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From: Frank Reed (no email)
Date: Mon Jun 06 2005 - 22:58:53 EDT
Robert E wrote:
"An old friend of mine, who passed away a few years ago, and who was an
experienced navigator for over 60 years, once told me that the noon sun shot
was overrated; that all you had to do was to take a few shots with an
interval of 2 - 3 hours then transfer one of the LOPs."
Absolutely. IF you have learned a general method of intercept/LOP celestial,
then ALL of the traditional sights (latitude by Polaris, Noon Sun, latitude
by double altitudes, etc.) are irrelevant because they can be treated just
like any other sight. And btw, your late friend is not alone in this belief.
It's an idea you'll find repeated in a fair number of navigational texts, too.
The advantage of this Lat/Lon by Noon Sun business is that it's very easy to
teach, learn, and re-learn, and requires an absolute minimum of equipment
and books. A navigation student who has been away from practice in navigation
for ten years may not remember how those tables work anymore, but you can pick
up Lat/Lon by Noon Sun in a few hours and have a decent celestial fix at the
very next noon.
And:
"Mind you the noon sun shot is fun to do and very simple to calculate. For
this reason, it should remain as one of the basic mainstays of
astro-navigation, however, taking and reducing a sun shot at any other time
is painfully easy with calculators and with HO 249 (AP3270 in Britain and
Canada)."
Tell me then, if it is so easy, why doesn't everybody do it?? I'm not
kidding. I have observed many students learning celestial and they tend to come
from wide-ranging educational backgrounds and skill sets. For many people, it's
all just damn confusing. I helped out a couple of years with a class in which
one of the students was a skilled, highly-paid surgeon. And he couldn't make
heads or tails of celestial navigation. His wife, however, loved it and
understood everything.
And:
"George has a very good point about crossing the ocean without GPS and with
someone who only knows how to take a noon sight."
Where is this world where one crosses oceans without GPS? Are you concerned
that yours might break down? The best backup for GPS is another GPS.
Celestial navigation is no longer a primary method of navigation. There are plenty of
people who want to do it for fun and challenge and maybe, just maybe, for a
backup in case something happens to the main GPS *and* the various spare GPS
receivers. There are others who do it for various certfications. But why
else? Wait, wait... I've got it! You're at war with another maritime power. You
are engaged in a naval battle and the other vessel surrenders. You send an
officer aboard to take your prize into port and discover that the enemy crew
have thrown overboard the ship's GPS receivers! How will you ever get your prize
back to port. Sure, you can borrow one of the three spare GPS receivers from
your own vessel, but what happens when you have captured two or three other
enemy vessels?? That is when you will need your sextant and celestial
navigation! (in case you don't recognize this, it is a rewording of a excuse for
studying 'longitude by lunars' from the late 19th century which I posted to the
list a while back).
And:
" This is something I harp on
when discussing GPS with the uninitiated. The argument that some students
will be detracted from learning astro-navigation if things become too
complex has merit, however, my response would be that I would not bother
wasting my time in trying to train someone who is not committed to learning
it properly. No pain, no gain."
Well sure. You can do that. Consider an alternative: even the most
enthusiastic students will enjoy being able to get a good position fix on the first
day of class. So teach lat/lon by noon sun, and then move on. If some students
decide that the rest isn't for them, they at least will take away one method
of celestial navigation that actually works and gives a real fix. The
students that stick it out will have something to fall back on if they are missing
one of the elements of intercept/LOP navigation when the day arrives that they
actually want or need to do celestial.
And concluded:
"I won't delve into the "what ifs" (what if my watch went overboard etc.)."
If you're willing to entertain the highly unlikely possibility that you
might cross an ocean without GPS, then dropping your watch overboard seems like a
sure thing! <g>
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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