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

[johnmckenzie]

NOTE: Please read fully before replying.

TRUE OR FALSE: "With a wet suit, a thin layer of water between the diver’s body and the suit serves as insulation."

It seems like a simple question and you probably have an opinion. But please read on. I've found that it is not so simple. The head of a major training agency calls this "one of the most long-standing debates in the scuba industry." He wants to have it resolved. So here is your chance to a be a true Mythbuster. Give us some science.

When we put the question on dive forums we get many passionate opinions on both sides, but respondents have not come up with anything conclusive. Some are convinced its a total myth and[FONT=Helvetica, Arial, Droid Sans, sans-serif] that "water always draws heat away from your body." Others say that a small amount of water in a modern wetsuit can help keep you warmer.

Even the experts differ. One respected researcher on diving physiology says it used to be a myth but that is changing with modern wetsuits. He says "[/FONT]that increasing your fluid volume will increase your total volume and thus your thermal inertia (stability).[FONT=Helvetica, Arial, Droid Sans, sans-serif]" He believes that water can help and can be heated above skin temperature in a wetsuit. But a professor or thermo-phisology and expert cold water survival says no you can't. He said, "if that were the case, why don't I cut a hole in my drysuit."

More confusion ensues because the term insulator (and cold) are only relational definitions. Water is an thermal insulator when compared with copper, but a conductor when compared with air.

But the bottom line questions remain, "does a thin layer of water in a well fitting wetsuit help at all?" and if so, "does the water help enough to be significant?" A more basic way to phrase these questions may be, "will a person stay warmer in a completely dry wetsuit or in a wetsuit with an unchanging thin layer of water."

Please reply with facts, science and research that can help divers and new students finally have an answer to this question. Please try to avoid replying with just another opinion. We need a strong enough scientific case that will finally call this myth -[/FONT] BUSTED or CONFIRMED.

Thank you.

 

[HowardE]

Wetsuits work on the principal of the thin layer of water between the suit and your skin is what creates the thermal insulation. You want a suit to fit so that you'll be a little wet, but the water shouldn't be exchanged. Meaning. You don't want the water to get flushed out regularly or that the water is trapped between the neoprene and your skin.

This is why wearing a lycra skin will result in less insulation than wearing additional layers of neoprene.

 

[fjpatrum]

Wetsuits work on the principal of the thin layer of water between the suit and your skin is what creates the thermal insulation. You want a suit to fit so that you'll be a little wet, but the water shouldn't be exchanged. Meaning. You don't want the water to get flushed out regularly or that the water is trapped between the neoprene and your skin.

This is why wearing a lycra skin will result in less insulation than wearing additional layers of neoprene.

Or could it be that lycra doesn't insulate as well as neoprene of the same thickness does, with or without the water? That's the problem with this "myth". It's hard to disprove because any method of changing the system under test necessitates a change in the system properties.

Neoprene holds air (or water) in the material. It's that air or water that provides the insulation, not the air/water against your skin... or some say. That said, when there is an exchange of warm water/cold water within my suit I definitely feel it.

I have no horse in the race; as long as I'm warm I don't give a damn whether it's from the water in the suit or the water against my skin. Other than wetsuit manufacturers trying to get better performance, I don't know anyone personally who actually does care.

 

[Malpaso]

It's as simple as asking if ice keeps drinks in your cooler cold. The obvious answer is yes, but, there's a diminishing return. If the drinks start out at a higher temperature than the ice, they cool, but the ice will melt. The drinks then become warmer.

Similarly, initially the warmth of your body heats the water layer in your wetsuit, but eventually the body, like the ice in a cooler, can not keep up the process. The water then cools down. The body then becomes cooler.

 

[CT Sean]

Wetsuits work on the principal of the thin layer of water between the suit and your skin is what creates the thermal insulation

This is what I always heard (and likely most divers have heard as well) but my opinion - (the one I realized wasn't asked for) is a myth. If it were true then wouldn't a 3mm and a 7mm wetsuit with equal "water trapping" ability provide the same thermal protection? Plus given the fact that water is a pretty good conductor of heat, It's hard for me to see the logic that taking a conductor and putting it in a human shaped neoprene sack turns it into an insulator.

 

[dfx]

It's a myth. Water isn't a thermal insulator, it's rather the opposite, a pretty good thermal conductor. Water draws heat away from your body -- but only if the water is colder than your body. In other words, your body will try to warm up the water. The less water you have around your body, the easier and faster this will be, and the less heat your body will lose in the process. Good fitting wetsuit = less water = less heat loss.

Once this is done (water inside your suit is up to or close to body temperature), then the wetsuit will perform its insulating function. It will prevent the water around your body from giving off the heat through the neoprene to the surrounding water (ocean, lake...). Which is why more neoprene = better insulation.

Take the water inside your suit out of the equation and nothing changes. It will still be the neoprene providing the thermal insulation. The only difference is that your body won't have to warm up a layer of water first.

 

[cloudflint]

Given my understanding of physics and my experiences of how loudly I scream when I hit the freezing cold water around here:

Assuming the same thickness of neoprene, I would be warmest in a wetsuit with no water in it i.e. a drysuit since the air conducts the heat away from my body much slower than water.

Next up for warmth would be semi-dry i.e. water in the suit but not flushing through. Admittedly it will pull heat away from my body pretty fast to start with but so long as the seals on the semi-dry keep the water from flushing out then once the water has heated up the speed at which it pulls heat out of my body will slow down dramatically.

Lastly for warmth would be wet suit i.e. a layer of neoprene with no seals on it. With this heat would be drawn out rapidly by the cool water and as it flushes through the suit would constantly be replaced by cold water resulting in heat being drawn out rapidly from my body.

Thats always been my understanding of it at least.

 

[Gachnar]

If you really want to scientifically measure the difference you need a 7mm neoprene drysuit and a 7mm wetsuit with thermal sensors inside to read the temps. But it isn't necessary as the science is pretty simple. We all know water conducts heat better than air, and that air is the better insulator. The water inside a wetsuit and the air in the drysuit are both heated by the body, but it takes more energy to heat the water, and it then will take that heat away quicker, so air is better for warmth.

Try this experiment. Stand outside in 80 degree air for 3 hours and see how you feel, then sit in 80 degree water for 3 hours.

 

[nimoh]

If you really want to scientifically measure the difference you need a 7mm neoprene drysuit and a 7mm wetsuit with thermal sensors inside to read the temps. But it isn't necessary as the science is pretty simple. We all know water conducts heat better than air, and that air is the better insulator. The water inside a wetsuit and the air in the drysuit are both heated by the body, but it takes more energy to heat the water, and it then will take that heat away quicker, so air is better for warmth.

Try this experiment. Stand outside in 80 degree air for 3 hours and see how you feel, then sit in 80 degree water for 3 hours.

I agree, and might add that I like this explanation.

However, in your experiment, the water would be allowed to circulate. Perhaps a better experiment would be to sit in the 80 degree water in a neoprene drysuit for 3 hours, then later, completely flood the drysuit, seal it back up and see if you can last 3 hours

 

[redacted]

Water is a rather poor insulator. Air is much better.

Thermal Conductivity of some common Materials and Gases