Thank you everyone for all the ideas. I won't criticize any of them since I asked for brainstorming; and I got it too, thanks!

My favorite one is Stepehn's suggestion of the tube that enters the inside of the beam where it will be least subject to water touching it.

Patrick, I did pressure test the hulls. There was not an above water leak where the air could enter. That was why the suction was allowing water to penetrate in the small sub-surface leaks.

By the way, I've had this problem on a few boats. The most common leak point on all of them as been the edges of the drain plug assembly. Not the plug but the base that the plug screws into. Pretty easy to repair with sand paper, alcohol or acetone, and some sealant.

Luiz, Thanks for the valve. It would require access to both sides of the hull which, I don't have. (It would also require a way to lift the small end unless the large part would be installed on the outside).

Robert, I'll certainly take a look at those valves. Might be just the thing needed but it sounds a bit larger than I hoped for.

Simon, sounds like the builder learned what I learned! Looks like they chose the driest part of the hull. This location will be easier than going inside the beam. I think I'll also use my duct tape idea to keep any additional water intrusion to an absolute minimum; only if the hole itself doesn't completely solve the problem first.

Waynemarlow, filling with epoxy and then re-drilling is definitely the way to do holes through a sandwich constructed hull.

Thanks again everyone for your ideas on how to accomplish this valve.

GARY