Ply ok to replace small part of inner carvel plank?

[TimDare]

Hi, I have discovered a bit of rot behind one of the chain plates on my 1950's twin planked keeler. Fresh water has obviously run down the chainplate, which comes down the inside of the hull, and rotted the top of one stringer and around the bolt going through the hull. I've removed the bolt, and cut out the stringer, the effected bit of the inner plank, and the rot out the outer plank. The effected area on the outside of the hull is small enough to allow me to use a wooden plug, which I plan to epoxy in place then re-drill a hole to replace the bolt. The inner plank is pretty thin, only about 8mm. The piece I've taken out is quite small - roughly 6inches (150mm) of a 6inch wide plank (it happens the piece is an odd diamond shape because i've made vertical cuts across a plank running diagonally, but that probably makes no difference. Can I use a bit of ply, sealed with epoxy, to replace that piece of the inner plank? The chain plate bolt would go though the wooden plug in the outer hull, then the ply, then the chainplate, then the new hardwood stringer. My guess is that the ply would be as strong as any timber I could put in there.
Cheers,
Tim

[Peerie Maa]

How is it fastened? Ply will be OK, but if it is trad riveted double diagonal, you may need to cut back further to "shift the buts" properly.

[TimDare]

Thanks. It's riveted. I can recut the inner plank square (I cut it vertically because of access issues, and thinking it would be good to leave as many fastenings untouched as possible, but I think a bit more time will allow me to sort that out), and that will shift the buts too. What should I be aiming for as far as positioning those goes? Paul, I see you're a local: do you know where one might get a short piece of 3/8ths Kauri? (Though as I write, talk of buying rivets and read lead, doing it traditionally and being bold is making me wonder whether I should just leave this bit of the job to a professional!)

[boattruck]

TD, I would guess you are going to want to remove a bit more than you have described to get a structural job that solves the rot problem once and for all, but I sometimes suggest my clients try the lower impact 'repair and treat' program and watch it like a hawk for a few years, if you've got it, great, if there is even a hint of trouble, get at it hammer and tongs and make it as good as new. You are also seeing the slight downside of double or triple skin construction, small repairs, out of necessity turn big, just to be able to reasonably stagger the butts...Cheers, Steve/BT

[TimDare]

Any ideas on how to bend a relatively short length (500mm) of 3/8ths Kauri, to use it as a replacement section for an inner carvel plank?. Across that short a length it's pretty stiff. I could start with a thicker piece (say 20mm) and shape it, but that's obviously not what's been done when the boat was built (though they were working which much longer lengths, so more flexible).