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    Re: Traditional navigation by slide rule
    From: Gary LaPook
    Date: 2016 Jan 11, 05:54 +0000
    The Pickett rules are made of aluminum. 
    For boat speeds you don't need three cycles, two cycles, 1 to 100, or even just one cycle, 1 to 10 knots or 1.5 to 15 knots , or 2 to 20 knots.


    From: Lu Abel <NoReply_LuAbel@fer3.com>
    To: garylapook@pacbell.net
    Sent: Sunday, January 10, 2016 6:24 PM
    Subject: [NavList] Re: Traditional navigation by slide rule (correction)

    Two (and a half?) small comments on Bob Gothe's note (which, because of its size I am not attaching):

    1.   I don't think making a rule out of aluminum would be an issue:

    a.  You're speaking of small changes in temperature (say, from room temp to the temperature of one's hands), not hundreds of degrees.

    b.  More important, as long as everything expands uniformly, accuracy would not change.

    2.  I don't think the range of calculations (1 to 1000 knots) would be an issue.   The "1" on a slide rule can stand for 1, 10, 100, or 1000.   What's important is relative values - a one knot set on an airplane traveling at Mach 1 is hardly worth noting, whereas us sailors would surely be concerned about a one not set at six knots.

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