Cruising Forums

atavist · 07-09-2007, 06:52 PM

I have been looking at sextants which range from a couple of hundred dollars for a simple one to several grand for a highteck led illminated ones. How much should a person spend on a sextant? How much technology at what point does the technology added become a crutch or weakness vice an advantage? What type do you have?

Ambling · 07-09-2007, 07:22 PM

Quote:

Originally Posted by atavist

I have been looking at sextants which range from a couple of hundred dollars for a simple one to several grand for a highteck led illminated ones. How much should a person spend on a sextant? How much technology at what point does the technology added become a crutch or weakness vice an advantage? What type do you have?

I don't think it's the price you have to look at. It's the quality of construction and ease of use. People have circumnavigated with only a $25 plastic Davis. ( not as accurate as a more expensive $160 one) but it will get you within a few miles of where you want to go. I have a Celestaire Astra 111B which sells for about $450 and I am very happy with it. Most cruisers don't seem to carry Sextants any more and rely on GPS only. The trick with a sextant is knowing how to use it and having the tables or a method of working the sight you just took. I would sugest if you get one to use it a lot to get used to handling it in a seaway when the boat is moving around. There are computer programs to run the sight(s) after you take them but if your electronics go down you're back to square one.

Trim50 · 07-09-2007, 07:59 PM

Take a look here:

http://www.tecepe.com.br/nav/

The software is super.

Nausikaa · 07-09-2007, 08:20 PM

IMHO the best sextants are the German Plath and Cooke's of Hull, U.K. I like the Cooke's because of its large telescope lens which alows a lot of light to pass through and the large mirrors, both of which make taking stars a doddle. But, I am a professional navigator ( of pre-GPS vintage) and have used sextants since 1970.

My advice would be to go for a good yacht sextant rather than a professional model. It will not be as good and there may be more error in the sextant but as the errors involved due to taking sights fro a small boat bucking arround the seas, slight errors in time-taking, not-perfect horizons all add up to more than the sextant error I would not concern myself too much with that. Professional navigators were quite happy if sights gave a position withi 2 to 3 nautical miles of the true position.

Whichever sextant you buy, the most important thing is to use it often so that you will be completely familiar with it if you MUST use it.

Aye

Stephen

Auzzee · 07-09-2007, 09:58 PM

I swapped a bulky metal job (can't remember the name) for a Davis Mk25. The Davis Mk25 is similar to a good metal sextant, but without the weight. It is fully adjustable, has a large telescope, and in all respects is a finely engineered navigation tool.

These days, I use a sextant purely because I can, and to keep practiced just in case the GPS clags. It is nice to be able to shoot a sight and 'prove' the GPS figure to within a few miles. The sextant is also good for triangulating your position from fixed objects ashore....and with all filters in use, it is a good way to observe solar eclipses.

Sight reduction tables and the everpresent 'Norries' look good in the bookshelf, but nowadays I use a handheld Merlin calculator to name stars and to calculate position from noonsights.

Cheers

David.

atavist · 07-10-2007, 12:06 AM

thanks for the input... that was pretty much what I was hoping for... that you don't need all the bells and whistles...

I'm pretty much a purist in everything I do, from flint knapping and making my own bows for hunting, to keeping up my trapping and tracking skills... i generally loath technology and plan to use a gps only as a double check when I finally set out next year... in the mean time i've dedicated all of my academics to navigational theory.

Auzzee · 07-10-2007, 01:20 AM

Hi Atavist,

If you like the minimalist approach, get hold of some of the cruising books by Lyn and Larry Pardey. Check their titles on the net through Amazon.

David.

atavist · 07-10-2007, 02:29 AM

Thanks for the tip... i just ordered 4 of their books:

Care and Feeding of a Sailing Crew

Self-Sufficient Sailing (which will look very appropriate beside my copy of Self-Sufficient Living)

The Cost Conscious Cruiser

Storm Tactics Handbook

Though I may not take it quite as far as they have I certainly want the ability to if the need arises.

daytrader · 07-10-2007, 02:46 AM

I love GPS. I have not had the ability to use it for water navagation yet. Any tips would be great. Is training in sextants as important now that GPS is around? I would think it would be good to know how to use.

Auzzee · 07-10-2007, 03:08 AM

Hi again Daytrader.

Sextant use for the sort of sailing you described in your other post, will be of no real benefit to you. You will need to have a thorough understanding of pilotage. Navigation skills such as you already possess for your aircraft license are easily adaptable to the water. GPS skills are similar to those required in an aircraft, except when plotting waypoints, instead of skirting mountains etc, you need to skirt reefs, headlands and such.

Cheers.

David.

daytrader · 07-10-2007, 03:12 AM

Quote:

Originally Posted by Auzzee

Hi again Daytrader.

Sextant use for the sort of sailing you described in your other post, will be of no real benefit to you. You will need to have a thorough understanding of pilotage. Navigation skills such as you already possess for your aircraft license are easily adaptable to the water. GPS skills are similar to those required in an aircraft, except when plotting waypoints, instead of skirting mountains etc, you need to skirt reefs, headlands and such.

Cheers.

David.

Ok thanks. Like I said we plan to only go maybe 20 miles out and hang out for a day or two then come back. In this time I do hope to get an education on other uses for latter time. I think you guys that sail all over have it made. I do not know how you do it, but its got to be relaxing. Its prob the most relaxing hard work you can do.

Frank · 07-11-2007, 06:02 AM

My choice for a good honest high quality sextant would be a Zeiss Freiburger.

What I have at the moment is a 1950 Plath - in the family since new - and a Tamaya Yacht sextant

atavist · 07-11-2007, 01:11 PM

Any idea if this is a legit functional piece of just a replica for setting on the bookcase?

http://cgi.ebay.com/brass-MARINE-MASTER-TI...1QQcmdZViewItem

Auzzee · 07-11-2007, 02:10 PM

Ebay is littered with these things. mainly they are made in India from inferior brass. I have seen some of the sextants they make. They look good sitting in the study/library/bar, but as instruments they are not so good. The micrometers especially are wildly inaccurate.

But, having said that, many was the hippy in the 1970's who sailed the world with a list of AM radio stations and a cheap transistor radio as their only form of nav gear. The ferrite rod ariels in the really cheap radios would only locate a radio station when they were held perpendicular to the radio beam. RDF for $3.

Equally, I guess these reproduction thingies could work in a pinch....But why would you bother?

Cheese

David.

atavist · 07-11-2007, 03:21 PM

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.

atavist · 07-11-2007, 05:40 PM

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.

Auzzee · 07-11-2007, 09:53 PM

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.

David.

atavist · 07-17-2007, 11:04 PM

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?

timtwickham · 07-15-2009, 10:52 AM

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