Rotten/delaminated 535 roof repair

[mabbs]

Hi

Hoping that some member has tackled this not so nice problem : cabin roof balsa laminate has become water soaked from failed mastic where grab handle screws enter through roof. Seems pretty serious, as the whole roof is spongy, including the "dashboard" between the windscreen and cabin, so I presume it is completely delaminated.

I was going to tackle the job myself by cutting away internally at the grp, remove all of the balsa and then re-laminate onto the undisturbed outer layer having cleaned with acetone using suitable thickness marine ply and then relay the internal grp sandwich with epoxy resin and matt, similarly to this repair http://www.practicalboating.com/forums/ ... php?t=9273

Only fear I have is for the outer skin maintaining its shape without the albeit rotten/soft core. Has anyone else tackled this problem and if so have you got any pointers or is this a job for a pro. I was thinking when the ply laminate were glassed to the outer to support the roof with vertical battens between the hull and the new material. I really want to see her repaired as shes been in the family for twenty years now and shes is otherwise a sound little boat.

A few pics attached........

[bobtooke]

I would think the outer skin will be fine as it's fairly flat. If it starts to bow, once you start to put the new board in, it will take shape again anyway. To get it firmly flat against the wood, I'd cut a bit of 9 or12mm marine ply to shape, cover it in resin and a sheet of heavy CSM then clamp it to the inside of the roof using 5 or 6 2" battens screwed down from the outside. Once the resin has cured you can remove the battens and screws then just fill in the screwholes using a mix of resin and fine chopped strands. After that iit will just be a case of relaminating the inside and making it look pretty again.

[IlsonMark]

I remembered seeing this thread on the Practical Boating forum a while back - http://www.practicalboating.com/forums/ ... php?t=9273

Looks like the person here has done a similar type of work to what you mention. No mention of how rigid the roof is or anything, but a few pictures which might give you an idea of what to expect when you cut away the ceiling.

[EvangelicalAtheist]

Hi,

This is my first post so hello all, I acquired my 535 18 months ago but have just got round to starting the restoration. I have stripped it right back to the shell and am in the process of repairing all the holes and cracks and a couple of more significant areas of damage.

Structurally it is in great nick, with a solid transom. The worst problem was the roof balsa was part rotten, completely soaking and as far as I could tell largely delaminated so I decided to repair it properly rather than risk trying to patch it up. In any case the lack of support and weight of the soaking balsa had made the roof sag.

I have got as far as cutting out the underside and removing all the balsa, it is plenty strong enough to support itself. It does sag a little but then it was anyway.

I am replacing the balsa with closed cell foam, and figure if I can somehow reshape the roof as I do it then it will return to a nice convex shape. I will cut oversize holes, fill and drill for any figments which should stop any more water ingress.

No doubt I will be looking for some help as I go so thanks for reading!

Tim