Celestial Navigation in SH4

[Pisces]

Originally Posted by fitzcarraldo

Many thanks for this literature tip.

Only I need a sextant in my SH4...I dowloaded the pack for celestial navigation, but I don´t have the sextant. I read the thread about the sextant in the Obs. periscope, but I like a simple sextant-rule as that I have in SH3.

Where is that sextant, if it exist?

Best regards.

Fitzcarraldo

In this thread it is called "the program Stellarium"!

[fitzcarraldo]

Originally Posted by Pisces

In this thread it is called "the program Stellarium"!

OK, I use Stellarium, but it is an external program. I speak about a sextant-rule style mod for SH4, as the Real Navigation Mod for SH3.

Many thanks and regards.

Fitzcarraldo

[Pilot_76]

Originally Posted by fitzcarraldo

OK, I use Stellarium, but it is an external program. I speak about a sextant-rule style mod for SH4, as the Real Navigation Mod for SH3.

Many thanks and regards.

Fitzcarraldo

I am really eager to start this Stellarium/SH4/SH3 "partnership" but I still have much to learn. What I've dug so far is that sextant mod works only for SH3, SH4 v 1.3. I tried to install it on the 1.5 version but with no success. Besides reading all these posts I agree that Stellarium is a much better tool and has more immersion so I am almost giving up the idea of using the Sextant mod at all.

Some doubts I have:

-How is it possible to remove completely our sub from the map? The no sub map mod partially does it.

-Is DR only good for ranges <600nm?

BTW: I posted a comment on WOTA's facebook page suggesting Cel Nav as an option. He got very interested. Feel free anyone to go there and support this thanks. WOTA is a SH version for iPad/ iphone (in other words, what Ubisoft chose not to design).

[Castorp24]

Thanks for the good work!
I recently uploaded a little modification that finally gets rid of ANY trace of the sub/ship in the navigation map (no tails, no little dots). Now it is just impossible to locate visually the thing in the F5 chart.

Download link here:
http://www.subsim.com/radioroom/showthread.php?t=190956

[castorp345]

Here's an update to Michael Jones' brilliant python script to include randomization-based error derived from sea state and own speed, as well as to work with Stellarium 0.11.4.

Please note that the attachment as included here needs to have its .txt extension removed (leaving just the .py of course), and that you need to edit the script to include your own proper directory locations!

Also, be sure to input the correct syntax for the date (yyyy:mm:dd), and UTC time (hh:mm:ss), otherwise the script won't load properly into Stellarium.

Many thanks, Michael, for your original work and for providing such a great & fun way to practice plotting fixes without having to lug my C. Plath around!
cheers,
hc

[Pisces]

I think the randomization is better applied to the individual altitude measurements. As that is what will be complicated by wind and sea motion. The randomization is now applied to the viewing location in this script. And so applies to all observed objects in the same way. But I understand this is not really possible to program into the startup-script. As it should be a post-fix correction.

Personally I would limit myself to the amount I can zoom in on the object (to simulate the amount of wobble in holding my sextant), and guestimate by eye at what distance it is at from the nearest altitude gridline in Stellarium. That means 3 individual opportunities for measurement errors. Increasing and distorting the size of the position-probability-triangle. Instead of a single offset applied to all observations making you calculate the position of where you are NOT at.

[TorpX]

Originally Posted by castorp345

Here's an update to Michael Jones' brilliant python script to include randomization-based error derived from sea state and own speed, as well as to work with Stellarium 0.11.4.

Would it be possible to make a script that would use a randomization-based error derived from sea/whether state and perhaps navigator experience, to return 3 lines of position? That is, you would pause your game and save as before, then retrieve 3 sets of coordinates for the LOP's and plot them in your in-game charts, and skip the Stellarium and tables part of the procedure.

I like the concept of navigational error and all, but find the whole Stellarium business much too tedious.

[in_vino_vomitus]

So - Celestial nav is something I've always wanted to learn, so when I found out about this method of using it in-game I was pretty happy. I've no idea how long it will take me to get competent at the maths and so far I'm only using it in the Pacific, but here's something that occurred to me. I have to input the GMT time and date into stellarium via Python, and I'm taking it from the tutorial that Pacific boats run on pearl time, i.e. Z-10, but when I move to the Atlantic or the Med, what's my time zone there? I have a map of time zones, does SH4 adhere to it? Someone mentioned saving a game at local noon and comparing a sun sight from Stellarium, which I'll probably do as soon as I know how but I wondered if anyone could save me exercising my mind by answering the question off the top of their heads?

P.S. - I had to use 2008 versions of Python and Stellarium to get them all to work together with the script in the download. I mention this just in case anyone has given up on this because of issues with the current versions. A couple of folks seem to have - Also it shows I read the thread before asking the question