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Old 07-11-2007, 03:21 PM   #15
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thanks for the tip... as a novice I wouldn't know the difference on my own... although I might gets suspicious after I was totally lost.
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Old 07-11-2007, 05:40 PM   #16
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Any opinions on the Astra sextants??

They are the cheapest ones I have found with metal frames... I'm sure the Davis ones are great but it really bothers me that they are plastic.

.... EDIT: NEVERMIND. I just saw Ambling's post he has the exact one I was looking at and gives good review.
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Old 07-11-2007, 09:53 PM   #17
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Metal sextants are good. But, have a look at the Davis in your local chandlery before you make a final decision. The plastic is not flexible, is very dense and 'spaceage'. The advantage of plastic is weight. Shooting a sight from a pitching deck is difficult enough at times. The difficulty is compounded by the weight of a metal sextant.

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Old 07-17-2007, 11:04 PM   #18
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I took a look at a Davis down at the local West Marine and it seemed sturdy enough. Still keeping my eyes open though since I'm not exactly in a rush.

Any opinions on Ross London Sextants?
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Old 07-15-2009, 10:52 AM   #19
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The biggest difference with sextants is whether they are plastic or metal.

The plastic ones deform quite a lot with changing temperature, so you will probably want to check the index error as you take the sight. The metal ones are a lot more stable.

A couple of useful bits of software:

WinAstro for doing the sight reduction calculations on your PC

Stellarium for identifying the stars.

Tim
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Old 07-22-2009, 07:04 PM   #20
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Check this

Vic-Maui Sextant Sights
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Old 07-22-2009, 07:54 PM   #21
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- - For all those out there who are looking at "sextants" - they are beautiful and elegant pieces of workmanship and visually appealing and look great on the book shelf or coffee table holding down a stack of magazines.

- - But in the reality of celestial navigation, the sextant is only minor part of a long process. Granted it is the most elegant part with yourself standing with feet apart on a pitching deck in your slickers, sextant in hand, and wind and rain sweeping across as you raise your instrument to the stars. Great Hollywood stuff. Reality is an hour or more of mathematics and tables and broken pencil points and worn out erasers trying to resolve that few seconds of sextant sights into something you can use. I get the feeling that the new folks think you can raise the sextant to the stars / sun - get a "sight" and turn the sextant on its side and read off your latitude and longitude. It does not work that way. Accurate DR plots, one tenth of a second accurate clocks, and a good knowledge of mathematics and table reading is necessary. And then your accuracy, if you are really good is as stated above - "a few miles". Quoted accuracy of really good celestial navigators it +/- 3 nm, Super good navigators maybe down to +/- 1.5 nm; and the rest of us +/- a continent or ocean.

- - Celestrial Navigation is a wonderful, historical "hobby" and can consume lots of spare time - but - it is not a safe method of modern navigation anymore than constant latitude sailing or even uncorrected DR. There is a reason why buying sextants, celestrial calculators and sight reduction tables is getting more and more difficult and more expensive - there is not any market for the equipment outside of hobbyists and museums (and coffee tables). Just like radio directional finding navigation or the old "A/N" radio beacon navigation for aircraft, it is fun but not valid in today's real world.

- - GPS based systems are the standard now for safe nautical navigation. And learning how to properly utilize GPS navigation and electronic charting also takes time, skill and practice. I have seen many a boat up on the rocks while sailing to a GPS waypoint that was improperly plotted or wasn't checked for intervening obstacles - like an island.

- - Bottom line, Celestrial Navigation (using Sextants) is a great hobby and it is very rewarding to resolve a sight down to a fix - as stated above - only a few miles off. But as a method of navigation when you are out in your boat it is unsafe and useless. Basic navigation using charting, bearing to landmarks, D.R. navigation, and GPS navigation is what you need and all that takes considerable time and effort to learn to do it properly.
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Old 07-23-2009, 05:07 PM   #22
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Suggest you give these folks a call:

http://landandseacollection.com/id2.html

They sell collectibles which are in good repair. They also have an Ebay site. Some of the best sextants available at reasonable price are from the 1970's - 1990's, so you'll be looking for something used--therefore this is the type of place to find it. We've been keeping our eyes open for one that was standard US Navy issue in the 1980's. Can't recall which one since hubby is the sextant-hunter. However, we know numerous former US military aviators (like hubby) who are particular about the optics they use and have purchased sextants from the fellow who runs the above site.

I have heard that there are some good plastic sextants out there and if one cannot afford a high quality metal one, a plastic one may be a better option than a low quality and similarly priced metal one. We have a friend from Russia who has an awesome plastic one that can't usually be purchased anywhere but Russia--we've a laundry list of things for him to bring back to us from Russia--a cool folding kayak and a sextant among them.

Osiris--You've already stated in other topics that you believe using a sextant isn't a good idea. It sounds like you personally must have had terrible experiences using a setant. It is very true that mathematics and geometry are more difficult for some folks than for others to learn and use. But, by no means can we group all cruisers together as dim-witted or impaired in some way that they would not be able to learn and properly use celestial navigation.

Telling folks that " [using a sextant] as a method of navigation when you are out in your boat it is unsafe and useless" is a little much, though . It is true that using a sextant, by itself, won't tell a cruiser much and other navigation skills are needed to use the input from the sextant. However, THIS topic is about good sextants for those of us who LIKE the idea of using sextants and want to own one. This is analogous to a topic on, say...what are the best...chartplotters...watermakers...refrigerators ...In those topics, folks who have an opinion on the good/best of each would opine away on that topic. Here, in this topic, those folks who don't use a sextant probably need not admonish those who are looking for one, ya know? We all have our opinions and we certainly want to be helpful to those cruisers who decide they'd like to learn and use all the navigation tools available.

Fair winds,
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Old 07-24-2009, 12:14 AM   #23
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wow I can't believe this thread is still alive...

well since I started it, jeez a couple years ago, might as well drop in an update... I did get my a sextant... I got the Celestaire Astra IIIB.... I picked it up in London last year for about 450 pounds... it's not a beautiful old piece of brass but it is a very well engineered functional navigation tool... which I use regularly to keep my skills up...

as for celestial navigation being just a hobby... I'm not sure there's a statement I disagree with more... nor is there anything essoteric about it... I can do a triple star site (including preplaning) in about 10 minutes (which is often all you have before you loose the horizon by the time the right stars are out) and then figure and plot it in about 5 more... once you get into a rythm with the calculations they become second nature... a siting like this can bring a very bad DR to a pinpoint positioning.. a noon site is even quicker... no real math involved at all if you keep up with the declination (or have a declination card) ...

saying you don't need a sextant for offshore work to me is like saying you don't need a city map because you have a tomtom... ... it's the GPS that is the nonessential piece of nav equipment in my book... and if there are dimwitted sailors out there it's because deviced like the GPS enable them.
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Old 07-24-2009, 05:04 AM   #24
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Quote:
Originally Posted by atavist View Post
saying you don't need a sextant for offshore work to me is like saying you don't need a city map because you have a tomtom... ... it's the GPS that is the nonessential piece of nav equipment in my book... and if there are dimwitted sailors out there it's because deviced like the GPS enable them.
Being able to use a sextant and convert its readings into accurate coordinates on to a chart is certainly a gift for some - hard work for others. To consign the use of the Global Positioning System to "dimwitted sailors" is probably very inaccurate and unfair.

The technology and the instruments themselves have been constantly improved. The Military depend on them when fighting wars. Cartographers use them for primary mapping. Aircraft use them to get from A to B. The list goes on.

As to their reliability, when properly used and cared for, there are few better digital instruments that are more reliable. Just consider the average computer - lap or desk top ? say no more!

I have 2 Garmin 45 GPS hand-helds which were bought some 15 years ago , still function perfectly (if they have new batteries)

The functions in these old 45s included :-

Creating and using waypoints

Man Over Board - hit button

Back track navigation

Creating and using routes

Compass & Highway steering guidance

Moving Map plotting

Recognising the correct chart datum

ETC...

and of course giving your current position and the bearing to your next destination.

Here is my position today :-Garmin_45.jpg

The 'Man Over Board' facility alone is just one good reason for a GPS on a cruising boat.
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Old 07-24-2009, 12:40 PM   #25
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By no means was I implying that people who use a GPS are dim-witted... I have a couple onboard and do use them as a convenience... all I was saying was that "if there are dimwitted sailors out there it's because the GPS has enabled them"...

as for the military et al... it's also good to keep in mind that the military also controls said satelites and does at time put in offsets to prevent foreign military using GPSs for targeting during times of war... so it may only put you 100 yards off... but guess what... if your relying on it for a tight pilotage...... oops... "but the chart plotter said!!!"
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Old 07-24-2009, 12:56 PM   #26
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Glad that you found a good sextant and are putting it to good use Atavist

Yea, the sextant that hubby wants isn't a thing of beauty either--just very functional.

I do think that any of us with military background have cautious expectations for the use of GPS simply because shutting down/messing with the GPS signal such that non-military receivers wouldn't have precise lat/long has been been discussed so much as a defensive strategy that could be used. Not to mention the fact that it's possible for satellites to go down or software to be scrambled. As such, I have much more faith in GPS than hubby does.
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Old 07-31-2011, 02:22 AM   #27
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My first post! I was searching for the best option to seek in sextants, and found this forum. This thread is old, but to a new sailor, it is an important one. I agree with everyone's superior experience, whether you swear by the GPS or the sextant, and hopefully both. I hope to enjoy sailing for the rest of my life, now that I've only just started (yeah, midlife crisis rocks!!). I joined here so I could comment (dimwittedly, lol!) on this topic. I want to learn to use a sextant because I think learning barebones navigation has to be the number one priority for someone hoping to cruise beyond the bar of their city's river, and out into the ocean. Does GPS aid you with reading the stars? Is there something reaffirming (sorry) about ritualistic sextant readings? I ask sincerely, because I can't imagine cruising blue water without at least the knowledge of celestial navigation. It's either the way you sail, or a last resort, but the skill set has to feel very safe and secure. I want to learn to celestially navigate so I can have a life saving skill, that is historic and unique, in the modern world; but also so I can confirm the GPS readings I'll certainly be utilizing. Although I own a computer, I still use pen and paper regularly. And it seems to me that a sextant is to a GPS what a sailboat is to a diesel outboard.
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Old 08-05-2011, 11:21 AM   #28
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Hello

If you want to learn Celestial Navigaton the Book (Celestial Navigaton by Tom Cunliffe ) is a good place to start, for the data you will need a nautical almanac, but George G Bennet's The Complete On-Board Celestial Navigator also provides all you need and costs a lot less. Plastic sextants are ok to learn with but you can get good second hand Freiberger Yacht sextant for not much more. After learning the basics I used NASA data to develope an EXCEL spreadsheet to save time with the calculations.

Good Luck

Peter Lee
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