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    Re: A chord based octant or quadrant (& emergency navigation)
    From: Paul Dolkas
    Date: 2012 Nov 4, 12:27 -0800


    Actually, I disagree. They can be sailed, and many came equipped with sails for that purpose. Some even had keels, of a sort – although serious tacking is out of the question. One can imagine trying to decide whether it’s best to stay put (i.e. drift), or make use of the prevailing wind and sail more or less downwind. You’d want to know where downwind would take you, which means you’d need to know where you are.
    I used it a few months back to try and locate my position (SF Bay area) by timing the meridian transit of Sirius (I think it was). My LOP wasn’t that far off, considering*. A noon shot the next day to figure out latitude would have given me a pretty good fix – which, as you point out would been good for morale, if nothing else.

    Even though I can’t scan the star map, I realized I can scan the text where it describes the business of angle measurement. I’ve attached it.

    -Paul Dolkas

    *My first attempt put me somewhere in the central valley. The main source of error turned out to be that the scales used to advance the star’s position didn’t take into account the Equation of Time, which accounted for something like 5 minutes.

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