[C320-list] Butyl Rubber and chain plates

[jim brown]

I re-bedded all my chainplates over a year ago because of a leak in one of the aft lowers. My experience was a little different and I wound up using butyl for the whole process. 

I completely removed the chainplates one at a time using a halyard for reassurance for each one (probably unnecessary doing one at a time). When I took off the deck plate of the one that was leaking I found that the original caulking had come away from both the chain plate and deck opening and a small amount of "standing" water had accumulate in the openings. When I removed the chain plate it just slid out of the surrounding caulk that in places had become greenish (mold?). The chain plate had a fair amount of surface rust on it that was easily removed. My deck was solid glass around the opening in the deck so there was no core damage. 

Since the caulk had pulled away from the deck and plate anyway, I decided to fill the entire cavity with butyl. The problem with either caulk or butyl is trying to fill the hole in the deck which is straight up and down while the chainplate is very much angled through that hole ( the upper portion of the chain plate almost hits the inboard part of the deck opening. I used heat to soften the butyl, stuffed the hole full of it, warmed the chain plate and pushed it through from the salon side. It seemed to fill the cavity pretty well. I then used butyl in the conventional way on the deck plate, bottom welded on plate, and nuts and bolts.  (I had to get longer bolts since mine were cut off flush from the factory and the butyl added a fair amount of height to the setup initially).
I did them all this way and found water in the deck cavity, shrunken brown green caulk, and some surface rust on them all. So I used lots of butyl. No leaks so far but then I had water in all the ones that were not leaking at the start. 

If I have to do it again I think that I'd take Warren's approach and remove all the caulk, fill the opening with caulk using a temporary "plate" in the salon to keep it in the hole and then push the chain plate through the caulk, then use the butyl just on the nuts and bolts, and upper and lower plates. Just seems easier it might be easier that way. 

Not sure why Catalina designed the chain plates the way they did but as designed, they really make a "bucket" in the deck that is bound to fill with water even before it leaks into the salon. I would have put the welded part of the chain plate on the deck with the free piece in the salon-but there is probably and engineering reason for the way it was done at the factory. 

Jim BrownDesafinado 973
      From: Kaare Wold <sailor3952 at charter.net>
 To: C320-List at Catalina320.com 
 Sent: Tuesday, October 18, 2016 8:45 PM
 Subject: Re: [C320-list] Butyl Rubber and chain plates
   
Dave, interesting thread on using butyl rubber and pictures in the link 
below
----- Original Message ----- 
From: "Warren Updike" <wupdike at hotmail.com>
To: <C320-List at Catalina320.com>
Sent: Tuesday, October 18, 2016 3:36 PM
Subject: [C320-list] Butyl Rubber and chain plates


I have been educated as to the use of butyl rubber for bedding from Compass 
Marine (http://www.pbase.com/mainecruising/rebedding_hardware) and have used 
butyl rubber on a number of bedding projects.
Recently, I had to address an inside leak from the center chain plate. I've 
wondered how I would go about using butyl rubber on chain plates.
Once I detached the shrouds and removed the deck plate, I found that the 
Polysulfide bedding in the deck was in good shape; but, the seal of the deck 
plate had failed and water was making its way down the bolts. Rather than 
removing the bedding, I cleaned up the deck, chamfered bolt holes, and 
bolts. Following info from the above link, I prepared the deck plate and 
bolts with butyl rubber and reassembled the chain plate. (Hold the bolts 
from turning when reassembling.) We since have had a rather heavy rain and 
no more leaking.
As for the bedding itself, I can see no practical way of replacing the 
bedding with butyl rubber, as whatever you use has to flow to conform to the 
space. With a proper seal on the deck plate, I see no way for water to get 
into the bedding in the first place.
If anyone has experience with this or would like to comment, bring it on.

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62
Middle River, Chesapeake Bay