Deck/hull joint care

Because of the outward turned flange design of the Hull/deck joint any impact to the rub rail can damage the sealent and cause leaking.This and the windows contrubute to most of the water that gets in.The best thing I ever did to my Laser was glass the hull/deck joint.Remove everthing you can to expose the joint from the inside and cut out as much of the old caulking as possible. I then ground the area three inches above and below the joint from stem to stern. You can start and stop at each bulk head and get behind the galley unit by removing the acrylic pannels, wood dividers and white plastic trim in there.I then filled the joint with a thick putty of epoxy, cabosil and chopped strand to almost flush with the inside of the hull.Do this in sections and before it sets apply three layers of glass tape starting with 3inch then 4inch and finally 6 inch. The job sounds worse than it is.Can be done in a couple of days. The result is stiffer and drier boat

I have been researching the idea of water proofing the joint, my aft berth (port) side has some leaks but the rest of the boat is solid and dry. So I was thinking of doing the same but I was also wondering if anything needs to be done on the outside of the joint. Remove the rub rail and do some epoxy work if needed, my fear is that where will the water travel to after it has been sealed off from the inside of the cabin?\Seawolf 

Glassing the inside may be over kill for the issue at hand and I question that it adds much stiffness to the boat. There is built-in form stability in that section of the boat owing to the turn-down of the deck which forms a beam, then there is the flange itself which is a deformity in both the hull and deck section which together form a mini-beam around the entire boat again. I changed my rail and saw how those were bonded, stapled, and pop riveted together and I don't think that joint moves. A crash might compromise the seal locally, but not the overall stiffness of the boat. On the other hand, if one thinks that grinding fiberglass inside a boat and itching like a bitch for a week after, then glassing the inside and sanding that fair is easier than addressing the outside of the rail and maybe going for a new rub rail, then glassing will surely stop leaks from the rail area. But you better have an "Ocean of Calamine Lotion", 'cause Lordy does that glass make you itch! Then you have to vacuum and extract all the micro glass slivers from the interior or you will be itching for a long time to come.

When I changed my rub rail, I ground the entire perimeter of the flange and coated it liberally with 5200. I let that set before replacing the rub rail during which time I filled the inside of the rubber section (just at the bottom of the invert) with more sealant that also contacts the outside of the flange. My flange section of the boat is dry.

These boats can leak in many places. Windows are an obvious place and easy to check. More difficult is that water that finds its way into the sail storage area aft of the head and on the other side (near fuel tank), and it migrates from the rear of the boat down into the keel well. Check the UHMPE tapered shim where the stainless piano hinge fixes the lazaret doors to the hull. Are they checked and cracked? Through those there are many screws that lead to the inside of the hull. This area needs to be addressed if you want a dry boat. Also, where the polyethylene lazaret flange meets the hull there should be a caulking. If that caulking is compromised, the boat will leak there and you won't ever see it unless you lay on your back and have someone flush the area with a hose for an extended period. Gouge out the old caulking (if silicon it will leak for sure), clean the area with acetone and Q-tips, rag with screwdriver, etc, and get it clean. Dry it with a heat gun. Then mask it and fill it with 5200. If your shim is weathered and cracked, make a new one. If you don't use marine grade PE or UHMPE, the new one will crack within 18 months if exposed to UV. When re installing the hinge and door assembly, seal it well with 5200 or similar.

One more suggestion, if one elects to go the glassing route, I would remove every single thing from the boat and go after the area of the structural beams as well and glass them to the hull. This area really does move and there is something structural to be gained in doing this one. As long as one is up to his elbows in glass dust, resins, and glass strings stuck to his elbows, etc, then much can be gained by glassing those sections together.