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Dennis Pogson Dennis Pogson is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 301
Default celestrial navigation anyone?

Capt. JG wrote:
"Edgar" wrote in message
...

"Capt. JG" wrote in message
news:J8ednTRMl5onF5bVnZ2dnUVZ_gqdnZ2d@bayareasolut ions...
Can you navigate (lat and long) at night with a sextant and a
compass, but without a nautical almanac, sight reduction tables,
the time of day, and without knowing the names of the stars? The
sextant has an error, but you don't know what it is, just that it's
off. You can keep your modern watch, but you just replaced the
battery and the time is wrong.


I say that you cannot.
Firstly because at night you probably cannot see exactly where the
horizon is.Even if you got an aeronautical sextant with a bubble
level they are very hard to read on a boat if it is at all rough
Secondly because you cannot derive longitude without an accurate
watch.


Does someone own a sextant? What model? I'm thinking about picking
one up.


You do not say what you want it for. For use aboard or just as a
talking point at home?.
You can get various plastic sextants that do a good enough job for
use on a small boat where pinpoint accuracy is hard to achieve.
But a proper sextant is a thing of beauty and mine is a Kelvin Hughes
dating from 1959 which is in pristine condition in its box with all
accessories. I take the odd reading with it from time to time to
keep my hand in in case both my chartplotter and my DR on paper
charts fail me. Mine is a micrometer type but retains the silver
engraved scale which is somewhat overkill for a micrometer since you
only need to use the scale to read whole degrees. But it is very
nice to look at an inlaid silver scale. Vernier sextants are older
and are collectable antiques now and regrettably mostly end up in
museums or hanging on someone's wall.
There are a lot of authentic looking but purely decorative ones about
which are not suitable for navigation. Make sure yours comes with an
authentic test certificate.



I never said it would necessarily be a boat that was in rough
conditions. That is always difficult.

The sextant would be a backup, a talking point, and something to mess
with.


They look great on the mantleshelf. A wow at cocktail parties. Buy plenty
of Brasso.

Dennis.