at least of the bunch I've known over the years.

I could be wrong, but of all the sailors I've met over the years, they're in pretty good shape, weight, as a group compared to the general population(more people motorboat). But again I can make no connection between the two.

Perhaps one. There's quite a lot of schlepping that goes with sailing and or cruising. Seems you're always hauling or otherwise moving stuff from ship to shore, and back, if you sail. Maybe just the fact we do that means we're willing to expend more energy in our general lifestyle, walk more, etc?

Somebody ought to do a study.