Rotten to the core



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.



Filed under Repairs and Modifications

12 responses to “Rotten to the core

  1. Antoine Maartens

    Same on Siskin my beloved wreck. I don’t worry about it. Just make sure that the stuff that needs to structurally sound is in good working order.

  2. Antoine Maartens

    And another thing, having looked at many boats this size and this build method – very many of them have this.

    Be glad we have an unstayed mast!

    This could well have happened to your shroud attachment points ( don’t know the correct terminology in English – sorry )

    • Yes, it seems like a common problem. I think it’s a slow rot, but our boats are getting old, and if we want to keep them to old age we’d better sort it out!

      “Shroud attachment points” makes perfect sense. Those attachment points are usually chainplates that often go through the deck. David Pascoe mentions them in his article.

      • Antoine Maartens

        Some Drascombes have it where the mast is stepped on the deck. As per builder no support underneath the mast – well you catch my drift.

        You are right that it is better to fix it, no doubt you are correct. But I doubt whether it is urgent on OUR boats. Seems like winter job to me. Address the whole lot in one go (and get good at it in the process).

        Still looking at putting a fixed dodger on Siskin and incorporating the attachment or maybe even the whole boomgallows into that contraption. MingMing’s seems / seemed to work. There is this youtube channel ( and the corresponding blog at where a Corribee was fitted with a fixed dodger that seems to work.

        Would love to have that during my winter trips. But I digress, sorry. My point is – that would take care of those attachment points as well. And one would have to go from bow to tail to investigate the crucial bits.

  3. I had this problem with my previous JR ‘Trivial Pursuit’. So far no sign with my Coromandel ‘Butterfly’. (Fingers crossed!) The thing to do, if you can dry out the balsa enough, is as follows. Cut out the hole from the outside. Fit a bent nail into the drill chuck and use it to rip out more dead balsa without making the holes any bigger. Hopefully you can get to dry-ish balsa. Cover the lower hole into the cabin (thin card and gaffer tape) then fill the excavation with thickened epoxy. drill out a new fixing hole in the epoxy! Sounds complex but is really easy honest!

  4. Annie

    I was about to suggest something similar: I would use a hole saw to cut out a larger area and, hopefully, get back to dry balsa. Then do as Mike suggests.

    • I think that if I were cutting back a lot of the sandwich I might lay some glass mat into the recess, since I’m already mixing up resin. That way the new material would be bonded to the old ceiling layer. On the Coromandel, Newbridge did exactly this under the important rigging (e.g. halyard blocks) but didn’t bother for less critical deck hardware.

      May as well make it bomb proof!

  5. Here’s a video from the wonderful “Sail Life” channel showing the consequences of having 1000 screws into a foam and wood cored deck.

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