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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 4:01 PM
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 6:23 PM
November 9, 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
