NavList:

Gary LaPook writes:

Many navigation publications are available on line for free at the government website:


http://www.nga.mil/portal/site/maritime/

This includes Bowditch, H.O 229, H.O 249, Pilot Charts, Light lists, etc.

gl

Bruce wrote:

Greetings to all list members.  I have been enjoying the list and
archives for a month or so.  I am in the process of continuing to
re-learn celestial navigation after a 25 year break.  I began to learn
the art years ago in a Canadian Merchant Officer college, but did not
finish the program.  At the time, we navigation cadets were very
reluctant to use the antiquated methods that were being taught to us, as
we ground through the lessons using "Norie's Stories".

Now, I am in the process of acquiring a new copy as my original seems to
have drifted away. I know that I will eventually succumb to the siren
call of my scientific calculator, or heaven forbid, a starpilot, but I
still want to wake up those brain cells that once knew how to use log
tables.  On a side note. I was formally taught how to use the slide rule
in high school too.  I saw my first GPS when I was a second year cadet.
It was on the bridge of a French bulk carrier that we were loading
directly into, from our self-unloader, in Sept Iles bay. The thing was
the size of a small desk. I was on a coastal ship and we only had
loran-c. RDF and radar.We didn't even carry a sextant, but the old man
made me box the compass. Yikes!

Presently, I have a spanking new copy of Geoffery Kolbe's  /Long Term
Almanac, /and John Karl's/ Celestial Navigation in a GPS Age. / I was
inspired by Geoffery's stories of navigation in the Sahara.  I did not
even realize that air craft sextants existed, and I am looking for an
A-12 as it would allow me to easily take sites without finding a
horizon.  I am also considering a used theodolite too, but I have found
the old mechanical ones still cost a fortune as they are reliable and
much in demand by surveyors in the remote Canadian wilderness.  I am
also fascinated by the Lunar Distance methods, so a naval sextant will
have to be a part of my kit, eventually.

Anyway, that is my rambling introduction, but I have a few questions for
the list.

1)Sextants are expensive precise instruments, but they are still made of
brass and aluminum. Why does no one use invar to make them more
resistant to thermal expansion?

2) It is supposed to be possible to get exact GMT by observing the moons
of Jupiter, but I have yet to find any tables that have more than a
minute accuracy.  Has anyone else tried and had better luck?

3) I have looked, and bid on, several a-12 air sextants on e-bay. Has
anyone ever had a good result with an e-bay A-12?  Are they fairly
rugged? I hate buying a pig in a poke, but celestaire is not cheap (like
me).

4)I have heard that it is possible to modify am A-12 to see the horizon
by inserting a prism somewhere. Has anyone done it, and can it be done
so that the bubble can still be used.

Here is a very old Norie's online.
http://books.google.com/books?id=OzwEAAAAQAAJ&printsec=frontcover&dq=norie%27s+nautical&lr=&as_brr=1

Thank You

Bruce Hamilton
Vancouver, BC, Canada

bruce.hamilton    (antispam you know what goes here) shaw.ca





  

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