keel alloy mechanical properties?

Discussion in 'Sailboats' started by water addict, Mar 11, 2005.

  1. water addict
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    water addict Naval Architect

    OK sailboat experts out there,
    What sort of mechanical properties are used in keel alloy analysis and design? I'm specifically curious about Emodulus, allowable stress, yield stress, ultimate strength for typical keel lead alloys, ie. lead-anitmony 3%.

    much appreciate if anyone could forward those numbers to me.
     
  2. water addict
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    water addict Naval Architect

    No takers? Someone in boatdesign land must have that info...
     
  3. Skippy
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    Skippy Senior Member

    I have a couple inklings on this subject, but that's about it. One guy building a back yard boat believes the lead should be alloyed with 4% antimony for hardness. Apparently X-ray shielding doesn't have the antimony, but automotive wheel weights do.

    Other than that, I would only want the structural materials to be very very strong.
     
  4. Ssor
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    Ssor Senior Member

    Lead keels are usually such thick sections that the only concern anyone would have is the ability to hold the cast-in bolts. If the lead is exposed, then grounding on rocks gouges the lead but lead is not used for its mechanical strength. That's why you never see lead center boards, usually wood weighted with lead, or steel or bronze center boards.
    Even alloys of lead are only relatively "hard". Zinc is much harder and you could chisel marks in any lead alloy with aluminum.
     
  5. dougfrolich
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    dougfrolich Senior Member

    Lead with 3% antimony has a Tensil Strength of 4700psi, an elongation of 16%, and Brinnel Hardness of 9.1. 5% antimony TS= 6360psi, elongation 29%, and hardness of 11.
     
  6. water addict
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    water addict Naval Architect

    Gracias,
    Any numbers for Emodulus or Yield (0.2% offset I guess)?
     
  7. D'ARTOIS
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    D'ARTOIS Senior Member

    If you are not satisfied with your keel(weight) then take low radiance Uranium,
    whatever the chemical composition of lead, you are not going to better it.
     
  8. Ssor
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    Ssor Senior Member

    Kinda hard to come by depleted uranium though. :rolleyes:
     
  9. FAST FRED
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    FAST FRED Senior Member

    A visit to Bagdad should solve the Depleted Uranium supply source problem.

    Scrap lead has been used for centuries , still the cheapest option is steel , although it needs to be a bit wider to have same CG. location.

    Steel is probably the strongest to run aground with,

    FAST FRED
     
  10. water addict
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    water addict Naval Architect

    OK, thanks for the clever quips-
    Any #s for Emodulus or yield?
     
  11. dougfrolich
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    dougfrolich Senior Member

    E= 2030 ksi for pure lead
    Tensil Yield Str. 1160 psi ( 2% offset)
     

  12. water addict
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    water addict Naval Architect

    Thanks mon
     
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