Patent ID: 8443663

Claim:
In a navigational aid of the type comprising four overlayed, relatively thin, flat, circular disks of varying size, being secured together by a means that allows rotatability about a common axis independently, retaining said disks in a juxtaposed, concentric relation; a. a first disk is a bearing disk, marked indicative of a nautical compass, comprising a peripheral scale graduated in degrees; b. a second disk, a variable disk, being of a lesser diameter than said bearing disk, is inscribed with a plurality of markings on a periphery, comprising an arrowhead to indicate apparent wind direction, 40° on either side of said arrowhead are fifty-seven equal dividing lines perpendicular to said periphery, which are further divided diametrically in half, providing fifty-six spaces, each space containing two semi-identic areas, comprised of an upper circumferential row, and a lower circumferential row, said upper circumferential row accommodating a predetermined numerical calculation, said predetermined numerical calculation means factored variations of transitioning boom/mainsail angles to apparent wind ratios; c. a third disk, a boat disk, being of a lesser diameter than said variable disk, is inscribed on the surface with a delineation comprising a hull of a sailboat, a bow that culminates at a bowsprit which terminates at said boat disk's periphery indicating 0° of a 360° circle, further inscriptions on said periphery include a graduated scale, in degrees, commencing at 90° and terminating at 270°; d. a fourth disk, a boom/mainsail disk, bears a depiction of a boom/mainsail emanating from said common axis, typifying a sailboat's mast.