Buying a Sextant

[miko]

I am looking at buying a sextant and would welcome advice on what I should be looking for. It will be used for learning navigation skills, and for occasional offshore passages. Are the plastic ones worth considering, or perhaps a second hand metal model. Is it possible to get spare parts, or servicing/calibration for sextants. How much should I spend to get something reasonable? I am not looking at spending a fortune. Any suggestions?

 

[geoffatstanpit]

I've got an Ebbco plastic one. It is much more accurate than its appearance would suggest. I've never used it for "proper" astro nav (though I did once use it with Polaris to prove that the lat of Cleavel Point was where it said it was on the chart) but it was great for horizontal sextant angles used with a station pointer (remember them?). Now I've got GPS it stays at home.

If you're likely to be easily bored by spherical trigonometry I recommend the Ebbco route!

No it's not for sale - I'll enjoy showing my descendants how we did it!

 

[jwilson]

I used an Ebbco plastic one for some years for genuine navigation (couldn't afford a better one). Accuracy tolerable, though you had to check index error every single time you used it as it kept varying. By averaging four to six sights and checking index error before and afterwards, I regularly got within a mile of known positions - more than good enough for real-life use.

Now I have a metal one (that's older than I am) which I bought when my eyesight started to get worse, although bank balance improved. Optics much better, and nicer to use. No significant practical difference in overall accuracy.

 

[Kilter]

A plastic one is fine for navigation, I carry one and always get it out on nice days just to keep my hand in. With practice you can get quite close to your actual position; a mile is my best!

 

[Budgie]

Many years ago I bought an second hand aeronautical clockwork bubble sextant from an MOD disposals shop. I haven't tried using it at sea, but it was great for learning astro at home. Using aeronautical tables I even managed to fix the position of my back garden to within 5 miles!

 

[davierobb]

Bought a Russian cho-t sextant on ebay and its the doggies bollocks (really good). Way better than what I need but a nice thing to have and use. see link for cho-t sextant cuurently on ebay cho-t sextant.

Apparently spare parts from a well known and expensive German sextant fit perfectly. Manuals are available in English from various web sites

If you go down the astro route then drop me an email and I’ll send you some excel sheets, sight proforma and Visio plotting sheets that I’ve created. The excel sheet is good for finding silly arithmetic errors.

 

[Budgie]

Further to above the bubble sextant is a Mark IX - one for sale on ebay just now, but I guess they come up from time to time.

 

[Kilter]

Bubbles do tend to come up from time to time! /forums/images/graemlins/wink.gif






Sorry! Sometimes I can't stop myself! /forums/images/graemlins/grin.gif

 

[keelbolt]

I bought a fifth hand Tamaya from Ebay. I had decided on getting a metal one rather than a plastic one, and spent ages trying to sort out which. In the end, I was chatting to a guy in the states who had a couple of Tamayas, and he sold me his second one for £60. It has been brilliant; no index error, no parallel error, and it just does the job. I think the model is a Tamaya Spica, but its an older version.

Its one problem is that, being metal, it does tend to put an ache in the wrist after a while, which can make evening star shots a little wearing if you don't get a few of them right off.

I used a plastic one on the way across biscay a few years ago, and was having to deal with over 30' of error off the arc. Not good.

My advice would be to go for whatever you can afford within the budget. Some of the plastic ones are fine. But you can, with a bit of care, get an elderly metal one (like I did). Tamaya are great, as are Plath.

 

[VicS]

[ QUOTE ]
My advice would be to go for whatever you can afford within the budget

[/ QUOTE ] Thats settled that then. A cardboard one from compass24.com for £13.95 or maybe wait to see if Lidl do them for less.

 

[miko]

Thanks for the feeback, looks like I should keep an eye on ebay for a while. Has anyone used a Davis MK 15?

 

[Jeannius]

Yep.. Bought a Davis mark 15 on ebay from the U.S., used it during an ARC although not as often as I should have. Usually got within a few miles which is all you need in the middle of an ocean. Any error was almost certainly caused by the user, not the instrument.

 

[Mirelle]

This may be unpopular advice, but here goes, anyway

First, I own and use a Plath, which I bought secondhand from J.D. Potter, which tells you how long ago it was.

Next, I run big ships for a living.

Let me tell you that sextant design has NOT stood still, and there have been very considerable advances in sextant design in the past few years!

You will do much better to get a modern metal frame one than to buy either a plastic one or an old metal one. The new ones are MUCH easier to use - they are lighter and have bigger mirrors.

The current Tamaya is the dogs bollocks but the current Chinese ones are probably just as good (at least, the ones that I pick up on board our ships are, so far as I can tell by handling them) and much cheaper.

The full width, rather than divided, mirrors, are a great advance.