St. Lawrence + 7mm wetsuit = how long a season?

[Kevin R]

I recently read an article that said using hot water to bring up the temp when cold water diving wasn't a good idea. Apparently all you do is trick the body into moving the warm blood from the core of the body to the extremedies where it cools further and then when it is returned to the core, your body must use more energy and heat reserves to warm up the re-cooled blood and you end up colder than before.

Pufferfish probably has a better explanation for this since he fixes people and I fix cars. Any thoughts that don't include air testing standards?

Kevin

 

[Mark L]

Kevin Ripley once bubbled...
I recently read an article that said using hot water to bring up the temp when cold water diving wasn't a good idea. Apparently all you do is trick the body into moving the warm blood from the core of the body to the extremedies where it cools further and then when it is returned to the core, your body must use more energy and heat reserves to warm up the re-cooled blood and you end up colder than before.

Pufferfish probably has a better explanation for this since he fixes people and I fix cars. Any thoughts that don't include air testing standards?

Kevin

Yes, Kevin there have been several articles supporting what you are saying.

 

[DPVDiver]

Sorry if I have advocated unhealthy behaviour. Any particular place I could read the articles?

 

[pufferfish]

Kevin Ripley once bubbled...
I recently read an article that said using hot water to bring up the temp when cold water diving wasn't a good idea. Apparently all you do is trick the body into moving the warm blood from the core of the body to the extremedies where it cools further and then when it is returned to the core, your body must use more energy and heat reserves to warm up the re-cooled blood and you end up colder than before.

Pufferfish probably has a better explanation for this since he fixes people and I fix cars. Any thoughts that don't include air testing standards?

Kevin

Sorry no thoughts at all unless it involves air standards

Just curious where did you read that? Sounds like possibly another one of those urban myths like argon is warmer than air in drysuits. Any how I have no expertise in environmental physiology other than what I have read and remember from school many years ago. Dr. Paul Thomas is probably the guy to ask on this topic but here is two cents worth anyhow.

I still dive wet and have done the warm water trick many times so I am a believer. A poorly fitting wetsuit is likely far more of a factor in becoming hypothermic sooner than pouring some warm water down your suit. First off the water usually is warm not hot and secondly it gets poured in just before diving. As even the best wet suit fit allows some water movement through it, the effect of the warm water causing or maintaining enough peripheral vasodilation so as to cool the core would only likely be on the order of minutes just not significant compared to the big factors like suit fit and body composition. Within those minutes convective losses occur with the movement of water into and out of the suit and the water will soon drop to the same temperature as if you jumped in dry, filled the skin/suit interface with ambient water and used your periphery to warm the water. Even if the wet suit was technically sealed the temperature of the warm water inside would equlibrate in minutes to some steady state dependent on conductive losses of heat to the outside surrounding water again probably in the order of minutes. So no I don't think using warm water would alter your core temp to any significant degree and I just don't like the shock of cold water running into my suit which likely induces all kinds of other negative effects like a sudden surge of epinephrine which then has all sorts of cardiovascular effects. Not only is the warm water more comfortable overall I suspect the gradual cooling over minutes is healthier than the sudden cold induced inspiration.

In anycase there are many chapters written on this stuff which you can read in any basic physiology book. Jolie Bookspan's book called "Diving Physiology in Plain Enlglish" available from DAN is an excellent starting point. Here is an article from here book on cold water tolerance linked to scuba doc's web site.
Acclimatization to Cold Water Diving

Bennett and Elliot say that saturation divers in the North Sea use essentially water perfused wetsuits. The temperature of the water flushing the suit is maintained between 35 to 40 C so as to minimize the gradient between the skin and perfusing water. These guys have been shown likely with rectal temp probes (yuk) to be able to maintain core temp for up to six hours at 525 feet in water from 4 to 6 degrees.

I think all of DPV's ideas are reasonable and I will have to try the duct tape trick as yes that would reduce the convective losses but I guess that really means no mid dive warmups from micturation

 

[pufferfish]

Dr. Bookspan answers the question right in the link. I had read the section in her book but not the link which is more thorough.

She states pouring warm water down your suit or sitting in a warm car between dives in more likely beneficial than detrimental.

I guess I should read things more closely before I post them, eh.
(I can't find that little guy hitting himself with the hammer on the head)

And just to head all the drysuit guys off at the pass on the argon issue just go and read the article by Risberg L. et al. "Thermal insulation porperties of argon used as a dry suit inflation gas." Undersea and Hyperbaric Medicine 2001: 28:137-143. If I recall correctly it was conducted by the Norweigan navy and said no difference in core temps. Just like fin testing where subjective perception by the diver is very different from the reality of real life physiological or engineering tests.

 

[DPVDiver]

Kevin has a good point. Back when I used to do cold water wet dives I would often fill my suit with warm liquid several times during the dive. If you know what I mean. It did get warm momentarily, however it did seem to cool me down more later!

Plus all that wetsuit shampoo was hard on the wallet! Not to mention the ride home with that Wetsuit in my car!

BTW, I have read those argon articles, but to me it seems warmer. It may be only Psychological but come January I'll take what I can get.

DPV

 

[Col.Cluster]

pufferfish once bubbled...
And just to head all the drysuit guys off at the pass on the argon issue just go and read the article by Risberg L. et al. "Thermal insulation porperties of argon used as a dry suit inflation gas." Undersea and Hyperbaric Medicine 2001: 28:137-143. If I recall correctly it was conducted by the Norweigan navy and said no difference in core temps. Just like fin testing where subjective perception by the diver is very different from the reality of real life physiological or engineering tests.

Dude

If I recall the article you are referring to correctly. The Norwegian’s were testing in 7mm neoprene suits only to 2ATA. The suits were not given a chance to compress completely. Therefore they were also testing the insulation factor of the suits on top of the argon/air. I also believe that the testing only went as far as to ask the divers if they were cold or not. There were no actual measurements of core temperature changes.

I could be mistaken, as I have not re-read the article. It was place in the appropriate file a while back.

All the best
CC

 

[Col.Cluster]

Air_Miser once bubbled...
Ok,

So this is my first season diving, and the equipment piggy bank had enough in it to get me fully geared, but not enough for a drysuit this year!

Just wondering around when you other wetsuit divers call it a season? Halloween?......Rememberance Day?.....

Let the bragging begin .....

Matt

Matt,

I have seen folks diving through into November in wet suits. A more pracitical rule of thumb would be to say I have seen folks diving wet as long as the charter boats are still in the water. All the wet suit divers I know suffer from the cold once they are back on the surface. Take measures to get yourself out of the wet stuff and into warm dry windproof gear once you get out.
Enjoy the dives
All the best
CC

 

[pufferfish]

Col.Cluster once bubbled...


Dude

If I recall the article you are referring to correctly. The Norwegian’s were testing in 7mm neoprene suits only to 2ATA. The suits were not given a chance to compress completely. Therefore they were also testing the insulation factor of the suits on top of the argon/air. I also believe that the testing only went as far as to ask the divers if they were cold or not. There were no actual measurements of core temperature changes.

I could be mistaken, as I have not re-read the article. It was place in the appropriate file a while back.

All the best
CC

I only have the abstract on hand. In the study they did use rectal and skin probes and the divers went to 33 feet. I do not know what type of drysuit they were using.

As this topic of argon seems to be one of those motherhood issues and I am a wetsuit diver I will defer to one of our own Canadian technical diving experts Dr. Sawatzky who has worked at DCIEM and who has spoken and written on the topic.
Diving Myths
Argon and Diving see page 3


I would have to agree with CC in that once the fall air temp drops if you are doing two tank dives and stay in that cold wet suit on the boat you are going to get even colder. It is on those second dives where one does have to be very careful about hypothermia if you are diving wet. Best to get out of the suit, get dry, and get in a warm area if possible. Drink warm fluids. If you have a few more $$ to spend the suits which have only nylon on the outside and neoprene on the skin side make a huge difference in dry time and often they are fully dry on the skin side in less than an hour. They go by the names like Goldcore from Henderson or Glideskin from Bare. I have a nylon two side and it is often real tough to put a wet wetsuit back on and jump back in forty degree water. Kind of builds character though.

As for rewarming the car or van is great but beware of a charter boat I saw in Brockville which has a large propane heater on board in an enclosed space for rewarming divers. Maybe Kevin knows what is given off as a byproduct of propane combustion as he works on cars

 

[Tom R]

Some one call Ripley's the Pufferfish actually agreed with someone.