best approach to take with older cold moulded hulls

[Corley]

I have an off the beach trimaran I'm currently rebuilding I'm reconstructing the main hull and have made considerable progress but my thoughts are also turning to the original floats.

The floats were built in 1962 but have been stored undercover for 30 years and are still in very good condition they were obviously constructed using the methods of the day using resorcinol based glue currently they are very dry and I'm wondering whether I should paint the inside of the hulls with epoxy to prevent water ingress and should I strip the exterior down to bare timber and recover with epoxy and glass as a sheath or should I let them be? The way I look at it the hulls are never going to be drier than they are now.

[John Riddle]

Corley:

I would absolutely recommend coating inside and out with epoxy. If the cold-molded shells are solid and dry, epoxy coating will keep them that way indefinitely, as long as the epoxy coating remains intact. I believe a 4 oz. or 6 oz. glass sheathing is worthwhile on the outside as well. It reinforces the epoxy across the veneer glue lines, reducing the minor cracking and print through of the glue lines that sometimes occur without it. With the coating, the wood will remain dry, stable and light-weight.

You may also consider a applying a fillet along the keelson on the inside if there is one. A radiused transition there will be less likely to develop small cracks from any flex in the skin, letting water into the skin/keelson joint.

Email if I can help with questions.

[Landlubber]

Corley,

John's suggestions ring true to my understanding and practical experiences too.

One thing for sure, as long as the original glue is stable, the epoxy can only be of benefit, and rescorcinal glue is a very good glue. I made a 32 footer with my next door neighbour in 1972, it was ply (rescorcinal glued) and timber framed (with rescorcinal), and that boat is as good today as it was when built. We covered the outside with epoxy and Dynel from new.

I see no reason not to do the same now on a boat that was not sheathed from new.

[Corley]

Thanks for the advice, much appreciated, hopefully I'll be starting the revamp on those hulls soon.

[gonzo]

Is there any adhesion problem between resorcinol and epoxy?

[Landlubber]

gonzo, no mate, and remember the seams of glue line are very fine anyhow.

[Boston]

resorcinol is a urea-formaldehyde glue if I remember right
stuff outgasses over time
I may be way off base but dose confining the gasses in epoxy eventually lead to this gas building up in the material and what problems might that cause

course I could be over-thinking this cause it seems like the plans been tried before

B

[Landlubber]

I could be over-thinking this...yeah I reckon so, we are talking about an old hull here mate, regardless if the glue gassed or not.....it is stable after age.

[Herman]

I have seen many resorcinol glued boats covered in epoxy, and none of them had outgassing related problems.

Problems I have seen are transoms dropping off (due to a failure of the construction, after 30-40 years in service) and there was a white type of glue, that, after 40 years, just disappeared, leaving you with "just the wood". Firewood, that is...

[Landlubber]

...well there ya go Herman, they are still useful.......