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    Re: Cross-tide strategy (was: DR plotting techniques)
    From: Richard M Pisko
    Date: 2003 Oct 25, 18:36 -0600

    On Sat, 25 Oct 2003 22:22:46 +0200, Philip Ouvry wrote:
    >You are in a boat capable of 4 knots intending to cross a wide river.   Your
    >destination is straight across the river.   In the centre of the river the
    >current runs at 7 knots but close inshore on either side it reduces to 2
    >knots.   What should be your strategy for crossing the river?
    >My strategy was to cross the river at right angles until close inshore on
    >the far side and then proceed against the current (2 knots) to reach the
    >destination.   Is there any other strategy?
    Maybe we don't need actual numbers, but they would be helpful for the
    illustration to say the total river width is ten, the "close inshore"
    is one, leaving eight as the seven knot current portion.
    Otherwise, you could try any number of variations between:
    (1) heading upstream first portion or last portion only, and heading
    straight across in the fast current;
    (2) a constant heading upstream calculated to land you straight across
    at the end of the journey.
    I rather doubt that a heading downstream in the center portion would
    save any time, but it should be investigated too.
    Richard ...

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