G'day seabreezers, could anyone please advise on a suitable sextant to learn on, preferable one that won't break the bank? From looking on the internet davis seems to be a good cheap brand. I only really need it to be good enough to learn the techniques (and to teach my young daughters one day) after which it will probably end up in a grab bag.
I'm concidering the one in the photo, could anyone advise or suggest a alternative. Thank you.

Nothing wrong with the Mark 25 to play with provided you treat it with care , always store it in its carry case after use . Keep away from humidity and heat and wipe off salt with damp cloth every now and then .
The index and horizon mirrors will deteriorate and need replacing eventually (15/20 years).
Have fun.

What we using today to calculate out in the blue ?
Those days, 40 years ago, I used to have Pub No. 249, it was shorther version
of Bub.No.229. Than was a Nav. Calculator.
I wonder what is practical these days,
perhaps off line something.

Hey thanks for the replies fellas, I'm currently learning off an audio book "celestial navigation" by Gene Grossman, I also found pub 249 on amazon cheap so if I start struggeling ill get that. Thanks for the advice.

In the 1970's I used the navy's navigation text books and they were difficult! I ended up using a copy of Mary Bluett's book from the town library. Made it all simpler.

www.ebay.com.au/itm/Celestial-Navigation-for-Yachtsmen-Mary-Blewitt-Hard-cov-Aus-Seller-Fast-n-Free-/202876379700?_trksid=p2385738.m4383.l4275.c10

Thanks for the suggestion, Ramona. Just bought it. And thanks awkward customer, I am tempted to buy one as well to indulge my fascination.

I found these 3 books useful










I had a go at teaching my neighbours teenage son to use the sextant. He had quite a bit of trouble finding the sun and spent too long gazing towards it. I stuck my auto darkening welding helmet on him and he then figured it out real quick as he was able to see through the glare and get his technique right.

I can think of better things to have in the grab bag. Sextant will not be of much use in a life raft.

If I was going to have a sextant a Freiberger is the only one for me.

www.ebay.com/itm/FREIBERGER-Marine-Sextant-730501-Nautical-Maritime-100-ORIGINAL-128/274311736681?hash=item3fde40ed69:g:vTcAAOSwel1ec1ze

I found a cheaper plastic sextant, currently $90 at Whitworths www.whitworths.com.au/mark-3-sextant
and it has a link to instructions there too.
When I used it, and a book of tables, I consistently got results within about 5 miles, here in inland Melbourne, and one result which was 200 miles out. I used an "artificial horizon" ( a dish of water, sheltered from wind) and halved the angle.
Practice makes/made perfect, and I could do the maths within about ten minutes.
Eventually I tossed the sextant out, because in practice, I will never use it. GPS is so much more accurate, in real time, etc.

Again thanks for the advice, I just ordered both the pub 249 and the mary blewitt books- they should look good onboard regardless of how I go . True there are better things for a grab bag and I already own a Garmin 601 (excellent little battery wrist gps) for emergencies.
I suppose in part I'm a bit motivated by the cover of a book I read as a kid.

I bought a new Davis Mark 15 a couple of years ago with the intention of learning how to use it for much more than your price for a Mark 25. I can do the readings, but need to learn the math to do the reductions. The other expensive side of it is buying the almanacs and reduction tables.

I agree that a Sextant is not a practical alternative to GPS units (unless someone turns off the satellites), and you can buy several GPS units for the price of a good sextant and a good wrist watch. It is more of an intellectual challenge and an insight into navigational heritage.

It's great you want too learn how to use a sextant and teach others.
I have to agree with Cisco though,there are better things to put in a grab bag.
On a crossing years ago we talked about making an app. Plug in the sight readings etc and it goes through the calculations with you.
Maybe there is something like this now or at least alminacs online so you dont have o buy them.
We decided there would be very few people that would download it and it would be quite a bit of work.

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Ramona said..
In the 1970's I used the navy's navigation text books and they were difficult! I ended up using a copy of Mary Bluett's book from the town library. Made it all simpler.

www.ebay.com.au/itm/Celestial-Navigation-for-Yachtsmen-Mary-Blewitt-Hard-cov-Aus-Seller-Fast-n-Free-/202876379700?_trksid=p2385738.m4383.l4275.c10

+1

The use of a sextant comes down to the calculation of the base of a triangle. Refer Pythagoras.
A noon shot will give you latitude.
A chronometer adjusted against GMT will give you longitude.
Reduction tables, accuracy of observation and calculation with interpolation will give you an LOP (Line Of Position), not an FOP (Fix of Position).
An FOP requires at least two LOPs. A fix on two LOPs requires DR (dead reckoning) which you get from compass and and log, I.E. direction and distance travelled.
The morning shot gives you your first LOP of the day.
That line carried forth by DR to the noon shot gives you a two LOP fix.
The afternoon shot gives you another LOP.
The previous LOPs carried forward to the afternoon shot gives you a three line fix which is the best fix for the day and what you need late in the day because what you will have overnight is only dead reckoning.

The use of a sextant to determine position on the open ocean is not really an art. It is purely mathmatical and takes some considerable time when one could be artistic cooking.

A hand held GPS unit will give you all of the above, except the cooking in abour 60 seconds.

Why would one bother??

Why does one bother? For the same reason we use yachts when a perfectly good engine will take us in any direction at any speed any time we like. Jeff Toghill's book Celestial Navigation is a really easy guide. He explains the tables well and how to adjust the sextant etc. He is Australian too, if that makes any difference.

You guys are all 100% correct, my motivation is much more of that its a fun/interesting thing to learn than much of a practical safety use.
I have a fair bit of spare time at the moment away from the water so have been occupying myself learning all the sailing stuff I've put off for years.
Aswell kudos to you cisco: your summary above pretty much covered what took Gene Grossman about two hours of audiobook time. Before I actually receive my sextant I have been trying to visualise how it works and as far as I can tell its basically just a one bearing resection that I know from land navigation apart from you are shooting the sun instead of a know land feature.

By far the simplest paper to learn how to use your sextant is a free download here: www.backbearing.com/files/Sextant-Users-Guide.pdf

I wrote it after I had borrowed 5 books from the library and still couldn't figure the damn thing out. With this guide you will find yourself by the sun in 1/2 hour. Guaranteed or your money back!

I think it would be a good skill to have if you plan on a long voyage, as a back up if all the electrics goes tits up.

At Foolish: mate this is incredible I litterally bought you book on kindle: Single Handed Sailing tips techniques a week ago I'm about half way through. Bloody good effort. Your step by step guide for single handed raising/dousing a spinnaker is the best I've come across. Haha youve made my day.

Have both a Celestaire Mk IIIB and the Davis Mk 25. The 25 is a bit of a toy compared to the other but the sights come out about the same. To be honest, I am crap at taking sights, never got much closer than 30 miles but I worked my way through HO 229 then Concise and finally ended up using a small programmable calculator ( sharp something ) and a couple of pages from an online almanac. Hated carrying a bunch of books and found using them very tedious.

Enjoy your new skill.

I have hardback Pub 229 vol 3 Lat 30-45 if anyone wants it send me a pm, first in best dressed

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awkward customer said..
At Foolish: mate this is incredible I litterally bought you book on kindle: Single Handed Sailing tips techniques a week ago I'm about half way through.

I'm glad you are enjoying them. It was only after I wrote the sextant users guide that I figured that a book can't be too hard :-)

Since the book was published, I've also written these papers for singlehanders.

I've learned a few lessons on singlehanded broaching. You can download my paper here:
www.sugarsync.com/pf/D7718709_68878570_6221527

And don't forget the paper I wrote on the invaluable gybing without shifting the pole here:
www.sugarsync.com/pf/D7718709_68878570_6206596

And my older paper on meal planning for improved performance in long distance singlehanded voyages here:
www.sugarsync.com/pf/D7718709_68878570_6823572

Have fun!

Good on ya mate! Thank you for the links/downloads. I like your writing style so kindled your new book while I was at it.

Get on the phone for this one awkward.
www.gumtree.com.au/s-ad/bundall/sail-boats/yacht-sextant/1255888434

German Freiberger

Hey thanks for the lead I apreciate it. I ended up ordering the Davis mk25, it got delivered last week now I'm just waiting for the wife to post it onward where I am stuck overseas. From memory though that one is a bargain I look into the Freiberger ones when someone suggested them but from what I could find they were way more expensive. Thanks anyway.