An answer for my centerboard trunk leak problem ?

Without a doubt, 5200 is the answer. It is the favorite among boaters, both wood & fiberglass. It is a caulking/sealant/adhesive and can be applied underwater. In fact, water helps it to cure. It is a 3M product and available at boat supply stores and hardware stores in various sizes.

Warning, it sticks to everything. I mean; fingers, hair, pants, shoes. But it can be cleaned with mineral spirits before it cures.

I've done some volunteer work at the NC Maritime Museum. They use a product called "5200". It is a sealant for just the problem that you describe. It is applied at the time of construction. You may have to do some destruction in order to correct the problem. I don't remember the company's name that manufactures the product. It may be 3M. Ask your local boat building supply company.

Good luck,

Andy 

I have a clinker granny-pram very similar to yours (though a bit smaller at 7 1/') which I use as a dinghy for my larger sailboat.  I had the same issue with leakage, and I resolved it by putting a clear epoxy fillet with fiberglass tape around the base of the trunk, a good coating on the inside of the trunk where it joins with the bottom, and also the front and back of the trunk itself.  One issue with these boats is that the trunk is not all that secure (usually braced against the bottom of the midships thwart), especially from side to side stresses caused by the board, so you might want to consider putting in a couple of small knees athwartships on either side of the trunk to give it additional support.  Also, unless your bottom is well-reinforced with a kelson, there is a lot of flexing of the bottom going on from grounding and generally batting around.  And of course, if you run aground at a rate of knots with the dagger-board down, you will be lucky not to destroy the trunk entirely, as well as the board!

I lived in southeast Alaska for 28 yrs and always had a boat. I never had good luck with silicone as a leak preventer.You may want to rout out a V groove around the seam of the trunk on the outside and fill it with an epoxy/micro balloon putty mix. Maybe this winter after your boat is completely dry. If you can't access the seam from the outside try doing the same thing to the joint on the inside maybe using a dremel to open that seam and get the caulking material into it. Its very difficult to force any kind of sealant into a crack. Also is your centerboard trunk braced well enough that while sailing its not working from side to side and opening up that seam? I agree ,those little skiffs are fun. We had a Pelican in Sitka. What a solid little ship. BILL