Centerboard trunk liner

[DanaDCole]

I've read about people putting counter-top laminate (Formica) on the inside of the centerboard trunk to give the centerboard a nice, slick surface to rub against. I've been giving this some thought. The laminate would be cut so that is a little smaller than the area left by the blocking strips. I'm thinking the laminate would be pressed into the final layer of epoxy before it starts to cure, and then weighted down.

The blocking strips would have to be milled slightly wider, i.e., 1" plus the thickness of the laminate times two, to allow the proper clearance for the centerboard. This would make the trunk slightly wider, but I don't think that would cause a problem.

I had thought of using thin sheets of plastic instead, but am afraid they might not stick to the epoxy. The rough masonite-like surface of the underside of plastic laminate should stick very well. I would also make sure epoxy seals the edges of the material, which might be porous.

Any reasons I have not thought of that would make this an absolutely stupid idea?

[truenorth]

I worry a lot about the centerboard /centerboard trunk. Once built, there's not a lot of ways to get in there if something goes wrong short of a jigsaw and plenty of epoxy (which I guess is true of most things anyway). This is probably the area where my boat will fail me.

Your solution would make things more smooth, but I don't know if I could bring myself to change the dimensions, however small, of something so structurally important. The centerboard barely fits as it is. There is very little clearance. And if you're like most builders, there's going to be some flex and imprecision to the build. I don't mean vast amounts, but even 1/16" here and there can mean the difference between a snug fit or not at all. Note, too, that the keelson needs to fit over the top of the trunk and then the whole thing has to support the floorboards, bulkheads, and then the sole. Changing one thing has repercussions throughout the design. Adding more stuff adds to the stuff that can go wrong. For me, this is one of those areas where I'd put faith in the plans. Of course, up to you - I'd like to see it work.

[DanaDCole]

Truenorth, thanks. Yes I was having some of the same concerns due to the location of the trunk and its importance to the overall structure. Get something out of kilter there and the whole project could be sunk (pardon the pun). That's why I decided to get on the forum and hear some advice before going ahead.

After I read all the posts, and if I still decide to try it, I plan to spend a lot of time dry-fitting and experimenting, etc. One thing I will definitely do is laminate some Formica to plywood using epoxy and put it through some pretty rigorous tests. I also think I can do some rabbeting along the edges of the trunk that have to fit other parts, especially the keelson without sacrificing structural strength (epoxy solves a lot of issues of that sort also).

BUT--I'm not about to do this unless I am absolutely sure it won't cause problems, and I have to say the likelihood that I will go ahead is pretty small. If it will work, though, I shouldn't have to worry too much about wear on the centerboard, and as a bonus I'll have a little less sanding to do.

[Bflat]

I added graphite powder to the epoxy and spread it out on the inner surfaces of the the centerboard case. I did two coats like that. It sands out perfectly flat and smooth and creates a tough and slippery surface. I plan to add a little graphite to the Centerboard itself too, but not as much because I'd rather the board wear out before the case for obvious reasons.
Bob

[DanaDCole]

Bflat, sounds like a great idea! Should be very smooth and slippery. I'll wait to hear some other opinions, but this sounds to me like a very good alternative. Have to give some thought to the idea of adding any to the centerboard, though. The trunk is built long before the centerboard, so that will enable me to do some testing first--especially before the trunk is assembled. I have plenty of graphite powder left from the rub strips I made for my kayak.

I wish I had done something like this I built my Skerry--even the simple Formica idea would have probably worked fine on that boat. The daggerboard is getting really worn on the sides. Not that big a deal, because daggerboards take a lot abuse (especially with me as pilot) and I'll be doing minor repairs to it this winter anyway--epoxy on the leading corner and re-finishing overall.

[Bflat]

I should add that before applying the epoxy/graphite mix to the centerboard case I masked off the areas where the blocking would go.
Bob

[I's the B'y]

What about doing away with the centerboard trunk altogether (egads!) and replacing it with chine runners a la Matt Layden's Paradox to provide the required lateral resistence? Put some extra ballast under the cabin sole near the centerline to compensate for the lost weight in the centerboard and voila!, a beachable Pocketship that sits up straight on her bottom and still tracks well. Anyone?

[3wtk]

To make sure the coating on the centerboard trunk does not wear out you might want to try the following: Add rock flour (available from Progressive Epoxy Polymers) to the epoxy coats for the inside of the centerboard trunk, then add graphite to the epoxy coats for the centerboard. This will make the trunk coating very hard and wear resistance while giving the centerboard lubricating properties. The coating on the centerboard can be renewed.

[herbt]

I like the graphite idea on the centerboard trunk and centerboard. I have used graphite powder on boat bottoms and it provides a smooth, hard, slippery surface that holds up very well. Wish I had thought about it on the centerboards for the skerry's I have built.

[Roy Widman]

I asked about removing the trunk and extending the "skag" also but either missed the reply or something. I live on a small lake in Wyoming with lots of rocks and lots of wind so doing away with the center board would help.