Sight reduction by pocket calculator

[Carduelis]

Can anyone recommend a calculator/formula for this?

I know there are lots of PC programs around, but I don't want to have to rely on a laptop for what will essentially be a backup system for the Transat.

 

[maxi77]

I must admit I haven't seen any thing in recent years, there used to be several smart calculatiors with software packages, the last I saw was a packed for Psions.

Your best bet would be something that would run on a PDA either in pocket exel or as a standalone package, either that or back to paper rapid sight reduction.

 

[calamitys38]

Try these:

Cos CZD = Cos LHA x Cos Lat x Cos Dec +/- Sin Lat x Sin Dec

Lat and Dec Same Names +
Lat and Dec different Names -

Intercept = TZD - CZD
(True Tiny Towards)

for A, B, C's

A = Tan Dec / Tan LHA
Named Opposite to Lat unless LHA between 90 and 270

B = Tan Dec / Sin LHA
Named same as Dec

C = A +/- B
A and B same names = Add (sum)
A and B Different Names = Subtrtact (difference)

Tan Az = 1 / C / Cos Lat

Does this help?

 

[Gordonmc]

Any scientific calculator with trig functions will be up to the job. Ie, http://www.calculatorsource.com/ti-86.html
This is a Texas Instruments model.
Not essential for sight reduction, but much more convenient.

 

[sarabande]

Tamiya used to make a dedicated model.

Here's some PDA s/ware. I haven't tried it out tho'.
http://www.soft32.com/Download/free-trial/Astronavigation/4-150200-1.html

 

[bilbobaggins]

Go find yourself a copy of 'Reed's Astro Navigation Tables'. Everything you might need to get to America - save a visa - is in there. The booklet is much lighter and cheaper than the traditional mound of ephemerides, and the author, Cdr Harry Baker, could provide you with an excellent pre-programmed facility.

Let us know how you get on....

/forums/images/graemlins/wink.gif

 

[maxi77]

The various tables of computed altitude and azimuth can be downloaded free from the NOAA site.

 

[bilbobaggins]

[ QUOTE ]
The various tables of computed altitude and azimuth can be downloaded free from the NOAA site.

[/ QUOTE ]

That's useful to know. Ta. /forums/images/graemlins/grin.gif

 

[Refueler]

unfortunately there are no longer calculators designed for it. The newer scientific jobs are good but a pain compared to the older. This is probably due to the advent of handheld PC's etc.

I still have my Texas Ti59 with Nav Module and it is superb machine. Texas Ti59 page Many others during my time at sea opted for the Tamiya Nav Calculator but honestly wasn't a patch on the Ti59 - which could even have a strip card run through with almanac - so not even need for book.
HP did a similar machine but were stuck in RPN language - a very strange backward style of working ! It also didn't have the pre-programmed module and relied on strip cards.

If you can get hold of a Ti59 with nav module - that will do all you want .... Mercator's, Great Circles, Running fixes, Polars, CPA's, Sun, Planets and Stars sextant work, Compass errors, plus of course you have one of the most powerful off-the-shelf calculators ever made ...

Failing that - for sheer battery life and convenience - it's got to be a Palm, plenty of older Palms out there and free software on internet. I have 2 - Palm V ( B&W very old !) and a M515 (colour, same design but much more powerful). You can even link GPS engines to them.
My best is the Mio Digiwalker 168 though with built in GPS, but battery life is not it's best attribute. So best run in a mount with car charger etc.
Last week I got hold of a Qtek 9000 Phone / PDA - marvelous machine which works well with bluetooth GPS, battery life again not as long as the Palm - which seems to just go on and on and on !!

There used to be a book that was devoted to calculator routines and also basic programs for input to hand computers like the Casio 850P's , 1000's etc. I have an 850P

with extended memory - it stays in my PC bag ready to do Ships Inspections. That used to have nav on it until I decided that there were easier ways to do it !

The upshot ? basically very few calculators out there now as there used to be for this work. Most people having migrated to more modern plastic-fantastic-brains !! /forums/images/graemlins/grin.gif

 

[BigART]

I can also recommend a cheap (relatively) Palm Z22 with a copy of Astronavigation (by Axel Fischer) and Tidetool (free and gives tides just about anywhere in the world). All you need for a circumnavigation.

Angus

 

[maxi77]

Woow a blast from the past the TI59. I used to use one with programmes I wrote for sizing ships stabilisers and steering gear. The stabiliser one used all but one programme steps and memory locations (they were interchangable) and was spread over 2 cards. That was over 30 years ago now, and I doubt if I could recreate that.

 

[maxi77]

Having a quick google and found this which seems to be the modern versions of the ones mentioned above.

http://celestaire.com/catalog/Celestial_Navigation_Computers/

 

[smartcom]

If you want something smaller and less power hungry than a laptop, you could get a Netbook running Windows XP or Vista and WinAstro home page (www.winastro.com)