What do I need for Celestial Navigation -apart from a Sextant?

you need an accurate chronometer, and knowledge of how much it is different from GMT, the other items required depend how you intend to do the calculations and what ype of calculations you are doing. You can do all the calculations on the computer, but that rather defeats the purpose of having a system that is not dependent on the electrical system onboard. Thus there are two systems that you can follow, the nautical and the air systems. The nautical system provides the means for doing all the calculations on all the stars and planets, but it is more complex and definitely more long winded than the air syste,(which most books now concentrate on)

With the air system in addition to the nautical almanac, you need The "Sight Reduction Tables for Air Navigation" This is a 3 volume set. you need vol 1 anway, but need for vol2 or 3 depends whether you are north or south of latitude 40 deg. They can be downloaded from here but yagain you really need hard copy versions.

You then need the appropriate forms for working out the different means of achieving your position, the book "Celestial Navigation" by Tom Cunliffe provides 95% of these answers, and also shows you how to set up your sextand to remove the errors.

You then need a plotting sheet .
 
If you need to ask this question then I think it would be a good idea to buy and read the following books :-

Tom Cunliffe - Ocean Sailing ( it's the updated version of the one Talbot refers to )

Mary Blewitt - Celestial Navigation

Kenneth Wilkes - Ocean Navigator

Why three books ?

No one book covers everything and you will get different slants on what can be, for some people, a rather awkward subject.

Good luck.

Thought about evening classes ?
 
We carry the necessary tables/books/paperwork mentioned by others but we normally use a piece of software called AstroCalc. The fun is taking the sight and seeing how accurate it is. Actually working it out by hand is for purists/masochists but it's worth reading the books so you understand it.
 
[ QUOTE ]
Actually working it out by hand is for purists/masochists

[/ QUOTE ]

Nope, the real point of having the capability of doing astro is in case of a total electricity failure (for example being hit by lightning). Whilst I agree that most of the inaccuracies are caused by poor handling of the sextant, lack of familiarity with the tables can also create some interesting landfalls.
 
Hi Ben

I would highly recommend you PM alant, you'll find him on here some where.

He is a fantastic astro nav instructor and will be more than happy to help.

Regards

Al Jones

PS. Tina says you're a star Mr T.!!!!!!!!!!! What does she mean?
 
[ QUOTE ]
[ QUOTE ]
Nope, the real point of having the capability of doing astro is in case of a total electricity failure (for example being hit by lightning).

[/ QUOTE ]

I didn't say don't have the capability, I was saying the calculations are a pain so we ended up going the software route. If we got hit by lightning we would take one of the handheld GPS's out of the oven. Another option is to handle the calculations on an astro calculator and carry lots of spare batteries. We also carry a 100 AH battery that isn't connected to anything and a towing log. Belt and multiple braces.
 
If you have decent forms, the calculations for the air system are really straightfoward. You just need to be able to add and subtract.
 
Precisely, and what does most of the world do to add and subtract...use a calculator. So why not use an astro programme or an astro calculaor in the first place. Don't get me wrong, if people want to handle everything by hand that's fine by me, we just choose not to.
 
Air sight reduction tables Vol 1 is for star sights (Vols 2 & 3 are for sun, moon and planets). It has the disadvantage that it goes out of date every 10 years whereas I still use the vols 2 & 3 that I bought 35 years ago (they aren't cheap).

As a beginner you'll probably be happy to work just with sun sights. Once you're happy with that you can go on to stars if you like.
 
an accurate clock (nearest second), sight reduction tables, clear skies and the knowledge of not only how to do it, but how to interpretate the results /forums/images/graemlins/cool.gif
 
Hi,

Youll also need the tools for generating a graphic solution, parelell rules, dividers, protractor, etc. I find it amazing that in this day and age the number of sailing yachts who do not find it important to carry these or even know how to use them.

I did write a program to run on a HP-41cx (nerd calculator), which solved all of the math instead of a graphic solution, but I was afraid if I used it, Id get rusty. I do keep a slide rule(!) on the nav station for quick trig problems, faster than a calculator.

I may add that twice now Ive had GPS units pack up on ocean trips on my boats, once as captain on another. It was merely an inconvience, not a drama. Further, remember that GPS is controlled by the US gov and can be degraded at will in specific locations in the world. If the big guy in charge gets another nightmare, how sure are you going to be of your position if you have nothing to check it to?

Best regards,
Michael
 
I used the st hilair method, and used calculation instead of graphics, but that was 30 + yrs ago before we had sat nav.

I am so rusty I am probably siezed up ......... but its like riding a bike.
I am amazed todays seafarer has a calculator and program, enter the time and sextant angle ..... and whollop, there is your answer. apparently they can take these machines into the exam room /forums/images/graemlins/shocked.gif amazing /forums/images/graemlins/cool.gif
 
You must log in or register to reply here.

Share this page

Top