[C38] Backstay chainplate bulkhead

[Tom T.]

Hi Phil,

The back stay knee is a weak link on the Catalina as several of us have found out.  Any water leaking down the back stay will eventually saturate the laminated wood inside the knee allowing it to rot.  The knee looks like 2" of solid fiberglass but is actually a piece of laminated wood bonded to the hull and transom.  When I removed the back stay chainplate, I was able to poke a screwdriver in the holes and the wood in the middle of my knee was pure mush.

I cut off most of the port side of the knee allowing easy cleaning leaving only the starboard side of the laminated fiberglass left.  I then used a meatloaf pan to lay up a "brick" of fiberglass to a thickness of about 1 1/2" as a plug to replace the missing wood.  I then bedded this plug where the old wood had been using clamps and long strand bedding putty.

Once the new insert was bonded and cured in place, I used more bedding material to finish off the seams etc until the new "brick" looked smooth and fair.  Use some bedding material to fillet the corners where the knee meets the hull and transom.

Finally I put many layers of fiberglass cloth over the exposed port allowing the glass to wrap around the corners to bond to the hull and transom.  This is a time consuming process but by using many layers of lightweight cloth, I was able to make the corner transitions without voids.  Carefully keep checking the thickness of the new knee between lay ups so the chainplate will fit properly when you remount it.

By squeezing out the excess resin on each lay up, the glass to resin ratio will be very high making a very strong repair.

Once the project is finished, a layer of white paint and it will look exactly like the original but  much stronger and rot proof.

Nothing could ruin your cruise worse than being on a high wind spinnaker run and seeing your standing rigging and sails try to outrun your boat when that old back stay knee failed.

I fixed my back stay knee in 2002 and it has looked perfect ever since.   I think I could now pick up my boat by the back stay chainplate but I'd rather it be overly strong than chance failure.

Tom T.
Renata, hull 95
St. Pete, FL




----- Original Message ----- 
From: Phil Gay 
To: Listserve at catalina38.org
Sent: 3/31/2008 12:09:57 PM 
Subject: [C38] Backstay chainplate bulkhead


While this is addressed to the Listserve, the question is specifically addressed to “the man with the plan,” our own tech tips editor, Tom T:
 
A couple of years ago, I noticed that the fore-aft bulkhead which the back stay chainplate is attached to was rotten.  As a short term fix, I added stainless steel straps on each side of the chainplate fitting that transferred the load down lower into the bulkhead and picked up the fiberglass tabbing of the bulkhead to the hull.  This seemed to arrest the forces pulling up on the deck.  Now is the time to go to another chainplate configuration or replace that rotten bulkhead.  I remember that you, Tom, did a little more thorough job of fixing the problem by replacing the bulkhead.  Could you detail the fix and tell me how good it has been in the long term.
 
Phil Gay
C38 049 Que Linda
Everett, WA
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