Preview: How to Build a Caledonia Yawl, Part 30 – Reinforcing & Ballasting the Centerboard

10 Responses So Far to “How to Build a Caledonia Yawl, Part 30 – Reinforcing & Ballasting the Centerboard”

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  Brian Waite says:

  Another question regarding the pouring of molten lead. Does it soften the epoxy to the point of delaminating your centerboard, and if so does it re-harden back into place?

  Thanks.

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    Geoff Kerr says:

    I imagine some of the epoxy is softened, but with the insulating qualities of wood I bet the effect limited to a very short distance (let’s say less than an inch?) It does reharden, probably with some compromise in strength, but given where that occurs it is of no matter.

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  Charles Neuman says:

  I’ve been leaning toward the epoxy/shot method as well.

  I can’t seem to get a definitive answer on how dangerous the fumes are from melting lead. Some say they are extremely dangerous while others have a more relaxed view of it.

  I’m also concerned about sanding lead. If the lead comes out proud of the surface, and I sand it down, then I’ve got lead dust everywhere. Even if I use a respirator to avoid breathing the dust, there’s still going to be dust everywhere that could get on my hands, etc.

  I guess one solution is to use the shot method, but be sure that it doesn’t come out proud of the surface. That avoids all the problems, but I’d still like to go into it knowing what the risks are.

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    Geoff Kerr says:

    I too have pondered the risks of lead exposure during this process, and had long rationalized that I was melting the lead, not boiling it, and that any sanding debris was coarse and not likely to be airborne. I have also been very politely taken to task by a student who is an industrial medicine physician and was appalled by the old-school techniques I employed. My current common sense techniques: organic respirator, nitrile gloves under my smelting/pouring gloves, take great care to underpour the flush surface so no or little grinding is necessary, and grinding over a drop cloth which gets saved for the next time. I grind with #36 discs, and give the lead a coat of fairing compound for the finish sanding…and wash my hands, etc. afterwards. I should note that I also work in a dedicated shop, and my work clothes barely make it into my house at the end of the day before I change. All of this makes epoxy encapsulating lead shot seem pretty sensible doesn’t it.

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      Charles Neuman says:

      Both melting, with those common sense techniques, and encapsulating shot seem pretty reasonable. Thanks for the tips.

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  Paul Gill says:

  I have about run out of sapele plywood. I’m thinking of building the centerboard out of solid mahogany. To assure a board that stays straight, I will edge-glue (with biscuits) two pieces of 6/4 mahogany with grain running in opposite directions, then plane and shape to size.

  The 6/4 will be expensive, but not as much as to have Boulter Plywood ship one sheet of plywood to Middlebury!

  Any thoughts?

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  Clyde Davis says:

  Welcome alternative for me Larry, thanks!

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  John Sims says:

  Just wondering; is the epoxy filled leading edge just for strength in case of contact with the bottom, debris, etc.? In any case, would a metal (bronze? SS?) leading edge be helpful in preventing that kind of damage? Been thinking about it for my centerboard & would appreciate Geof’s views. Thanks! Gorgeous boat! Sure do want one!!

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    Geoff Kerr says:

    The epoxy leading edge is just a simple way to provide a little armor against hard and sharp things. The fact is that I pulled Ned Ludd’s unadorned Khaya board after a dozen years of hard use and found surprisingly few dings worthy of attention. You could certainly add a metal edge band with relatively little difficulty. My thinking is that I’ve got the board and epoxy in the same place at the same time, so why not?

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  Larry Cheek says:

  An alternative to melting is to pour lead shot into the CB cavity, then seal it in epoxy. The shot is more expensive than collecting scrap wheel weights, but for me that’s balanced out by not having to buy a turkey deep-fry apparatus. And by not having to deal with the hazard of handling molten lead.

  Since the epoxy/shot mixture has less weight by volume than pure lead, the ballast cavity will have to be larger—about 20-25% in my experience.

  I’m not advocating this as a better way than Geoff’s, but just an alternative for those of us with less industrial fortitude.