. I can usually tell translations from German into English, but his English was perfect.

I saw Mark's credentials. He'd been diving since 1993 and a diving instructor since 2000. He had almost a thousand dives to his name. He was a PADI IDC Staff Instructor, an Emergency First Response Instructor Trainer, a DSAT Tec Trimix Instructor, a DSAT Gast Blender Instructor, and an IANTD Technical Cave Instructor. He was also certified as a Closed Circuit Rebreather cave diver, Trimix diver, cave scooter diver, and specially trained on the Mealodon rebreather. So Mark was certainly no noob or amateur. A look at Mark's diving highlights is a trip around the world. He'd been diving and cave diving all over the place, with extensive cave diving, sometimes weeks at a time.

Mark reported on a two week dive trip to the Ginnie Springs area where they'd penetrated 3,800 feet, past the Hinkel restriction. In April of 2007 he did his Megalodon training with a true diving legend, Jill Heinerth of RebreatherPro.com and Jill was highly complimentary of Mark both as a person and as a skillful diver. Mark himself, on his site, was completely aware of the pros and cons of rebreathers. "Some people who dive rebreathers think that once you buy one you must do every single dive with it." Mark wrote, "I don't agree at all. A CCR is a dangerous device that could kill you at any time, why take the risk of using one on a simple dive that could be done more safely with open circuit?"

Another entry from November 2007 describes a full month of cave diving with the Megalodon rebreather in the Americas. This is where he got his CCR Cave and CCR Trimix certifications and also descended down to 272 feet in Eagle's Nest. He was enthusiastic and wrote, "Now I realise what closed-circuit rebreathers are for - it's totally changed the way I can dive caves." He went on to say, "The bad part is finding a dive buddy for this kind of diving. Even in cave country it's tough and I had to do most of the dives alone. ... Now, feeling rather limited by the duration of my CO2 scrubber, I purchased a new radial scrubber, which should easily be able to handle durations of up to ten hours. I can't wait until my next trip in February."

Again I was surprised by the consistently high quality of his English, then found that Mark wasn't Swiss. He'd been born in South Africa, then had lived in New Zealand, Australia, England, Germany and finally Switzerland. He was truly an international citizen, always traveling and exploring new things and places. Switzerland was not going to be his final destination and even after having been away from my native country for over 30 years, I chuckled at Mark's comment that he yearned "for a place where he can shop on Sundays, take a shower after 10pm". It's true. Your neighbors may call the police if you take a shower after 10pm, shops are rarely open, bars close early and at last in my days, you had to register with the police if you moved from one neighborhood to another.

What made me cry was another part of his website. It was about his wedding. He had proposed to his sweetheart and they were going to get married on September 6th of 2008 in Venice. Mark had it all planned out, described every step. He had his whole life ahead of him. It is just so very sad.

At this point I was abundantly clear that this was not just another reckless diver who didn't know what he was doing. This was an extremely accomplished, very smart man who planned meticulously and left nothing to chance. I have done quite a few things in my life, have moved around, seen many different places, have had different careers, but nothing like Mark who was only 36 years old when he died. Looking at his many other interests, I saw that he'd been learning Japanese and wanted to live there someday, was enthusiastic about biodiesel in Australia, Pilates training in Switzerland, all on top of being a certified Cisco engineer.

But there was more. Mark also initiated a discussion forum for English speakers in Switzerland, the englishforum.ch. There was a need for that as Swiss German is as close to a legal secret code as it gets. Mark had commented that while "he was fluent in German, he was completely baffled by Swiss-German and unable to understand even more than a few words." That's because you cannot learn Swiss German. It is only a spoken language. So Mark created a place to help English speakers in the Swiss society. I know the software he used as I use it to run a large forum/community myself. His setup was, of course, completely up-to-date and nicely customized. An "In Memoriam: Mark Fyvie (1972-2008)" was posted on March 13. Within days it had over 300 replies and testimonies to what a great and wonderful person he'd been and how many he had helped. His work had touched people's lives. From all I read about him, I guess he just couldn't help helping others.

Jill Heinerth herself wrote a post and tribute to Mark, her student and friend. She said Mark was a "peer among a very elite group of the world's extremely accomplished and capable technical divers" and that "Mark contributed more to the cave diving community than can ever be measured." In a eulogy on her own website at rebreatherpro.com, Jill wrote "But the reality is that manipulating your own atmosphere for life support is the most dangerous thing you will ever do. Add to that advanced activities like cave diving and exploration and we are on the razor’s edge."

In the end, Mark's time was up, much too soon. In my reading I have often come across divers' frustration when a fatality is simply dismissed as drowning, leaving up to speculation what actually may have happened, and why. Sometimes it's obvious, often it is not. The Megalodon is a rugged, modular and highly regarded electronically-controlled closed circuit rebreather with redundant electronics and a HUD display made by InnerSpace Systems. Mark had indicated he had purchased a radial instead of the standard axial scrubber. The radial scrubber would be able to last as much as ten hours underwater. Inner Space says CisLunar scrubbers also work on the Megalodon and according to an evaluation of the Meg on spiralbound.net, others do as well, though only the CisLunar is mentioned as being radial. Whether or not that made Mark's unit experimental I don't know.

Now one is not supposed to dive solo, though I've read of many wreck divers who feel solo is actually safer under certain conditions where panic can easily result into two fatalities instead of one rescue. As is, my Cavern/Cave Diver Workbook by the National Association for Cave Diving says to "dive with a properly trained and equipped diving partner and maintain diving team continuity throughout the dive." However, that only seems to be a philosophy and not a requirement. As far as safe cave diving goes, "The NACD strongly advocates diving with a partner as the best approach to safe cave diving." Mark had already concluded that finding a suitable buddy for extended time diving was difficult and that he had to do most of his dives alone.

It is equally important to let others know one's dive plan in case something goes wrong. His dive plan was known as he was enthusiastic about his plans and wanted to share with his friends, and at least that aided in the recovery.

The rest is mystery. I'll likely never know what happened, exactly, and it is none of my business. I did not know Mark personally, but his story, so well documented, deeply touched me. May he rest in peace and his loved ones find some sort of solace, nearly impossible though that is.

Posted by conradb212 at 08:23 PM | Comments (0)

March 17, 2008

The Florida Springs

Carol took another flock of her students for certification to Ginnie Springs, Florida, and I was reminded how much I like those springs. And also how peculiar it is that a good deal of my diving experience to-date is in the springs of Florida and not some of the more exotic dive destinations like the Carribbeans. So while she was assessing the skills of her students I began searching the web for more information on the springs, and as usual, one thing led to another and before I knew it I had spent the entire weekend just reading about the various springs.

It's really an amazing thing, those Florida springs. I mean, when it comes to Florida, most people think of sandy beaches, the keys, spring break madness, alligators, swamps, and -- if they are old enough -- perhaps Miami Vice. They'd probably associate Florida with diving, but in the ocean and not inland and certainly not in some of the clearest, freshest water anywhere. But that is what you get in Florida's springs.

How did it all happen in what most people think is just swampland? Well, the northern part of Florida has a vast underground aquifer with several hundred springs. Together they discharge almost ten billion gallons of fresh water a day, with some of the larger ones contributing hundreds of millions of gallons to that total each day. It's all part of a giant storage system. The water originates as rainfall that then penetrates limestone where it is filtered and accumulates in fissures and holes. Combined with carbon dioxide and decaying plant matter, the water becomes mildly acidic and, over many thousands of years, enlarges cracks and holes and creates passages. What it all means is that there is a vast underground system of caverns and caves, many interconnected, in northern Florida and this is the source of all those springs.

The term "springs" is perhaps a bit inadequate because the vast freshwater resources contained in the Floridian limestone system creates all sorts of natural wonders. There are, of course, springs, and they often come right out of the ground. Somehow I associate springs and rivers as something that originates higher up, in the mountains, and then makes its way towards the sea. But Florida's springs come from underground. When you dive, you often see holes at the bottom, with water pushing out of them. Sometimes it's just little boils in the sand. You see them in the clear water, see individual grains of sand twirling around, and feel the flow when you put your hand on them.

But all that water also created grand caverns, nearly endless caves, and also many sinkholes. When we think of sinkholes we generally think of the evening news reporting on a hole in the ground that all of a sudden opened up, collapsing a road or swallowing a home. Those sort of things are usually blamed on human transgressions such as draining or over-using the watertable. However, sinkholes also happen naturally when water slowly eats away at limestone until a ceiling collapses and forms an open entry into the underground spring system.

A good explanation of all this can be found on the "The Journey of Water" webpage of the Florida Department of Environmental Protection.

What does all this mean to divers? It means that Florida has perhaps some of the best diving in the world, and it is in places where you'd never expect it. Instead of sandy beaches, tropical islands, and dive boats, Florida diving seems all shallow rivers and small ponds, some of which covered in duck weed and hard to spot. Once inside, the water is usually crystal clear. That's because it is not stagnant like in a lake, but constantly replaced by the vast volume of water from the underground springs. This phenomenon is exploited by a good number of popular parks and campgrounds located around those springs. People go there to swim and snorkel and just have a good time.

To me, this is what makes Florida's springs so fascinating. There is endless variety. To some people they offer an enjoyable get-away in one of the well-maintained parks with their lush, prehistoric-looking groves and clear, refreshing ponds. Some come to watch the Manatees which like to hang out in the springs. And some dive the caverns and the caves where things can get quite extreme. Manatee Springs state park, for example, both contains a friendly pond and the entrance to a vast underwater caves system that's testing the very limits of courage, skills and endurance in the exploration of many thousands of feet of labyrinthine cave.

During my online explorations I was reminded again of the thin line that separates harmless, enjoyable fun from entry into a deep twilight zone that's as challenging and dangerous as exploring outer space. When Carol and I last dove the Catfish Hotel sink in Manatee Springs state park, I both marveled at the dreamy underwater world that looked like right out of a Pixar movie and shivered knowing that the dark cavern at its bottom was the starting point of Sheck Exley's explorations into the black unknown of endless caves and also where just a few days prior a young man had died when the water had sucked him into the cave.

Ginnie Springs where Carol certified her class likewise has a bright and a dark side. The water in the small spring/pond area is gin-clear, as the location's name implies, but just yards away, underground, lies a massive cave system that has claimed many lives. None other than the great Sheck Exley almost died at Ginnie early in his cave diving career. And, as she later found out, a week before Carol's certification trip, a cave diver had perished deep inside the Ginnie system. Sometimes, a dark side lies just beneath the sunny, friendly surface, and most never even know it's there.

I was reminded yet again of the interesting role Florida's springs play when I found a website dedicated to Florida Springs with almost 50 trip reports and descriptions of springs, rivers and sinkholes in the state's northwest, north and central regions. The site offers an hourlong DVD, entitled "Florida Springs -- The Unexplored Florida" on a good dozen of the more interesting springs. I ordered it and it arrived just a couple of days later. Watching it was an experience. Not only did I see some of the places I had been to myself, but I was reminded again of the secret nature of those treasures. Even the state parks are mostly visited for picnics or swimming and not that many divers know about them.

I also realized once again how diverse the springs are. Some are popular and easily accessible whereas others are virtually unknown or closed off to public access. Some are bright and friendly, others look dark and forbidding. In some you are not allowed to dive at all, in others you pay a fee at the park ranger's office, and some require special permission. According to the DVD, there are even some where you need to check in with the local sheriff and get permission there.

All of this made me want to go back. I'll most likely never dive a cave, will never see what Carol saw, but I may get my cavern certification and poke around some of the better known ones. I cannot wait.

Posted by conradb212 at 04:31 PM | Comments (0)

March 08, 2008

I feel like a total scuba failure

I feel like a total scuba failure. I really do. It's been since last August that I was diving, a couple of pool sessions not included. I really feel awful about that. In a few short months it'll be two years since I got certified and all I have to show for it is about 30 legitimate dives. And this website. How could I create this rather comprehensive website, write the equivalent of a book into this blog, and only have 30 dives to my name? I am not a slacker or procrastinator. How could this happen?

I think of all the excuses I could have for not going diving. I have no dive buddy here. Work doesn't leave me enough time to go diving. Diving trips cost a lot of money. It's cumbersome to get all my dive gear together. There's no place close-by where I can go diving. The small class of people I go certified never stayed in contact. I wasn't ready for a wreck dive in the ocean when my local dive shop invited me to go. I couldn't leave my 11-year-old son on the shore when I was all ready to participate in a salvage operation organized by a local group of divers. And so on, and so on

But those excuses don't really wash. I may not have a regular dive buddy here, but others have overcome this obstacle. I even do the diving website for a local group of divers who regularly invite me to come to their meetings and go on their trips (I never do). My work really isn't a problem. I run a suite of websites and can do most of my work from anywhere as long as I have a computer and internet access. And finding someone to look after my cat really shouldn't keep me from going on a trip. Yes, dive trips can be quite expensive, but it's not that bad. I could afford one or two year. Yes, I don't live by the beach on a tropical island where I can go dive anytime, but Lake Tahoe is closeby and so is the Northern California coast. And if the four people in my dive class didn't respond to my emails, hey, they are not the only people to go dive with. And my gear, well, it's really all neatly packed in my dive bag. It's a lot of stuff, but I do know where it all is, and I keep it all properly maintained.

So it gets back to the same thing: how can I be enthusiastic enough about diving to get certified, do my advanced class, take the Nitrox class, read enough books about diving to -- in theory -- become an expert, do all the research to do this website, and still not go dive on a regular basis?

It's not that I don't want to. I absolutely cherish the memories I have from my few dives. I think of my first night dive and how spooky that was. I think of snorkeling with the Manatees. I think of diving underneath all that duckweed at Catfish Sink to see a magical world and take a picture looking up from the bottom, exactly where the great Sheck Exley once took a picture. I think of testing all those underwater cameras. And I think of locating Rubicon wall in Lake Tahoe and then descend to 110 feet in 48 degree water. I think about the five minutes of fear and uneasiness I always have before I go under (less so in my most recent dives). And I think of the thousands of pages I read about scuba, then summarized in book reports for this website, and how I resolved to experience some of what I read firsthand.

Yet, here I am with my 30 dives. Fact is, I never did actively seek a local dive buddy. Maybe I am the kind of person who needs a kick in the butt to do something. I don't see myself that way, but at least as far as Scuba goes, apparently I am. That bites. I hate it. Sometimes it seems like, for me, diving is like going to a party. I need a major push to go, but once I am there I really enjoy myself and resolve to accept invitations more often.

As is, I have no one to blame but myself for the measly 30 dives in my scuba log.

Posted by conradb212 at 03:36 PM | Comments (0)

February 15, 2008

The submersible Rinspeed sQuba car

Back in 1977, in the James Bond Movie "The Spy Who Loved Me," Roger Moore's agent 007 had a very special Series 1 Lotus Esprit that converted from a sports car to a submarine. The Lotus had propellers and rudders and even a battery of harpoon launchers to help Bond fight off the bad guys. The submarine Lotus was more than just a prop; it did go underwater and the rudder and propellers worked. However, it wasn't actually water-tight, and so a stuntman with Scuba gear operated it inside behind the dark glass. The picture to the right shows a scale model of the submersible Lotus.

Well, now there is a real diving Lotus. Rinspeed, a Swiss tuner and builder of exotic concept cars and other futuristic vehicles built the Rinspeed sQuba, a drivable, divable concept car that really works. Based on a Lotus Elise, the electric-powered sQuba is the brainchild of Rinspeed founder Frank M. Rinderknecht, who never forgot that submersible car from the James Bond movie. “For three decades I have tried to imagine how it might be possible to build a car that can fly under water. Now we have made this dream come true,” Rinderknecht said.

How did they do it? First, there had to be some practical thinking. For example, even though the Lotus Elise is a very small car (only about 150 inches long), the enclosed volume of about 70 cubic feet would have required adding 4,400 pounds of weight. The necessary ballast tanks would have made for a large, bulky vehicle that didn't look anything like a sleek sports car. So Rinspeed decided to build the sQuba as an open vehicle with its passengers using built-in scuba gear while underwater. The car floats on water, then sinks when the doors are opened and water enters the car. However, without passengers it surfaces on its own.

What all did Rinspeed do to make this possible? Well, they removed the combustion engine and replaced it with a variety of electrical motors. For operation on land, the main electric motor makes 73 horsepower and 118 foot-pounds of torque at 4500 rpm. Rinspeed estimates the top speed to be "over 75 mph," but given the weight (less than 2,000 pounds) and power it's probaby over 100 mph. Floating in water, the sQuba uses two propellers in the back, powered by an 800 Watt electric motor each, good for a speed of about four knots. Underwater, propulsion is via two electric 5-horsepower Seabob jet drives that breathe through rotating louvers and expell the water through light but twist-resistant Carbon "nano tubes." That gives the sQuba an underwater speed of about two knots. Power is supplied by rechargeable Lithium Ion batteries. Rinspeed states "the sQuba's filling station is the water reservoir,” referring to the electric hydropower the Swiss are experts in. Operating diving depth is around 33 feet.

When going under, the car's occupants use an integrated air supply system with two gas tanks -- one 15 liters, the other 18 liters -- and Scubapro regulators, specifically Scubapro's classic and very reliable air-balanced G250V second stage. The Scubapro gear and the tanks are mounted behind the passengers.

The sQuba is chuck full of interesting technology, and not only for underwater operation. On land, it uses a laser scanner system to essentially drive itself. For underwater operation, Rinspeed and its partners designed a cockpit and instruments that's inspired by the elegant shape and lines of a Manta Ray. Individual instruments seem to float and have dials that are lined up like lenses. The main control cluster is futuristically lighted and sits behind a protective sheet of glass with a fisheye effect. Controls can be operated even with diving gloves.

How real is the Rinspeed sQuba? Real enough for an impressive video of its operation on land, floating and diving. You can see the movie as well as pictures on Rinspeed's website. It works. But it's also a concept and not meant for production at all. For that, it'd need a more powerful motor, and the market for diving cars is likely very small. But none of that matters. Concepts are limited only by the imagination. "For three decades I have tried to imagine how it might be possible to build a car that can fly under water," said Frank Rinderknecht. "Now we have made this dream come true.” Very cool.

Posted by conradb212 at 12:37 AM | Comments (0)

January 17, 2008

The Dive Computer Blues

January is never a great time for divers unless, of course, you're lucky enough to have booked a dive trip to some sunny paradise, like I promised myself I'd do, but never got around to it. So it's cold outside and the last dive seems ever farther away and you don't know when you get to dive again. That's when you spend time reading dive magazines, go to scuba sites, or catch up on reading dive books. This morning I perused the latest issue of Alert Diver, the bimonhtly publication by DAN, the Divers Avert Network. It's a 64-page saddle-stitched production that makes up in good content what it lacks in commercial design and polish. I like reading it and learn something new every time.

What caught my eye this morning was an article entitled "Deep Calculations, Deep Trouble -- Exploring Safety in Dive Computers." This is a topic I am greatly interested in. I love computers in every shape or form and cannot imagine life without them. But dive computers are somehow different, and I don't feel anywhere near as at home with them as I do with any other computer, and that goes for the ones under the hood of cars and such. I trust my dive computer, and like everyone else, I think dive computers undoubtedly revolutionized diving and made it safer and more convenient. But there are dark sides.

The DAN article, written by Rick Layton, reported on the results of a recent Scuba STAR Network safety survey that investigated how scuba divers use their dive computers, what they know about them, and what experiences they've had with them. The survey didn't have a huge sample, just 42 divers, and may or may not be statistically significant. However, the results are pretty much what I expected, and they are alarming.

The survey said that only 10% of the divers actually learned to use their dive computer with an instructor or in a class. The vast majority simply used the manual that came with the computer, if anything at all. A oood half felt that the training materials were lacking and too complicated or disorganized. The survey also showed that divers are unhappy about the almost total lack of dive computer training in formal scuba classes. They suggested at least a review of all the common features, advantages, disadvantages and problems associated with different types of computers.

An appalling 60% of the respondents reported problems with their dive computer. Many felt screens were unreadable. Others reported blank screens, erroneous data, frozen computers, loss of some functionality, battery problems, and so on. Some computer failed to register depth, failed to display desaturation time, reset themselves, stopped displaying remaining air, or had inadequate rapid ascent warnings. As a result, almost 2/3rd of the respondents said they take along dive tables, and almost a third carries a spare computer.

That is certainly no vote of confidence. And I could definitely relate. Although my own dive computer has worked flawlessly for the year and a half that I have had it, I consider it far from perfect. Its user interface is virtually impossible to figure out. So much so that I have essentially given up trying to understand all the many features it has. I gave the manual several serious tries, but it is so poorly written and organized that I simply cannot figure it out and always give up in frustration. Too bad that there is not a large enough market to warrant a separate "Idiot" book for dive computers. That I understand. But why the manufacturer of my dive computer cannot have a tech writer overhaul their atrocious manual is beyond me. I mean, it could save lives.

The same issue of Alert Diver had another article on dive computers. It was entitled "Living with Dive Computers" and written by Dr. Neal W. Pollock. Dr. Pollock, a research physiologist at the Center for Hyperbaric Medicine and Environmental Physiology at the Duke University Medical Center, listed the various advantages of a dive computer, but also the many things it cannot do, or cannot do yet. However, he starts out saying, "You should know not only which buttons to push to make your computer work, but which mathematical model or model derivation it employs for decompression computation."

I agree, of course, that divers should know which buttons to push, and it's really, really sad that I, who consider myself somewhat of a computer expert, do not know which buttons to push to properly use my dive computer. Heck, I can barely see half the tiny little numbers and symbols on its tiny little low-contrast LCD. But now I am even supposed to know which mathematical model it employs for decompression calculations and, presumably, what that means to me?? Though I have a doctoral degree myself, and in a technical discipline, I don't think that expectation is remotely realistic. And if it isn't for someone like me who always wants to know how things work, I think there are others who may struggle with the concept.

But let's say it'd indeed be prudent to a) learn what buttons to push, and b) know the mathematical models that are used in dive computers. What would that mean? I'd say even the former is nearly impossible. Virtually every dive computer is different. I've seen more than one Scuba instructor unable to explain the operation of a student's Dive computer, and those were good instructors. Dive computers do not have a common interface, like Microsoft Windows or the Mac OS, or eve common controls, like computers have a mouse or a touchpad. So instructors may begin spending as much on dive computer basics as they do on dive tables.

Then they may have to get into the difference between table-based computers and model-based computers. Table-based is simple; the computer just uses the dive tables and quickly calculates all you need to know. But most dive computers are model-based, i.e. they make all sorts of assumptions. The oldest and most traditional model uses the Haldane models, named after the Scottish scientist who developed the theories and tables for the British Royal Navy. Haldane tables and concepts still form the basis for most die tables and dive computers, but there are many others as well.

What this means is that a diver would have to know not only about the Haldane theories, but also about statistical models, variable permeability models, reduced gradiant bubble models, slab models, Series models, and EL (exponential/linear) models. Add to that the various proprietary models, hybrids and assorted secret sauces manufacturers use in their computers, and the likelihood that many divers know what mathematical model their dive computer uses and what that entails is essentially nil.

Can we hope for standardization? Probably not. Will there be ongoing research that in conjunction with advancing technology will result in ever more sophisticated dive computers? Definitely.

Posted by conradb212 at 10:47 PM | Comments (0)

November 28, 2007

Pony bottles -- a good thing to have, or not?

To keep in shape I am going for a run every other morning. Religiously. I've been doing this for about five years now, without fail. I missed perhaps half a dozen runs in all of those years, and that's when I literally could not make it out of bed because of the flu or some other nastie. My run is only a couple of miles or so, but it's uphill and downhill and thus gives me a good workout. My heart and breathing rate go way up and every run hurts. No pain, no gain, I suppose. It's never easy and it never gets any easier, or at least it didn't after the first couple of weeks or so when I first took it up.

One thing I am always aware of when I run is air. Early on I determined that I was going to breathe through my nose the first part of the course and until it gets really steep. Then I remove that restriction and gulp in as much as I can. Ever since I took up scuba, I've been looking at breathing differently. I now know more about how our bodies use oxygen, why we have the urge to breathe, and the whole complex mechanism. When I run uphill -- "run" is perhaps an exaggeration; "slowly jog" is more like it -- I breathe so hard that it just doesn't seem possible that my muscles need that much oxygen, yet the urge is there. And I know that should my air be cut off, I'd instantly ... what? Die? Collapse? Pass out? I don't know, but it's hard to imagine not having air. Fortunately, that's just not an issue when you go running.

Underwater it is. No air, you're dead. That's why sharing air with your buddy is one of the first things you learn in Scuba class. Do not panic. Calmly signal your buddy, then assume the position and use the buddy's backup octopus second stage. Or you may have agreed that the buddy will use his or her integrated backup second stage, like the Scubapro AIR2 I have on my Knighthawk BC, and let the buddy use the primary that has a longer hose. If worse comes to worse and there is no secondary, you do buddy breathing where you share a single second stage on the way up. In theory those are good solutions, but I've always wondered what it might look like if you're at 80 feet with low visibility, your buddy has temporarily gone out of sight, and that is when something goes wrong with the air.

Now I know that by and large, scuba gear is extremely reliable. Things are not likely to go wrong, but there really is always something that can go wrong. Stuff can jam, break, rip, get lost, fall off, or you simply run out of air. And when you're down there, that's deadly. I've read a fair bit about cave diving, something that I'll likely never do myself but that fascinates me, and the first rule there is that everything must be redundant. Every system has a backup, and usually even the backup has a backup. That makes sense. Pretty much everything we use in life has a backup if it is really important. The brakes in a car, for example, have multiple backups.

So why does standard scuba equipment not have a backup for air? Everyone except tech and speciality divers just dives with a single tank, and should something go wrong, it's quickly finding the buddy and sharing. To my way of thinking, that's simply not a very good solution. Especially since there are ways to have backup. They are usually called "pony bottles."

Pony bottles are small air tanks with a separate regulator meant to be used in emergencies. Which makes a lot of sense to me. But from what I can tell, few people use them, and there is an amazing amount of controversy over them. Much more than I'd expect over something that seems to so sensible and logical. The primary bone of contention seems to be size.

One company that specializes in backup air is appropriately named "Spare Air." Their standard model has 3 cubic foot of air, a bit bigger than their original bottle that had just 1.7 cubic foot. The company claims that over a hundred thousand of those little mini tanks are in use. The bright yellow spare air bottles are packaged in neat systems that include mounting gear, an integrated regulator that sits on top of the bottle and does not use a hose, and a carry bag. Problem #1 is that they are not inexpensive. They cost around US$300 which is a bunch more than most big 80 cubic foot tanks. Problem #2 is that neither 1.7 nor 3.0 cubic feet of air gets you very far. The company estimates 30 and 57 breaths, based on 1.6 liters per breath. That's on the surface. Which means it's half that at only 33 feet, and a third at 66 feet. If things go bad at 66 feet, ten breaths won't help all that much, and neither does 19. And even that's assuming that you gulp in just the estimated 1.6 liters, and not a lot more as people tend to do when things go bad. Oh, and they are usually filled by connecting them to your main tank. So if you have a low pressure tank like my big old Steel 95s, then you'll get less air in the baby tanks yet as filling them to capacity assumes you start with 3000 psi.

So what about larger bottles? Pony bottles are made by many manufacturers, and they generally come in sizes between six and 40 cubic feet. They cost less, mostly because they don't come with a regulator, so you have to get one. With these pony bottles it's actually possible to bring along a fair-sized backup, enough to bail you out. But now it becomes a question of balancing the amount of backup air with the inconvenience of shlepping along a sizable second tank that needs to be mounted somewhere. A little 3 cubic foot Spare Air clips on just about anywhere on your gear. A 20 or 30 cubic foot tank, that's already another story.

Those firmly opposed to pony bottles say just that: if it's small enough to not be a bother, it's useless because it does not have enough air to be of any practical use. It simply lulls its user into a false sense of security. If it is large enough to have enough air for a serious emergency, then it is also large enough to slow you down, increase the chance of getting entangled, and just generally is a bother to lug around. So either way, they're no good and relying on your buddy makes much more sense.

Does it? I don't know. I've never been in an iffy situation, and I hope I never will. I do know that the thought of having my own backup sounds comforting. The motto of the Spare Air folks is "Because Self-Rescue is the Ultimate Buddy!" and that makes a good deal of sense. I wonder how the majority of divers feel. I rarely see anyone with a pony bottle, so perhaps most do indeed rely on their equipment and their buddies. Fortunately, I know I can rely on mine, always.

Posted by conradb212 at 04:01 PM | Comments (0)

November 22, 2007

Oceanic Datamask: MUST - HAVE - IT - NOW!

A couple of weeks ago I received an email invitation to the Grand Opening of a new dive shop, Fish Eye Scuba, in my town. Timing was bad as I had planned on going racing that afternoon and evening and so I thought I'd probably stop by the new shop some other time. Well, on my way to the track, the car wasn't running right and I decided it'd be too risky to push things at the race track. As luck would have it, the new dive shop was on my way home, and so I went to check it out.

I love dive shops as much as book stores and maybe more. Whenever I go to one, I never spend less than an hour or two perusing all the gear, asking a bunch of questions, compare notes and all the fun stuff we do in dive shops. And I almost always end up buying something that I may or may not need, but that I absolutely have to have.

I was early and they were still gearing up for the Grand Opening. So they set up all the food and drink, and a disc jockey prepped his gear. I got a chance to meet the owners, chat a bit and then look around while the place wasn't totally crowded yet. It wasn't a large store, but it was neatly laid out and decorated, had lots of interesting gear, and some of the high tech touches I am a sucker for. A huge flatscreen ran underwater footage in glorious high definition.

So I grabbed a sandwich and a bottle of water and checked out the gear. They are not a Scubapro dealer, unfortunately, and 90% of my gear is Scubapro, but I love to look at and try out new stuff. By now people were trundling in, greeting and hugging each other and soon the place was packed.

That's when I saw it. In a locked glass case.

It was the Oceanic Datamask, a combination of mask and dive computer. My Open Water class instructor, Chuck Odell, had mentioned it to me early on. As a former Navy SEAL he was close to such things and I think he may have mentioned that he'd get one of the first ones. That's because the Datamask began life as a joint development project between Oceanic and the US Navy's Coastal Systems Station. Its original name was the "Combat Diver Display Mask". The idea was to combine mask and computer, have an optical readout right in the field of vision of the diver, thus reducing the need to interrupt operations to look at a wrist-mounted dive computer. One might argue how important that is in the larger scheme of things, but it is certainly high-tech and a fascinating idea.

So they did it, and the civilian result of it is the Oceanic Datamask HUD, with HUD standing for Heads Up Display. It's been available from Oceanic since early 2007 or so, and the company has been demonstrating it at dive shops and scuba get-togethers. I had never seen it in person, but now here it was, in that glass cage.

One of the Fish Eye Scuba sales staff was kind enough to open the case for me and a couple of other interested parties and so we got to check out the Datamask. At first sight it looks like a regular single-lens black rubber/silicone mask, but then you discover that there's more to it. There are some protrusions on the right side, and the lens is asymmetrical, with the right side of the glass area being smaller than the left. That's to make room for the electronics and also the integrated LCD screen. Doesn't that make the mask heavy and bulky? Amazingly not. The mask really feels like any other mask, it has fairly low volume (which I like), and it has excellent fit, with a well designed skirt.

I should mention here that the Datamask is both air-integrated and wireless. It comes with a wireless receiver that screws into the regulator's first stage. If you wear both the Datamask and a conventional wireless dive computer as a backup, the signals won't cross as they operate on different frequencies.

So how does it all work? Well, it's simply a case of the functions of a modern dive computer being built into the mask. If you look straight ahead, you have the same unimpeded field of vision as with any other mask. If you want to see the computer, you look down to the lower right. This is where the LCD screen sits, but you don't really see it as an LCD screen. It feels more like the data is floating ahead of you in space, or rather in the water.

How do you operate it and what can it do? Here, the Datamask's designers came up with an ultra simple method that uses just two buttons, one on top of the mask and one on the side. Each button has two functions: push and release, and push and hold. Those two buttons control all of the functions and display modes of the Datamask. Like all dive computers, after initial setup it'll simply work if you put the mask on and go dive, but if you want to really use its features, there'll be a bit of studying and practicing. And maybe quite a bit. The Datamask (which is Nitrox compatible up to 50%) has a significant number of screens both for setup on the surface and then for diving. It has automatic altitude adjustment, the main battery in the mask lasts about 160 dive hours and the one in the transmitter 1500 hours, it can store 24 dives and comes with a USB interface cable and software for data analysis on a PC. Setup lets you select alarms, units, sampling frequency, lighting, a concervative factor, and tons more.

When you dive with the Datamask, there's a main screen that displays the usual primary data: depth, air pressure, remaining dive time, air time and a tissue loading bar. Push a button and the display goes on to three additional screens with more data. Those then revert to the main screen. There are also screens for safety stops and deco stops.

Now obviously, I have not (yet) been diving with an Oceanic Datamask and so cannot say how it all works in real life. I do know one thing, and that is huge for me. While I have 20/20 vision I do need reading glasses, and that is forever a pain with wrist-mount dive computers. I tried stick-on lenses that either seem to be in the wrong spot (often due to the design of the mask lens) or come off (at times because manufacturers edge writing on the inside of the mask exactly where the stick-ons are supposed to be). No good. I tried masks with magnification windows pointing down, and found that distracting. Amazingly, I can see the HUD display of the Datamask clearly and in perfect focus! That alone would make me want one!

How DOES it work in real life? Well, I searched the web for reviews and found surprisingly little. A couple of people had used it during one of Oceanic's demo tours and written about it. There was one single actual review of the Datamask. It was fairly brief. The reviewer found the mask amazingly easy to use, felt that the LCD display was unexpectedly basic and at times difficult to read, that pushing buttons on the mask was a bit weird at first, that having one's computer inside a mask made it impossible to show it to the dive buddy, and that a backup was a good idea in case the mask comes off. And he wondered how it works with thick gloves on. All in all, he liked it. On various scuba bulletin boards others had issued various sight-unseen opinions: Too expensive. Can't do this, can't do that. I'll wait until they come down in price.

So what's the price? Well, currently US$1,495. That's one expensive mask, of course, but then again, no more expensive than my own UWATEC dive computer and Scubapro Frameless mask combined. So there.

The guys at the dive shop offered me a deal and I came THAT close to whipping out my VISA card right then and there. I really want that mask. I wish Oceanic would let me test one. Hey, after all I have written over a thousand published reviews of electronic gear. But the scuba industry seems stingy with eval units and so I may have to buy the Datamask after all.

Posted by conradb212 at 06:23 PM | Comments (0)

November 09, 2007

Nitrogen Narcosis

I've been thinking more about nitrogen narcosis, the threat to divers when they dive too deep. Given that humanity knows so much about just about everything, from putting hundreds of millions of transistors onto microchips the size of a fingernail, to decoding the human DNA, to building giant bridges and tunnels to running remote-controlled vehicles on the planet Mars, it's amazing how little we know about nitrogen narcosis. Almost every dive book mentions it, yet there seems little agreement on it other than that it can be dangerous and divers are susceptible to it and react to it in different ways.

The most common explanation is that as we go deeper, the higher partial pressure of nitrogen has some sort of impact on our consciousness. It's conjectured that perhaps at these higher pressures nitrogen dissolves into nerve membranes and thus causes them to function differently, perhaps affecting the way signals travel inside our brain. Some view that as a cool thing. Jacques Cousteau called it "rapture of the deep," which has a nice ring to it and doesn't exactly sound dangerous. Others have mentioned looking forward to some pleasant buzz. But even Cousteau, of course, knew it could be dangerous.

Almost everyone agrees that nitrogen narcosis can lead to unanticipated feelings and thus behaviors, and that is not a good thing when you have a hundred feet of water above you and your well-being and survival depends on logical thinking and remembering what you have learned. But how can you deal with something when you don't know what to expect, when to expect it or what it'll make you do, if anything at all?

I am an avid reader, and for the past year or two it's been mostly dive books. Nitrogen narcosis is mentioned in almost every one of them. In older books, or when quoting older passages, nitrogen narcosis is often likened to having a dry martini (consisting of mostly gin (or sometimes vodka) and a bit of dry vermouth) for every 50 feet of depth. So if you're at 100 feet, that's supposed to be like downing two dry martinis, and 150 feet three of them. That is a lot of booze on an empty stomach, and poured down the hatch. Others use the "martini law" with different rules, like narcosis effect being like one additional martini for every 33 feet, starting when you reach 66 feet. Some writers describe the martini comparison as politically incorrect.

My friend Dave, a former diver who let his skills lapse and hasn't gone diving in many years, remembers his experience with narcosis. He said he was diving off the coast of some nice, sunny, friendly place when suddenly everything seemed to look really cool and colorful and he saw some irresistibly interesting things down deeper. So deeper he went to check it all out. Next thing he knew his dive buddy had grabbed him and brought him back up to the 70 feet or so where his narcosis had set in. So for him it definitely had been "rapture of the deep," even if it wasn't particularly deep.

One area where most experts and accounts appear to agree is that unlike alcohol induced impairment, you can get rid of narcosis simply by ascending. So the assumption is that the impact of nitrogen narcosis is directly proportional to water pressure, or depth. So if you have the experience and presence of mind (or the luck) to be able to recognize and control narcosis, you simply ascend a bit if the impact of narcosis becomes too much. However, there are dissenting opinions. At least a couple of authors stated that, no, the impact of narcosis lingers, just as does the impact of alcohol. Perhaps not for as long, but it definitely won't just vanish if you ascend.

Everyone seems to agree that nitrogen narcosis is hard to pin down as it affects different people in different ways, that it can manifest itself in different ways, and that its onset is unpredictable even within the same individual under similar diving conditions. Not even the depth at which nitrogen narcosis begins to show itself is a given. Some are affected at fairly shallow depths whereas the onset occurs much deeper for others, and some seem almost immune (or at least able to control it effectively).

The symptoms described in literature vary to a great extent. Narcosis may cause pleasant feelings such as exhilaration, happiness, thrill, giddiness, or negative ones like anxiety, depression, or general gloom. As a result, judgment becomes impaired, vision may become impaired, and things can go bad. Most texts state that nitrogen narcosis affects all divers, that its effects are rarely noticeable at depths of less than 60 feet, that serious impairment happens at around 100 feet, and extreme depths of 300 feet or so on air result in narcosis induced halucinations and loss of consciousness (using the various "martini" rules, that'd be six to eight of them; I'd definitely be unconscious!)

Almost every dive book describes examples of narcosis, and, as expected, they vary greatly. In one book, an experienced wreck diver was said to become "addled" and essentially unable to think and function at just 85 feet. In other accounts, deep dives to well over 200 feet on air describe narcosis as just a minor nuisance. Everyone agrees that environmental conditions have a big impact on narcosis. If it is cold and dark, it seems to affect people worse. Then again, it hit my friend Dave at just 70 feet in friendly, optimal conditions.

These days technical divers use special breathing gas mixes to reduce the impact of nitrogen narcosis. For relatively shallow dives Nitrox, the breathing gas with more oxygen and less nitrogen, reduces the risk of narcosis, though it is primarily used to extend bottom time due to less nitrogen being absorbed into the diver's body. Nitrox is unsuitable for deeper dives because then the oxygen becomes the limiting factor as high partial oxygen pressures result in seizures. The answer is Trimix where oxygen, nitrogen and helium are mixed for optimal results (or least potential for damage) at deeper depths. A certain Trimix concoction may contain the proper percentage of oxygen to give the diver enough to sustain life but not so much as to cause seizures; a percentage of nitrogen that will result in enough bottom time for a given depth without the penalty of excessive decompression stops; and the rest in helium, a costly gas that has its own issues, some of them poorly understood and hotly debated.

There are examples of deep divers who used air and simply learned to cope with the impairment, others who switched to Trimix and praised the sudden clarity of thought they had during their deep dives where they'd become used to having to muddle through, and yet others who paid dearly for avoiding the cost of Trimix gasses in favor of plain compressed air.

So how does nitrogen narcosis affect me? Up to recently I simply did not know as my deepest dives had taken me only down to just under 70 feet. My high altitude dives in Lake Tahoe were different. The visibility was good, but several other factors might well have affected the onset of narcosis. I had never gone nearly that deep. The water was cold, down to 48 degrees. And then there was the impact of high altitude diving where equivalent depth is even deeper than actual depth.

So did it affect me? Well, on the first dive I felt a bit uneasy because it had been several months since I'd been diving and because, following my dive buddy Carol, I quickly found myself deeper than I had ever been before. We stopped around 80 feet or so and I felt uneasy. I looked up, knew I had 80 feet of water on top of me, and suddenly felt a slight onset of panic, the kind where you feel not quite right. When that happens on land, you may lay down or drink a glass of water or whatever. At 80 feet that isn't possible, but I knew I did not want to stop and needed to keep moving to keep the uneasy feeling from grabbing a hold of me. So I slowly swam around Carol, and the feeling passed. When she gave me the Ok? sign, I answered back. Ok. And followed her deeper. I had never expected the dive to be so deep and so impressive, but it was. Carol showed me the depth reading on her dive computer every ten feet and stopped to take pictures of it with her underwater camera. I'd taken mine along as well, the Olympus 770SW.

We were now pretty deep and Carol, who was a few feet below me, motioned for me to come down to her. I checked my dive computer and saw 94 feet. She had wanted me to experience 100, but for now 94 felt enough to me. I did not feel compromised or disoriented or buzzed in any way. On the way down to 94 feet I did realize that I had probably flooded the camera. The 770SW has a depth rating of 33 feet without deepwater housing, and I'd taken it down to 67 and Carol to 77. So it was not that I had simply forgotten about the camera; I simply expected it to continue to work. I did not write that off to narcosis, as in I'd completely forgotten that I had the camera with me. I hadn't.

The second Lake Tahoe dive was the Rubicon wall dive. Here we knew we were probably going to go deep, just not how deep. We didn't even know at what depth the wall started. This time we used hoods and gloves so that we'd be less affected by the cold. Despite the unfortunate flooding episode, this time I took two cameras along, both Sealife Reefmasters. We found the wall at 70 to 80 feet. I'd wondered how I'd feel one I came face to face with the wall, where there suddenly would no longer be a bottom. Once I got there, I felt neither elation nor uneasiness, but simply followed Carol over the wall and down. It quickly got much colder, and Carol, who wore only a 4mm wetsuit stopped at 100 feet. I wore my hefty 7mm suit and felt fine. To the best of my recall, I still felt neither anxiety, giddiness or anything else unusual. I just felt good and in awe of everything I saw, as I always do on dives.

I was proud that I had finally reached 100 feet, but all seemed so well that I decided I wanted to push a little farther. So I motioned to Carol that I intended to go down to 110 feet. I didn't use the proper hand signals. Instead, I pointed at my depth reading, then signaled a number as I would on land. I pointed down, then showed five fingers, five fingers again and then one, for 11, or 110 feet. Then I slowly descended, watching my depth gauge. Once I reached 110, I was satisfied (well, very pleased is more like it), and ascended again to 100 feet where Carol hung. By now she was very cold and we began our ascent.

Had I experienced nitrogen narcosis? Was narcosis what made me feel uneasy for a minute or two on the first dive and also flood my camera, and then brave enough to descend another ten feet once I had reached the magic 100 mark on the second? I don't know. I don't think so as I never felt compromised and never did anything that either Carol or I felt was irrational or out of control.

So I don't know. Maybe I am one of the lucky ones who have a fairly high tolerance for nitrogen narcosis. Maybe it just didn't happen on those two first deep dives. Maybe it did happen and I just didn't notice. I don't know. Most likely I'll eventually find out.

Posted by conradb212 at 11:21 PM | Comments (0)

October 10, 2007

Watching "The Deep" again

Last night I watched "The Deep" again. Given the significant popularity of the sport, there are not a lot of diving movies, just as there are not a lot of diving books. Sure, there may be the occasional diving scene in an action flick, but movies where scuba takes center stage are few and far between. And some of those where diving does play a prominent role are not exactly academy award material.

I remembered "The Deep" as a pretty decent movie, though I hadn't seen it in 20 years or so. The novel and screenplay were done by Peter Benchley, who also had his hands in any number of creature movies, including Jaws. Peter Yates was the director, also a man with considerably experience. His movie "Bullitt" with Steve McQueen remains an all-time classic. And, of course, the stars of "The Deep" had considerable drawing power: Nick Nolte, Jacqueline Bisset, Louis Gossett Jr., and actor/writer Robert Shaw who had some 50 movies to his name (including Jaws and a couple of James Bonds) and died shortly after "The Deep" was released in 1977.

So this was diving 1977, and that alone was enough to make me want to see "The Deep" again. But there was another reason. Diving legend Stan Waterman had worked on the underwater scenes of the movie, as both a director and a cameraman. I have met Waterman, a diving legend and now in his 80s, personally and enjoyed one of his eminently entertaining and educational lectures.

The movie is about a young couple vacationing and diving in Bermuda. They dive a WW II wreck and come across a large stash of morphine ampulles, worth a fortune on the drug market. Word gets around, and the bad guys, led by Louis Gossett Jr. are soon on their trail. But there's more. Seems that storms sort of mashed that WW II warship and a much older vessel together, and so there is treasure. Treasure is good, but it's really worth a whole lot more if its authenticity can be established, and so the stage is set. Bad guys after drugs. Good guys doing research on the suspected treasure. Throw in some ghastly VooDoo, motorcycle chase scenes to liven up the somewhat twisted plot, and then there's the diving, lots of it. That's what primarily interested me.

This is 1977, really not that much past all the Cousteau documentaries I'd watched. Yet, whereas Cousteau's footage always had sort of a Buck Rogers back-to-the-future look to it, what with their sleek, futuristic, aerodynamic gear and their double hose regulators, diving in "The Deep" looks surprisingly modern. It must be warm as Nolte and Bisset only wear bathing suits. In Bisset's case, a rather revealing skin-tight T-shirt with prominent nippleage was probably sensuous enough to send censor types into shock. Other than that, modern-looking regulators, modern looking masks, single tanks, nothing that would look out of the ordinary today. Except for one thing: no BCs. In 1977, buoyancy compensators did exist. Scubapro developed the stabilizer jacket in 1971, and so called adjustable buoyancy life jackets had been around since 1961. So I don't know if by 1977, it still wasn't common to use BCs.

The dive masks they used looked like something you'd buy today. Light and clear and low volume. The underwater photography was terrific in every respect. As is usually the case in movies, some things made me wonder. Like, they penetrate this wreck they do not know without protective gear or lines at all. More interestingly, silting never seems an issue. They swim around, push, pull, fight, yet hardly any silting at all. Visibility is always a-okay. The shipwreck used in the movie was supposedly that of the RMS Rhone that sank in 1867, with filming taking place at 75 feet in the bow section. Much of the diving actually looks much shallower than that, which makes me wonder how the picked the title "The Deep." Oh, and this was before dive computers. Still, no one ever runs out of air, and I don't think I saw a single decompression stop or anything like that.

There was some excellent shark footage. The bad guys threw fish and bait into the sea to attract sharks, and the resulting footage is awesome, especially for the time. I could just picture Stan Waterman, that pioneering shark cinematographer, behind the camera, not quite knowing what to expect. Another bad guy critter is a truly giant moray eel in the wreck. Morays always look evil. This one actually ends up crunching Lou Gossett Jr.'s head and biting it off. Ouch.

All in all, it was nice watching "The Deep" again. It is not a very good movie, especially given its illustrious cast, but the dives scenes were great. And Jacqueline Bisset sure looked good underwater. Maybe that's why they didn't wear bulky BCs.

Posted by conradb212 at 11:21 PM | Comments (0)

October 03, 2007

Less dive time for NAUI divers?

Two friends, a NAUI diver and a PADI diver, decide to go on a dive trip. Though they have dive computers, they decide to play it by the book and use dive tables. They also decide to take it easy and do just two dives each day, though some are fairly deep. They know the dive sites, decide on surface intervals between each day's dives and begin working out their dive plans. When they are done, they compare their plans and find something very peculiar. For their second dives of each day, the PADI diver shows a total permissible dive time of 443 minutes whereas the NAUI diver arrived at only 301 minutes. They recheck their calculations. They are correct, yet for each dive except one, the PADI diver finds longer allowable dive times for the second dive, sometimes by a lot. For example, after a 60 foot dive and one hour surface interval, the PADI diver can do a 61 minute dive to 50 feet. The NAUI diver can stay only 42 minutes. After a 40 minute dive to 70 feet, the NAUI diver can hang around at 40 feet for 69 minutes, whereas the PADI diver can stay for 115 minutes (if he has that much air). After a deep dive to 133 feet, the PADI diver can, after three hours on the surface, make another deep one to 90 feet for 21 minutes whereas the NAUI diver has only 18 minutes.

What gives? Aren't all those dive tables based on the same principles? Should they not yield approximately the same results? True, the PADI and NAUI tables are different, with PADI breaking things down into 26 "Pressure Groups" while NAUI has less granularity with just 12 "End-of-Dive Letter Groups." So you'd expect the tables to occasionally produce slightly different results, but not by much. Sometimes PADI would show more bottom time and sometimes NAUI. But that does not appear to be the case. The NAUI tables seem to consistently yield more residual nitrogen time and less maximum dive time for repetitive dives.

Does that mean NAUI is more conservative? I don't know the answer just yet. Based on my own experience, I've come to view PADI as more tourist and recreation oriented, and NAUI as more technical and detailed. If that were indeed so, then one would expect PADI to be more conservative so that its broader and perhaps less experienced diver base stays within safe limits at all times. Instead, the respective dive tables almost always allow less repetitive dive bottom time to the assumedly more experienced average NAUI diver.

Could definitions have something to do with it? Just like the PADI and NAUI dive tables are different, so are the two competing certification entities' terminologies and definitions. As a result, as if dive tables weren't confusing enough, those trained by different agencies must also figure out if "Actual Bottom Time" is the same as "Adjusted Maximum Dive TIme," and "Total Bottom Time" the same as "Total Nitrogen Time." That's just not good.

Looking at my notes and instruction materials, I find that NAUI defines "actual dive time" as "the time from the moment of descent until returning to the surface." Breaking the surface or starting to return to the surface? For PADI, on the other hand, "bottom time" is "the total time in minutes from the beginning of descent until the beginning of final ascent to the surface." So the NAUI "total nitrogen time" which adds "actual dive time" and "residual nitrogen time" would yield a larger number than PADI's "total bottom time" that adds "actual bottom time" (which does not include the time it takes to ascend) and "residual nitrogen time." Confusing for sure.

And there's another difference. PADI states that "if you don't plan to dive for at least six hours, the residual nitrogen has little consequence. True enough, if you look at the PADI Recreational Dive Planner, you find that after a six hour surface interval you are no longer in any pressure group at all and a second dive, even if the same day, would apparently not be treated as a repetitive dive. NAUI, on the other hand, categorically states that "any dive made less than 24 hours after a previous dive" is a repetitive dive. Which means that no matter how long the surface interval on any given day, for the second dive you'll always start out at least in End-of-Dive Letter Group A.

What does it all mean? Nothing for most divers because very few will ever agonize whether to use the PADI or the NAUI dive tables. And most divers simply rely on their dive computers anyway. But those large discrepancies between the tables are still amazing after being taught in class that even a couple of minutes of extra bottom time can be the difference between a safe dive and the prospect of getting bent.

Posted by conradb212 at 11:20 PM | Comments (0)

September 17, 2007

Taking a handheld computer underwater

When I took that advanced NAUI class I was exposed to all sorts of disciplines. Night diving, light salvage, advanced buoyancy, navigation, deep diving, rescue, using scooters -- all were pa