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

[lmorin]

I’m sorry, but that’s flawed logic.

Whether clothing is tighter or not depends on the fit, nothing to do with the thickness. Remember with Boyle's Law an 8mm think suit will only be 4mm at 10m and 2mm at 30m. The compression happens from the inside as well as the outside so the suit feels slightly looser at depth, allowing some flushing which may not happen at shallower depths.

Actually, the logic is not flawed.

Assume equal materials in a 1 mm suit and in a 7 mm suit. The former will stretch more than than the latter because the latter resists stretching 7 times that of the 1 mm material. Therefore, the tightness will be greater for a 7 mm suit with a cut identical to that of the 1 mm. Moreover, because the 1 mm stretches more than a 7 mm made of the same material, it will be correspondingly thinner, hence providing even less insulation.

Although it might very well seem far fetched, my suggestion that suit tightness influences the warmth of the wearer is not unreasonable. Its face validity is evident from the fact that water does indeed get inside a wetsuit next to the skin and does remove body heat when the water moves outside the suit while swimming (evidenced by the fact that if you pee in your suit at the beginning of the dive, it is not still there an hour later as indicated by the absence of odor). By no means am I suggesting that suit tightness accounts for all the body heat-maintaining effects of suit thickness (my previous comment was made rather tongue in cheek), but it will certainly have some effect--at least to the extent that tightness influences water movement without simultaneously thinning the effective insulation of the suit.

 

[dfx]

Assume equal materials in a 1 mm suit and in a 7 mm suit. The former will stretch more than than the latter because the latter resists stretching 7 times that of the 1 mm material. Therefore, the tightness will be greater for a 7 mm suit with a cut identical to that of the 1 mm. Moreover, because the 1 mm stretches more than a 7 mm made of the same material, it will be correspondingly thinner, hence providing even less insulation.

No. A well fitting wetsuit won't stretch to fit. It will fit because it fits. Therefore, a 7mm suit won't be any tighter than a 1mm suit, or the other way around.

Your assumption is based on an ill-fitting wetsuit. Not a good starting point for any sort of comparison.

 

[freewillie]

Water is definitely NOT what keep you warm in a wetsuit. If so, a 3mm and a 7mm won't make any difference. And we know that isn't true

Neoprrene is what keep you warm in wetsuit. But water getting into a wetsuit is inevitable. The key here is no water exchange. Once water get in for the first time, it should be trapped inside the suit, you body warm up that small amount of water, but then it is the neoprene that insulate the outside cold water from the inside water, which has been warmed up by your body. A badly fit wetsuit with lots of water exchange is a cold wetsuit

This is perhaps the most accurate response yet. Fact, water is a poor insulator. What makes a good insulator is air. What makes neoprene a good insulator is the amount of air in the neoprene. The difference in quality in neoprene wetsuits is the quality of the neoprene but realistically it is the amount of air that is in the rubber. Also, with increasing thicknesses there is increased air between the diver and the outside water.

The better fitting the wetsuit the less water is exchanged through the suit. The best wetsuit would ideally not allow any water into the suit, and conversely poorly fitting wetsuits are the least comfortable because they large amounts of water into the suit. As the water enters it will be warmed by the body and you will have a thin layer of body temperature water. But as you move the warmed water is being moved out and cold water enters again and must now be warmed by your own body heat. The water then is stealing your body heat. So, the less water that enters the warmer the wetsuit.

Dry suits are warmer because there is no exchange of water and their air in the suit provides the insulation. But, you still need to wear layering garments under the dry suit. The layering garments are also designed to wick away moisture from the skin to prevent evaporative loss heat through sweat and also trap air in the fabric creating insulation from the cold.

 

[Primalchrome]

I've always thought of it as being akin to wind chill factor. The water really isn't insulating, the neoprene is...but if the water is constantly cycling through the wetsuit, it is taking the water somewhat warmed by the energy leeched from your body away...and replacing it with fresh cold water. If you can limit or stop that exchange logically you are allowing for a closer temperature differential between the neoprene/water/skin layers....same general concept as wind chill. >shrug<

 

[captain]

A good wet suit fits like a second skin, it minimizes the amount of water between it and the body and restricts water movement in and out of the suit. Zippers are bad on a wet suit, the fewer the better. People usually buy wet suits too big and with too many zippers because they are easy to get into and out of. A good fitting wet suit is not particularly comfortable, it is constricting. Wearing something like Nike or Under Armor compression shirt and and pants make it easier to get it on and off.

 

[jezellw]

Drink fast and you won't notice the change in temp.

 

[CT-Rich]

I have to go with the fit and thickness of the wetsuit be most important. The specific heat of water is very high. You will lose more energy heating up say, a half liter of water, than a half liter of air. Once the water is heated, though, if it is not cycled through the wetsuit out in to the open water it will retain much of that heat (Yes you will lose some heat through conduction) but that is a function of the thickness of the wetsuit. i.e. the thicker the suit (more air bubbles in the neoprene) the warmer you be. The advantage of the air in the neoprene is that air is completely static, no exchange, no flow. The down side it that it is compressible and loses gas volume / increase heat conduction with depth. As you go deeper and material gets more and more compressed, more water will enter your wetsuit. If the suit does not have the ability to allow water (or air) in, you will get a suit squeeze (just like diving dry) and lose mobility as the small airspace between your skin and suit collapse. In a proper fitting wetsuit this won't happen, even if no extra water could get in, because water is incompressible.

Exposure suits need to be selected based on the diving conditions, not on the hypothetical effectiveness of a particular suit. Diving a 30' reef in the tropics with an argon gas fill drysuit would be warmer than a 1 mm, but not necessarily more comfortable.

The old science guy in me needs to point out that a hypothesis needs to take a point of view. example: Water in a wetsuit is improves insulation, busted or confirmed?

Giving me two choices and then asking me to decide busted or confirmed, give four possible outcomes and therefore not really good science.

 

[tamas970]

I haven't browse through all 100 comments, just my 0.02$:
The real semidry suits (=good seals & waterproof zip) stay more or less dry during shallow submersion or a surface swim - this is when they insulate the best. Deeper some water will get in the suit anyway.

To the original question (help or hurt): Let's skip the case of the overheated diver, who took a 7mm suit in 30°C water. If the water is cold and the diver is shivering, of course, water - especially which is continuously exchanged - is a problem. The dry period of the semidry suits or a dry suit has a significant advantage.

Comparing semidry and wetsuits - even the best semidry ones are still no more than really good wetsuits: if water from the outside doesn't get in, sweat will. And the heat conductivity of water is far larger than of air/argon.

Which suit to wear/buy? It depends on the depth, temperature and on the personal preference of the diver. In cold/ish waters I suggest semidrys, if deep and cold meets than dry suits.

 

[Storker]

Which suit to wear/buy? It depends on the depth, temperature and on the personal preference of the diver. In cold/ish waters I suggest semidrys, if deep and cold meets than dry suits.

What's your definition of cold/ish?
IMO, Nordic waters are cold(ish). Summer temps go from 18C to ~14C bottom water with 25-15C air topside unless you dive far North, above the Arctic circle. I guess that's fairly similar to the situation in Northern USA and Southern Canada.

Unless you dive almost exclusively in the far South of the Nordic countries, where temps are in the upper range of what I quoted, I'd definitely go for a dry suit from day one. If nothing else, for the SI. And I guess most diving centers in our neck of the woods agree with me, since they generally use dry suits for their OW courses...



--
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[tamas970]

What's your definition of cold/ish?

Our swiss lakes late summer, no deeper than 20m . That's around 12-18°C. I plan to visit Alta once for king crabs - I'll definitely bring my dry and not the semidry.