Posted by right on November 20, 2000 at 18:37:24:
In Reply to: Re: Insulation posted by Gerry on November 20, 2000 at 18:04:47:
OK, I have to nit-pick here, but a vacuum isn't exactly a super insulator for heat. According to the high school physics book, heat can be conducted, convected, and transmitted (radiated). Convection is right out of this discussion (besides, it seems more like moving conduction to me anyway, but I'm no expert). So the idea is to cut down on the conducted and radiated heat. The conducted part is removing your body from physical contact with a cold object, say, the ocean. So extra "loft" will help to reduce conductive loss. However, your body also radiates heat, which is what the garments are for. They trap air, which absorbs the heat radiated from your body, keeping it nearer to you. That's why you want warmer materials (a la wool or polartech).
And I think that polartech is a trademark of one of the manufacturers, the others have different names for the same stuff. We just call it fleece.
If you really want a good suit, why don't you sew your own. It isn't rocket science, and the material can be purchased at any fabric store. I think that a fleece lined wool suit would probably be the warmest per volume, and it would even be a little heavier (more dense). You can certainly do one for less than $100, and I bet less than $50 (including zippers and elastic). And it will be the perfect size, because it's tailored specifically for you.