Filling a Void

[Quetzalsailor]

I've got a not-really-a-plastic-boat question. But, since the old boat is/will be totally encapsulated in epoxy, it really is a plastic boat question.

The centerboard trunk sides extend forward to become the maststep. The forward end of the trunk is formed with solid mahogany as are the trunk sides. The maststep itself, structurally, is the top edges of the trunk sides. The rest of the keel extending into the bow is sandwiched between the trunk sides. However, between the front of the trunk and the back of the rest of the keel is a void, presumably to save weight and wood. This void is about 6 inches deep, 12" long, 1" wide, and open to the top. It is provided with drains into the bilge on each side. I cannot adequately clean the old varnish, etc., off of the inward facing surfaces of the void, except for the top 1 1/2 inches. Thus I cannot adequately recoat and maintain the new finish. The whole encapsulation idea only works if the wood is wholly encapsulated

What to do???

My thought, currently, is to fill the void with epoxied-in balsa blocks and cap the void up where I can get a good bond to clean wood. To leave room for the tenon on the heel of the mast, the cap would be about an inch down. The void would become a sponge-able inch deep and coated out.

I've only been mulling this second-to-last problem since 2001. (The last real problem is cleaning and coating out the interior of the centerboard trunk.)

Better ideas?

[tpl]

as an alternative to adding material, have you
considered removing some? The problem is, you can't
clean inside the void--well, what about cutting some
access? A pair of paired 4-5" holes removes a good
deal of troublesome material, furthers the "lighter
is better" program, and permits cleaning. Structure
might not be a problem, depending just where is
the step--might look pretty good, too

[One Way David]

An appropriately shaped oval would provide arches and should maintain structural integrity and might give enough access for you to drive yourself nuts trying to scrape and sand the 1" wide cavity to encase in fiberglass.

[Oscar]

Plug the holes, fill cavity with thinned epoxy. Wait five minutes, drain into container, use the goop to treat a non cosmetically important area. Repeat as necessary. As an afterthought, stick hose in the holes, enlarge if needed, so it squeezes in tight, then bring the hose above the fill level during the saturation phase. When done lower hose into container.

[Quetzalsailor]

For tpl and OWD, thanks for the two, similar out-of-the-box ideas. The geometry of the problem and the importance of the sides (the extensions of the centerboard case) made the cutting a bad idea. Generally, though, removing excess material from a raceboat is the way to go!

And, Oscar, your idea is excellent, too. The negative is that the interior surfaces were impossible to clean adequately, or I would have done it that way, or similar.

I will be doing a variation of Oscar's idea on the inside of the ends of the centerboard trunk. Since the trunk is, maybe, 55 inches long, one inch wide and 10" deep, that's a lot of epoxy to use elsewhere or to waste. But, since the boat weighs only about 280 lbs, I'm most tempted to lift it between a pair of scaffolding towers and alternately tip it bow and stern down, at the angle which puts the end of the trunk level. Then the dam need be only a half inch high to form a relatively small puddle of epoxy, and give it time to soak into the ends. And I will be able to clean all the surfaces before treatment.

Anyway, I did the balsa fill and cap as described above. I filled the old oddly-shaped drain holes with epoxy filled with mahogany dust. I coated out the interior of the slot, and the balsa blocks. I used epoxy filled with the lightest of the fairing fillers (the yellow stuff), since I did not need strength, to bed the blocks. I made up plywood using three-plies of 1/16" mahogany veneers and capped the balsa. Probably added a pound or so. Done. Looks good.