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Old 04-12-2014, 16:43   #1
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Easy to Use Sextant

I am attempting to learn celestial navigation. Could someone please help me to decide on a sextant ? There are so many to choose from I'm getting dizzy. Also I need the dead reckoning work sheets. What about online courses? Any info would be helpful.
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Old 04-12-2014, 17:09   #2
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Re: Easy to use Sextant

If you want to train and see if CN is for you, the Davis plastic models are perfectly adequate and not expensive. Then if you are sure you want to continue, there are many quality, and more expensive, ones in the marketplace.
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Old 04-12-2014, 17:10   #3
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Re: Easy to use Sextant

Buy the cheapest plastic sextant going. For a newbie it should do. Then if you still want a sextant get a Chinese one unless you have a lot of spare cash. It'll be heavier and easier when taking sights. I think the days when mariners used to go from ship to ship with their sextants in their mahogany boxes are gone. Sad but it is 2014, nearly 2015.
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Old 04-12-2014, 17:49   #4
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Re: Easy to use Sextant

I traditionally navigated all over the South Pacific with a plastic Davis Mk 15 sextant and a Walker Taffrail Log... It was super fun.

I found the plastic sextant accurate enough for my ability. However, I had to let it warm up in the cockpit, to stabilize its temperature, then find the error every time before I used it.

My father-in-law bought a nice Japanese sextant on eBay for not much more than a Davis 15. He also accidentally bought a fake/decorative sextant on eBay before that. It looked right in the photos, but as soon as it arrived he realized it was not made to be used.

There's a short book about buying a used sextant and dialing it in-- The Sextant Handbook.

I printed my own dead reckoning and sight reduction worksheets. I found other people's worksheets to be tedious, to have too many steps. If you are comfortable with math and the concepts you can simplify quite a bit.

Have fun!
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Old 04-12-2014, 18:23   #5
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Re: Easy to use Sextant

I bought a 1945 vintage David White sextant on Ebay. It cost about $200 and appeared to have never been used. And yes, it came in a nice wooden box. As for learning celestial LOP calculations, you can't to better than the William F. Buckley DVD. He explains all the steps and goes over each in simple language. Highly recommended.
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Old 04-12-2014, 18:39   #6
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Re: Easy to use Sextant

If you can, find a local group (often from planetariums) that uses sextants, or someplace you can lay hands on a few. While they are all good enough to learn on, there are many differences. On some, the telescope barrel rotates to focus from the rear, not the front. So if your eye is on the telescope and you rotate the sextant...it goes out of focus.

On some, like the high end Plath, there is a slight red cast to one mirror half and a slight green cast to the other. In daylight you'd never notice it, but at night it makes stars "pop" into a whiter color when they are precisely aligned. All bells & whistles perhaps, but if you are planning to use one regularly, you may want to check out the many variations out there.

Plastic is often disparaged because it will never have the same accuracy as finely made metal. Perhaps, but they are light, which makes them easier to hold up, and atmospheric distortions make it hard to get closer than within two miles of any position in coastal work, diluting the accuracy of fine instruments just where you'd want it most.

Celestaire is a good resource for celestial nav. But in a sailing town like Ft. Laud, you might check out the consignment shops, pawn shops, as well as online sources. Just avoid the many "decorative" brass sextants, usually made in India with British names, that are really just decorative.
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Old 04-12-2014, 20:59   #7
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Re: Easy to use Sextant

Any micrometer sextant, plastic or metal, will work just fine. Prefer metal sextants as they give stable readings and the weight, up to a point, makes them easier to get accurate sights. You can spend a ton of money on a German made one or a lot less on a Chinese version. Thing the best buys are on Russian surplus models. Used a Tamiya without the scope to sail to French Polynesia and back without any problems. If you buy used, be sure the mirrors are not corroded. You can have them resilvered but it's not that cheap to do.
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Old 04-12-2014, 21:39   #8
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Re: Easy to use Sextant

Freibergers are the best value for money these days... they were standard kit on many of the world's merchant ships for years... this chap gets them from the ships being broken up in India, he has a good reputation. Marine Sextant VEB Freiberger NO 65791 Boat Nautical Maritime | eBay
Or you could go for the more basic Freiberger yacht sextant such as this one.. Rare Vintage German Freiberger Yacht Sextant 103614 W Original BOX MSRP $849 95 | eBay but I would be wanting to pay a lot less than what the big F'bergers sell for.

If you want some good ( in my opinion) stuff on learning celestial then PM me with your email addy,
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Old 05-12-2014, 10:00   #9
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Re: Easy to use Sextant

For learning I bought the plastic Davis Mark 3 ($30 w/ shipping on Ebay from Doug Russell) If the Sextant is a little tight when you get it, just rub a bar of soap on it for lubrication.

I read this free and understandable Teacup Navigation writing... Celestial Navigation There is a downloadable PDF. I also bought another authors book for my e-reader... can't recommend that though, too hard to flip from diagrams to text.

It was a lot of fun learning, and it doesn't bother me when my $30 Sextant sits for months at a time unused
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Old 05-12-2014, 10:20   #10
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Re: Easy to use Sextant

The sextant is the easy part. It's all the books and stuff that's the hard part! I assume there must be a better device to give you all that now days?
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Old 05-12-2014, 13:51   #11
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Re: Easy to use Sextant

I suggest you buy a Davis Mark III for about $45, buy David Burch's book on celestial navigation (easy to comprehend, lots of practice questions) or take the online course through Starpath and then decide if you want to invest in a more expensive sextant. The Astra IIIB is a relatively high end sextant that is reasonably priced.

I read David Burch's book, practiced with my Mark III and then wrote the Canadian Yachting Assoc. celestial navigation certification exam and had no problem.

My friend has and Astra III professional, we were standing side by side, did a the same sight reductions, I was within 1.3 NM of our location, he was 1.5 NM off. To qualify, we were not moving, calm water.
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Old 05-12-2014, 13:57   #12
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Re: Easy to use Sextant

Like many have said start with a plastic one. I also suggest starting with sun sights and learn how to advance lines of position. Once you master this you can move on to stars. Far fewer corrections with sun sights. I found the moon too fast moving for my brain!
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Old 05-12-2014, 14:07   #13
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Re: Easy to use Sextant

I would also suggest getting a sight reduction program, for the computer or smartphone or even an old Palm PDA. That way if you are taking the sights correctly, but getting screwed up in the reduction process, you've got a check on your math.


I know a lot of folks poo-poo the software approach, but for many of us it eliminates a whole big set of possible errors.
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Old 05-12-2014, 16:33   #14
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Re: Easy to use Sextant

Quote:
Originally Posted by hellosailor View Post
I would also suggest getting a sight reduction program, for the computer or smartphone or even an old Palm PDA. That way if you are taking the sights correctly, but getting screwed up in the reduction process, you've got a check on your math.


I know a lot of folks poo-poo the software approach, but for many of us it eliminates a whole big set of possible errors.
This amuses me. If you're relying on a computer/tablet/smart phone/whatever to do the math, why not just use it's GPS function in the first place instead of messing with a sextant?

But I understand the allure of celestial navigation. As recommended above, I picked up a cheap Davis practice sextant and I've been having fun playing with it. Just noon sun sightings for now, and I'm not yet up to speed on all the corrections, so best I can get is position within ~10 nm. But ... it looks real impressive to my crew!
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Old 05-12-2014, 17:16   #15
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Re: Easy to Use Sextant

It is so far-and-away easier for me to get a good shot with my AstraIIIB deluxe than with any of five or six plastic sextants I've used, that I think it's worth the money to learn on, especially if you're going to be sailing anyway and prudence dictates it's presence. It's probably good to carry a plastic sextant as a backup in case your primary sextant gets damaged or deep-sixed, but by all means invest in a metal one. I can't stand sight reduction forms--I just write all my data out on a sheet of paper, in a way I developed over time to work well for me. It's easy enough to remember the sequence of writing things after you do it a few times.
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