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    Re: Longhand Sight Reduction
    From: Francis Upchurch
    Date: 2014 Jun 27, 04:48 -0700

    Hi Hanno,

    I'm just out of hospital post op, and doing fine. But beached and therefore restricted to sextant readings and playing with slide rules while lying down in the garden overlooking the ocean. Tough life!

    Coming round from the anaesthetic, (great for lateral thinking!) I had an idea re the Fuller 2. The main problem is lack of cosine scale, which means I have to convert all cosines to sines first. Simple, but tedious, time consuming and an unecessry source of errors.  I never use the log scale on the big fuller 2, so have replaced it with another sine scale,same size ,but with cosine numbers in red and green going the other way. So I can now do all my cosine formulae cel nav calcs direct which halves the time.

    I have adapted the minifuller 2 , with the sine scale now having added  cosines numbers  in red going the other way too. Works ok, but the big fuller 2 replica is  more accurate and best for shore based work.

    Over the next few days I'll do some comparative LOP  calculations using long hand Haversines or Versines, Fuller 2, mini Fuller 2 and Bygrave and see what we get in terms of accuracy and speed. For lunar clearance, I suspect the big fuller 2 will win, but the minifuller 2 probably adequate and more seaworthy and with the Otis King format, a bit faster with less moves.

    Best wishes

    Francis

       
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