How Cold is Cold?

[grouchyturtle]

I asked this on one of the other sections of the board and someone suggested I post it here.

When RDP tells you to calculate 10' deeper for cold water, is this a real number?

If so what temp would be considered cold water?

Or is it more of a comfort level thing? So my buddy, who's like a little girl when it comes to the cold, he's been known to put the heat on full blast, driving home froh LBI, NJ in the middle of August, could technically be 1 pressure group higher than me after doing the same dive, since the cold doesn’t really bother me that much?

 

[Dr Deco]

Hello gruntzer:

“Real Number “

I m not sure what a “real number” is in this sense. Certainly time and pressure are real numbers, but they do not give absolutely “real” dive tables. This means that dive tables are not “titrated” to the individual characteristics of each diver. The tables are calculated such that virtually everyone making that dive, under the test conditions, will experience a DCS-free outcome. Since the test conditions might be less severe than your dive conditions, a table designer might “hedge his bet” by suggesting that you “peg the table,” that is, add extra decompression time in some circumstances.

Cold Water

If the water is cold enough to make you move about more in order to maintain your body at a somewhat comfortable temperature, then you should consider truncating the dive at a shorter time. :cold:

In this case, they suggest that the rule of thumb would be to use the no-decompression time for the next deeper ten feet. This is reasonable. In addition, if you were increasing your heart rate and blood flow for a reason such as swimming against a current, then you should also adjust your bottom time.:wacko:

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[Poulpe]

Some Uwatec computers are taking into account the T° of the water to calculate the deco ut:

But as Dr Deco said, if you feel cold, do a longer stop at 10 feets before going to surface

 

[MonkSeal]

Poulpe once bubbled...
Some Uwatec computers are taking into account the T° of the water to calculate the deco ut:

Which is no so smart - what if I dive in 7mm semidry or dry suit, my body feels different then if I dive in 5mm wetsuit.

I don't think that computer can take body condition in any calculation.

 

[DA Aquamaster]

MonkSeal once bubbled...

Which is no so smart - what if I dive in 7mm semidry or dry suit, my body feels different then if I dive in 5mm wetsuit.

I don't think that computer can take body condition in any calculation.

I think the idea is just to add another safety factor. If the water is cold (say 50 degrees or less) it's reasonable and safer for the computer to assume you may potentially be colder in what ever you are wearing for thermal protection. Sounds pretty smart to me.

 

[MonkSeal]

DA Aquamaster once bubbled... I think the idea is just to add another safety factor. If the water is cold (say 50 degrees or less) it's reasonable and safer for the computer to assume you may potentially be colder in what ever you are wearing for thermal protection. Sounds pretty smart to me.

Well, I believe that this is something diver himself has to decide. If some conservatism is to be added to algorithm then let me to that - the same principle I would apply when using tables.

 

[Poulpe]

And wich table would you use to calculate a higher deco stop regarding T° ?

 

[MonkSeal]

Poulpe once bubbled...
And wich table would you use to calculate a higher deco stop regarding T° ?

I would use values for next greater depth.