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?
