@mark2
tomorrow I am shutting down for a week for surgery. If you do not find those leaks, send me a private email in about two weeks and I will respond back. Crazy Dave
Dave, thanks for the brilliant idea of pressurizing the hull and using soapy water. It did not reveal anything (directly)... smeared soapy water all over the inside of the centerboard slot with the board removed (most likely leak location). Tight as a drum, not a bubble to be found. Went under, went from the topside. Nada. Soaped the entire exterior hull. Nothing.
But... I did notice that at the top rear of the centerboard slot the top hull is glued to the vertical walls of the slot. It is not clear if this is intended to be water tight, I think it is above the water line by a fair bit. But there was plenty of air coming through that joint (I could hear the air rush). It must be this, but I thought this was above the water line (maybe it splashes a lot up there?).
Now how to fix (assuming this is the problem)? First, is 3M 5200 sealant a good choice? I have used it elsewhere on the boat and it seems to remain flexible and holds up well. Second, how in the world to get it there? It is at the top of a 2 foot slot that is only about 2-3 inches wide. I don't think the caulking tube would fit, much less my hand/arm. Any tricks/suggestions for caulking is such a tight space?
I sure hope this is it... the wife is threatening to sell the boat if we cannot find the leak!