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post #15 of Old 04-26-2019 Thread Starter
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Re: Mast Step leak PSC 34

Originally Posted by DaveMancini View Post
Same thing happened to us. The mast step is made to shed water through the limber holes, so the only likely access is down the standpipe. I also thought I had sealed ours well, but discovered it was leaking all the way down the groove in the compression post into the bilge. After much sleuthing I discovered rainwater was leaking all the way down the wires in the mast from poorly bedded masthead stuff, including one 3/16" hole left when a masthead light was changed to another brand.

After the holes/leaks at the masthead were fixed and everything was dry at the standpipe opening, I force pumped MARINE GRADE silicone sealant (no acetic acid) into the top of the standpipe using a quality caulking gun until I could see it oozing through from under the deck at the top of the compression post. Then I pumped it around the wires at various locations in the bundle where it entered the standpipe and, finally, shaped a mound of silicon above the standpipe and worked it around the wires with gloved hands.

We sailed the Pacific for eight years after that through tropical deluge and monsoon. No more leaks.

There is really no issue with the deck core getting wet as it is sealed around the pipe, at least it was in our 1996 PSC34. The real problem is the laminated oak compression post. Oak rots if left perpetually wet in a poorly ventilated area and the laminations are also in jeopardy if there is a lot of dry/wet cycling because oak expands and contracts significantly. As part of the fix. I coated the entire groove of the post with West System epoxy, just in case I got any further leaking (never did).


I discovered the leak as I was cleaning the deck with a hose - somehow water is getting into the boat even if the water isn't flowing over the standpipe. My current working hypothesis is that it wicks underneath the mast step into the deck opening that the wires pass through. I'm getting the mast pulled on Tuesday, so I'll have a better idea then. I'll probably need to rebed the mast step. Do you know if the standpipe passes through the deck?

Once I've sorted this, I'll follow your advice about coating the inside of the compression post. I'll take a look at the mast head as well.


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1995 Pacific Seacraft 34
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