Light bulb goes on . . . This explains some of the trouble I was having in Florida. I'd go a little head down to put in a tie, and have to fin like a madwoman to keep from splatting my face in the silt. I've never had that trouble in Puget Sound, but I wear much more undergarment!
My air-shifting issue with light undergarments is probably mitigated by my weight belt acting as a partial stricture across the lower back when I'm horizontal.
If I wasn't using a weight belt, the shifting air could travel unimpeded in the gap next to the shell. It would quickly pass the body's usual pivot point and travel to the highest area, the shoulders or feet.
With a weight belt on, I feel the shifting air accumulate on one side of the weight belt. Of course, it will eventually work it's way underneath, through the compressed undergarment, but it's slowed down considerably.
Some drysuits, like my DUI CLx450, have an "internal waist adjustment cord", which is simply a 3/16" bungie cord installed in a channel across the back. I was wondering if this could effectively create some stricture to slow the shifting air, but it seems only capable of improving the fashion statement.
Alternatives to create a stricture to slow the shifting air could be as simple wearing a non-weighted belt cinched up around the waist.
Another would be to glue an internal cinch strap inside the suit's low back area, to be tightened in the front.
Another solution would be to improve the "waist adjustment cord" by lengthening the bungie so it could be tightened in front before zipping up the front-zip suit. That narrow a ligature might be uncomfortable, though.
I guess I'd go with a belt with no weights, 'cause I'm lazy....
Dave C
