Finishing a wood hull?

[newracer]

I got a Dumas Big Swamp Buggy for x-mas and will start building it soon. What is the best way to seal and finish the hull? Including the inside? The manual says to use some K&N products but my LHS doesn't have them, they haver all the Aerogloss stuff. It is a plywood hull. I was thinking about laying some fiberglass over it after construction but I don't think I want to try that just yet.

[RickE]

You can seal the wood with a solvent-based polyurethane or by spreading a 30-minute epoxy resin thinned a bit with denatured alcohol, followed by a nitro-proof paint like Formula-U or Lustercoat, each of which is sold through Tower Hobbies. The epoxy resin can also do a good job on the inner sections of your airboat, as it'll waterproof/seal it in one step.

Hope this helps,
RickE

[newracer]

to finish the one I had before I used several thin coats of polyurethane then some fuel proof spray paint, that was about 10 years ago. It seamed to work pretty well but I wasn't sure if there were better methods now.

what about a fiberglass resin without the fiberglass?

[laxmasta2039]

rick,
i've always used fiberglass w/ fiberglass resin on all my wood boats, but the finish has taken weeks to look good- a friend of mine who is currently working on a hull that we will both be racing has decided not to use the glass cloth and just uses the resin, your idea of denatured alcohol sounds like a good plan for him. where can we get denatured alcohol? this may sound stupid, but is it just plain hydrogen peroxide?


Joe

[newracer]

you can get it at most hardware stores and paint supply places

it's not hydrogen peroxide

[laxmasta2039]

thanks newracer i'll tell matt to do that as soon as this ice storm passes by [im in Richmond, VA and we've had nonstop ice for 24 hours]



Joe

[RickE]

Newracer, there's an article in the August 2002 issue of R/C Boat Modeler Magazine on covering a wood boat with fiberglass cloth and resin. It's on page 62 and if you don't have access to this magazine you can order a back issue via the magazine's website.

Sorry it took so long to reply,
RickE

[DavidJ]

Epoxy resins should not be thinned. According to the Gougeon Brothers' Book on Boat Construction when the solvent evaporates it leaves tiny holes in the hardened resin.

The best way to apply a thin coat of epoxy is to scrape the surface with a plastic scraper, playing card, squeegee, or old credit card. I lightly sand after each coat. It only takes two or three coats to get a thin, smooth surface.

Also fiberglassing over a wood hull can provide extra strength, though in my opinion the extra weight and poor look of the cloth offsets the usefulness.

Polyester resin(fiberglass resin) has poor bonding properties and does not stick well to wood. It is not actually waterproof. The strength of fiberglass comes from the composite properties, resin on it's own is quite brittle. Using it as a sealer over wood without the cloth would be stupid.

[DavidJ]

One thing I should point out is that a really thin cloth works great to seal wood hulls that have many seams. Scale boats for example that are built plank on frame. I was recommending against it on racing boats where they are usually made out of fewer pieces of wood and lightness is a factor.