Yacht Keels

Discussion in 'Boat Design' started by Ian Rob, Feb 27, 2005.

  1. Ian Rob
    Joined: Feb 2005
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    Location: Melbourne

    Ian Rob New Member

    I have been building an Infanta design 'cousin' to Sopranino and Trekka [all designed by Jack Laurent Giles] but instead of the fixed fin keels of these 2 my design has a fixed hollow fin with a swing down centre-board.
    The dimensions of Infanta are - loa: 20'1" lwl:17'6" beam: 6'3" draft 2'6" & 5'6" with the plate down, ballast: 1000lbs in the fin.
    I have built the fin of sheet steel and have developed the fin in such a way that I can detatch it [with a bit of bother] to inspect it if necasary.
    However I am becoming concerned about the on-going maintenance of a centre board with marine growth etc getting into the C/B slot and wondered if there is any alternative out there in keel development that gives you shallow draft with windward efficiency - wings on the keel? etc ??
     
  2. Skippy
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    Skippy Senior Member

    You could try twin keels.
     
  3. mattotoole
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    mattotoole Senior Member

    I don't know how they compare to modern winged designs, but Scheel keels can perform pretty well for shoal draft applications.
     
  4. Skippy
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    Skippy Senior Member

    Looks like a well-integrated bulb keel with the bulb shape acting as an end cap.
     
  5. tspeer
    Joined: Feb 2002
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    tspeer Senior Member

    Unfortunately the physics of keels says their drag due to lift is inversely proportional to draft-squared. So while you can perhaps make some minor improvements, shallow draft is going to impact windward ability.
     

  6. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The great Herrishof figured that a 7-1 ratio between LWL and draft would work in all cruisers going to windward.

    So a 28 ft waterline would have about 4 ft of draft.

    No in calm water she wont point as high as a "race" boat sailing on the Keel , just dragging the hull along, but in the ocean where some HP is required to advance into seas , the combo of hull and 1/7 draft keel works just fine.
    And is BETTER in light airs with less wetted surface than the lead mine.

    Going around the buoys or the world , ???

    FAST FRED
     
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