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    Re: The mathematics of tacking downwind
    From: Bill B
    Date: 2016 Jul 30, 15:25 -0400

    On 7/30/2016 4:28 AM, Francis Upchurch wrote:
    > Thanks Bill,
    > yes, you are right.Ocean racers do need the maths as you suggest, and
    > even during  our local  cruiser race from Penzance, round Scillies, I've
    > been known to draw polar diagrams with the help of calculator, GPS/
    > Autopilot, slide rule etc.But my dinghy (Laser)  sailing son usually
    > corrects my course by "feel" of the wind ,tide, leeway etc and gets a
    > better result than with  my poor maths.
    All the opinions expressed are correct in way or another. I had the
    pleasure of being slipped next to a Tartan 10 meter? (hull #1) racing
    sled in Dusable Harbor, Chicago, IL. It had all the pods etc even for
    for round-the-marks racing, and had a diver cleaning its hull pre-race.
    Serious folks.
    I raced a Hobie 16 in a Portsmouth fleet on our local pond, so a lot of
    hard-and-fast rules go out the door. For example, I can rarely point
    high enough to roll an M Scow, MC Scow or Finn to weather. If I try I
    will be "upped" into oblivion. With a good run, thanks to a
    high-aspect-ratio sail plan with a tall stick, I can duck through their
    lee a few boat lengths away without getting stalled out by a wind
    shadow. Also interesting is the concept of sailing a "proper course,"
    especially after rounding a mark. What may be a proper course for a mono
    hull (hull challenged:-) boat that can tack on a dime may not be the
    proper course for a Hobie which may lose a lot of ground when coming
    about or gybing. Same when I am tacking down wind and the fleet is at
    hull speed and on the rhumb line.
    That combination of algorithms and heuristics, my blow-boat racing
    friends, is what makes it so much fun. Part science, part art. Truly a
    case of "everything you know is wrong" quite often.

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