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

The disadvantage is that each position depends upon the previous one, so
that small errors may build up to be large ones.

No, you can go a number of days referencing the last fix.

Don't understand... yes, you can go a number of days, but after that it
seems to me it would start to get way off.


If you are on a long voyage, you may find that the original stars are no
longer visible at a time when they are useful.

Yes, this is a problem.

Thus, I good idea to take several batches of stars in your observation, so
you can fall back on a second or third set.


Before this happens, you will need to pick some new stars, and take a
double round of sights - one for the fix, and one to establish a basis
with the new stars.

The other problem is that getting the compass bearing of a star is not
that easy.

Well, yes... that hard any time...

I would recommend that anyone interested in emergency celestial navigation
get a copy of "Particularized Navigation: How to Prevent Navigational
Emergencies" by Francis Wright, which shows how to do "good enough"
navigation with paper sextants, etc. Unfortunately, its long out of
print, so a bit of work would be needed to adjust some of the tables to
current dates.

BTW, I own three sextants (two WWII vintage, one antique) plus two
"lifeboat" sextants, but I haven't taken a sight on board in a dozen
years.


--
"j" ganz @@
www.sailnow.com