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

[cloudflint]

Another experiment you can try to demonstrate these principles is to run your car for an hour and see how hot it is. Then take a hammer to the waterpump and run it for an hour and see how hot it is. Finally rip off one of the hoses so all the water comes out and run it for an hour then see how hot it is. You should find that:

1. with water circulating past the engine it is kept cold
2. with water being in contact with the engine but not moving it gets warmer than if water is circulated around it.
3. with no water in contact with the engine, the engine is kept nice and hot.
4. you have just ruined your car .

NOTE: do not do this!

 

[g1138]

Comparing the insulation properties of water and air, it would be better to have air as an insulator. Basic physical characteristics of heat conduction between air and water. Air conducts heat better than water; therefore air will allow you to retain your heat better than water.

If you dive in with minimal to no water in your suit, you stay warmer. Even with little to no air between your skin and wet suit, you will be warmer than with a thin layer of water.
If you're chilled between a dive, you cannot heat up the water. Even your pee will eventually chill below body temp which does more to chill you further.

The effects are better seen on a skin-in wetsuit. These wetsuits let in minimal to no water, especially if it's custom fit and if you get a pair of gloves and booties that do the same. If you're completely dry below your skin-in wetsuit, you're very very toasty. A clear way to tell is to suit up and stand in the sun. You'll be burning. Now dump a bit of warm water inside the suit, and you'll feel much better.

 

[boulderjohn]

An ideal wet suit would let no water in. The next best thing is a wet suit that allows a little water in but does not let it out. As the water is warmed by the body, it will conduct less heat away than it did upon initially entering the wet suit, but it will still conduct heat away. It will not insulate as well as the wet suit material will, so any water between you and the wet suit is a negative that you want to minimize.

People in general are told things in their training, and they tend to repeat them as truth uncritically. In my case, I heard the "water insulates" theory first, and the "no, it doesn't" theory later. I considered the two and selected the one that made sense to me. Anyone reading this thread will have to do the same.

 

[Damselfish]

This is not a myth, it's an old wives tale that won't die. Probably started by a marketing person with no grasp of physics - perhaps a relative of the one who marketed the "titanium" lining.

 

[spectrum]

Water for all intents and purposes is a comparable insulator to your mainly water body so insulating value is unlikely . The OP cites an increase in mass/thermal stability but there is also a corresponding increasse of detrimental surface area if this layer has a dimension. Water, even if contained such that there is no external exhange will remain a fluid moving body warmth to relatively colder suit surfaces. This layer of water also ensures an intimate path of conduction to the suit surface. So far I see no good coming from a layer of water.

The OP has constrained this discussion to a perfect world scenario analagous to a good semi-dry (i.e. Mares Isotherm) wetsuit. That is to say, water is likely to be admitted but exchange is low/non existent. Some users of said semi-dry suits do consider them more effective.

Also as mentioned wetsuit features are moving towards what had traditionaly been call semi dry. As wetsuits approach this more evolved ideal form the traditional analysis begins to be irrelevant.

In a common wetsuit water primes a peristaltic pump that serves to strip the diver of thermal energy through water exchange. In an ideal, zero exchange wetsuit the most you can expect is that your body will tolerate a layer of water. The water will not enhance the thermal protection as it is an extension of the body make-up.

Just say no to water in exposure protection.

Pete

 

[archman]

As others have said, it's really a question of the leakiness of the wetsuit.

Semi-Dry pwns Not-At-All-Dry. Heh.

 

[johnmckenzie]

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.

 

[Texasguy]

The attractiveness of a wetsuit solution is its price. Why it is so cheap? Because it does not use expensive methods of keeping the water out. It monetizes on not fighting to keep a wetsuit airtight but permits water in and keeps warmth that way.

Any solution you might think will not be as cheap and popular.

A possible messy solution is to use a gel with bad temperature transferring properties. Before a dive you would put it all around your body like honey, then put a wetsuit on. The viscosity of the gel should keep the water out and keep you warm. The problem is clean up afterwards and the necessity to buy more gel for another dive.

 

[johnmckenzie]

Water for all intents and purposes is a comparable insulator to your mainly water body so insulating value is unlikely . The OP cites an increase in mass/thermal stability but there is also a corresponding increasse of detrimental surface area if this layer has a dimension. Water, even if contained such that there is no external exhange will remain a fluid moving body warmth to relatively colder suit surfaces. This layer of water also ensures an intimate path of conduction to the suit surface. So far I see no good coming from a layer of water.

The OP has constrained this discussion to a perfect world scenario analagous to a good semi-dry (i.e. Mares Isotherm) wetsuit. That is to say, water is likely to be admitted but exchange is low/non existent. Some users of said semi-dry suits do consider them more effective.

Also as mentioned wetsuit features are moving towards what had traditionaly been call semi dry. As wetsuits approach this more evolved ideal form the traditional analysis begins to be irrelevant.

In a common wetsuit water primes a peristaltic pump that serves to strip the diver of thermal energy through water exchange. In an ideal, zero exchange wetsuit the most you can expect is that your body will tolerate a layer of water. The water will not enhance the thermal protection as it is an extension of the body make-up.

Just say no to water in exposure protection.

Pete

Thanks Pete. This is response is helpful in moving us forward. Could you suggest a good way of telling instructors how to explain water in wetsuits to students which could replace the original quote of "With a wet suit, a thin layer of water between the diver’s body and the suit serves as insulation."

 

[Doc]

NOTE: Please read fully before replying.

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 - BUSTED or CONFIRMED.

Thank you.

This has been done, probably by wetsuit manufacturers or some Government Agency.

First, you're going to need various remote sensing thermometers placed in a wetsuit that has had all of the leak points sealed-off with tape.

Then, takes the same diver, some period of time later, rinse and repeat... Without the sealed leak points.

So many variables here that you would need multiple subjects, which, in and of itself adds another variable... The wetsuit fit variants between subjects.

The other huge variable is that there are two kinds of people: those who pee in their wetsuits and those who lie about it.

Those remote sensors aren't going to be cheap, but there's your answer. This really has insufficient widespread public interest, so I doubt you'll talk Jamie Hynaman out of his dry suit.