 Check out the bookstore at IRBS.com |
|
|
|
|||||
|
||||||
Subject: Sextants
From: Rick Emerson (rick@XXX.XXX)
Date: Tue Jul 27 1999 - 13:59:14 EDT
Barry Colman writes:
> Im a beginning Celestial Navigator and am seeking some
> advise...I have access to a Davis MK25 Sextant to learn with..or
> SHould I purchase the Astra IIIb to learn with..?? I don't plan any
> crossing in the immediate future...One other thing, I was also
> thinking of purchasing the Celesticomp V for checking my math and
> learning with it. or should I pass on the puter to learn the
> conventional way....
This is indeed an old thread but one worth re-visiting.
The Davises are OK but are generally an uphill climb to work with.
The mirrors are small, the optics less than ideal, and the sextant
should be checked for index error after every shot. On the other
hand, the price is roughly half that of an Astra. If the object of
the exercise is to find out what celestial nav is about and little
else, why spend the money. OTOH, if you're heading offshore, want to
have a backup for your electronics (or don't want electronics at all),
the Astra is a good value for the money. With some judicious
shopping, however, it's possible to find a good used Plath or other
sextant. It depends on your patience and shopping skill.
The same applies to the Celesticomp. If the idea is to learn a little
about the theory and practice, $250 a lot to spend on curiousity. If,
however, you plan to do serious navigation, the Celesticomp is worth
its price and more. It's a simple device, batteries last for a long
time, and it's easy to use after a little practice but an occasional
walk through the tables is a good idea.
BTW, the intermmediate results for tables and the Celesticomp will
rarely agree closely but only because of how the Celesticomp and HO
249 work. The final fixes will, of course, agree assuming you've done
your work correctly.
Rick
S/V One With The Wind, Baba 35
|