Originally Posted by MastUndSchotbruch
Hm, to add a negative note, I rebedded all my chainplates with grey butyl tape but most of them are still leaking. The holes in the deck where pretty big (chainplates not well fitting) and it was hard to exert enough pressure with the cover plates to squeeze the tape into shape (the plates are held by small screws). I am considering taking them all out again and redo with polysulfite. Big disappointment!
Butyl works best in compression and it sounds like on your boat you can't get enough compression with those big holes, and only screws not through bolts. Probably not the best fit for butyl.
I've bedded lots of chain plates with butyl, and none have leaked, but I choose them carefully. I don't however use butyl on all chain plates and base my decision for its use on the particular design I am working with.
The original chain plates on our CS lasted 31 years without leaking. I only pulled them to inspect them. I then rebedded them with butyl and they've been bomb proof. Our chain plates are a different design though and the plates are through bolted...
Butyl is not always ideal for every bedding situation so don't let one situation get you down on it.