Yippee..just bought a sextant!!! any advice?

melandnick said:
Just spent a whole load of money at AMAZON on books including Cunliffe's ( though its out of stock at present ) so hopefully it will all make sense.
Sextant should be with me on Wed next week.
Never looked forward so much to sticking my head in a book and learning something!
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I forgot to mention...

You'll need a means of timing your sights accurately, for 4 seconds error on UTC/GMT/Z Time can amount to up to 1 nm. ( I know, I know.... )

I've used an electronic stopwatch taped to the inside of the sextant handle, with the buttons accessible by my right forefinger. I've also used a strap-on kneepad from an aviation shop, for me to write down the times/Height Sextant of each of a series of sights. That became a smaller strap-on left-forearm-pad.....

And two IKEA 2B pencils, rubber-banded together, in case one lead breaks....

And a small pack of Kleenex tissues, to wipe off the sea spray that lands on the mirrors just as I'm seated at the mast and ready....

And.... and....

:D
 
what about using a holographic lens, with an associated CCD detector, so that you can take 3 simultaneous sights ?

If you then tune that CCD to operate in the far red light band (about 0.7 mum) you should be able to detect stars of visual magnitude 5 at sea level in daylight, identifying both alt and az.

The electronics subsystem would also contain a star catalogue, assorted ephemeres, and next week's lottery numbers.

Linked to both radar and conventional GPS, the electronic sextant can then act as the Horizon Examination / Location Planner, and automate the sounding of appropriate fog signals and switch on the nav lights. The data rate would allow for real-time processing and a hominid-friendly format, to back up the traditional practice of celestial navigation. A significant advantage is that the system cannot be subject to intentional or accidental jamming, and does not therefore depend on what the President had for breakfast.


Ackowledgements: Surface Warfare, 21, 2; and PBO Jan 1867 Vol -254, "How I learned to give up my sounding lead, and love my octant. Kim Tumliffe, Dandy Modrator, and Brian the Parrot.
 
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Astro-nav book

Get "Astro-navigation from Square One" - by Alan Murray 2010- great explanations/examples/diagrams - you will also need NP314 - nautical almanac for 2011 + NP303 Rapid sight reduction tables - vol 1 for stars and vol2/3 depending on your latitude.
Also a calculator - eg Sharp EL509W - to handle cos/sin inputs in hexadecimal notation (so you do not have to convert degrees and minutes to decimals but can put them straight in).
All the books are available from Bookharbour at Southampton - www.bookharbour.com
 
Check the index error and put a note of it with the sextant. Buy Mary Blewitt's astro book it's the only one written in English. Buy the astro. Get a progam such as Astrocalc but make sure you can use the tables before using it.
 
A simple but effective guide

KellysEye said:
Buy Mary Blewitt's astro book it's the only one written in English. .
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But the one written in American is very good too. I can't remember where to download it from but someone on this forum kindly set me on to it. In it he says something to the nature of: I didn't want to know where I was to the nth degree. I only wanted to find Hawai!

That summed up my approach. So far I only wanted to find Porto Santo; and I did. Next challenge is to find Graciosa :o

Can any one point Melandnick to this?
 
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