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Subject: Re: [worldcruising] Electronic Charts systems
From: jan bruggeman (jan.bruggeman@XXX.XXX)
Date: Thu Jan 25 2001 - 03:55:40 EST
Hello list,
<snip>
> Perhaps the operating systems used for the GPS satellites themselves are
> using Win 95 or Win 98? I would strongly urge you to reconsider
alternatives
> to relying solely on GPS for navigation.
</snip>
Good joke ! I personally hope they are running linux. As for electronic
charts systems, I have not used any, but I would certainly go to a
computer-based system rather than a proprietary system. Being a computer
programmer, it's working in a known environment. But for the non-computer
specialists, it still preserves some advantages:
- The same computer can turn into other uses on board: weatherfax receive,
pactor operation for radio based email to name some. And you certainly don't
need the latest model, I'm still running a 486 eventough I just found a free
dell pentium 75 mhz ;-)))
- A computer, or better, the ability to easily change software on it, will
always give you more possibilities than on proprietary systems. After 20
years in computer business, my experience is that those "open" systems make
it in the end.
- Loss of your hardware will not turn into loss of software (you have
backups, haven't you ?): after purchase of a new computer, your old charts
still work.
And I'm sure this discussion can go on and on. Let me make just some more
point for astro-navigation !
- Do you know that you only need 4 almanacs, of 4 concecutive years ? the
5th year, you just use almanac 1 over again, and so on. This will only
induce a very small error, much smaller than the errors in the almanac
itself (due to rounding of numbers). You can certainly use almanacs of
2001 - 2004 until 2050 ! of course, within 200 years or more, the error will
become bigger. The theory behind this:
* every 4 years we add 1 day to the calender (29 february) to cope with "the
biggest error" : that's why I say you need 4 concecutive almanacs
* after 400 years we take away 1 day out of the calender (there was no 29
february 2000 due to this rule) because rule 1 is too rough.
So using almanacs over and over again will induce an error of 1 day in 400
years. Perhaps you're better to buy new almanacs now as we've just lived
thru such a correction, they will be usable till the end of your sailing
carreer, unless your under-age while reading this ;-)
And the feeling you get when you manage to make a point on the chart after
your sextant work is reason enough to go thru the whole process of learning
!!!
mvg,
Jan Bruggeman
mail: jan@XXX.XXX
web: http://jan.bruggeman.com
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