Lot's of points to cover as this thread has wandered all over the place.
First, as far as a non-hooded apnea suit goes, look at some of the Picasso models on the DB store. Ted, UNIRDNA, has one and it works out really nice for trips and summer diving- it's a one piece 3mm with opencell inside. For a warm water hooded suit look into some of the 1mm Riffe suits.
Second, as far as suits in warm water goes, I always used a suit, and a hood, on my warm water scuba trips. I also know of another instructor, from Wisconsin, who uses a 7mm jumpsuit and a 3mm beanie when diving in 84 degree water (F) down in Cayman. The reason we wore our warm suits in warm water was because we were doing 90 minute photgraphy dives, meaning little or no movement, 4-5 times a day. Over the period of a week this starts to take a toll on you. Some people would make fun of me at first when they saw the suits we would wear, but when our dives are, consistantly, 40 minutes longer and we STILL come back with more air in our tanks they would start to understand why.
Third, I wear a much thinner suit for freediving and stay much warmer than I do when scuba diving, and still overheat. Even in winter when we freedive I just need to swim for a few minutes to warm up. I recently ran a bunch of long-time scuba divers through some freediving training and the first thing they realized is that they can get by with a MUCH thinner suit and less weight.
Fourth, everything I had read, and experienced, when it comes to cold adaptation, states that the more you exercise in cold weather the more accstomed you get to being in it. It shouldn't surprise anyone that a couple of Canadian's can stay warm in water that scares off the Texans, but I wonder how well the Canadians would do when working out in extreme heat if not properly adapted???
One thing I have played around with on cold nights in Wisconsin is to simply do a couple of breath holds to contractions to warm when I am cold- it works! Not as much fun as shared body warmth, but it still does the trick.
Fifith, Moving water sucks the heat away quick! All you need to do is borrow a dive scooter some time and see how much faster you cool down compared to just swimming, or even sitting still at static. Hanging out in a 72 degree stream of high flow water would seem to cool someone off quite quickly- which is why the extreme cave divers down there use argon in their drysuit along with their thinsulate underwear.
Jon
