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    Re: leeway
    From: Buck Godwin
    Date: 2001 Dec 06, 7:45 PM

    Ross Garrett wrote that leeway is proportional to the sine of the heel
    angle and inversely to the square of the boat speed.  He cites a
    proportionality constant of 464 based on model tests of for a
    particular 12.2 meter boat when using leeway in degrees and boat speed
    in knots.  In section 3.5.3 he presents a graph that shows good
    agreement between the model test data of the actual leeway and the
    leeway calculated from full-scale trial data.  He recommends the
    proper constant be determined for each boat from trials.  It is fairly
    independent of sail area, unless heavily reefed.  I believe the
    constant would depend on the hull bottom condition.
    
    Rather than measure leeway by your wake, steer a steady course from a
    floating marker dropped overboard and take a bearing on that marker.
    Leeway is taken as the difference in the relative bearing and 180
    degrees.  Don't use a tethered buoy, unless there is no current.
    Measure heel angle and boat speed as well, to determine your boat's
    constant of proportionality.
    
    I am quoting from "The Symmetry of Sailing" by Ross Garrett, Adlard
    Coles Limited, 1987
    
    
    Buck Godwin
    
    > -- --from Ocean Navigator #45 p. 72
    >
    >58.5*heel/boatspeed^3
    >
    >Is an approximation of leeway.
    >
    >Steve Tripp
    

       
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