Hi Jim
I had a heap if water getting into my hulls, tried sealing everywhere and it was still coming in. Then finally worked out it was getting in through the top of my pylon. When i was flying a hull the other was well down in the water and the water was pushing up under the cap. I have sealed around the cap and i dont have a drop in my hulls after a full days sailing. The water may be getting in there.
Good Luck!!

Rat