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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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