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

[boulderjohn]

Thank you all for the interest. However the responses so far are an fine example of the problem. People look at the question and pick the one that make the most sense to them. We really need some science here. Has anyone done or know someone that has done experiments that would lead us to a resolution. Even though it SEEMS logical that a person would stay warmer in a completely dry wetsuit or in a wetsuit with an unchanging thin layer of water; some of the experts we talked with say that may not be the case.

One expert says this: "that increasing your fluid volume will increase your total volume and thus your thermal inertia (stability). It is theoretically possible for a suit with good seals to allow in a relatively small volume that could be more or less preserved (or at least, convective losses minimized). This, conceptually at least, is similar to increasing your total volume. It is not that you would warm the water in the suit higher than skin temperature, but that you would slow the rate of skin temperature decline. The trick is that it would take a very good suit to make this combination work."

So again. Does anyone have the studies to help those who write the curriculum be sure of one way or the other.

Maybe I'm not reading this well, but the expert you cite seems to be saying the opposite of what you think. Take a look at these sentences: "It is theoretically possible for a suit with good seals to allow in a relatively small volume that could be more or less preserved (or at least, convective losses minimized). This, conceptually at least, is similar to increasing your total volume. It is not that you would warm the water in the suit higher than skin temperature, but that you would slow the rate of skin temperature decline."

As I read it, it is saying that water is not good, and that the best you could do, in what is later called "a very good suit," is minimize the amount of water in so that the problem of heat loss through water is minimized. Your expert is NOT saying that in a wet suit, a thin layer of water keeps you warm.

 

[archman]

I'm not entirely comfortable speaking for the physicist community, but I am of the assumption that a "study" like this would be more of a word problem in an upper level college class. Seems like all one has to do is enter in several variables and plug into a equation.

Speaking as a marine biologist, water is superb for heat storage. It's well known that critters with a low surface:area volume ration but high overall fluid volume are optimal for reducing heat loss. Ergo, if John Doe *seals in* some water in his suit, he's effectively turning himself into a fatter and better insulated manatee.

Which is exactly what was posted here:

One expert says this: "that increasing your fluid volume will increase your total volume and thus your thermal inertia (stability). It is theoretically possible for a suit with good seals to allow in a relatively small volume that could be more or less preserved (or at least, convective losses minimized). This, conceptually at least, is similar to increasing your total volume. It is not that you would warm the water in the suit higher than skin temperature, but that you would slow the rate of skin temperature decline. The trick is that it would take a very good suit to make this combination work."

 

[dumpsterDiver]

The increased volume of water leaked into the suit does not increase your thermal mass. It steals heat to warm it.
Water is an excellent conductor, it is not an insulator.
In a good fitting wetsuit, the volume of water that leaks in is minimal.
If you a have really loose wetsuit, it may help to wear a sweater or wool garment under the suit to trap water and to primarily prevent it from being pumped out of the suit when swimming and moving. IF you fill the suit like this with warm water (from an external energy source) then the suit will be warmer than otherwise.
Loose wetsuits should be avoided if you want to stay warm.
A perfectly sealed wetsuit that leaks no water can be a problem. I have experienced some terrible nut squeeze in a very good freedive suit. It may help a lot to piss or to add a tiny bit of water to prevent a squeeze "down there".
And how the heck would water be warmed by your body above your skin temperature.. that is plain silly.
Also, you normally need to allow some water to enter the hood, or you will get an external ear squeeze.

 

[manni-yunk]

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.

Except that your body is a machine that is continuously generating heat while the ice is finite in its ability to maintain temperature and destabilizes quickly. The ice itself in you analogy has no other cooling forces acting on it, and heating occurs. THe body continues to have heat generation. The question is the suits ability to capture and take advantage of that heat.

 

[dfx]

The increased volume of water leaked into the suit does not increase your thermal mass. It steals heat to warm it.

However, after you have warmed up that water, it will take longer to cool it down if the volume is larger, thus it will retain warmth better. I think that's the point that was meant to be made.

But that's a moot point. It only matters if the outside temperature would suddenly drop, and even then would only have an effect for a short while.

The amount of water present really doesn't matter much. The only difference it makes is: it increases your surface area, thus increasing heat convection. And it's likely to have a negative effect on the seals, thus increasing water exchange with the surroundings.

 

[billt4sf]

I got this one.

I'll explain the science, but you actually don't need science to answer it. Just consider a loose-fitting wetsuit. It will not keep you warm, because cold water has more space to enter and exchange with the outside cold water. Thus, it is not the water that insulates, it is the neoprene. So when you buy a wetsuit, get a good fit!

Heat is the random kinetic energy of molecules or atoms. It can be exchanged by three methods: conduction, convection, and radiation.

The science part is just that the wetsuit shuts down the heat convection to the surrounding water. That's the primary benefit of the wetsuit. In a good-fitting wetsuit, a small amount of water enters and your body heats it up until it is a near-thermal equilibrium with your skin. Consider a greenhouse. Why is it warmer inside? The sun heats up the air and it cannot be lost to convection because the air doesn't escape. Same for a wetsuit -- the warmer water next to your body can no longer be convected away.

[Technically, and to answer the original question, it doesn't matter if there is water next to your body or not. In either case, the convection is (mostly) shut down.]

Now, conduction. Water is a better thermal conductor than neoprene is. One might ask: why is water better conductor of thermal energy than neoprene? That has to do with how well or poorly the molecules and atoms of water and neoprene can be jostled by the kinetic energy of the random (heat) motion of the surrounding atoms. When a water molecule hits into another water molecule, it jostles it and heat (kinetic energy) is conducted -- bang, that water molecule shoots away, to hit another one. That's heat conduction. When a water molecule jostles an adjacent atom of neoprene, the neoprene atom doesn't move as much and heat is not as easily conducted.

Shall we talk about radiation now?

I hope that helps.

Bill

 

[archman]

The increased volume of water leaked into the suit does not increase your thermal mass. It steals heat to warm it.

Your mass overall increases, as water has mass. Regarding heat loss, that is an *initial* concern, but once you have reached thermal equilibrium (which any endotherm can accomplish), your overall thermal "heat capacity" (to be technical) increases. Heat in living organisms is not a static value but a positive rate, so all a critter has to do with (sealed water) in the wetsuit is slowly "conduct" heat into it until you hit equilibrium.

Water is an excellent conductor, it is not an insulator.

I believe there is some cross-purpose miscommunication with these terms. Water has very high heat capacity at the molecular bond level. This makes it a superb substance in living organisms to stabilize internal temperature. This is one of the primary reasons that all living organisms retain liquid water volumes of over 70%. An "insulator" is a substance that by definition also is an environmental stabilizer.

Ipso facto, if water in your wetsuit *leaves your body*, you lose the heat energy you imparted to it. That would be heat loss via "conduction".
Conversely, if water in your wetsuit *stays in your wetsuit*, you retain the heat energy you imparted to it. That is still "conduction", but functionally speaking you are just shifting more energy into an adjacent tissue compartment. You don't lose any heat at all, and in fact increase your "insulation" capacity. You are creating a blubber layer.


So, leaky wetsuits suck. Semi-dry wetsuits suck less, and may actually help you stay warm. If you *really* want to insulate yourself, flood your drysuit with hot water and hope your metabolism doesn't exceed the heat loss to the ocean (else you'll bake yourself). It is possible (and fairly common) for an organism to overheat due to inability to export metabolic heat.

Nut squeeze sounds terrible.

 

[dumpsterDiver]

Your mass overall increases, as water has mass. Regarding heat loss, that is an *initial* concern, but once you have reached thermal equilibrium (which any endotherm can accomplish), your overall thermal "heat capacity" (to be technical) increases. Heat in living organisms is not a static value but a positive rate, so all a critter has to do with (sealed water) in the wetsuit is slowly "conduct" heat into it until you hit equilibrium.



I believe there is some cross-purpose miscommunication with these terms. Water has very high heat capacity at the molecular bond level. This makes it a superb substance in living organisms to stabilize internal temperature. This is one of the primary reasons that all living organisms retain liquid water volumes of over 70%. An "insulator" is a substance that by definition also is an environmental stabilizer.

Ipso facto, if water in your wetsuit *leaves your body*, you lose the heat energy you imparted to it. That would be heat loss via "conduction".
Conversely, if water in your wetsuit *stays in your wetsuit*, you retain the heat energy you imparted to it. That is still "conduction", but functionally speaking you are just shifting more energy into an adjacent tissue compartment. You don't lose any heat at all, and in fact increase your "insulation" capacity. You are creating a blubber layer.


So, leaky wetsuits suck. Semi-dry wetsuits suck less, and may actually help you stay warm. If you *really* want to insulate yourself, flood your drysuit with hot water and hope your metabolism doesn't exceed the heat loss to the ocean (else you'll bake yourself). It is possible (and fairly common) for an organism to overheat due to inability to export metabolic heat.

Nut squeeze sounds terrible.

Water conducts heat; it is not an insulator. You seem to confuse heat capacity with thermal insulation capacity.

also, flooding a typical dry suit with warm water will NOT keep you warm! Flooding a WETSUIT with warm water may keep you warm. They make commercial hot water suits...

Flooding a tri-laminate dry suit with warm water will cause you to conduct heat much faster into the surrounding water.

 

[archman]

Heat = Thermal.

Capacity = Storage

Insulation = Environmental Stabilizer

I have some openings available in my Majors Biology class if you are interested in Properties of Water as they relate to living organisms. I can also recommend a Comparative Animal Physiology course from one of my colleagues. It doesn't close enrollments until Thursday. Heh.

 

[dumpsterDiver]

This is thermodynamics not some silly biology class where you misapply terms to suit your argument.