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  1. #21
    dunedin is offline Registered User
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    Quote Originally Posted by CAPTAIN FANTASTIC View Post
    Depleted uranium is highly radioactive and anyway, where did they get it from?
    I think Club Med was supported by the French government / shipyards - so presumably had access to the huge French nuclear industry

  2. #22
    VicS is offline Registered User
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    Quote Originally Posted by wklein View Post
    I was under the impression it was depleted uranium which if i can recall my school physics becomes lead when it has finished reacting. I would imagine it was just lead but more pure and dense. I would be interested in someone with a genuine understanding of the science's input.
    If you'd actually been paying attention you would also recall that U 238 ( the major, and non fissile, constituent of natural uranium ) has half life of 4.5 billion years so you are in for a long wait for your uranium keel to turn into lead.
    Sea Wych Owners Association: www.Seawych.org

  3. #23
    Mad Pad is offline Registered User
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    Please lads..the keel was inert to all intents and purposes,Alain died at sea I seem too remember years later,(I know Tabarly fell overboard in the Irish Sea at night..and he was the advocate of NOT wearing a saftey harness).I also seem to recall the uranium was sold and maybe replaced with something else........What do I know I was only there far better to Wikopedia it ..Nite Nite

  4. #24
    William_H is offline Registered User
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    Back to the OP. Iron does rust and unfortunately expands with the rust products. So a GRP keel filled with Iron punchings or similar can rust and expand so splitting the GRP keel. A cast iron keel with paint treatment inevitably seems to rust. The rust products pop off the anti foul paint so giving premature fouling.
    Lead while more expensive is more inert. Fine for inside GRP fin and Ok for exposed lead (with antimonyfor strength).
    So if the OP is looking at a boat to buy. Cast iron keels are tough and the iron can be treated with epoxy to give reasonable protection between repaint but expect to retreat each winter. good luck olewill

  5. #25
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    Bertie Reed's Allied Bank had a depleted Uranium keel too. Rodger Martin design IIRC.

  6. #26
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    Quote Originally Posted by Stork_III View Post
    Perhaps you should tell the Swedes then. Antimony is added to the lead to make it sufficiently stiff for the keel,with some residual softness, great for those Baltic rocks. Even Bavaria offer lead keels on some if not all models.
    The slight softness of lead also helps, as Stork says, if you hit a rock: it has considerable shock-absorbing properties and reduces the chance of hull damage at the aft end of the keel root - the usual consequence of hitting a rock at some speed with an iron keel.

  7. #27
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    Downside of DU, tungsten, gold etc (anybody else remember Desmond Bagley's book The Golden Keel?) or ununpentium - the new element that's just been announced, although having a keel that auto destructs is probably not a good idea - is that most rating rules ban it. E.g., IRC rule 19.4 In the construction of hull appendages, no material with specific gravity greater than 11.3 is permitted.

    Means you can't go and race it. Might not matter to some, of course, but something tells me that the sorts of people willing to fork out for a DU keel are probably competitive, racing types.
    Last edited by Keen_Ed; 29-08-13 at 08:10.

  8. #28
    geem is offline Registered User
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    Quote Originally Posted by maby View Post
    I was under the impression that most supposedly lead deep fin keels are actually iron keels with a hollow bulb that is filled with lead - it's more a performance thing than durability. Filling the bulb with lead allows you to get the balast weight lower and to reduce drag since a given weight occupies less volume.
    My Trintella 44 has a deep lead keel of some 6 ton. The yacht has 2.2m draught. boat is 33 years old and sails like a dream.

    if you want less volume than lead than go for tungsten. Tungsten is 50% heavier than lead

  9. #29
    Twister_Ken's Avatar
    Twister_Ken is online now Registered User
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    Another advantage of lead over iron is that for the same righting moment you can have a shallower keel. Conversely if you want a deep keel you get less wetted surface area with lead cf iron.
    Next time, it'll all be different.

  10. #30
    macd is offline Registered User
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    Quote Originally Posted by VicS View Post
    If you'd actually been paying attention you would also recall that U 238 ( the major, and non fissile, constituent of natural uranium ) has half life of 4.5 billion years so you are in for a long wait for your uranium keel to turn into lead.

    Clearly wklein's memory of school physics has a somewhat shorter half-life.

    And to MadPad: Pen Duik's keel had a fairly short full-life, as you say: according to Wiki it was later replaced with lead.
    Mac

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