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---------- > Från: Kent Lind <klind@al*.ne*> > Till: techdiver@aquanaut.com > Ämne: RE: Cold water risk > Datum: den 4 september 1998 09:41 > > Ingemar Lundgren wrote: > > > I would like to start a discussion about the risks involved in cold water > > diving especially regarding dry suit failures. You > > don't have to bee diving in cold water to have a life tretaning situation > > in case of a suit failure. WKPP for example are diving > > in relatively warm water but they have in water times of 15 hours. Even in > > 18-20 C water you will probably not survive with > > a completely flooded suit. In really cold water you will probably not > > survive even 30 min. In open water you can always > > skip part of the deco and still have a good chance of survival but in a > > cave, hours from the exit it is anouther story. > > Ingemar: I have given a great deal of thought to these issues and > I'm not sure I've come up with any useful answers. I suspect that the > conditions here in Southern Alaska are quite similar to what you encounter > in Scandinavia. In the past 3 years the coldest ocean water that I have > encountered was 33 F (0.5 C) and the warmest water I have encountered > at depth was 48 F (9 C). Typical winter water temps are 37-38 and > typical summer temps at depth are 43-45. About the same tempratures. In summertime we can get up to 15C at very shalow depths. Below about 20m the temprature is a constant 3 C. in cave however the temprature is the same regardless of seson. > > You guys have some serious balls to do deep cave penetrations in > water that cold. You aren't just facing the drysuit failure issue. I > would be even more worried about dealing with a long zero-vis situation > with heavy gloves on. How difficult will it be for you to follow > a line for several thousand feet through touch contact if your dry > gloves are torn and your hands have gone numb? I think that would be > one of my biggest fears. You could die back in that cave grasping > around for a lost line with hands that have gone so numb that > you can't feel the line when you find it. We have spare wet gloves. I have never had a silt out that extends more than a couple of meters. If i silt the palce up to much i will turn the dive. Important to look back often in small silty tunnels. It is however more dificult to follow the line with dry gloves. But the gloves we use are suprisingly agile. > > Back to the drysuits. I've read various suggestions about wearing > a drysuit over a drysuit or wetsuits under drysuits. While I haven't > actually tried any of this, I would look with a great deal of > suspicion at such ideas if they detract from your mobility. You > may fix the leaking drysuit problem but you're likely to end up > so over-stuffed that you will reduce your ability to deal with other > more likely situations such as a freeflowing regulator that > requires quick access to your valves. Not to mention what that > sort of dress will do to your buoyancy. A drysuit is already > somewhat confining. I think that any extra nonsense that makes > it more difficult to manouver and reach all your equipment > adds unacceptable risk to serious wreck and cave diving. I agree on your points. I don not want to sacrifice to much mobility. I'm > not sure the commercial diving solutions are that useful. > Commercial divers rarely do much swimming and use surface support > equipment for anything deep. Although I'm not a commercial > diver, I'm not sure that commerical diving requires the sort > of agility that free-swimming cave and wreck diving requires. My > first priority is to be able to swim out of any hard current > or restriction and get to all my gear quickly and efficiently. Definatley cant use a hot water suit that demands a hose from the surface. Jim Cobbs sugestion might bee worth cosidering in an emergancy however. > > What is my answer? I don't have one for deep cold water > cave penetrations. For the local wreck diving I do in Alaska > we simply just don't do the sorts of dives that reqire massive > deco. I just don't do dives that require more than about 1/2 > hour of deco using Abyss tables and for most of these dives > I could probably completely blow off deco in the event of an i avoide long deco in OW as much as i can but sometimes i have to do long decompressions. The hot water bell system seems to bee a solution for both emergencies and extended botom times. The more i think about it the better it sounds. I could infact make it partally dry so that only the head of the diver is above suface to allow for comunication and stuff. This would reduce the amount of weight needed for a 3 man bell to about 1000 kg. I have a boat with a crane that can lift 1000kg so that is not a problem. > emergency and suck the O2 down on the surface. I keep an extra > 80 of O2 on the boat for this eventuality. With a seriously > ripped up drysuit you'd have to figure out where the danger > from hypothermia exceeds the danger from DCS. We have this planed as a last option. we also use suface supplied O2 for deeper dives but we still carry o2 bottles. The worst > I've encountered is the typical leaky neck seals and leaky > zippers where you get damp but not seriously wet or cold. > I dive a CF200 with the heavy thinsulite and polypro against the > skin and have never had worse than cold hands. For really > cold water, I'll add a fleece ski vest for extra warmth > over the torso, and of course, argon. I have had many small leaks as any dry suit diver have had. Being damp is not a problem but a complete flood is very serius. Even a very small hole will flood your suit. > > I think a portable decompression chamber is the only real solution > for seriously deep seriously cold wreck dives where blowing > off deco is absolutely not an option. The "poor man's" > chamber would be to keep a spare drysuit and rig ready to > go on the boat so if you've shredded your suit and are > risking hypothermia, you could always surface, change out into > fresh warm dry underwear and spare drysuit, toss your spare > rig on (single tank rig is probably OK), grab a deco bottle > and drop back in. Can you do this in less than 5 minutes with > help? If so, you can try to follow in-water recompression > techniques. If you can do it in 5 minutes you can continue the deco with out any modification to the deco times. Obviously, you'd need to have everything laid out and > ready to go. I usually keep my single tank Zeagle rig on my > boat ready to go when I'm diving doubles so I can throw it on > at a moments notice if something comes up where I need to get > down quick for support or to do a rescue. I don't, however, > have a spare drysuit laying around. > > None of this has any application for the long cave penetrations > that you are talking about. For that sort of thing, the > ONLY thing I can think of is to build an air habitat inside the > cave as a staging point. Or, you can do what you guys do and > just accept the risk but try to minimize it through choice of > drysuit and underwear. The majority of the deco in Plura is done 950m in to the system. The first 900m of the cave is shaloow from 10- 34m. A habitat is impossible to install. > > Most commonly a dry suit only floods partially but even a quite small hole > > can flood almost the entire suit. In Plura a small > > hole flooded 80% of the dry suit and this was from a small hole of 1 cm in > > length. > > > On every long cold water cave dive or > > even long OW decompression dive i make i face a very serious risk in case > > of a suit flood. > > The reason for this post is to ask if anybody can come up with a solution > > to the problem. A decompression habitat would > > do the trick for OW diving and in some cases cave diving. But a > > decompression habitat is often very impractical. it required > > heavy weights, several tons and a big boat with a powerful crane for OW > > use. What i have been thinking of is making a > > habitat filled with hot water. This is a lot more manageable on even a > > rather small boat as there is no lift created from the air. > > The problem is that huge amounts of water needs to bee circulated trough > > the habitat to keep the temperature. This calls for > > a very powerful heating device. I have not been able to find a heating > > device that is both practical and powerful enough. If > > any one have made anything similar or have some helpful information it > > would bee greatly appreciated. Also If somebody > > thinks this is an idiotic idea please do enlighten me. > > > > Other solutions might bee the use of hot water suits but they require a > > hose to the surface and can therefore not bee used. > > If any body have any ideas that you would like to share it would bee > > greatly appreciated. > > If you get any great ideas via private email, please post them. > > Kent Lind > Juneau, Alaska > klind@al*.ne* > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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