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Thread: Melted lead vs lead shot in epoxy

  1. #1
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    Default Melted lead vs lead shot in epoxy

    Hello. I am not really eager to melt a bunch of lead and pour it into a cavity in my centerboard. The centerboard is 3/4" plywood and the plans say the cavity is supposed to be 5" by 6", which comes to 22.5 cubic inches, or a little over 9 pounds of lead. I am debating buying a 10 pound bag of lead shot and pouring as much of it as will fit into the cavity suspended in epoxy. How much less do people think this would weigh than solid lead, and would it make a significant difference in the performance of the centerboard? Thanks.

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    Default Re: Melted lead vs lead shot in epoxy

    Tungsten pellets can also be used for setting your weight into epoxy. This is what is used for weighting golf clubs. It is much heavier than lead and even heavier than gold. Many modern boats are ballested with Tungsten pellets.
    Jay

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    Default Re: Melted lead vs lead shot in epoxy

    The lead is just enough weight to make sure the centerboard stays down when sailing. I think that anything that gains you 9 lbs within the same volume should work.

    But I went ahead and melted lead for mine.

    http://www.willmarsh3.net/el/elver071804.html
    Will

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    Default Re: Melted lead vs lead shot in epoxy

    You can just cut a hole in the board and epoxy in some diving weights.

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    Default Re: Melted lead vs lead shot in epoxy

    I did a quick google search and came up with 436 pounds per cubic foot for #8 lead shot. I couldn't find a chart for different sizes. As the shot gets smaller, the density probably increases. This is really just academic because all you have to do is pour 9 pounds of the shot you purchase into a container and measure the volume. Or guess, then pour the shot into the cavity and see how much it holds. If not enough, then cut the cavity larger. Pretty simple.

    Or, take a deep breath and pour some melted lead. The process is really quite simple.

    Jeff

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    Default Re: Melted lead vs lead shot in epoxy

    Quote Originally Posted by Gkaler View Post
    Hello. I am not really eager to melt a bunch of lead and pour it into a cavity in my centerboard. The centerboard is 3/4" plywood and the plans say the cavity is supposed to be 5" by 6", which comes to 22.5 cubic inches, or a little over 9 pounds of lead. I am debating buying a 10 pound bag of lead shot and pouring as much of it as will fit into the cavity suspended in epoxy. How much less do people think this would weigh than solid lead, and would it make a significant difference in the performance of the centerboard? Thanks.
    1% less, that's what I think. (1% of 9 lbs, = .9 lbs. result... 8.1 lbs) You could increase the increase the cavity by 1% (to 24.7 cu in) and be Kosher.
    Last edited by jackster; 07-23-2017 at 04:43 PM.

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    Default Re: Melted lead vs lead shot in epoxy

    What design is the boat?There may be a much simpler alternative.

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    Default Re: Melted lead vs lead shot in epoxy

    The boat is a 15-1/2 foot Chesapeake Crab Skiff, designed by Doug Hylan.

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    Default Re: Melted lead vs lead shot in epoxy

    I wouldn't get to hung up on the exact size of hole or mass of lead.Its just there to make sure the board has negative buoyancy and this will depend on the density of the wood you used.You could even use a piece of square bar let into the tip.If the case had a slotted capping and a handle to adjust the board position,I would have suggested a six inch length of rubber hose as an adjustable source of friction.

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    Default Re: Melted lead vs lead shot in epoxy

    shot in epoxy seems to me to be MUCH easier than dealing with molten metal.
    I might throw a few handsful of chopped glass into the mix.
    Tungsten costs about ten times as much per pound as lead.

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    Default Re: Melted lead vs lead shot in epoxy

    This isn't rocket science. A cubic foot of lead weighs 708 pounds. As mentioned above, a cubic foot of shot weighs 436 pounds. Do the math.

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    Default Re: Melted lead vs lead shot in epoxy

    From doing some Google research, it looks like lead shot in epoxy is abou 436 pounds per cubic foot, as opposed to 708 pounds for solid lead. So, it looks like I would get a result of about 62 percent of the weight of solid lead. I am thinking that I should make the cavity correspondingly larger, if I want to get approximately the same weight. So, about 5.5 inches by 8.75 inches, instead of 5 by 6. I am wondering if this is approaching the point where making a bigger cavity weakens the centerboard?
    Last edited by Gkaler; 07-23-2017 at 06:46 PM.

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    Default Re: Melted lead vs lead shot in epoxy

    Jackster: Don't forget that other zero, .09#
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    Default Re: Melted lead vs lead shot in epoxy

    I bought 1lb lead ingots on ebay and epoxied them into my centerboard. They were easier than dealing with shot, and took up less space in the board. They stack together nicely and you can determine hole size based of how many you have stacked together.

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    Default Re: Melted lead vs lead shot in epoxy

    For the 13 lbs in my centerboard I epoxied in sheets of lead flashing. Works like a charm.
    Gerard>
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    Default Re: Melted lead vs lead shot in epoxy

    There are four perfectly good solutions here. More Google/Wikipedia will tell you that you can't do better than 65% with packing spheres, so 62% is a good achievable number. A larger hole can be any shape you want, so weakening is not a problem. A steel plug, stacked sheet or cut plate is 70% as dense as pure lead, and I would not be surprised if the board is glassed, so neither corrosion nor a larger hole should be a problem. 9lb of 1/4" steel plate is 129 in², so a laminated board would be stronger, but my vote goes to Gerard's lead sheet. Epoxy sticks well to lead.

    Quote Originally Posted by Gkaler View Post
    From doing some Google research, it looks like lead shot in epoxy is about 436 pounds per cubic foot, as opposed to 708 pounds for solid lead. So, it looks like I would get a result of about 62 percent of the weight of solid lead. I am thinking that I should make the cavity correspondingly larger, if I want to get approximately the same weight. So, about 5.5 inches by 8.75 inches, instead of 5 by 6. I am wondering if this is approaching the point where making a bigger cavity weakens the centerboard?
    Quote Originally Posted by John Meachen View Post
    I wouldn't get to hung up on the exact size of hole or mass of lead.Its just there to make sure the board has negative buoyancy and this will depend on the density of the wood you used.You could even use a piece of square bar let into the tip.If the case had a slotted capping and a handle to adjust the board position,I would have suggested a six inch length of rubber hose as an adjustable source of friction.
    Quote Originally Posted by wizbang 13 View Post
    You can just cut a hole in the board and epoxy in some diving weights.

    Quote Originally Posted by Gerarddm View Post
    For the 13 lbs in my centerboard I epoxied in sheets of lead flashing. Works like a charm.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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    Default Re: Melted lead vs lead shot in epoxy

    Further up the thread, mention was made of density might vary with different size of shot. The % of space occupied by sphères of the same size is constant, though I don't know how it works if you mix different sizes.

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    Default Re: Melted lead vs lead shot in epoxy

    It seems like a lot of trouble to go to just to avoid doing something you haven't done before. You can melt ten pounds of lead in an iron skillet on a stove without any trouble. It's easily faired to the face of the centerboard with a wood plane. It's not rocket science.

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    Default Re: Melted lead vs lead shot in epoxy

    Depleted Uranium?

    Wiki: "Depleted uranium has a very high density and is primarily used as shielding material for other radioactive material, and as ballast. Examples include sailboat keels, as counterweights and as shielding in industrial radiography cameras."

    IF you do use it, can you call your boat "Marie Curie II"?
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    Default Re: Melted lead vs lead shot in epoxy



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    Default Re: Melted lead vs lead shot in epoxy

    Quote Originally Posted by Bob Cleek View Post
    It seems like a lot of trouble to go to just to avoid doing something you haven't done before. You can melt ten pounds of lead in an iron skillet on a stove without any trouble. It's easily faired to the face of the centerboard with a wood plane. It's not rocket science.
    I second this view. First time I had to melt lead I was pretty nervous, but now that I've done it a few times I'd rank it's complexity right up there with making a cup of tea.

  22. #22
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    My son calculated lead shot plus the weight of the epoxy to be around 70% iirc. Lead shot packs perfectly.
    I did lead shot in epoxy on my centerboard instead melting lead, wasn't much work, it was quite easy.
    Last edited by peb; 07-24-2017 at 03:57 PM.

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    Default Re: Melted lead vs lead shot in epoxy

    Thanks everyone for the feedback. I found lead flashing available on Amazon in various sizes. I ordered a sheet 1/16" x 12" x 36". I should be able to easily cut this up into 5" x 6" pieces and stack up and glue twelve of them into a 5" x 6" cavity in the 3/4" plywood centerboard. After shaping the centerboard into a foil shape, I'm going to cover it with fiberglass cloth, so the lead weight should be pretty securely held in place and sealed against water intrusion. Thank you gerarddm for the flashing suggestion.

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