How to fix leaks along gunnels

Oct 24, 2010
2,405
Hunter 30 Everett, WA
I had a similar chainplate setup in our Mac 26D. I removed the SS covers (Rivets on our boat) and picked out the old goop as best I could, then I squirted in sealant and put the covers back on. The leak disappeared for 3 years or so, after which I redid it. Today I'd consider using butyl tape instead of messy goopy stuff. When you tighten the screws it should put pressure on the sealant forcing it to seal up tight.

Ken
 
Oct 22, 2014
20,993
CAL 35 Cruiser #21 moored EVERETT WA
It appears the leak is coming from the Chainplate.
20170410_180219.jpg
I would remove the two cover plate screws and the nuts that are holding the chainplate to the sides of your boat.
20170410_180427.jpg
Inspect the metal of the chainplate. You want it to be shiny stainless. No pits or rust. you may need to do some work on it. Can not tell till you have it out and can take a picture.
Your repair to the hole for the chainplate may make your pause. Water is entering the boat so it could have been seeping any to the wood deck in that area. This is the hard discovery part. If you find the wood surrounding the hole for the chainplate is wet you need to dry it out and make sure it is solid not rotting. That is another probem.
Ok You find all is ok. With a dremel tool bevel the sides of the chainplate hole so you create a space for the caulk material. Here is a picture of a round hole with a beveled top.
countersunk-beveledHole1.jpg (from Maine Sail)
You want to run a bevel around the chain plate hole. Then you want to bevel the two screw holes as in the picture. Not so big that these screw holes become part of the chain plate hole.
Now for the fun part. Wrap the chain plate generously with butyl. It is a good caulking for this type of repair. The wrap needs to be such that as you slide the chain plate in and down from the gunnel the butyl contacts your hole before the plate is in position filling the hole and the bevel you made. Stuff in more if you need it. Do it on a warm day and the butyl will adhere to the hole and bevel filling the space. Secure the chain plate in place
Put the two screws into the cover. Wrap butyl around the screw beneath the cover. Slide the cover over the chain plate and the butyl around the screws should fill the screw holes. Tighten the screws and you should have butyl ooze out from under the cover. Let it set for at least an hour. Then using a sharp edge clean up (trim) the excess butyl from around the outside of the cover plate.
There you have got it.
Note nothing was pushed up from under the deck. Always seal from the outside. Then if there is a leak it will make it self known before it can damage your deck.
Good luck.
Here is a link to MaineSail's site and how to bed deck hardware.
https://marinehowto.com/bed-it-tape/
 
Jan 24, 2017
150
Chrysler C26 Lake Sakakaweea
What JS said. I bed everything with Butyl tape. Also called windshield replacement kit at an auto parts store. 5/16".