Leaks Where Shroud Passes Through Deck

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Aug 30, 2011
19
Catalina 310 Edmonds
In surveying a 1995, 320 I hope to buy I found a slight discoloration around the plate inside of the boat where the shroud passes through the deck. A surveyor once said that this kind of thing could indicate problems because water could be collecting inside the decking material. There are no signs of actual drips or even water but I was wondering if anyone has experience with this.
 

mortyd

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Dec 11, 2004
952
Catalina 30 easy living
negotiate with the seller to deliver the boat with no leak and a dry internal deck, and to orove it.
 
Jun 8, 2004
3,012
Catalina 320 Dana Point
Common, I once heard Gerry Douglas suggest that the deckplates should be rebedded every 8 years. My 2002 320 had leaks when I purchased 2 years ago, I found on my boat that thru deck openings were coated to prevent leaks wetting the deck core. After taking one apart I felt comfortable just lifting the deckplates, scrapping out the old white caulk with dental tools and rebedding with butyl tape. If you check the 320 association site there's several different people who have done everything from completely removing chainplates etc. Even my method took a while, I could only do 1 a day, very tedious to get the old stuff out completely.
 

Faris

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Apr 20, 2011
232
Catalina 27 San Juan Islands
OK, here's the problem. The chainplate passes through the deck. That point at which it passes through can leak, allowing moisture to enter that space where the chainplate is passing through the deck. Two things can happen here, neither is good, but neither is necessarily a deal-breaker if you know what you're getting into.

One thing that can happen is that corrosion occurs, but just in the narrow space where the chainplate is actually passing through the deck. So, though the chainplate may look fine, it may be on the brink of failure where you can't see. Since the chainplate is discolored, that tends to suggest that some corrosion may have occurred. If this is the ONLY problem, the chainplate is easy enough to replace, and not prohibitively expense.

Now, also water can seep into the layer between the deck surface and the cabin ceiling. There is typically a layer sandwiched between two layers of fiberglass, and if water seeps in there, it can cause delamination and failure.

If you have corrosion of the chainplate, you probably have water in the deck. The inverse could be true but it is somewhat less likely. The surveyor should have used a water meter to tell you if there is moisture in the deck around the chainplate.

A little bit of moisture is not a big deal if you eliminate the problem and prevent it from repeating. If delamination occurs, it's kind of a big deal to fix, though not at all impossible.

So, if you buy the boat, regardless of what the problem turns out to be (if any), you really must:
- Remove, inspect, and rebed the chainplates. (Replace as needed.) You really shouldn't tolerate much corrosion here since failure can be pretty catastrophic. Any signs of cracking anywhere and you should have both inspected with die penetrant or just replace.
- While the chainplates are out, carefully inspect the area around the hole in the deck for any signs of moisture, rot, delamination, etc. and repair as appropriate.

If there is not severe delamination, none of this is a big deal, but you really should pull the chainplates to find out.

Depending on the price of the boat, you may be able to convince the owner to pull at least one chainplate for inspection.

If it were me, I would just plan on a $1000 repair and budget that into my negotiation. If you do the work yourself and there is no problem, it could be only a few dollars and a weekend of work. But, if you take it to a professional to do major deck repair, you'll pay more than $1000 when all is said and done.
 

Jon_E

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Mar 19, 2011
119
Catalina 27 Marina del Rey
...The surveyor should have used a water meter to tell you if there is moisture in the deck around the chainplate...
I agree with everything Faris said. A method outlined by Don Casey in his book is to take the butt end of a heavy screwdriver and knock around the deck, especially near deck fittings, and especially-especially near the chainplates in question. You are listening for the change of pitch, that is, the sickening "thud" sound that indicates possible rot between the layers caused by prolonged moisture penetration.

If rot is found between the layers of fiberglass in the deck, it can be fixed but it will take some doing.
 
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