Beginner seeks Sextant Navigation advice - books etc.

I recommend two books

Norries Nautical Tables and the Nautical Alminac. And a pocket scientific calculator.

I can’t comment on Tom Cunclifs Book I’ve never seen it up close. I like Bowditch if you can get a copy second hand it’s a good reference. Not an easy read though. Not popular in the UK. But it is a good complete guide. To date I have not found a better British book.
If you have any questions just ask I will try and answer. Although I have never taken an RYA course. I have heard there is no official RYA method.

The Nautical Alminac has an explanation of two methods.
1 Method using the concise short method tables in the Alminac.
2nd Method using a calculator using the formula used to create the short method tables.

If interested Norries contains a great deal of information. Norries uses the Havesine formula to resolve the triangle via logarithms.
 
Robert Wilson said:
Well, I asked for it, didn't I?:rolleyes:

To keep my reply short I would just say that higher maths gives me the wobbles; reading and understanding I'm OK at providing it isn't too technical, scientific or cosmic physics!

I'll have a go first with Tom Cunliffe's as I like his style and approach to "things".

I really just want to dip my toe in the water, so to speak, as I don't have any immediate plans for ocean sailing; but challenging the "little grey cells" is I think good for those past the first flush of youth (by a lonnng way!)

Thanks folks, very helpful responses.:encouragement:
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I am no mathematician either. Left school 40 years ago having scraped together the minimum marks for a “C” O Grade on my second attempt. without actually know what algebra was and wondering why the hell anyone would ever need it. My kids had completely passed my understanding of Math less than halfway through high school. When I last asked my son what he is doing in University. The answer I got was. “It’s ok dad you wouldn’t understand it”. While annoying it’s true.

Fortunately for me Navigation is not complex math. The surprising thing about navigation. It’s a bit like applied math. It’s Math with a purpose and a reason you can see. Which my simple brain found makes a huge difference.

It certainly would have helped if I had understood just a little bit of basic 1st year algebra or geometry.
 
Air navigation tables mean you just have to add up and take away a bit. Anything more complicated and the aviators would have been driven to the depths of the hotel mini bar in despair. :)
 
Uricanejack said:
I recommend two books

Norries Nautical Tables and the Nautical Alminac. And a pocket scientific calculator.

I can’t comment on Tom Cunclifs Book I’ve never seen it up close. I like Bowditch if you can get a copy second hand it’s a good reference. Not an easy read though. Not popular in the UK. But it is a good complete guide. To date I have not found a better British book.
If you have any questions just ask I will try and answer. Although I have never taken an RYA course. I have heard there is no official RYA method.

The Nautical Alminac has an explanation of two methods.
1 Method using the concise short method tables in the Alminac.
2nd Method using a calculator using the formula used to create the short method tables.

If interested Norries contains a great deal of information. Norries uses the Havesine formula to resolve the triangle via logarithms.
Click to expand...

Bowditch, the bible of the US mariners, is available free on line.
 
TQA said:
If you read the op's post 1 he clearly says "
but wish a guide to explain it all."​

A lot of the books give a sausage machine approach. Turn tha handle get the result but you don't see how it was done.

.
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Oh dear, I reckon that was a pretty dum slip of the keys.
I suppose I ought to have written "not all and everything, but enough to get me started."

Even more responses, with even more suggestions. Time for a wet towel and a day with the curtains closed.
 
capnsensible said:
Air navigation tables mean....... the aviators would have been driven to the depths of the hotel mini bar in despair. :)
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We were, anyway.

This ould aviator likes Cdr Harry Baker's 'Reeds Heavenly Bodies' as a one-volume easy set of lookup tables. ( I hear they're prissily calling it something else now. )
 
I did the RYA YM ocean theory course and also had a copy of Cunliffe & Blewitt.

Personally I struggled to bridge the gap between the conceptual ideas of spinning globes and the sun/earth and the mathematical "just do this" proforma styles of learning. Ultimately, I went through enough sites and went between sources such that the understanding of the two aspects came together for me in the end.

For the actual practical implementation, the foolish muse pdf and this site and its downloads, got me moving quickly

https://www.backbearing.com/index.html
 
Another interesting starting point is "Sextant" by William Collins (see http://www.ybw.com/forums/showthread.php?422002-Sextant-Book-review). Again, not a blow by blow account of how to do it, but a useful, incremental approach to understanding the principles involved, illustrated by various historical examples!

Once you know the principles, the mathematics is straightforward in its theory but complex in its application! Spherical trigonometry really has only two general expressions, the Sine rule and the Cosine rule. With these two, you can solve any spherical triangle given enough starting information (like a plane triangle, there's several possible minimum sets of information required). Knowing it is possible doesn't always make it easy, and knowledge of other things like trigonometric identities comes in handy.

Nearly all the pro-forma methods are designed a) to make the computation straightforward, avoiding several nasty mathematical pitfalls (it's possible for the computations to involve taking the difference of two large but close numbers, with catastrophic loss of significance) and b) make it fast - especially true of the air navigation tables. Unfortunately, both these laudable aims tend to obscure the relatively simple theory of what you are actually doing, and if you're like me, that doesn't work.

The maths was (when I did it in the late 60s, early 70s) ) A-level stuff.
 
AntarcticPilot said:
Another interesting starting point is "Sextant" by William Collins (see http://www.ybw.com/forums/showthread.php?422002-Sextant-Book-review). Again, not a blow by blow account of how to do it, but a useful, incremental approach to understanding the principles involved, illustrated by various historical examples!

Once you know the principles, the mathematics is straightforward in its theory but complex in its application! Spherical trigonometry really has only two general expressions, the Sine rule and the Cosine rule. With these two, you can solve any spherical triangle given enough starting information (like a plane triangle, there's several possible minimum sets of information required). Knowing it is possible doesn't always make it easy, and knowledge of other things like trigonometric identities comes in handy.

Nearly all the pro-forma methods are designed a) to make the computation straightforward, avoiding several nasty mathematical pitfalls (it's possible for the computations to involve taking the difference of two large but close numbers, with catastrophic loss of significance) and b) make it fast - especially true of the air navigation tables. Unfortunately, both these laudable aims tend to obscure the relatively simple theory of what you are actually doing, and if you're like me, that doesn't work.

The maths was (when I did it in the late 60s, early 70s) ) A-level stuff.
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Ouch!
I think I'll see what Tom C has to say, then probably put the book away in a cupboard and rely on my plotter, AIS and Garmin hand-held.
Especially regarding the "A level maths" comment
I struggled with "O level Additional Maths" - and failed it....:(

Thanks all of you, but I'd be bighting-off more than I could chew.
Pity
 
Robert Wilson said:
Ouch!
I think I'll see what Tom C has to say, then probably put the book away in a cupboard and rely on my plotter, AIS and Garmin hand-held.
Especially regarding the "A level maths" comment
I struggled with "O level Additional Maths" - and failed it....:(

Thanks all of you, but I'd be bighting-off more than I could chew.
Pity
Click to expand...

I left school without any A level’s or higher’s and struggled with the O level’s. having been in Scotland was O grade’s.
Don’t be afraid of the Math.
If you can do adding up and taking away. You can manage. If I was able to do it anyone can.
 
Without ignoring all the other suggestions, I had a quick peek at this one, and it looks on first glance to be a good starter.
No doubt I'll attack the others as time goes on.
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I hope you enjoy it. I wrote it after going through 5 other books and not understanding a damn thing!
And while you're at it, take a look at my free singlehanded sailing book at: http://sfbaysss.org/resource/doc/SinglehandedTipsThirdEdition2.pdf
 
Uricanejack said:
I left school without any A level’s or higher’s and struggled with the O level’s. having been in Scotland was O grade’s.
Don’t be afraid of the Math.
If you can do adding up and taking away. You can manage. If I was able to do it anyone can.
Click to expand...

I'm feeling a bit more positive this morning, so perhaps I should persevere!
Thanks for the encouragement.

Foolish Muse said:
I hope you enjoy it. I wrote it after going through 5 other books and not understanding a damn thing!
And while you're at it, take a look at my free singlehanded sailing book at: http://sfbaysss.org/resource/doc/SinglehandedTipsThirdEdition2.pdf
Click to expand...
"Step-by-step Sextant Guide" looks very useful too. And the "Thoughts and Topes etc"

Christmas present wish-list sorted!

Thanks
 
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