|
|
Subject: Which Celestial Computer..??
From: Richard B. Emerson (navsys@XXX.XXX)
Date: Fri Jul 07 2000 - 08:46:33 EDT
Barry Colman writes:
> I think I am in the market for a celestial computer to
> practice with...Since there only two that I am aware of the Starpath
> using the TI-86 or of course the Celesticom V.. Does anyone have any
> opinions pro-con to either..??
I have both. If you look around on eBay, you can get "New In Box"
TI-86's for something like half price (the interface to download
software is $20 and eBay prices aren't any great savings there).
Download the manual and software, pay the license fee, and the price
for a Starpilot is almost the same or slightly less than a Celesticomp
(forget the expensive Celesticomp "Pro" version - it just adds weight
management for cargo ships). That's the price comparison.
The StarPilot manual is on-line in PDF format. It describes the
features reasonably well although there are a still a few places that
need tuning. The manual presumes the reader already has nav skills
(no surprise - this isn't an Intro to Nav 101 text) but still explains
some basics. There are screen displays in the manual. Earlier
editions had some serious typos and a couple still exist in the
amended V1.55 manual (V1.54 manual plus four pages of comments and
errata). Proofreading has never been a strong suit at Starpath
(sorry, Luis and David, but you know it's true). The Celesticomp
manual is shorter (fewer features - see below) and not on-line. Since
each screen display is just one line of text and numbers, there's no
need for screen displays. The manual does an adequate job of
explaining the calculator although the writing could use some
editorial tuning. OTOH, I've read other software manuals that were
incomprehensible so things could be worse. Celesticomp would do well
to follow Starpath's lead on organizing the manual with section
headers and so on but the Celesticomp manual is still short enough to
find needed material without too much trouble. That's the
documentation comparison.
In terms of ease of use, the Celesticomp is smaller and therefore
takes up less space on a crowded nav desk. The buttons are far less
complex. The TI-86 screen is larger although some of the displays
take a little thought to follow. Here's what a sun line reduction
screen looks like:
SUN-Lower Limb
#/WT/Hs/Zn/Int(nm)
1
015:35:42
054o58.8
214.3o
9.5
Translated, that's the sight or shot sequence number, watch time,
sextant reading, bearing, and distance to the intercept. Celesticomp
doesn't repeat the shot time or sextant reading but, one line at a
time, shows Hc, the computed altitude, the bearing, and distance to
the intercept. The display advances only on user input (no "write it
down fast" blinking numbers). The TI-86 has a bunch of buttons
although most of the time all you use are the number buttons and
ENTER. That's the display and user interface comparison.
Either computer has enough tools to let you do a good job of
navigating with a mix of DR and celestial work. Both have
star-finding capabilities and both have various additional tools for
wind triangles, etc. The Starpilot, however, has a host of added
"chrome" beyond the Celesticomp including reductions for distance off
from sextant altitudes (e.g., measuring a known height to determine
your distance from the object), dip angle (for close-in horizons), and
lunar distance reductions. In features, the Starpilot is way beyond
the Celesticomp.
All of these features, however, make the Starpilot far more complex to
use. Unless you use it daily, you have to have the manual handy for
even sun lines (on a recent trip, I didn't have a printed copy of the
manual I could get to and I couldn't remember how to get Starpilot to
remember by Height of Eye and Index Correction factors instead of
entering them for each shot, for example). The Celesticomp, however,
is generally straightforward although in a couple of places the
prompts are bit confusing. For example, after entering a series of
shots and getting LOP's, one of the first prompts in the FIX program
is "Use Good Cuts". Say what??? Actually, it's just a reminder and
nothing more but for some time I thought the program was unhappy about
the intersection angles of my LOP's. That's the feature comparison.
So which one should you buy? If all you want to do is celestial work
and don't want a lot of "chrome", the Celesticomp is the call. If you
want a lot of gee whiz features and pushing buttons makes you smile,
go with the Starpilot. Still can't decide, flip a coin! [laugh]
Rick
S/V One With The Wind, Baba 35
|