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post #7 of Old 10-23-2011
Deck Hand
Join Date: Jan 2009
Location: The middle of nowhere in Eastern Washington State
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Paul Comte pretty much nailed it. The problem results from placing two pieces of plywood under compression. As most of us understand, resisting compression isn't something plywood is supposed to do, especially in a damp environment. Apparently the engineers who actually built the boat didn't know or didn't care. Because of deck leaks around the mast, our '79 Islander 28 had both the 3/4" plywood sole and the 3/4" plywood countertop rot and collapse which resulted in the mast dropping well over 1". The wooden post you mention is firmly attached to the bulkhead so unless it is rotted I would leave it alone. When you jack up the mast, gaps will appear above and below the wooden post as the weight comes off and you can chisel out the old plywood. Replacing the teak veneer countertop was a major proposition which involved removing all those beautiful teak plugs covering the wood screws on the counter rail, jacking up the mast and pulling out the remains of the countertop to use as a template. When we replaced the countertop, we left a circular hole in it the size of the bottom of the steel compression post and cut an aluminum disk to fit between the steel post and the wooden post that you see in the head. Be sure to leave a slot in the disk for the mast wiring. On the bottom, we cut away the sole and placed more aluminum plates bridging the two stringers in the bilge. Because we were replacing 3/4" plywood we backfilled with 3/4" aluminum sheet stock. If you are going to replace the countertop, I would also recommend treating the sole as well even if it doesn't look bad right now. You don't ever want to tear things up again. We did all this in our marina berth with the mast stepped using a 2 ton hydraulic jack but it requires nerves of steel to listen to all the cracking and creaking as the mast comes up. My wife had to leave - I had to have a ration of grog. It would be much easier to do it on the hard with the mast removed. Sorry for the long reply. I suppose I should have just sent some pictures. Please let me know if you have any other questions.
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