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----- Original Message -----
From: "Marc Bernstein" 
To: 
Sent: Saturday, December 14, 2002 5:13 AM
Subject: Non-traditional Sight Reduction


> More and more navigators are still using their sextants but using software
> for sight reduction

Your question ranges across both computing platforms as well as
software.Also, some of the software you mention is for GPS charting puposes
only, I think.Anyway, here are some of my views.

I am currently playing around with celestial software on three platforms:

1. A laptop loaded with the shareware version of Navigator Light 32. That
program is  easy to use, and I think I will buy the registered version when
I finally "set sail". However it has no provision for sailings and piloting
calculations.

2. A HP 48GX calculator with a Sparcom Nav48 card. This software has "all
the features" and will do everything that you want. However, the HP 48GX is
a little quirky to use, and one needs to be using the calculator and the
software regularily in order to be able to easily  move between the program
menus and enter data. Its also a little unforgiving in recovering from
mistakes in data entry and errors of calculation. Nevertheless, a very
strong, robust package...simple and effective.

3. A very recently acquired Palm Vx loaded with CelestNav, John Manson's
Pilot Navigator, and several "sky" programs and a tide program. I find
CelestNav easy to use,  generally favour it, and will probably buy it.
However it is fairly expensive, and doesn't have a current/set/ drift
facility(hint, hint to a contributor on this list!). The shareware version
of Pilot Navigator only has provision for sun sights, nor does it seem to me
that the registered version includes the planets and stars. I will probably
keep the shareware Piloting part of Pilot Navigator to provide a
current/set/drift calculation facility to complement CelestNav.

I have had the laptop with me on several yacht trips....basically I have
found it belongs below deck, clipped down somewhere protected, and with
access to ship's power. Although its an ultra slim laptop, I don't feel
comfortable with it above deck. It's cumbersome , there is nowhere to put it
and it seems vulnerable.

The HP 48GX is much more portable. It will work in a sealed plastic bag, and
fits in a large pocket, on deck or in a coat. It seems robust, the batteries
last a fair while, and are easily changed. With a bit of learning, the HP
can be programmed through the keyboard to do any special calculations that
you might want.

The Palm Vx....aaah, what a wonderful tool! Why did I not buy one years ago?
It will do everything required for celestial calculations, and then
more...much more. It is small enough to slip in a shirt pocket. It will work
in a plastic bag. It is ideal for calculations on the fly, being so readily
at hand. Apart from celestial calculations, I use it for star
identification...using Planetarium, I zoom to the segment of sky of
interest, hold the Palm up against the sky, and voila, there is the star in
question.Tide Tools gives me the tide anywhere in the world...it is a little
bit inaccurate for here in Australia, but certainly good enough to give a
first impression. Apart from the celestial software I have mentioned,
programs such as EasyCalc allow the user to readily solve their own
mathematical expressions on the fly, without recourse to programming. ( The
HP 48GX will also do this, but not quite as conveniently)

The downside is that the Palm screen is a little hard to read, especially at
night. Battery life can be an issue...The Vx has an internal battery that
can only be recharged....however, I have a clip on battery pack that will
keep it going in emergencies. Other Palms have replaceable batteries, but
are larger in size as a consequence. The internal battery has a life of 2-3
years, but can be replaced. Also, in sea and night work the stylus is easily
lost...have replacements on hand.

The clock in the Palm (as with any PC) is not reliable, showing noticeable
drift after 2-5 days. If one wants to use the clock in the Palm for
celestial calculations, it must be regularily calibrated. I use a connected
GPS to regularily calibrate the time.

The Palm will of course do much more than celestial work....address books,
data bases, shopping lists...anything that can be programmed into it. It is
user programmable, but not readily...programs are usually written in C/C++
on a PC, compiled and debugged there, and then transferred to the Palm.

I like my HP, it has a nice feel and from the nostalgia point I have been
using HP calculators for nearly 30 years. However, the Palm has become my
daily companion in my business and social life, and I think for celestial
work it is going to replace the HP.

One project I must get onto is investigating and comparing the accuracy of
the various bits of software mentioned above. I need some sort of benchmark
data/calculations with precisely calculated results to run through the
various programs. Still thinking how to do that.

Lee Martin

PS for Robert Eno: The Vx is a classic amongst PDA's, but is now obsolete,
no longer being made. I bought mine new off Ebay for $80US complete with a
few accessories. Another $80 bought several new clip on devices for the Vx:
a folding keyboard(has to be seen to be believed, ideal for word
proccessing, entering volumes of data, etc. on the fly); a GSM phone and
modem, and a Magellan GPS. Oh, and a hard metal case to protect the Palm

   

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