I have never been sure how wetsuits work -- and I sometimes wonder whether they really DO work -- as far as keeping you warm.

I know that wetsuits work when you are actually in the water -- something about them trapping a layer of water between the rubber and your skin and your body heat warming that water and helping to keep you warm?

But once you are wet and are out of the water, when the wind is blowing on you and evaporating the water, it makes you very cold; doesn't it?

I know that when I wear my wetsuit when it is very hot outside, it makes me sweat, and that makes me cold.

Is a wetsuit supposed to be a little bit loose on you so you can get some water inside it next to your skin? Or is it supposed to fit like pantyhose?

How much difference does the thickness of the neoprene make as far as warmth? And what is the trade-off as far as your flexibility being limited when you have a thick wetsuit?

And, as far as warmth and comfort and durability for sailing, what are the differences between an all-rubber wetsuit, a wetsuit with cloth on the outside, and a wetsuit with cloth on both outside and inside?

These are all things I have never thought much about before.

It used to be that you would go into a Hobie dealership and try on a wetsuit, and if you could get it on and bend over and touch your toes without being launched into a backflip, you bought it.

But I suppose wetsuits and wetsuit materials are getting more advanced now, just like everything else involving sailing.

you want your wetsuit to be tight. as you stated it works by trapping water between you and the suit. the neoprene is an insulator and is what actually keeps you warm. you will feel cold when you get out of the water as the water on the outside of the suit evaporates. the heat to evaporate the water has to come from somewhere. surfers use suits that are slick on the outside so the water rolls off the suit instead of having to evaporate each time they get out of the water.

i have several suits for diving, sailing...

i have a 5mm semi dry suit which is actually a wetsuit with baffles in the sleeves and legs that slows down the water. i have been to 90 feet and surfaced after 20 minutes and still been dry around the torso. it is way too thick for sailing in tampa. it is useful because at depth the suit compresses and causes the insulation value to be reduced. for sailing (in tampa) i have a 1mm suit that i wear under a henri lloyd hammerhead top and anaconda trousers. the trousers and smock have no insulation, but keep the water off of the suit and reduce the evaporation. the suit is for the occasion when the boat flips and the water is a freezing 58 degrees. i have worn it in 60 degree air temperatures and have been very comfortable with only a bathing suit and rash guard under it. my wife (who gets cold very easily) has the same setup and it also works well for her.

the cloth on the inside helps to keep you from bathing in sweat although you will likely still need a rash guard to keep from chafing in the armpits and back of your knees. like i said earlier, the cloth on the outside serves to hold water on the outside of the suit when you get out of the water (this is bad).

as far as bending over without being launched, you are pretty much right on target. tight is good. cutting off the flow of blood to your hands and feet is bad.

by the way, a neoprene cap is one of the best ways to stay warm (besides a wetsuit). you lose something like 10% of your heat from your head due to all of the blood vessels.

dave

Mary,
I am a sailor but I also spend a bunch of time surfing. Most of the time I surf in MA or RI and the good waves happen in the winter, and the water is very cold, so I know a little about wetsuits. Surfer do not wear drysuits because sometime you need to "duck dive" waves in order to make it past a large breaking wave or set of waves. You cant dive under water very well in a drysuit. Drysuits work by trapping air in the suit and allowing your body to heat it. Wet suits work the same way with water. The reason you get hot and cold is that you are probably spending most of your time on the boat and not in the water and your wet suit is allowing the water (heated by your body) to evaporate or get cooled down by a chilly wind. Since water transfers heat much more efficiently than air, your body notices these changes faster and you get hot or cold very fast. You can also get in trouble in a wetsuit if the water is warmer than the air. A cold wind cuts through a wetsuit. Wetsuits work better up North when the water is cold and the air is warm. I have surfed in 35 degree water, in 40 degree air temp with boots and gloves and a hood and been fine more than 2 hours. I sailed at Tradewinds last month and I was close to hypothermic because I got wet and then the wind blew and I got cold fast. I was wearing the 3/2 shorty that I figured would be fine for average 70 degree weather and 75 degree water.

I have a collection of wetsuits that work great for sailing depending on the water temp and the air temp. Wetsuits also come in different thickness. Most of the wetsuits on the market are called "3/2" That means you have 3 mil neoprene in the chest and groin and 2 mil in the arms and legs. You can also get 4/3, 5/4, and even 6 mil wetsuits. The thicker the material the warmer. The newer materials have woven material in the neoprene and they are much warmer and more flexible.

Some shops sell rash guards, these are thinner cloth than help keep you warm and stop the wetsuit from chaffing you. I have a pair of Shark Skin brand rash guard shorts and they are great for keeping your groin warm and free from chaffe. This Shark skin has a softer synthetic fabric on the inside for more warmth. They make tops also.

All the wetsuits I own are have a slick fabric coating on the chest and mid section, I dont know why this made like this, but all of them seem to have it. I dont know what you are referring to with the cloth on the inside and outside question.


The secret to sailing in a wetsuit is to have a spray tosp on or a spray pants and a spray top over a 3/2 shorty (short legs and short sleeves) or a spray top over a full wetsuit if it is cold out. If you are going out on a warm day (over 75) and the wind is blowing, you can get away with a 3/2 shorty and no spray top. Depending on the conditions this is a very comfortable combination if you get it right. If you get it wrong, you will be either very cold or hot. I dont own a dry suit and I am a little uncomfortable in the fact that a dry suit might leak and then I would have no protection.

I have sailed very comfortable for long distances in the right wet suit.

If I had know that it was going to in the 40's at Tradewinds I would have brought my 3/2 full or my 5/4 with the hood.

Wetsuits should "fit like pantyhose" to use your description. They should not be loose. They should not leak, they should fit tight and have tight zippers. They should not have holes in the butt or around the zippers. You should rise your wetsuit after each use in clean water and hang it to dry in the shade. The sun will kill it and dry out the rubber. If you want to find the right wetsuit or at least learn more about wetsuits, go find a surf shop and talk to the owner. Forget about buying one anyplace else. Surfers really know wetsuits.

I like wetsuits when I am sailing my catamaran because they give you a little protection from cuts and bumps on your knees and elbows and other parts of your body that always seem to get banged up sailing or racing. I think they give you a little more protection in the groin when you spend a while in your harness.

The downside is you look really dorky at the party after the race walking around in a wetsuit. Especially if you didnt go to the surf shop to buy it and you got a neon green or neon yellow one at the Hobie dealer.... stick with black.

Thank you, Dave and bvining. That is all great information and exactly what I was hoping for. Especially interesting about the surf suits that are slick on the outside so you don't have the evaporation problem.

I never thought about the outer layer being slick either - that makes good sense. Before I had a dry suit, I used to wear a 3/2 steamer and a $20 rainsuit from Walmart over the top. The rainsuit kept the wind off the suit and made it MUCH warmer - it's important to reduce the evaporation to stay warm.

That was great advice. I'll keep mine short. I dive, surf, sail, etc.

Here in the gulf coast of TX., a tru dry suit is expensive overkill. I use my 'poor man's dry suit'. If it's really cold, various neoprene shortys or full suits, UNDER a 1 piece spray suit (water/wind proof). When it's not that cold, just the spraysuit. West Marine type, looks like a dry suit, but has velcro cuffs at the neck, wrists, and ankles.

With just the neoprene, get back on a boat from a capsize on a cold/windy day-now thats cold, like an evaporative cooler.

more like a wetbulb thermometer. the temperature will tend to drop to the wetbulb temperature. for those of you without a psychrometric chart, if it is 75 degrees and 50% relative humidity, the wetbulb is near 55 degrees.

I guess if you're trying to decide between wearing a wetsuit / spraysuit / or combination thereof, a wetbulb reading might come in very handy! Do any of the internet sites have wetbulb predictions?

Windchill is one thing but it doesn't tell you what it's going to feel like when you're wet on the boat!

Does the web bulb factor only apply when you are wearing a wetsuit, and wearing ONLY a wetsuit?

And another question resulted from a local conversation last night -- and this is about a drysuit:
If a drysuit works by your body heat warming the air inside the drysuit, will it still work if there is no air inside?
Dave White prefers drysuits to wetsuits, and he also uses a drysuit when he has to work on big boats in water sometimes up to his chest. As he goes deeper and deeper into the water, the air in the drysuit rises to the top. He then pulls out the neck seal enough to let the air out, so he ends up being sort of vacuum-packed, making the material plaster itself to his body, which makes it easier for him to work.

I asked whether he still stays warm even working in the water for an hour or more, and he said it keeps him plenty warm.

Of course, the water down here is 70 degrees, so it isn't a very good test. But I just wondered if less air in the suit would mean less warmth.

I'm asking in terms of being on a boat, not in the water. If you were in the water in a survival situation, I presume you would want as much air in there as possible, both for warmth and for extra flotation.

But I have always been very uncomfortable in drysuits, because I feel bulky with all that extra material. The "vacuum-packing" idea sounds interesting.

the 'wetbulb factor' applies whenever there is an unlimited water supply (always), air moving over the wetsuit, and the heat source is your body. it would also apply to a drysuit that is wet on the outside although the heat transfer is much slower and the effect would not be as pronounced.

a dry suit works by trapping air between the suit and your body. in the case of the drysuit, the insulation is the clothing you wear under the suit. i doubt you could float out enough ait to significantly reduce the insulation value of the clothing you wear under the suit (typically fleece or long underwear). they work very well, in fact, most likely too well for florida except when we get one of those really cold days.

my brother dives for noaa and used a drysuit for a few years when he was at woods hole in mass. he is now in florida and doesn't plan on using it until he is reassigned to somewhere cold again. he said that even his new suit sometimes leaks leaving his clothing under the suit wet at the neck and wrists.

the object is to keep the air in the suit from moving around thereby reducing the heat transfer due to convection. the problem with a dry suit is they do not breathe. any sweat will stay inside the suit and if it is not cold enough, you will become very uncomfortable.

if you are planning on staying on the boat and getting wet every so sften due to the boat flipping (like a few times a season), i would stick with a thin wetsuit and a spray suit over it.

a calculator can be found at http://www.pipingnews.com/psychrom.htm situation 3 is the one to use. it gives a whole bunch of other data that is useful in HVAC design, but not too useful for this application. for those of you who do not know, I-P is inch pound units

by the way, i read the psychrometric chart incorrectly. the wetbulb is actually near 63 degrees at 75 drybulb and 50% rh. i have been using these things for over 10 years and still misread them every once in a while. if anybody wants to see one, let me know. i can scan one and post it so you can see what i'm talking about.

Dave,

I just wanted to add a follow-up to your post on the drysuits. As you noted, the function of the drysuit is simply to keep the insulation dry. It is the insulating layers that you wear inside the drysuit that provide the warmth. Wearing a drysuit alone offers little thermal protection. This was tragically pointed out a few years ago on the New Jersey coast when a kayaker capsized in cold, winter waters only a few hundred yards from shore. He was wearing a drysuit, but nothing underneath. Onlookers at the beach could do nothing to help the man. The cold water quickly overcame the paddler and he drowned before help could arrive.

As for breathability, Goretex drysuits have been on the market for several years (at a premium price). While I have not used one, I'm told by those that do that they love them. (Personally, I've had a hard time with the idea of forking over $600 - $900 for the Goretex suit.)

Mary,
The wind chill factor and the wet bulb temperature are part of the same effect, evaporative cooling.
I think the "wind chill factor" is a wet bulb temperature specifically related to its effect on human skin.
Liquid evaporates and sucks up heat around it. Evaporation occurs at all liquid or solid temperatures. Ice can evaporate(freeze dried).
Cold does not exist, only the absence of heat.
The wet bulb factor always applies when liquid is involved. The trick is to keep the effect away from your skin.
A diving dry suit is very different from what we and kayakers call dry suits.
Diving dry suits are neoprene, with air tight cuffs, a valved air vent on the chest and the legs and arms fit tight but the torso is a little loose. They have considerable built-in insulation value. That is a relative statement because they are in 40 degree water for hours.
The diver usually wears long underwear for warmth. They can inflate and deflate the suit to adjust their bouyancy.
The dry suits we wear look like coveralls with rubber cuffs and neck. They are far more mobile than diving suits. Some are simply PVC coated nylon, like a rain jacket, and do not breathe. They can become damp inside due to perspiration. The good ones, like my Stohlquist Gore-Tex Tsunami, breathe out the sweat and stay very comfortable. They are both very thin and have almost no insulating value. If you are in the water with one of these, the air rises to the top and pushes out and the cold fabric, dry or not, is directly against your skin. We must wear insulating underwear for warmth. At a minimum I wear a duofold long sleeved shirt and neoprene shorts.
Using our dry suits requires a "layered clothing" calculation. "How cold is the air?" How cold is the water?" How wet will I get?" How fast will we be going?" "How must heat from the sun will I get?" How many times will we flip?"
The regular wet suits are popular because they are so cheap.
The diving dry suits are expensive.
Non-breathing dry suits are reasonable.
Breathable dry suits are very ($600up) expensive, but aren't you worth it?

Mary-
One suggestion about drysuits (and maybe Kevin will jump in here)- I have an older style "rubber" (ie non-breathing drysuit) and it IS bulky with lots of "extra" material in the torso. At the recommendation of a friend I got a breathable dry suit made for kayaking (stohlquist Maytag model) which has a form-fitting band around the middle for the kayak seal to attach to. This greatly cuts out the bulkiness and air trapped inside the suit. I have heard one danger of dry suits (especially the "bulky" ones) is inversion- ie floating head down - which can happen if your legs get above your head as you go into the water- all the air rushes to the legs part of the suit- One reason not to leave/let too much air in.

Kirt

Are there two-piece wetsuits -- separate bottoms and tops, so you can buy one or the other or both? I have never seen them for sailing, but I think it would give a lot more versatility as far as mixing and matching for the weather. I always used to wear a full length wetsuit, no matter what the conditions, just to protect my legs from being cut and bruised, but when it was warm I sure wished I didn't have to wear the top.

Mary,

Yes, there are two piece drysuits. (Or, at least there used to be. I haven't looked at what's out there for a while.)

More common, though, is the drytop alone. It is often worn by kayakers to keep the torso warm. (The legs are in the boat.) They are typically worn over the top of a farmer john wetsuit and do provide a measure of versatility. I will often wear a 3mm farmer john. Over that, I'll add pile layers as needed on the torso and then slip on the drytop. The downside is that it's not as completely waterproof as a full drysuit and if you spend a lot of time immersed, water does seep in, albeit very slowly.

As for Kirt's comments above about air in the drysuit, I typically squat down into the fetal position once I've got mine on, then pull open the neck gasket to "burp" the suit, releasing excess air.

Kevin, I was asking about two-piece wetsuits, not drysuits.

Yes, Mary, wetsuits are available in any number of configurations. What you will see most often are: Full-body suits, usually long-sleeve, long-legged; same, but short-sleeved and short-legged, known as shorties; Farmer Johns (think overalls - long legs and tank tops; and then jackets and shorts are also available separately. I sail in South and Central Texas, and have never felt the need for more than my shorty. If it's too cold for that (even with a spraytop over the shorty) the regatta is cancelled anyway.

good luck, Mary

Well, I want wetsuit bottom with full-length legs (not shorts), and I do not want a top. A female friend of mine wanted the same thing and could not find it, so she had the pants custom-made.

i have never seen this arrangement, but i'm sure you could have a farmer john or full suit midified at pretty much any dive shop. this arrangement will leave your torso exposed and in the event you wind up in cold water, could cause problems. if the object is simply to keep your legs dry, you might check out the henri lloyd anaconda pants. i think gill also has a similar item.

if you let us know exactly what you wish to accomplish, someone might know of a readily available solution.

Heck no, I don't care about keeping my legs dry, and they wouldn't be dry in a wetsuit anyway. The object, at least for the crew, is to protect your legs from cuts and bruises.
If I were sailing in cold weather/water, I would wear a full wetsuit, but we don't get much of either down here. So bottoms-only would be perfect. As a bonus, if I were trying to lose weight in my lower half, I could wear them to bed.