Deco procedures in thermocline

[tyrell]

Hello

Have some question regarding diving in different water temperature and bounce dive. I know that this is not the recommended dive profile but these are the site conditions.

The question refers to a certain wreck dive that the differences in the temperature in one place in the wreck and the outside of the wreck can be more then 7 c deg.

The dive is a decompression (with all the necessary gases) the wreck, because it is lying on the side, u can go in 20m go down to 35 go up to 20, go down to 35 and go on go into hot water and then go back to cold water again. At the end if the dive when u go up to 10 m the temperature ( at a thermo cline)rises in 3-4 c deg. I know it might be dangerous

Lets leave that these conditions are far being optimal conditions. Its something we have to deal with.

Since this kind of dive cannot be planned with a deco soft ( and there is no deco software that can calculate different temperatures during the dive) and since this is a bounce dive, the question is how much time i need to add to the deco stops and where.

To be more specific. in certain parts of the wreck the temp is around 15 c and when u go out from the ship the water temp can go up to 21 c,. is it necessary at this time to make a deco stop, I believe it is, but for how long and where. In the cold part or in the hot part (Ito my opinion in the hot water) I could not find any publications regarding deco procedures in thermo clines. To add to the dive the bounce factor, i believe it quiet close to the edge.

To add 50% time to each deco stop is it enough, or do i need to add 100%( double each stop). Are there any other rules that I should follow (except not doing this dive)

Is there a place I can read more about how drastic change water temperature affects the bubble formation.

Thanks

Mark

 

[Dr Deco]

Hi Mark:

Considering the large degree of latitude allowed in recreational tables, I doubt that the thermocline would result in much of an increased hazard. Certainly if you were in the cold portion for a long period, and were moving about to keep warm, this would increase gas loading.

However, jus moving up and down in the thermocline should not be bad. Folks dive in the Northwest portion of the US an Canada where the water is cold and the boat is warm and they do not report excessive decompression problems.

Dr Deco :doctor:

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

 

[Doppler]

Hi Mark... any challenges you may encounter would likely come from bounce dive profiles and not from the slight differences in temperature that you describe... here in the Great Lakes we have often conducted deep trimix dives (80 m and more) with 4 degrees on the bottom and 24 degrees on the surface without "special" precautions for temperature...

Which algorithm are you using to cut tables?

 

[BRW]

Folks,

Seems topics keep jumping up that bring
in RGBM, and phase mechanics.

The RGBM treats temp effects on bubble
growth, formation, etc. thru equations of state
(EOS) for lipid or aqueous surfactants. The
dependences over nominal diving temps are very
mild. So are all other EOS related quantities
in RGBM, that is, linkages to temperature.
Nothing new in physics since the absolute
temperature scale (K) requires hefty changes
in EOSs to make dramatic effects.

We do not worry about them. Nor have we
seen any probs in staging with and without
temperature considerations.

Picture is painted (with EOS equations) in
book "RGBM IN Depth" (Best Pubs) if you
want to track it

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Leader
ut: