Telegraphing with strip hulls

[Bill Baillie]

I have heard a few people here on the Forum say that when you build a hull with strips you often don't have to cut coves and beads on them. I understand that if the glue is a good gap filler the glue and nails will give you a good strong hull.
I have a question about this technique. Does anyone know if the glue lines will telegraph through a layer of fibreglass and epoxy over time? If it does, is there anything you can do about it? If you used resorcinol between the strips instead of epoxy, would it make any difference?

[imported_Conrad]

They will telegraph, as will the planks in cold molding. The issue isn't so much that you used glue to fill the gaps as opposed to B/C or other fitting techniques. It's that the epoxy shrinks as it reaches a final cure and the wood stabilizes.

There's really only two solutions. Either heat the hull to about 135-140 degrees for a minimum of 12 hours (which is what premium yacht builders do) or just figure you'll be repainting in a year- and then it will be/remain perfect!

I've painted small boats with black primer, then set them out in the summer sun for a week. That'll do the trick too, if you live where it gets into the 80's or so. ;)

[Magnus]

The one I built used "canoe cove" bits to make assembly smoother, so less sanding later. Over this I used 6oz glass and no telegraphing after several years.
Do fill the weave well and let it set 15 days before top coat painting, sand last time just before the color coats, or clear. Oh yes, I used Pro-Bond weather resistant glue with wood fibers in it, cloth and epoxy sticks well, no mixing, pot times or problems just easy and fast.

Happy stripping, Cal cal@epud.net

PS-- Got caught in a nasty situation with the boat, no problems no delamination, but Whew!!
Final score, light, fast, and safe, not bad for a tunnel hull design of my own.

[TimothyB]

Yes, if you use resorcinol between the strips it will make a large difference because:

1) The joinery required for using Resorcinol is much finer than needed for epoxy.. in other words you need to have a good dry fit before you glue it up and
2) Resorcinol doesn't shrink

That being said, if you are going to go to the trouble to use Resorcinol, then you might as well just do the boat 'Traditionally' as the strippers were built for many, many years from offcuts. You wouldn't need glass, if you used wood large enough to plank her. By gum, ye'd have ye a gud WOOD boat then, shore ting! ;)

--T

[cs]

When you talk about the strips telegraphing I assume you will be painting. I'm doing my canoe without bead and cove, but I will be finishing bright so I don't see this as much of a problem. Sure you will see the glue line, but that is part of it.

Chad

[Bill Baillie]

Conrad, I'm glad you told me about the black primer. I guess if I tried this in the kitchen oven there would be problems.
When you say that resorcinol needs a better fit, that would mean bevelling each strip into place. If I can, I would like to avoid that as it is too time consuming and I'd like to get sailing before the end of the decade. Cove and bead is pretty wasteful in a 22 footer (Peterborough Pal) so I thought I would try it with square cut. I'll set up a test panel and cover it with the black primer and put it in the sun...see what happens.
Thanks for your responses guys.

[Buddy]

Not to argue with anybody, but here's the explanation given to me by the tech people at Gougeon about faint telegraphing on a ten year old cold molded hull I was refinishing.
Yeah, the epoxy does shrink as it finally cures and makes depressions. But when I refaired and refinished the hull, it looked "invisible" for many months, but after a summer of use.... they're back.
I was told that because the boat was now in use, water vapor does gradually enter the wood through the epoxy and the wood has swelled the least bit, and to look for it to cycle back down over the winter. The epoxy crack filling is now, cured for so many years dimensionally inert, but the wood will never be.
Nobody sees it but me, and I've learned to accept that like "the slight variations of weave are a characteristic of handmade (fabric) and in no way are to be flaws."

[Bill Baillie]

Thanks Buddy,
I was wondering, if I were to use a mixture of epoxy and filler (sanding dust, microfibres, etc) to repair some dings or flaws in the hull during fairing, would the lack of stability in the wood make these patches show? If the hull needed a lot of filling it might look pretty schkanky after a few years.