Roll Stablilisation - Bilge Keels

Discussion in 'Boat Design' started by MDV, Nov 11, 2005.

  1. MDV
    Joined: Feb 2002
    Posts: 31
    Likes: 1, Points: 0, Legacy Rep: 60
    Location: Singapore

    MDV Junior Member

    Does anybody have direct experience with the effects that the addition of bilge keels have in terms of reduction in speed. rather than guess's I'm looking for quantative results based on real experience. The question is asked in relation to possible fitting of bilge keels to reduce the excessive rolling on a semi-displacement round bilge boat which currently operates at about 18knots. Any fitting of bilge keels would be done in the most effective manner with tank testing etc. to establish the flow lines.

    thanks,

    Michael
     
  2. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 110, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    We have 8 inch deep about 30 ft long 3/4 thick bilge keels on our Ex Usnavy Utility launch. They seem to work with no loss of speed compared to other launches.

    But its only a 12K boat that seldome goes that fast. they should be strong enough to take the ground , good way to protect the keel cooling.

    I would only add the computed surface area (minor) to the hull surface for calculations. They DO work when the vessel is stopped to reduce the roll.

    For a fast boat the Quantum stuff seems great although big $$$.
    Works at anchor TOO!
    Perhaps the cost can be defrayed by the use of the stab fins for hydronamic lift at high speeds.

    Framm roll tank is still the seamless choice , but lots harder to engineer.

    FAST FRED
     
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