Hull Damage

[Ward H]

Most seem to recommend butyle tape, also 3M 5200 is what local sailors told me to use.

Let's back up to sealing the deck around the chain plates.
DO NOT USE 3M 5200.
3M 5200 is a permanent sealant/adhesive. It is made to seal or glue thinks together that will never need to come apart.
Chain plates require maintenance, something like every 10 years they should be inspected and resealed. They also need to be sealed with something pliable as the deck/bulkhead combination may flex a little under load. That is why butyl tape is highly recommended.
You should also seal the edges of the slot with epoxy to seal the wood inner layer of the deck so if a leak does occur it drips inside instead of being soaked up by the wood.

Here is a link on butyl tape.
Bed-It Butyl Tape (LINK)
And a link how to use it.
Rebedding Deck Hardware

 

[JRT]

Excellent input Ward, I messed up with the 5200 input. I'm doing the butyl tape with mine.

 

[Brian S]

BTW, if your bulkheads are rotted at the bottom from water, your compression post is probably also- I would take a good look at that. Mine was when I redid all my woodwork; had to make a new one out of an oak 2x4 .

Just a note, for god's sake, don't use red oak for this project. Red oak has a structure like straws, which draws water up into the wood, and rots in no time.