Here's a problem I've been having with my full body harness. In order to walk upright on the beach, I have the shoulder straps loose. Once I get out on the wire, I reach inside my life vest and snug the shoulder straps down fairly tight, tight enough that I can lay my shoulders back to flat body, and relax my stomach muscles.

BUT, when I come in off the wire for a dowind run, and try to sit up straight on the tramp, the shoulder straps are now too tight, and if I were to get off the boat with them set at the "upwind" setting, I could never stand up straight without loosening them quite a bit first. Cranking down on the shoulder straps compresses my vertebrea as well as supporting my shoulders and upper body, due to the nature of them wraping over the top of my body and going back down to the waist area.

I can really feel it in my back the next morning if I have been sailing "compressed" the day before. Is there a harness with shoulder straps or other type of upper body support that does not compress your spine when you tighten them up?