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    Re: wind effected by tide?
    From: JC Sutherland
    Date: 2000 Feb 20, 19:48 EST

    Russel
    Forgive me if I have missed the point of your topic,but I dont have your
    original question. It seems to me that you maybe refering to a creation
    or modification of a wind by the tide. This is a normal occurrence. In
    the simplest  example, suppose a boat is  dead in the water with no
    sails or engine power, the tide itself will move the boat along. In turn
    this will generate an apparant wind over the deck in the opposite
    direction and with the same speed of the tide, this is sometimes known
    as the 'Tide wind'.
    To cut a long story short let me give an example of its application.
    Suppose you are heading for a destination which is to windward. In the
    absence of a tide either tack will serve as the initial course.but if a
    cross tide is flowing then the tack which puts the tide on the lee bow
    will allow the boat to point more up into wind and this in turn will
    shorten the distance to go.
    In the English channel this is a common way of crossing from one side to
    the other as the tide runs east/ west as the boat crosses north/ south.
    A six hour board, lee bowing the tide on one tack  then changing tack on
    the change of tide will significantly reduce the time of crossing.  You
    can easily loose a race if you don't get this right.
    It is the direction of the apparant wind over the deck of the boat that
    determines the best point of sail  and the 'Tide wind'  vectorally
    adding to or subtracting from the 'Meteorological wind' causes a
    modification to this direction . Obviously strong tides and light winds
    will give the greatest effect.
    Clive Sutherland.
    

       
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