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    Re: Silicon Sea: Leg 82
    From: George Huxtable
    Date: 2001 Dec 04, 12:01 PM

    Dan Hogan said-
    >Definitions from The American Practical Navigator, Pub. No. 9, Bowditch, 1995
    >Heading n. The horizontal direction in which a a ship actually points or
    >heads at any instant, expressed in angular units from a reference direction,
    >usually from 000deg at the reference direction clockwise through 360deg.
    >Heading is often designated as true, magnetic, compass, or grid. Heading
    >should not be confused with COURSE, which is the intended direction of
    >movement through the water. At a specific instant the heading may or may not
    >coincide with the course. The heading of a ship is also called SHIP'S HEAD.
    >Compass Course. Course relative to compass north.
    >Course, n. The direction in which a vessel is steered or intended to be
    >steered, expressed in angular distance from north, usually from 000deg at
    >north, clockwise through 360deg. Strictly the term applies to direction
    >through the water, not the direction intended to be made good over the
    >ground. The course is often designated as true, magnetic, magnetic, compass,
    >or grid as the reference direction is true, magnetic, compass, or grid north,
    >respectively. TRACK MADE GOOD is the single resultant direction from the
    >point of departure to point of arrival at any given time. The use of this
    >term to indicate a single resultant direction is preferred to the use of the
    >misnomer course made good. A course line is a line, as drawn on a chart,
    >extending in the direction of a course. See also COURSE ANGLE, COURSE OF
    >Dan Hogan WA6PBY
    >C27 "Gacha"
    >Nav-L Page: http://www.wa6pby.com
    and others have contributed to the discussion on the distinction between
    heading and course-through-the-water.
    But nobody has mentioned the word LEEWAY!
    Don't sailing vessels make leeway any more? Perhaps list members' interests
    are confined to power craft. Even these can suffer from the effects of
    leeway under certain conditions.
    In general, the main reason why a vessel doesn't travel through the water
    in the same direction as it points is because of the effect of LEEWAY.
    George Huxtable.
    George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    Tel. 01865 820222 or (int.) +44 1865 820222.

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