Those of us with teak decks will some day experience leaks around the hatches that are impossible to stop no matter how much gunk you put on them.
Well, there is a way. But first, why do they leak? In the diagram below, note the screw imbedded in the teak deck board. When these screws rust (yes, stainless rusts), the rust swells and opens the hole in the deck laminate enough to admit water. Of the many hundreds of screws one never knows which ones leak or where the water goes before entering the cabin. One place it will find for sure is the hatch rim mounted on top of the teak boards.
Note that on all Siltala's models since the NC32 the hatches are mounted on a ferule cast right in the deck laminate. Herein lies a big hint for us soggy Nauticaters. Come up with a way to duplicate this ferule and we too will be without leaks.
Bill Adams on NC33 KINSHIP and Campbell Tellman on NC 33 DULCINEA plus Judith and I on NC33 WESTWIND have dismounted the hatches and cast a fiberglass rim upon which to remount the hatch. All of us have enjoyed drip-free hatches at long last. Bill and Campbell have cast their rims in a mold and applied them to the deck laminate after cutting back the teak just the right amount.
I have done the same by cutting back the teak with a router guided by the inside edge of the finish molding and set to skim the gelcoat surface. Using epoxy resin mixed with a filler, I cast the rim in place between the new edge of the teak boards and a spacer taped to the finish molding. Then, as you can see in the diagram, the rim is bonded to the deck laminate and the hatch frame is sealed to the rim with adhesive caulk. I have put only 4 short screws into the new rim so as not to invite new leaks. Two of these are at the hinges.