Polypro under a neoprene wetsuit?

Your reasoning is entirely faulty.
“Who cares?” Who cares what works, that’s who cares.

Huh? A wetsuit works by providing a
thin layer of insulation. It will work on land as well as in water. Of course we do most of our paddling in “land” conditions, because we are in the boat and not in the water.

In case of a swim, the wetsuit provides two or three millimeters of insulation. If cold water gets in under the suit, that’s not good. A dry suit over polypro prevents intrusion of cold water. Polypro under a wet suit provides extra insulation, but if you take a swim, water will invade the polypro to some extent. Polypro soaked with water will conduct heat from the body much faster than “dry” polypro. But those millimeters of neoprene may be the limiting factor on heat loss.

When I read stuff about how warm water under neoprene insulates the body, I wonder how many people have actually ordered a wetsuit, used it, and taken a serious cold water swim in it. I have.

A wetsuit is a good wind barrier and insulator as long as you are dry, but water immediately gets in under your wetsuit when you take a swim. And that water initially is just as cold as if you had no wetsuit on.

Water conducts heat from your body 20 times more efficiently as does air. But having a well-fitting wetsuit will retard the rate at which water is circulating and conducting heat away from your body. There will still be water circulating against your skin into and out of the wetsuit, but at a much slower rate than if you did not have one.

Covering yourself with a thin cotton sheet in bed really doesn’t provide much insulation. It does impede the circulation of cool air against your body and thus retards convection of heat away. Neither the sheet nor the wetsuit warms the air or water next to you, obviously. Once you are no longer immersed, your body will warm the water trapped beneath a wetsuit, but it takes a little while.

Always a layer of water under a wetsuit
I was a New England whitewater boater for years. We would go out in wetsuits in February. I don’t think I have ever paddled in a wetsuit in winter without perspiring from the exertion of paddling. Hence, there is always a layer of perspiration water under the wetsuit in any paddleable climate – i.e., any climate that has liquid water to paddle.

Having polypro under the wetsuit won’t avoid this perspiration water. Nor will the polypro, when wet, serve as an air insulation layer, as it would under an outerwear shell. All you will have, in my experience, is damp polypro under your wetsuit. I have my doubts that damp polypro under neoprene will insulate better than damp bare skin against neoprene. It may be worse as an insulator.

Perhaps a layer under the wetsuit could serve as an insulator if it was effectively a very thin wind block fabric, which I think divers may call a diveskin.

I wear polypro more often than not
It seems warmer to me and you aavoid the clammy feel.

Also a diver friend told me a trick. Take along a plastic grocery sack and put it over your hand or foot before slipping it into the wetsuit. It helps the suit slip right on without bunching up the under layer if used. Once the arm/leg is in, grab the bag and pull it out the end of the sleeve and use on the next limb.



neoprene does not breathe…

– Last Updated: Aug-24-09 10:21 PM EST –

You're looking for ultra-light poly under a breatheable drytop/drysuit.

So the final answer is …
… no one knows.

(Seems to be a common final answer here.)

Some wear poly under rubber; some don’t. Some think poly insulates better than nudity; some don’t.

Having been a researcher all my life, I of course did the perfect Google search on “polypro under neoprene wetsuit”. The first hit was … haha … this thread.

(Is circularity a common phenomenon here?)

Better, if not final, answer: Get a drysuit or move to Florida.

It always 'depends’
A layer of any fabric under a wetsuit will give a more snug fit and SLOW the flushing of water through the wetsuit. Slower flushing means slower heat loss.

Don’t have your doubts. Damp
polypro between skin and neoprene will add insulating value. That’s because it will have additional air spaces. Even fully soaked polypro between skin and neoprene will insulate better than an equivalent thickness of plain water, because the fabric will inhibit heat transfer due to circulation.

I’m mainly concerned with sinking the myth that a layer of water (not just perspiration) between skin and neoprene somehow serves as an insulator. It does not. It cannot. The warmth of such a water layer represents heat loss from your body, and is a transfer path for heat from your body to the neoprene. You would be much better off with an air space than water between the skin and the neoprene, even though that air space would not feel as “cozy.”

And, of course, we should have ditched wetsuits by now. I still wear Patagonia neoprene shorts, but they do not interfere with my twisting my torso while paddling, and they mate and seal with a drytop pretty well, at least for short swims.

Thermodynamics/Thermal Mass/Transfer
You are fixated on water being an insulator not as being a storage source for heat generated by metabolism by your body and muscular exertion creating heat. Water has a much higher specific heat capacity than air. You may need to look up what that means, but the heating the water in the thin layer stores thermal energy better than heating the neoprene or displaced air. The Neoprene is the insulator. I made a company several million dollars designing automated chemical reactors. I don’t think I’m an uninformed idiot even if you do.

Fabric under the wet suit gives…
A wetsuit is supposed to fit “skin tight” which means only a “thin” layer of water can get between your skin and the neoprene. If you need fabric to make your suit fit snugger to avoid “flushing” then your suit isn’t fitting your body properly. Many people do not fit the manufacturers idea of what constitutes a particular size, a medium from one company may not be the same as from another for instance. If you are not a standard size, as many people are not, then you are a candidate for a custom made suit. Wearing polypro or another fabric beneath your wetsuit may feel better to you while paddling, but that is not the function nor purpose of a wet suit. It’s designed to help preserve body heat while in the water. In the old days wetsuits wern’t lined with fabric, it was neoprene on both sides. The lining of wetsuits came about for two reasons, one: to make the suit easier to get into and two: to make the neoprene less prone to tearing. Those of us who were divers back in ancient times, mostly agree that the non lined suits were warmer as less water was between your skin and the neoprene. Consequently, adding more fabric to the fabric already lining the wetsuit makes little sense, at least to me.

There is no point in storing heat
between your body and the wetsuit. Water in that space will conduct body heat into the neoprene faster than air. A layer of warmed water will not retard heat loss into the neoprene, it will somewhat accelerate it. A layer of polypro (if there is room, considering the fit of the wetsuit) will provide an insulating layer of air cells, and if the polypro gets thoroughly wet in a swim, it will still insulate better than just a layer of water sloshing around.

If you can show where any of this is wrong, go ahead.

Custom made wetsuit?

– Last Updated: Aug-26-09 8:39 AM EST –

I guess if you want to go to the trouble and expense to get a custom tailored wetsuit, you will have a second skin (which would be fine for DIVING, but this site is about PADDLING). Paddling in a skin-tight wetsuit is somewhat less than pleasant. My wetsuit has a snug fit, and I like the feel of polypro rather than neoprene against my constantly twisting and moving torso and shoulders. Easy to launder the polypro and just rinse the wetsuit as well.

Just wear cotton NM

agree except your last sentence
Wetsuits have their appeal and use.

Same here
The wetsuits that fit snugly enough to prevent much water entry would be tough to pull over even thin long undies.

The one suit that is too big (it’s the only one that feels like it stretched), I can fit a 1.5mm neoprene vest underneath if I want additional protection from the cold. But I’ve only done that once or twice, because when it’s that cold, I’d rather use the drysuit anyway. Meanwhile, I still use this suit in warm conditions when a little cool water coming in is no big deal.

The suits that are snug also stick to the skin very nicely with a little sweating, which helps keep water from entering. That bit of moisture seems to suck the neoprene tight to the skin. Makes taking the suit off a chore, though.

Doesn’t have to be gross at all
I paddle 2 to 4 times a week and I wash the wetsuits after EVERY paddle. It’s no big deal: take it into the shower with you, run water on both sides of the wetsuit, then rub bar soap on the “gross” areas and work it in. I use the sniff test to make sure I’ve washed it well (and my sniffer is ultrasensitive…ask my husband!)

My washed wetsuits smell like plain ol’ neoprene. YMMV, of course.