Sextant - Bargain or not?

Re: As a Sextant user and ex Merch Officer ....

"and no i couldn`t post in another language at all and wouldn`t even try to.
happy new year"
------------------------------------------------------------------------------------------------No capital letters - 'people in glass houses!' and all 'power to the elbow' to those who will have a go.
 
Spend the money on a spare GPS. That way you will at least know where you are.

Sextants are a hsitorical curiosity I reckon. /forums/images/graemlins/grin.gif
 
Capitals used ...

in single words as I did is emphasis .... used across a sentence is shouting ...

'nuff said.
 
Re: As a Sextant user and ex Merch Officer ....

As a Naval Officer and ex Sextant user...

With the class A sextants I used, I agree that the tab error was usually small enough to disregard, but I would be highly suspect of a "personal" error. Unless you can measure it empirically it's just a guess and best left out. It's also been quite some time since I've swung a sun-gun, but I think the table covers centring error and the mechanical slack in the worm and gear. The remaining error of course is IE - the residual error from the correctable bits but I trust you check and apply it as necessary?

Kevin
 
Re: As a Sextant user and ex Merch Officer ....

Sorry - but it is common and I accept that many will not take the effort to obtain average correction for it ... I was shown it by a Master who kept his hand in even though bods like us did the real stuff.
As you know - there are various ways to ascertain errors .... sun lower limb to upper limb - giving error near zero on scale ..... suns lower limb to horizon then upper limb to horizon .... giving error at that angle of scale ..... etc. etc. Which with care also will in comparison of results indicate personal error.
Personal error usually results from horizon sighting whilst also sighting the body .... some people find they are better with half horizon glass - others with full.

As you know yourself - no two people are same on any instrument ... sextant or other ......
 
Sextant errors

While I'm sure your old Master had gobs of experience, I'd say the personal error is an 'old seaman's tale.' I agree that different folks have different accuracies with various instruments, but I would say they are more likely ranges of error, rather than a fixed error. Bob's sights are within 2', rather than Bob's sights are always 2' low. Although you say it's common, I don't recall ever hearing of it. Don't have a copy of AMN around to verify that, but the good folks at Bowditch didn't mention it - http://www.irbs.com/bowditch/pdf/chapt16.pdf
Good site for anyone interested in sextants.

Kevin
 
Woah ... hold on a mo ......

I never said it was an officially accepted or documented error. I was shown it by a Master ... it was supported by years of standing on bridge wing comparing noon sights etc.
The actual reason for it can be a lot of different matters ... but as he indicated ... a lot of people do have own errors ... the trick is to average out and allow for it. If you don't - then nothing lost as blimey we are talking 1 mile maybe added to the already 1 -2 mile cocked hat ... and please I'm not ready for others claims to super accuracy in sights - especially sun sights with run up position lines etc.

We beg to differ on this personal observation - no problem ... I am not bothered .... as many have plyed the oceans sextant in hand without allowing for it ... no matter - they are not wrong ...

A friend of mine has an antique shop in town out here ... and she has 3 sextants in boxes .... in apparently good nick as well ... may just pick one up for display in the house .... !!

On a slightly different note ..... thinking about antiquated marine objects .... who has ever noticed the glaring error on HMS Victory ..... ?? The Magnetic Compass that has been placed on her ?? Well shall I say better - was and I believe still on her ???? I shall leave the post at that - to see how many know what is wrong with it ......
 
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