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Sat Mar 18, 2017 8:42 am

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SCAMPers:

I've got the lead now glued into my centerboard halves. Nice. Now, I plan to glue and clamp the halves together. Once done, I want to complete the assembly. The kit halves are rather rough on the outside, since the machining goes through the layers of plywood. So, quite rough with a number of voids. I gave it a rough sanding, but clearly it will need some fill or fairing. So, do I fair and fill with 407 before glassing, or do I glass, then fair, then put on the last layers of epoxy? And in terms of final finish, since it is underwater or in the trunk not exposed to UV, do I not paint it? Should I just finish with graphite mixed epoxy? Wish I knew what I was doing!!!

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Daniel
SCAMP build #330



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Mon Mar 20, 2017 2:01 pm

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Hi Daniel,
You can save yourself some work by fairing the CB and the Rudder blade with some fairing compound added to the epoxy. As I remember, there are several densities of fairing compound, and the more robust would probably be better for putting directly on the wood [after sealing with epoxy, of course] before sanding smooth and glassing. Mixing the compound to be like runny peanut butter and spreading it on is one approach, but West Systems has some interesting monographs on using a notched trowel to make shaping the first coat easier, and then filling the grooves with a second fairing coat. Longboard sanding will give a smooth and straight surface, and one more sealing coat before the 'glass will make things stick nicely. There are more articles from West System about how to form the leading edges, and they are well written and produce really great results. Good luck, and happy sailing!
Mike #170 TOR



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Mon Mar 20, 2017 2:10 pm

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Thanks for the reply! Do I need to put two layers of glass on, or just one? It is confusing in the manual.

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Daniel
SCAMP build #330



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Tue Mar 21, 2017 8:50 am

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I put more than two on the bottom and leading edge in case of grounding, and that has served me well. The rest of the foil isn't really subjected to abrasion, so one layer should be good enough. Once the cloth is on, you can recoat while the epoxy is "green" with a layer of epoxy with a small amount of light fairing mix added to increase viscosity. This fills the weave very nicely. Sand this, again with some kind of long board, and finish with a final sealing coat of epoxy and Bob's your Uncle. I've painted the CB with the same bottom paint as the rest of the boat, but my boat spends some time in salt water. Using a stiff pad that is about 18" long [they come in plastic with two handles] and double-sticking some wet and dry sandpaper on works well for a long board. If you use it "up and down" on the foil,m you end up with a very smooth surface. If you go through a few grits ending in about 400, you will have a "car fender" like finish.
Happy sanding!
Mike



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Tue Mar 21, 2017 9:22 am

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Thanks for your advice. Really helpful. My board is very rough presently with the CNC cutting that came with the kit. So, I think I will wet it out with epoxy, then put on some fairing compound to at least get a regular surface for the glass. Then glass, light fairing compound as you suggest, etc. I will go with one layer, and perhaps some glass tape on the leading edge and bottom. That should do it! I will make the final layer epoxy with graphite. I guess I won't paint it. I sail in salt water, but the boat stays on the trailer otherwise.

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SCAMP build #330



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Tue Mar 21, 2017 9:50 pm

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Hi Daniel,

I didn't really know what to do either, so, at Scamp Camp, I talked with John and Simeon and Howard to get some ideas before tackling the (kit CNC-cut) foils. Their instructions were to sand the CNC ridges all down to the bottom of the "valleys". That's the desired shape, remove all material to that point. I used a long board with a very coarse grit to knock most of it off, and finished at 80 grit before glassing. One layer of 6 ounce E-cloth, plus an extra layer on the bottom edge only. Like Mike says, a bit of fairing filler in the 2nd coat of epoxy, sanded with 80 grit, one more epoxy coat, lightly sanded. Then I used three coats of the same paint used on the hull (Petit Easypoxy), sanding with consecutively finer paper between coats, maybe ending with about 200.

The centerboard looked fricking beautiful when I dropped it into it's case three years ago, and I haven't seen it since! (The rudder looks just as beautiful, like a race-boat foil, and I get to see it all the time!)

Like Mike, I sail in fairly-cold salt water in the pacific northwest, but haven't left her in the water very long, 10 days at most. One time I had tons of baby barnacles all over the hull after 2 days! (no idea what's on that CB, but at least it still goes up and down :-)

Cheers,
Dale

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Tue Mar 21, 2017 10:32 pm

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Ah, excellent! This is the info I need. Good stuff. I wondered about the peaks and valleys. Really rough. OK, I will sand down to the valleys!! Should make the board thin enough to not bind when I build it up with epoxy, glass, and paint.

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Daniel
SCAMP build #330



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