Does water in a wetsuit help or hurt. A myth to be BUSTED or CONFIRMED

[Storker]

Foxfish: Good explanation. I just wanted to clarify one point, for the benefit of those who haven't dived dry suits.

A dry suit is potentially the warmest which is why they are worn in frigid conditions. There is no heat transfer through convection if the various seals hold. I've never worn a dry suit. An air gap will certainly reduce the heat transfer through conduction but my guess is that the suit would to some extent cling to the diver and at those locations the air gap would be minimal.

There are two (or three) reasons for adding air to your dry suit when descending:

• To avoid squeeze
• To keep a volume of air between your skin and the suit, thereby upholding the suit's insulating properties
• For buoyancy (and this is a point which can be debated ad nauseam: Primary buoyancy control with dry suit, or primary buoyancy control with BCD).

Some people (like me) like to add a couple of kilos of weight in the winter, accommodating more air in the suit and thus better insulation when it's really needed. And when the water is around 4-5 degrees C (around 40F) you need good insulation...

Wearing an undergarment would help to maintain the air gap and hence improve the insulation properties of the suit and minimise heat transfer through conduction.

I've never met anyone who dived dry without undergarments, whether they used a membrane suit or a neoprene dry suit. The only difference is the thickness of the undergarments.

 

[nimoh]

A dry suit is potentially the warmest which is why they are worn in frigid conditions. There is no heat transfer through convection if the various seals hold. I've never worn a dry suit. An air gap will certainly reduce the heat transfer through conduction but my guess is that the suit would to some extent cling to the diver and at those locations the air gap would be minimal. Wearing an undergarment would help to maintain the air gap and hence improve the insulation properties of the suit and minimise heat transfer through conduction.

I wouldn't go so far as to say "no heat transfer through convection". The bubble of gas in your drysuit will be above you and convection will result in the warmer gas moving up and away from your body creating a greater temperature differential with the skin of the drysuit, and then increasing conduction to the outside water. The thermal insulation you wear reduces convection by making it difficult for the warm gas to move up.

 

[cascas]

but it takes more energy to heat the water, and it then will take that heat away quicker, so air is better for warmth.
.

Hence the difference in thickness in wetsuits... thicker for more insulation.

Once the thin layer of water is warmed up, the neoprene prevents the water and you from cooling off rapidly. You will cool off, but not as fast as without suit.

Wetsuit vs drysuit... it all depends. A good wetsuit can keep you warm for a longer time than a drysuit with inadequate thermal protection underneath.

 

[Panama Jones]

I think experiment is in order.

1. Wetsuit dive to about 30 feet in cold water for 45-60 min.
2. Same wetsut, same dive, but covered with a drysut shell (no isulative value) so that the wetsuit stays dry. (make it a day apart to recover body heat)


30 feet should provide enough painless squeeze but keep the suit tight so that there is no air to insulate and compression on the wetsuit would be approximately equal. One could argue that the drysuit shell would provide some insulation value but this would not be enough to make a huge difference. In other words, if the person is WAY warmer dry, then out goes the thin layer of water theory.

i'd do it but don't have a drysuit.

 

[nimoh]

an alternate experiment would be to do the same dive in a drysuit, then flood the drysuit and do the dive again.

wait....I have done this experiment. flooded my dry suit at the end of a 20 minute dive to 110' in 40 degree water, but was perfectly warm during the dive. Decided to proceed to do the second dive after a 2 hour surface interval with wet underwear, and after about 10', got cold. Toughed it out for 5 more minutes then aborted the dive.

 

[AbyssalPlains]

There is nothing to debate. A wetsuit would keep you even warmer if there was no water between the skin and the suit. Why? Because water conducts heat much more easily and faster than air. How do I know? Just compare a wetsuit to a semi-dry and you'll know. ;-)

 

[Foxfish]

an alternate experiment would be to do the same dive in a drysuit, then flood the drysuit and do the dive again.

wait....I have done this experiment. flooded my dry suit at the end of a 20 minute dive to 110' in 40 degree water, but was perfectly warm during the dive. Decided to proceed to do the second dive after a 2 hour surface interval with wet underwear, and after about 10', got cold. Toughed it out for 5 more minutes then aborted the dive.

Spot on. There will be no heat transfer from the suit through convection in both cases providing there is no leakage. Heat is lost from the suit through conduction in both cases. Since air is a better insulator than water, a dry dry suit is warmer than a flooded dry suit.

Reducing the flow of water through a dive suit reduces the heat loss from the suit by convection. If water gets trapped between the skin and suit it will eventually warm up. It's not intended as an insulator. The warm water is just an indication that the dive suit is well sealed and is trapping in the warmth.

 

[jezellw]

Being as I seldom dive in water cold enough to really necessitate a wet suit, those times that I do wear one I have never been fine tuned enough to tell the difference. One thing though, when wearing a wetsuit and needing to pee, I really enjoy the warm and fuzzy feeling that entails when you do this. Just be sure that you are heading into the current so warm and fuzzy will be leaving around your ankles and not your neck.

 

[redacted]

Being as I seldom dive in water cold enough to really necessitate a wet suit, those times that I do wear one I have never been fine tuned enough to tell the difference. One thing though, when wearing a wetsuit and needing to pee, I really enjoy the warm and fuzzy feeling that entails when you do this. Just be sure that you are heading into the current so warm and fuzzy will be leaving around your ankles and not your neck.

Fuzzy??? FUZZY??? Maybe you need to visit the DOC.

 

[Edward3c]

I've never met anyone who dived dry without undergarments, whether they used a membrane suit or a neoprene dry suit. The only difference is the thickness of the undergarments.

When I first changed from wet to dry - it was a nice warm and sunny day, water a balmy 16'C.

I decided I’d just ware shorts for a 15m dive. In the water it was great not to hot, but when I came to get out of the suit it was stuck to my skin. I’ve always wear at least a thin full body under layer ever since.