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Thanks Hewitt,
Do you have a copy of the Luce article? I can only get the not very informative abstract.
Best wishes, and still love your book, my first that hooked me on celnav and 
actually slide rules to do same back in the early 1980s Muchas Gracias.
(After a life changing dive on HMS Association , Scillies, found your book and 
Letcher in a Falmouth marine second hand  bookshop. Changed my life! Not sure 
if for the best!
Oh well!
Francis


-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Hewitt Schlereth
Sent: 26 July 2018 16:16
To: francis@pharmout.co.uk
Subject: [NavList] Re: How close without a good Lunar?

Francis, thank you for the 'mention in dispatches'. The Summer 1977 issue of 
Navigation magazine has an article by J.W. Luce that sets out another 
plotting-sheet version of Longitude w/o Time.

Hewitt

thanks On Jul 24, 2018, at 7:01 AM, Francis Upchurch  wrote:

I agree with Greg,

I think we are talking about using lunar altitudes to estimate time/longitude? (not lunar distances)

Letcher describes his method Ch 17 page 96.

Chichester describes a simplified graphical method in Along the Clipper way 
page 170. This method is explained with worked example in Hewith Schlereth 
(yes, our very own!) Commonsense Celestial Navigation page 134.

I've tried the Chichester graphical  method a couple of times, not very 
accurate (about 30-40  miles out) but probably better then nothing.

Bye the way, Chichester was a bit naughty I  think, implying his idea was original. 

He had Raper's Navigation circa 1840 on board to find out how to do lunars. He 
didn't like the maths so came up with his simpler altitude method..

What he doesn't mention is that there is a whole chapter devoted to longitude 
by lunar altitudes in Raper! Albeit not his graphical  method, but surely he 
must have seen that to stimulate the idea? Nothing new under the sun (or 
moon!)

Best wishes

Francis



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