Some time ago I read an excellent article by David Pascoe called “Attaching Hardware to your Boat”. I highly recommend it, and all his other maintenance articles too.
To summarize: bolts and screws through your deck core will eventually make it rot away.
Now I have proof!
I’ve been sitting aboard Tammy Norie in the rain for several days recently. That gives me a good chance to look around for leaks. I noticed some drips in the heads compartment, and traced them to a nut on the ceiling. It was a bolt from the boom gallows attachment.
I remembered David Pascoe’s article, and decided it was time to grit my teeth and investigate the deck core. So on the next dry day I dismantled the boom gallows and used my 20mm hole saw to cut out the inner fibreglass layer and core (but of course not the deck).
What came out was not pretty. Instead of crisp balsa, I got brown mush.
You can see here how the balsa wood has lost its integrity.
And here are the damp sweepings from drilling out the other three holes.
Looking in to the cut out I could see the dark brown discoloured wood. I can only hope that now that it’s exposed to the air it will get a chance to dry out. It won’t regain structure, but at least I will have stopped the rot.
Out of the four bolt holes, only one looked good. You can see the contrast in the colour and texture. Note that only one of the bolts showed any evidence of leaking. That means two of them were secretly leaking into the core.
I re-fitted the gallows using new bolts backed with washers through just the deck layer, all sealed with butyl tape. These stayed dry on the next rainy day. Even if they do leak a little, the water should drip off the bolt and not touch the wood.
David Pascoe recommends sealing the exposed wood. I will do this once it has had a chance to dry out.
So take heed! If you have bolts through your deck core, get them out before it’s too late. Don’t delay!
I’m now looking at all the other fixings with suspicion, and will be working my way around them all.