wetsuit vs cold air

[debajo agua]

Awhile back, my gf asked me, if wetsuits work so well in the water, then why don't people using them when dealing with the cold outside the water? Needless to say, I didn't have a good answer for her. Yesterday, I got some first hand experience of being perfectly comfortable in the water with my wetsuit, but 10 minutes out of the water, and I was cold. I pulled my wetsuit down to my waist, dried off, and put my jacket on, and in a few short minutes, I was comfortable again.

I think I understand the concept of a wetsuit i.e. to create a thin layer of water between the body and suit, and once that thin layer is heats up, heat loss from the body will be minimized.

So my question is, why won't this same concept work in a dry environment
i.e. once you get out of the water? I suspect evaporation is at play here but I have a well constructed suit with a good seal, in other words, i don't feel like my suit is allowing for evaporation to be a factor. Does anybody want to take a stab at the physics going on here?

As always, TIA

 

[AfterDark]

Awhile back, my gf asked me, if wetsuits work so well in the water, then why don't people using them when dealing with the cold outside the water? Needless to say, I didn't have a good answer for her. Yesterday, I got some first hand experience of being perfectly comfortable in the water with my wetsuit, but 10 minutes out of the water, and I was cold. I pulled my wetsuit down to my waist, dried off, and put my jacket on, and in a few short minutes, I was comfortable again.

I think I understand the concept of a wetsuit i.e. to create a thin layer of water between the body and suit, and once that thin layer is heats up, heat loss from the body will be minimized.

So my question is, why won't this same concept work in a dry environment
i.e. once you get out of the water? I suspect evaporation is at play here but I have a well constructed suit with a good seal, in other words, i don't feel like my suit is allowing for evaporation to be a factor. Does anybody want to take a stab at the physics going on here?

As always, TIA

If water can get in then it can evaporate out. Evaporation is what keeps us cool.

 

[vladimir]

I think I understand the concept of a wetsuit i.e. to create a thin layer of water between the body and suit, and once that thin layer is heats up, heat loss from the body will be minimized.

That is the misconception of how a wetsuit works. It actually works because the nitrogen bubbles in neoprene are good insulators.

So my question is, why won't this same concept work in a dry environment

If you don your wetsuit on a hot day and wait a while to dive, it will quickly become apparent that they are good insulators in a dry environment as well.

I suspect evaporation is at play here but I have a well constructed suit with a good seal, in other words, i don't feel like my suit is allowing for evaporation to be a factor. Does anybody want to take a stab at the physics going on here?

Your suit dries as you sit on the boat post-dive, doesn't it? Then evaporation is a factor. It is drying by evaporation and removing heat from your body as it does.

 

[spectrum]

Vladimir nailed it...

1) The water in your wetsuit has no insulating value, at best you are tolerating it and the less the better.

2) It's the gas bubbles in the suit that provide the insulation and it sure does work topside.

3) Once wet on the outside evaporation cooling overwhelms the suits insulating capability and you ability to warm yourself. Get out and dry off or at least cover up to dry the outside and limit the airflow against the wet suit.

Pete

 

[DA Aquamaster]

Some wet suit history before we get to the problem and the solution.

The early wet suits had no nylon at all and were just cut from a sheet of neoprene. Some were textured on the outside and the material had names like "sharkskin", but the reality was they were not overly durable and were prone to getting a nick, that could then quickly become a tear when pulling it on or off.

Then came "Nylon I" wet suits, which had stretchy nylon fabric glued to one side of the neoprene to 1) make it easier to slide into and 2) to add some strength. The downside is that the nylon fabric was largely unidirectional in terms of stretch, so the suit was less flexible than a sharkskin type suit, and while stronger, the outside was still relatively easy to damage.

Then there was "Nylon II" wet suits that had nylon fabric on both sides. That allowed for a suit that was better protected, but even less flexible and more challenging to fit as there was a thin line between large enough to get into and too large and cold during the dive. the popular colors at the time were blue and black and I was advised way back in the day that the reason for that was that the nylon fabric dyed with those colors retained a bit more stretch than with other colors. I have no idea if it was true, but it made sense at the time.

The other factor here, the one relevant to the thread, is that, unlike an outer surface of plain neoprene that shed water and dried very quickly, the nylon surface of a Nylon II suit held moisture and became what amounted to a whole body swamp cooler. So in the summer, if you are suited up on the dive boat for the first dive, you'll get really hot. However on the second dive, with the suit wet/damp you stay much cooler.

Modern wet suits use Lycra or other fabrics that are bi-directional in stretch and the neoprene is generally softer and stretchier itself as it does not have to be as strong, so the suits are quite flexible, but they still have the swamp cooler effect. However, if you can reduce the evaporative cooling you can stay warmer in the suit without taking it off. The Surf-fur style boat coats are better than nothing by reducing air flow on the suit fabric (and it adds some insulation) but you can also just use a waterproof rain suit - the kind made of treated or coated nylon. A rain jacket and pants will cover all of the suit and prevent evaporation and will be small enough when rolled or folded to fit in a small bag. In this case, cheaper is better a a breathable fabric like Gor-tex is not what you want as breathable = evaporation. You want something you'd sweat to death in on a hot, humid rainy day. Then if you have one a Sur fur over the top will keep you even warmer.

You may still want to take the suit off depending on the circumstances as there are some points of diminishing returns with either strategy in terms of temps, times, locations, etc, but a nylon rain suit can add to your list of options for very little cost.

 

[Lorenzoid]

Standing around in a wet wetsuit will chill you because as the water evaporates it takes heat away from your body. Water evaporates from the outside of the suit, which takes heat from the suit. Water also escapes through the seals, as good as they may be, and air gets into the interior in its place. Your body warms the water on your body's surface, and more evaporations occurs inside the suit; the vapor escapes through the seals. It also depends on the thickness of the wetsuit. You could probably stand around in a thicker wet wetsuit longer than a thinner wet wetsuit before you would feel chilly. Even the thickest insulator (that is, a poor heat conductor) will slowly conduct the heat from your body to the environment.

If your question is why wetsuits aren't used on dry land to insulate against cold, well, I suppose they could be. But a down jacket would be lighter and more comfortable for a given amount of insulation.

There was a good thread a few months ago about "how wetsuits work" that dispelled the myth (which I had believed, because my instructor had told me so) that it has something to do with the thin layer of water between you and the suit. You could search for that thread, but I think people have already repeated the wisdom here. The "thin layer of water" thing is a total myth, perpetuated even by instructors. Neoprene is a closed-cell foam, which means it is full of trapped bubbles and, generally speaking, it insulates in the same way that most air-based insulative materials work, including things as straightforward as a down jacket or blanket. Neoprene is used as an insulator in other products; it isn't unique to wetsuits. For example, it's used to make pads to keep a camper in a sleeping bag insulated from the ground. Neoprene is a favored wetsuit material because it's insulative, flexible enough to make a suit out of, and relatively economical.

 

[ermaclob]

one time for fun on a cold windy day here in miami. i put on my wet suit and then normal cloth over it. then went out for half the day. it was a very rare day, ~55 - 60 degrees in the morning. i felt very nice, some times to warm. granted i wasn't wet.

 

[CindyMac]

For "a woman of a certain age" and living with hot flashes and the like, I gotta say I stay warm in mine. I actually got a little warm this past Sunday afternoon/late evening as the hot flashes were particularly vicious. Air temp was low 60s. :hehheh:

 

[fnfalman]

Google "Evaporative Cooling Effect" and then you'll know why wetsuits (or wet clothings) against your body is no bueno.

 

[Rhodesaz]

For "a woman of a certain age" and living with hot flashes and the like, I gotta say I stay warm in mine. I actually got a little warm this past Sunday afternoon/late evening as the hot flashes were particularly vicious. Air temp was low 60s. :hehheh:

That's the main reason I hug my wife at night during the winter!!! LOL