In my state of near-panic over being told I might have to be in the water for two hours at a time in the class I'm taking next month, I broke down and ordered myself a heated vest. It's polarfleece (heavy fleece) and powered by a Li Ion battery smaller than a pack of playing cards. It has three power settings, and according to the literature, will run for up to 7 hours on low (I think, from the last couple of days, that that's pretty optimistic).
Anyway, I wore it around the house last night and it worked well. Low heat was plenty, and it ran for several hours.
Today, I dove with it. It was WONDERFUL. I used it in place of the 200g Thinsulate vest I normally wear, and removed a layer of fleece underneath as well. That left my buoyancy pretty much unaltered. I activated the vest before I zipped up my dry suit. It worked well through an hour dive in 46 degree water, and then I turned it up to "medium" on the way home in the car, which was delightful.
I am going to put the battery and controller (the only water-damageable parts) in Zip Lock bags, so that it would take a water-sloshing suit flood to damage them, and if I have one of those, I suspect I have more to worry about than salt-ruined batteries.
Anyway, I wish I'd done this a long time ago.
Anyway, I wore it around the house last night and it worked well. Low heat was plenty, and it ran for several hours.
Today, I dove with it. It was WONDERFUL. I used it in place of the 200g Thinsulate vest I normally wear, and removed a layer of fleece underneath as well. That left my buoyancy pretty much unaltered. I activated the vest before I zipped up my dry suit. It worked well through an hour dive in 46 degree water, and then I turned it up to "medium" on the way home in the car, which was delightful.
I am going to put the battery and controller (the only water-damageable parts) in Zip Lock bags, so that it would take a water-sloshing suit flood to damage them, and if I have one of those, I suspect I have more to worry about than salt-ruined batteries.
Anyway, I wish I'd done this a long time ago.