Christmas Present

[brookiesailor]

I just have to share....
I surprised my husband with a Platt sextant for Christmas. He has always wanted one. Now I need to find the tables and worksheets to go with it! I live in Dubai but go to the States often I just don't know where to look


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[brookiesailor]

That would be a Plath lol


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[carstenb]

Originally Posted by brookiesailor

I just have to share....
I surprised my husband with a Platt sextant for Christmas. He has always wanted one. Now I need to find the tables and worksheets to go with it! I live in Dubai but go to the States often I just don't know where to look


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you can buy them from Amazon. If he doesn't know how to use a sextant or make the calculations, this is a goood book

Celestial Navigation: Tom Cunliffe: 9781898660750: Amazon.com: Books

You'll need a 2015 Natical Almanac and a set of the sight reduction tables. I believe the Epoch for the stars volume ends in 2015 - (these are 5 year epochs) soo you will have to buy the 2010-2015 edition (but then you know what to get him next christmas).

When buying the sight reduction table be sure to look and see what latitudes it covers - you might need to buy a couple.

Do yourself a favor - and learn how to do this together - it is fun and if you both can then you can have some gentle marital oneupmanship going when you check your results against the GPS

[brookiesailor]

Carst. Thank you. I ordered the book for myself as hubby already knows how. Ordered the 2015 almanac too. I am excited


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[carstenb]

Good for you!

Don't forget the sight reduction tables - can't do the reductions without them - although I believe you can get them on the net

you can download them here:

Maritime Safety Information

[PDA1]

You really don't need the buy the NA or HO 229 or HO 249 unless you absolutely must. The Nautical Almanac is nice reading and very informative.

You can download HO 249 Volume 1, 2, 3 here-

https://www.celestaire.com/pubs/category/3-pub-249.html

Print out the primary Latitudes from HO 249 you'll be working in just to keep everything small and simple. HO 229 relies upon LHA so you'd be printing out a pile of paper just to get 1 degree of latitude.

To get the Nautical Almanac (not the printed one- just the online versions that have data for the Sun, Moon & Stars)

Here- Celestial Navigation: Compiled Manuals - Download Section

For any sight reduction all you really absolutely need is the Nautical Almanac to get the GHA (or SHA) or Declination of any principle celestial body. Then you can do a sight reduction using 2 (somewhat simple) formulas;

Note- I use a Casio fx-300ES Plus calculator

To get Hc-

Hc = asin[sin(Declination) x sin(Latitude) + cos(Latitude) x cos(Declination) x cos(LHA)]

Entered in Casio- Sin-1(Sin(Assumed PositionLatitude) x Sin(Declination) + Cos(Assumed PositionLatitude) x Cos(Declination) x Cos(LHA)


When the heavily body's Declination is South enter the negative sign before it.


Determine Z (Azimith)


Z = acos[(sin(Declination) – sin(Latitude) x sin(Hc))/(cos(Latitude) x cos(Hc))] Entered in Casio-


Entered in Casio- Cos-1((Sin(Declination) – Sin(Assumed PositionLatitude) x Sin(Hc)) / (Cos(Assumed Position Latitude) x Cos(Hc)

Also, William F. Buckley's video here- Amazon.com: Wm F Buckley Celestial Navigation Simplified: Movies & TV

It's really great, simple and easy to understand but only covers Sun sights.

Hope that helps.