Thanks SD. I have NO experience with them, so I appreciate the note about breaking water. If they're not TOO sensitive to water over the deck, then they should work just fine. I just don't want to have to close it every time we're beating to windward in 15 knots of wind. The idea is to have it open all the time, afterall! I don't mind closing the vent on the occasion that we're really in some nastiness.
The location on our boat will be on the cabin top, forward of the mast and off to one side (starboard in our case). So it will be somewhat sensitive to spray, etc.
I've heard of other venting the Airhead into the anchor locker, which we could do, but I don't really like the idea. I'd prefer the vent be exhausting out into the open.
1984 Sabre 34 Mk I