Astro Navigation

[co256]

Does anyone have an e-mail address for George Jepps?

If he was to run a basic astro course, I would be very interested.

Many thanks!

 

[beneteau_305_553]

I dont know him but for a good intro

http://www.davisnet.com/product_documents/marine/manuals/00026-710_IM_00025.pdf

includes tables quite accurate enough for normal use on a yacht.

 

[srm]

Davis tables only accurate to +/-15' = 15 miles. I would expect to be more accurate than that most of the time if using nautical almanac, accurate watch and pocket calculator. Not too keen on the plastic sextants I have handled as the frame tend to flex while correcting it, but fine if the budget is tight.
The RYA Ocean course uses air navigation tables, which are expensive. Take two or three pocket calculators with basic trig functions and use formula, may be easier to understand what you are doing and is a lot cheaper than reduction tables.

Have fun.

 

[Gargleblaster]

[ QUOTE ]
Davis tables only accurate to +/-15' = 15 miles.

[/ QUOTE ]

I think 15 miles is not too bad out at sea. When I first did a crossing this Century using celestial navigation I was checking myself against the GPS and on a good day I was within 9 miles.

I use a plastic Ebbco although I have a metal Plath that I keep at home as I am afraid I will damage it if it goes flying around the cabin. For the sort of accuracy you need in the middle of the Atlantic I find the plastic Ebbco is fine. The major issue is never the accuracy of the sextant but the visibility of a celestial body. My major deviations from my known position have been caused by going for several days without a sighting rather than the accuracy of my sites or my mistakes in reckoning. It is a worry when the ships are travelling north south when you believe they should be travelling east west.

An alternative to buying the nautical almanac is to buy the one that lasts forever from Pangolin. About US$40.
http://www.pangolin.co.nz/almanac.php

I tend to just print out the bits for the months I need and the latitudes I expect to be in. Saves weight and I don't mind so much when the pages get wet through and all stuck together.

 

[co256]

Hmmm....

....so many ways to approach the same task?!

It seems that everyone has a different method with a different set of tables, hopefully one day I'll figure it all out?