Yacht Keels

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

  1. Ian Rob
    Joined: Feb 2005
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    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
    Joined: Nov 2004
    Posts: 568
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: cornfields

    Skippy Senior Member

    You could try twin keels.
  3. mattotoole
    Joined: Nov 2004
    Posts: 200
    Likes: 1, Points: 0, Legacy Rep: 13
    Location: Potomac MD, USA

    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
    Joined: Nov 2004
    Posts: 568
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: cornfields

    Skippy Senior Member

    Looks like a well-integrated bulb keel with the bulb shape acting as an end cap.
  5. tspeer
    Joined: Feb 2002
    Posts: 2,319
    Likes: 295, Points: 83, Legacy Rep: 1673
    Location: Port Gamble, Washington, USA

    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.

    Joined: Oct 2002
    Posts: 4,519
    Likes: 111, Points: 63, Legacy Rep: 1009
    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 , ???

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.