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    Re: 'pacing' for boat speed
    From: Hewitt Schlereth
    Date: 2011 Apr 14, 09:38 -0400
    Before electronic instruments were around (early '60s) I sailed on a 73' experiment (early aluminum) and our method was to carry a .22 rifle to the bow and fire a shot into the water. The bullet made a circular splotch of foam the size of a dinner plate. Hearing the shot, a guy at  the stern would start a stopwatch and get the time when the splotch passed the transom. We kept a table of time/speed taped to the bulkhead at the nav station.

    Hewitt

    On Thu, Apr 14, 2011 at 5:39 AM, Paul Werner <paul.werner{at}comhem.se> wrote:

    apacherunner wrote: "�finding boat speed by counting the time it takes a piece of flotsam to move along the hull."

    I know that as the "spitlog". I think moist snuff was preferred as "instrument".
    It is very easy to calculate and use in the metric system.
    1kn = 1nm / 1hour = 1852m / 3600s = 0,51 m/s ≈ 0,5 m/s.
    Thus for a boat: Speed (kn) = 2*Length (m) / Time (s).
    For my boat, 10m, I divide 20 with time in seconds.
    It can't be used on short high-speed boats.

    Paul Werner

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