cold water exposure suit debate

[BoltSnap]

The discussion above gives much credibility to Scubapro's idea of taking the effects of cold into its computer's algorithm for sure. Their enhancements of the deco algorithm do have scientific basis after all despite of the noise of some SB members concerning this matter. I wouldn't be surprised to find out that the other factors they take into consideration in their computer algorithms are also valid.

Good to know

 

[tbone1004]

the problem with trying to factor in water temperature is the fact that water temperature has absolutely nothing to do with your body temperature. You can put someone in 20c water in a 3mm, give them a profile that bends them like a pretzel, then put them in a heated drysuit 24 hours later and they might be perfectly fine.

No computers on the market use their temperature data for anything other than reporting it now for the reason above.

Also, many of us are doing extremely long dives without thermoclines which means the decompression is just as cold as the bottom and that is very annoying. I wish that the caves heated up to 85* in the deco rooms, but alas, they stay at 70 +2, year round, all depths. Very annoying. The biggest thermocline I've seen in a cave was 3*F and that was a weird scenario but the thermocline was actually at depth and was a cool pocket so deco was just as cold as the rest of it

 

[BoltSnap]

the problem with trying to factor in water temperature is the fact that water temperature has absolutely nothing to do with your body temperature. You can put someone in 20c water in a 3mm, give them a profile that bends them like a pretzel, then put them in a heated drysuit 24 hours later and they might be perfectly fine.

No computers on the market use their temperature data for anything other than reporting it now for the reason above.

Also, many of us are doing extremely long dives without thermoclines which means the decompression is just as cold as the bottom and that is very annoying. I wish that the caves heated up to 85* in the deco rooms, but alas, they stay at 70 +2, year round, all depths. Very annoying. The biggest thermocline I've seen in a cave was 3*F and that was a weird scenario but the thermocline was actually at depth and was a cool pocket so deco was just as cold as the rest of it

You are contradicting yourself here. Does cold/warm have anything to do with decompression or not? Computers that measure body/water temperature such as the Scubapro computers factor that in their algorithm and decompression calculations.

 

[tbone1004]

You are contradicting yourself here. Does cold/warm have anything to do with decompression or not? Computers that measure body/water temperature such as the Scubapro computers factor that in their algorithm and decompression calculations.

there was no contradiction. I believe water temperature has nothing to do with it, but body temperature does. A computer that factors water temperature into it's algorithm is imho an unsafe computer and in the discussions and papers by Pollock et al. they state that. 85* water will kill you from hypothermia, slowly, but it will kill you. With the proper analysis, one that factors in body temperature could help a small handful of DCS cases every year, mainly for the commercial and Navy divers. In recreational deco diving, most of us will just lower our GF-Hi if we know we are going to be shivering on decompression and with a GF-Hi of 70, the odds of you getting bendy are pretty much negligible, just sucks because you are shivering for that much longer....

 

[Neilwood]

You are contradicting yourself here. Does cold/warm have anything to do with decompression or not? Computers that measure body/water temperature such as the Scubapro computers factor that in their algorithm and decompression calculations.

I don't see any contradiction here - the water temperature and diver temperature are completely different things.

The studies are clear - that temperature does affect on/offgassing. What isn't shown is how the appropriate clothing affects the process - the studies were done without thermal protection IIRC.

You could have a diver wearing a drysuit with the DC on the outside diving in near freezing water. The diver inside it is wearing appropriate undergarments or heated vest etc for the water temperature and is toasty warm. Will the cold water affect his on/offgassing? Probably not a great deal as the diver inside of the suit is probably as warm as when he started the dive. The computer will register that it is affecting it though as it is on the outside of the suit and subject to the extreme temperature.

You also have another diver diving in 20C water wearing a thin wetsuit. Will the water temperature affect his on/offgassing? The computer would tend to suggest not as the water temperature is higher so less risk but the reality is that the diver will feel the cold a lot more, may be shivering or even heading towards hypothermia and at a far higher risk of DCS.

The computer can not take the appropriate thermal protection into account - the diver on the other hand should change his conservatism accordingly.

 

[BoltSnap]

I don't see any contradiction here - the water temperature and diver temperature are completely different things.

The studies are clear - that temperature does affect on/offgassing. What isn't shown is how the appropriate clothing affects the process - the studies were done without thermal protection IIRC.

You could have a diver wearing a drysuit with the DC on the outside diving in near freezing water. The diver inside it is wearing appropriate undergarments or heated vest etc for the water temperature and is toasty warm. Will the cold water affect his on/offgassing? Probably not a great deal as the diver inside of the suit is probably as warm as when he started the dive. The computer will register that it is affecting it though as it is on the outside of the suit and subject to the extreme temperature.

You also have another diver diving in 20C water wearing a thin wetsuit. Will the water temperature affect his on/offgassing? The computer would tend to suggest not as the water temperature is higher so less risk but the reality is that the diver will feel the cold a lot more, may be shivering or even heading towards hypothermia and at a far higher risk of DCS.

The computer can not take the appropriate thermal protection into account - the diver on the other hand should change his conservatism accordingly.

This applies to every single factor in decompression, heat/cold, fitness level/body fat, hydration level, rest/fatigue, bad day/good day, etc. etc. The diver should have the common sense and knowledge to plan accordingly. You need to take the whole discussion in context and not just a microscopic view of what Tbone has been talking about since the beginning of the thread.

The body temperature issue can be taken care of with what SP has done in its newer computers with the chest belt (assuming that it measures body temperature but I am not sure).

 

[tbone1004]

there's actually a lot of speculation on hydration being a relevant variable in decompression.

Chest belt from SP can only measure skin temperature, which is better than water temperature, but only relevant for that tissue compartment, not necessarily for the slower ones.

 

[BoltSnap]

there's actually a lot of speculation on hydration being a relevant variable in decompression.

Chest belt from SP can only measure skin temperature, which is better than water temperature, but only relevant for that tissue compartment, not necessarily for the slower ones.

Everything in decompression and diving is speculation and the experts change their minds every few years. Decompression calculation by computers are only using mathematical equation to "simulate" what is happening in body physiology based on speculation and they can't really know what is actually taking place in the body without invasive methods to monitor what's going on which isn't an available option. Even the "tissue/compartment" modeling is speculation and guesstimation and not actual direct model.