| I think there is one very important point being missed here. A catastrophic flood is not simply a question of how long your body can endure the cold.
The effects of sudden cold water immersion are massive, there is a loss of breathing control -- breathing rate increases by 6-10 times in cold water within the first minute or two. At say 80m, that's a diver going from 160l/min to 1600l/min to give it some perspective, or emptying a stage bottle in a minute or two and the chances are that the reg will freeflow or be overbreathed. Even when stabilised, the breathing rate will increase by a lot. The ability to hold one's breath is reduced to about 10-15s which could compound the problem of donating a reg when the gas runs out. Severe panic is an inevitable side effect of cold too.
The other physiological effects of cold water shock on otherwise healthy people is that cardiac arrest is a very real possibility. Very few people who die by sudden cold water immersion actually die from drowning or hypothermia and most actually die within a few metres of safety.
The diver's ability to maintain some level of mental control enough to do any task underwater will be greatly impaired, assuming they remain concious. Even if there was enough gas to get them through a long deco, it is questionable if they would still be able to function adequately and manual dexterity would be pretty much nil.
Of course, these are the effects of a sudden and massive failure of the drysuit in cold water. A relatively slow leak where cold water shock isn't a factor will not have many of the above symptoms but will introduce a new set of problems. One diver from the CDG survived a torn wrist seal in a cave at 120m a couple of years ago. As long as you can do something to stem the leak then it is a fairly minor event (he used a snoopy loop round the torn seal). |