HP-71B Software for navigation

[Erwin]

Hello to all

Cause that I want to use my HP71b for my sailing trip in August I was looking for a software which fit my needs. The NAVIG program from PPC Paris has outdated ephemerides and my try to contact the author of this program was not successful. The main question was how to put new ephemerides in the program cause those one in the program are not valid anymore. The great circle calculations, dead reckoning, ... are running successful.

Next I tried the HP41 navigation program cause I have the FRAM71 and the HP41 Translator PC inside. So I gave it a try with the help of @rprosperi but as I see I have to dig deeper in the HP41 programming. I'll plan to do this in autumn.

So I was looking for another solution. I found an EXCEL program (SUNSIGHT) from www.backbearing.com and looked through the solution. It looks quite good for me cause for position estimation I want to use at first the sun with my sextant.

Next step was to transfer the EXCEL in HP71-BASIC. I did this this weekend and finished testing today. The results are the same as with testing data in EXCEL program so I'll use this on my trip and see how it's running in the daily use. This has the advantage that no paper for the sun's declination, GHA, etc is necessary and all calculations are done within the program. It is possible to draw the result on a navigation sheet use for dead reckoning (where I'll use the NAVIG program from PPC).

Please do not wondering about the code - for to have a quick "translation" I did this very close to the EXCEL program. If the program is well usable in practice I will optimise the code after my return. There is also no error protection - so if you try this be careful with the input data - I'm not responsible for wrong results or damages out of the use of the program.

EXCEL program, HP71 program code and some of the testing results are in this post. I got the permission from Andy of http://www.backbearing.com (as the intellectuel owner) to put the BASIC program on the HP forum and he also wrote back: "Would you believe my Excel program started out as a program for an HP calculator back in the 1980’s? Not in Basic, but Reverse Polish Notation"

best regards and thanks to those members (rprosperi, sliderule, Thomas Okken, Sylvain Cote, Didier Lachieze) supported me in looking for a solution. Feedback is very welcome.
Erwin