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Of the many responses to this querry, I have yet to see one that addresses the 
joy in handling a precision instrument.

Patrick -

The plastic Davis Sextants are acceptable and clearly a viable method for 
occasional use.  I would hardly put the Davis Sextant in the precision 
instrument category.  They are just too sensitive.  The measurement is 
affected by temperature.  If I didn't have a large budget and had to have a 
sextant, then the Davis is certainly a way to go.  However, and this is a big 
however, the feel in my hand is 'cheap'.  Perfect for a little fun but not so 
good for multiple and repeatable observations.  You will play with it for 
awhile but then hunger for the 'real thing'.

Buy the best dang sextant you can afford.  Get all the attachments you can.  Treat 
it like the beautiful instrument that it is.  Take it out and marvel at the 
construction.  Note the smooth play of the index arm.  When you hold it, it 
has heft.  You are holding a precision instrument!  You will be able to 
perform accurate and repeatable measurements, really only limited to your 
eyesight and practice hours. Once the thrill of obscure mathematical practice 
has come and gone and mastery of the equations is obtained, what remains is 
the actual measurement with your sextant. Why cheapen that experience?   Get 
a good one!

As Frank properly points out, unless the sextant has been badly abused, you can 
always recover it.  How?  Commander Bruce Bauer's book 
(http://www.amazon.com/Sextant-Handbook-Bruce-Bauer/dp/0070052190) is 
excellent for knowledge about and for tuning your sextant.  I use Cmdr 
Bauer's book and can highly recommend it.  If that doesn't work, you can 
always ask us!! We will be thrilled to help you.

So which one to buy on eBay?   For starters, I would avoid the sextants used for 
aviation navigation.  They have lots of moving parts and tricky bubble 
adjustments.  Many folks have come to the NavList seeking refurbishment 
advice for that type of sextant.  Avoid any sextant which does not come in 
the box.  No box means missing parts.  Unless you are very sure, avoid any 
sextant which does not have a square//rectangular box.  The reproduction 
folks seem to think that a sextant should come in that odd keystone box.  
Reproduction sextants are junk.  If the sextant is bright and in one of those 
keystone boxes, it is usually a tip off that the sextant offered IS a 
reproduction,.  Yes, the very old sextants (octants) did come in that type of 
box.  They are coveted by collectors and the price will swiftly reach the 
stratosphere.  When you look at the photos of the box, look for empty slots.  
Is there a spot to hold something and that something is missing?  Avoid.  If 
it appears that every spot that would hold something is in fact holding 
something, then the sextant most likely has NOT been abused!  Further, 
sextant manufacturers did not waste money adding holders for parts not 
provided.  If there was a part, there was a spot.  This gives you an accurate 
method of determining the completeness of a potential instrument.

Modern sextants, such as the Astra, do come up on eBay.  They are usually a sextant 
someone purchased and never or used lightly.  These will be discounted from 
new but offer new performance.
Of course, you can always go brand new.  There are several firms which do offer 
them.  Celestaire, as well as Weems and Plath, offer new sextants.  No worry 
about missing parts or abused sextants.  Everything is there and ready to go. 
 Higher priced than used (no surprise there), but total peace of mind.  It 
will work right out of the box.

There are also many firms on the web, find them by searching for "antique nautical 
instruments", which will offer complete sextants.  These may not necessarily 
be adjusted for immediate use but certainly can be using Cmdr Bauer's book!  
Joel Jacobs at www.landandseacollection.com is quite knowledge-able and a 
NavList contributor.  He certainly can be trusted to outfit you with a 
quality instrument, limited only by your budget.

"What actually do I need?"  That's a little harder to answer.  Almost any 
non-reproduction sextant will work, assuming it is complete and adjusted.  
Yup, even the Davis models will work.  Need differs from want.  What you need 
is an instrument that provides repeatable, reliable measurements.  Once that 
is obtained, the differences between, say the whole horizon vs the split 
horizon mirrors come down to want and preference.  There are attachments 
which are really nice to have but are not needed.  An astigmatizer shade is 
in the want category, not the need category.  Telescopes of varying apertures 
are in the want category.  Artificial Horizons are generally in the want 
category, moving to the need category for landlocked navigators.  Of course, 
I have told my wife I 'need' every one of these ;-))

I hope this helped.

Best Regards
Brad Morris



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