The stage on the Temptress is inside. Wind shouldn't be too much of an issue even though they do open up the windows for air flow.
I think I preferred the stack tape just because the crowds on the boat tend to be a little "chatty" (imagine that on a booze cruise ).
I tape on this boat a few times every year:
http://www.blidosundsbolaget.se/index.phpScott is right on. The passengers aren't always into the music, since companies bring their staff for booze cruises. There's a lot of walking around, huffing and puffing, and spilling beer on other passengers if you're close to a staircase or a door, steer clear of those areas. The rockier the ride gets, the more beer gets spilled. Cover your gearbag with plastic if you're at risk! ;-)
Anyway, you should make sure to be there early, if possible before the doors open. It's tricky to find the sweet spot on a boat because of space constraints, and it also depends if it's an "all seated" gig or not.
And don't be late! You can't "walk in" once the boat takes off! ;-)
I never had wind issues either, although the windows are usually open here too.
The nice thing about boat gigs is that the band have to make their way from the dress room to the stage, so you get a chance to meet and talk to them...
Good luck!