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    Re: New compact backup CELNAV system
    From: Gary LaPook
    Date: 2009 Mar 17, 16:26 -0700

    I am real happy that I kicked off this topic and am impressed by the
    level of interest shown in using this simple to produce modification
    of the Bygrave for a backup celnav system. I am also impressed by the
    improved scales created by the other members on this list. A while ago
    I contacted Ken Gephart at Celestaire to get his opinion on whether he
    thought there would be any interest in a commercially produced version
    but he didn't think there would be. He thought that a simpler system
    would be better considering the lack of celestial training of your
    everyday sailor. I started this discussion stating that it was meant
    for those knowledgeable in CELNAV, the virtue of this system being its
    compact size and its low cost. He said that if they already had the
    Nautical Almanac they had the reduction tables already published in
    the N.A. (I, for one, really dislike those tables, your mileage may
    vary.) Work out an example with the N.A tables and compare the work
    with the came computation with the Bygrave and I think you will agree
    the Bygrave is easier to use. Those same non celnav sailors wouldn't
    be expected to buy an N.A. every year either so another advantage of
    this system is the long term almanac.
    
    So Ken, any more thoughts about this considering the great interest
    shown on this list?
    
    gl
    
    
    On Mar 17, 1:09�pm,  wrote:
    > I am another long time lurker, who got all excited about Gary LaPook's flat 
    Bygrave scales, and also got cracking on my own version of scales. 
    Unfortunately it took me a while to complete due to distractions like family 
    and job. So Dave beat me to it by a month or so.
    >
    > In any case I decided to publish my version of scales as well. Not because 
    they are better than Dave's, but because they are written in Postscript, and 
    can be easily customized by each individual user. It's easy to change width 
    of scales to the size of your sheet or cylinder, number of lines, font size, 
    frequency and thickness of tickmarks etc.
    >
    > The files cot.ps and cos.ps can be edited with text editor like notepad, and 
    then converted to PDF using free Ghostview tool. To do that you also need to 
    install Ghostscript. Here are links to download page.
    >
    > http://pages.cs.wisc.edu/~ghost/doc/GPL/gpl863.htmhttp://pages.cs.wisc.edu/~ghost/gsview/get49.htm
    >
    > You could even easily define other scales using this template e.g. 
    sec()/csc() for Ageton method like Andrew suggested in one of the previous 
    posts. Though this would require to write up the function in Postscript stack 
    based form using just (sin, cos, and atan) as these are only available 
    trigonometric functions in postscript. I would be glad to help, if somebody 
    decides to do that.
    >
    > Note that common procedures for drawing the scale are in scale.inc file and 
    it must be in the current directory when opening .ps files with ghostview.
    >
    > And I must also repeat Gary's warning, when printing PDF files make sure to 
    set Page Scaling to None. I wasted few transparent sheets before figuring 
    that out.
    >
    > Martin
    >
    > �cos.ps
    > 1KViewDownload
    >
    > �cot.ps
    > 2KViewDownload
    >
    > �scale.inc
    > 2KViewDownload
    >
    > �cos.pdf
    > 23KViewDownload
    >
    > �cot.pdf
    > 85KViewDownload
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