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Thread: Metal keel fin

  1. #1

    Default Metal keel fin

    I have some 3/16 aluminum plate, and I need another fin or two, so I was thinking that if the fin was made of metal, then you could decrease the amount of ballast (keel bulb) at the bottom, right?

    thx
    Sail honest.
    Rock music.

  2. #2
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    Default Re: Metal keel fin

    Yes, but do you want too?

    The problem is that you want the the fin to be as light as possible so that the lead is as heavy as possible. You want the lowest possible CG. Doing what you propose would raise the GC and make the boat more tender for the same total weight.
    John Ball
    CRYA #895
    IOM CAN 307 V8

  3. #3
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    Default Re: Metal keel fin

    Yes, although the weight would not be positioned in the ideal place. Ideally you want all your ballast as low as possible, to increase the righting moment. That is why keel bulbs are used instead of sandbags in the bilge -- to keep the weight low, together, and balanced. That said, an aluminum fin probably won't weigh so much that you will throw your ballast too much out of wack... although, that may in itself defeat your purpose of trying to cut the amount of ballast. Your other option -- if you are simply trying to cut down on bulb size -- would be to cast a keel entirely out of lead, or part of a keel. It could be argued that doing so would cut down on drag at the end of the keel as well, however, once again, if you look at any racing keelboat today, they all have bulbs... there's a reason for that.

    oops, hiljoball beat me to the punch... ah well, it bears saying twice!
    the pessimist complains about the wind, the optimist expects it to change, the realist trims the sails.

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  4. #4

    Default Re: Metal keel fin

    It seems to work on the solings, which are pretty much solid lead top to bottom.
    Sail honest.
    Rock music.

  5. #5
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    Default Re: Metal keel fin

    Quote Originally Posted by TomoHawk View Post
    It seems to work on the solings, which are pretty much solid lead top to bottom.
    But that's not a good analogy. The Soling has a balasted fin keel. Your boat has a fin and bulb.

    You want the weight as low as possible.
    John Ball
    CRYA #895
    IOM CAN 307 V8

  6. #6
    Join Date
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    Default Re: Metal keel fin

    ^^ What the man said ^^
    the pessimist complains about the wind, the optimist expects it to change, the realist trims the sails.

    Footys:
    USA 39 Bearfoot
    USA 62 Stiletto
    USA 190 Eclipse
    USA 97 Orange Crush
    USA ??? Albatross (in progress!)

    Sparkman Micro Marine
    builders of Footy hulls

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