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    Silico Sea 26 set, drift, and leeway
    From: Bill B
    Date: 2004 Jul 5, 17:40 -0500

    >> "Regarding SS 26 could I impose on you to work the problem?"
    > Can remember from doing them some time ago that the Red Sea passages had a
    > few inconsistancies.
    > Agree with official answers for Q:1, and with date/time for Q:2. But for the
    > DR there seems to be some confusion, with the distance covered consistant
    > with the SMG of 12.8k but the course, 126.4dT, is the course given before
    > the current effect is factored in.
    Corresponded with Mike outside the list as it included attached diagrams.
    I questioned what type of keel she has.  Leeway tables for Beaufort 4 on
    something between a run and broad reach could range from negligible to 2
    degrees.  Best guess would be between 1/2 and 1 degree depending on keel and
    old rollers vs. new mashed potatoes.
    Also wonder if they factor in wind-induced surface currents.  The Annapolis
    Book of Seamanship would suggest an additional .25 knot current for Beafort
    4 running at a 45 degree angle to the right of the direction the wind is
    blowing.  Since the wind is out of 310, it is toward 130.  Add 45 to that
    and you wind up with 175.  Almost parallel to the stated 5 knot current and
    in the same direction so almost 5.25 knots.  With that and leeway, speed
    over ground would be 13 knots.  With wind induced current, set, drift, and
    leeway factored in speed-over-ground would be about 13 knots and COG with 1
    degree leeway would be approx. 146 degrees.

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