Which celestial nav book (another try)

Cantata

Cantata

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I am acquiring a sextant (from the For sale forum) and would like a book on the subject for Christmas. Should I ask for the Mary Blewitt, or the Tom Cunliffe? (or any other?).

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Mary Blewitt is still the clearest to understand. If the Tom Cunliffe is as good as his tutorial on the RYA/Admitalty Electronic Chartplotter it must be a close contender, though. If you can afford them why not both?

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Hate to plug Tom Cunliffe as his channel pilot irritates the hell out of me, but his book on celestial navigation is pretty easy to follow.

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I like the Mary Blewitt book, I picked a copy up at LBS last year, but don't know if it is still available.

The relevant section of the Admiralty Manual of Seamanship also gives a very detailed coverage, but harder to understand.

There is also a section in Bowditch, now available on line, which is probably worth a look (as it's free).

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Gerry Smith does a book. Judging by his "Coastal Nav" book it will be excellent on "How To..." but less good on why. If you would be happy being able to turn a sextant fix into a position without (at first) knowing why then he's the author to choose.

With that caveat, I rate him above Blewitt, Cunliffe, Langley-Price & Ouvray (sp?) etc.

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I have both and found the Tom Cunliffe one the easiest to follow, although others swear by Mary Blewitt.

It all depends on your own personal learning style, I suppose. Try to see if you can get a quick look at both, and see which one suits you.

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You could try or <A target="_blank" HREF=http://www.celestialnavigation.net/> here

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More recommendations

Personally, I like MR Rantzen's "Little ship astronavigation". It departs from Mary Blewitt in promoting the use of NP 401, the ship tables, rather than AP 3270, the Air Tables; this is a fairly fundamental difference, because it affects what you buy to go with the sextant in terms of tables and almanac. The explanations are very clear and you don't forget them.

The difference in accuracy of the two methods is not important,

I strongly recommend getting a copy of "The Sextant Simplified", as well; the new edition is more yachtsman-friendly

<hr width=100% size=1>Que scais-je?
 
Re: More recommendations

Is there a difference in accuracy between the traditional approach and using AP 3270?

Anyway as I understand it RYA have dropped star sights from the Astro syllabus /forums/images/icons/smile.gif

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Mary Blewit was my choice years ago. But I also have a Casio FX progamable calculator which I fed with a program written in 'basic' and taken years ago from a series of articles in PBO. This covers sun, moon and stars plus there is a prediction program that helps identify a star before you even know which it is. I have a more basic (DOS) program on my laptop which was a freebie from a NZ site, (Pangelin I think?) but this only does sun sights. Both of these programs include built in almanacs valid for more years than I will be sailing for.

So with 3 GPS sets, a sextant and 2 separate electronic almanacs plus the Air Tables, oh and an old RDF, Walker log and pencils I think it might be safe to try another SB Cherbourg trip, in company of course - just in case/forums/images/icons/smile.gif



<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>
 
Have both but think the Cunliffe one is much easier. Personally I don't think the sums are the hard bit - it's what you do with the mirrors etc - unless you have someone to show you - and Cunliffe has some excellent pictures.

<hr width=100% size=1>a pragmatist is an optimist with a boat in the UK - but serious about not being in the UK !
 
Not really \"traditional\"

The answer is "theoretically, yes, because NP 401 are worked to a higher degree of accuracy" but "practically, no, because you and I, waving a hambone about on the deck of a yacht and without daily practice, are not going to get that accurate a sight anyway".

NP 401 are tables like AP 3270, so I don't think they are any more traditional, in the sense of Having Fun with Haversines. There is a good yachtsman's description of the "traditional" way of working a Sumner line in Claud Worth's Yacht Navigation and Voyaging and if you want to be really traditional (pre-1837, so to speak!) he also covers Long. By Chron.

The "Bible" of the traditional deepsea navigator was Lecky's "Wrinkles in Practical Navigation" - worth finding a copy in a secondhand bookshop.

Theoretically, you need six volumes of NP 401 tables but in practice until you set of round the world the volumes for 30-45 deg. and 45-60 deg. are enough.

<hr width=100% size=1>Que scais-je?
 
No one book tells you the whole story.
For me - start with Tom Cunliffes book 'Ocean Sailing', this will prepare you for Mary Blewitt ( who is not for 1st timers in my opinion) then progress to Wilkes 'Ocean Navigator' his explanation of Traverse Tables is excellent.

Langley Price Ouvrey's ' Ocean Yachtmaster'is too dry for me and the subject is dry enough already......

3270 or 401 ?
3270 works to 1 nm of accuracy but is limited to declinations less than 29 degrees.One of the three volumes has to be replaced every 5 years.
401 works to a tenth of a mile (this accuracy is impossible to obtain on a yacht}however it covers all declinations and lasts for ever.
On the other hand a complete set is 4 times as heavy as a complete set of 3270.
The choice is yours...
Stephen

BTW I use both, depends on what I'm prepared to carry.....

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by stephenh on 29/10/2004 13:42 (server time).</FONT></P>
 
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