Real Navigation Mod coming soon...

[Munchausen]

Originally Posted by The Joker

Yeeeeeeeeeeeeessssss! I was just looking at that thread too! Right now, I just settled on a pseudo star navigation system. I made a little mod to remove the sub marker on the map, and just Ctrl+Click & mark to simulate the navigator getting a fix at times when it would be possible. Makes sailing a lot more fun!

Radar on ... hoping you'd post the specifics of your little mod. If vanjast ever figures out how to correct or compensate for the lack of Zulu time in the game, I'll install his sextant mod ... but, until then, your fix sounds like the next best thing.

:hmm: So ... please, what changes did you make to get 'er done?

[skookum]

This is the most exciting mod I've seen in a while.

[vanjast]

Slight delay in this mod, as I've had to construct a bit of software to convert USNO almanac to SH4's almanac.... see pic below. This proggy will probably become a 'biggy' but will be free for all as it assembled from freestuff - Thanks to those concerned


The proggy will write a CSV format (excel) file, or other formats (pm me) for printing.
This is just prelim - More stuff later..

[vanjast]

Originally Posted by tater

Make sure the moon and sun are actually ~1/2 a degree across.

You'll probably notice the Celestial Adjustments - 'Size' section in the proggy

[Munchausen]

That's gotta be the coolest celestial computation program I've ever seen.

[Satch]

[quote=DeepIron]

I've always hated being off the coast of Japan and still in darkness at 11:30 AM, etc...
Cheers.

I assumed the game clock was on Pearl Harbor time or GMT. Anyone have thoughts on this? The QM had a GMT clock and he set all the division clocks to local time.

[Rockin Robbins]

Originally Posted by tater

Make sure the moon and sun are actually ~1/2 a degree across.

Find a way to put the moon in the correct position at the correct phase at all times. It's hardwired, so the deal is already broken.

[vanjast]

I can change the game sun size, but the glare surrounding the sun is a problem at the moment. The moon and sun are just pictures, that can be changed AFAIK - looking into this.
As far as putting the moon in the correct position, I'm not sure of this at the moment, but you never know.

More later

[skookum]

Just did a quick test using the periscope to roughly measure the sun's altitude and azimuth. Checked them against a perpetual almanac and was surprised to find that the numbers were in the ball park (within 5 degrees) of my very (VERY) rough measurements. Of course for this kind of mod to work, we would need to be able to measure celestial body altitudes to the minute, rather than degree. And we would somehow need to confirm the accuracy of the in game celestial sphere against marine almanacs (or generate an almanac specifically for the SH4 celestial sphere).
Celestial navigation is pretty neat. Here's a link to a good site on the subject.

http://www.celestialnavigation.net/

[vanjast]

Originally Posted by skookum

.. Of course for this kind of mod to work, we would need to be able to measure celestial body altitudes to the minute, rather than degree.

As the game was not initially intended for this type of thing, It's going to be a matter of making do with the best we can come up with. I think the accuracy is going to be somewhere around 5 minutes of arc for Latitude measurments.

Originally Posted by skookum

.. And we would somehow need to confirm the accuracy of the in game celestial sphere against marine almanacs (or generate an almanac specifically for the SH4 celestial sphere). Celestial navigation is pretty neat. Here's a link to a good site on the subject.

With regard to Longitude, I'm busy with a piece of software that will adapt the USNO almanac to the game alamanac. The game celestial objects/almanac are a simplified version of real life, so the idea is to try match it and produce a 'game almanac'. Here the accuracy will be down a minute of arc/time.

So all in all, with celestial nav asssited by nav logs, and visual sightings, one can produce a fairly accurate navigator for game purposes. I expect to start testing my 'almanac adapter' in the new year...

[skookum]

Will I be able to plot St. Hilaire intercepts from an assumed position based on the measurements in your mod?

[vanjast]

You can as the almanac uses nearly all the same formulas. You'll have to keep accurate logs when doing running fixes.

This (or something similar) was done by someone with the SH3 version, and they claimed a 100m accuracy !!

I should make Cosine/sin Tables for manual calculations...
More later.

[6SJ7GT]

Vanjast,

Can you use the Almanacs I made for Celestial navigation? I recently added 1939 and 1940 for the SH3 CO's to the collection of 41 to 45 almanacs for SH4.

They are in the Nautical Almanacs folder on my filefront site
http://hosted.filefront.com/6sj7gt

Mike

[Rockin Robbins]

Originally Posted by vanjast

You can as the almanac uses nearly all the same formulas. You'll have to keep accurate logs when doing running fixes.

This (or something similar) was done by someone with the SH3 version, and they claimed a 100m accuracy !!

I should make Cosine/sin Tables for manual calculations...
More later.

vanjast, you have used real celestial navigation and you know that even on dry land you're not going to get 100m accuracy (except by coincidence). At sea, 50 miles is considered a bullseye! That is why when navigating for a port, for instance, it is standard practice to know your expected error and aim to one side by a bit more than that. Then, when you encounter land, if you aimed south, for instance, you would know to turn right.

If you tried to hit the port dead on, you would be somewhere in the error cone and at landfall wouldn't know whether you were north or south of your destination. You'd have a 50% chance of turning the wrong direction!

[vanjast]

Originally Posted by Rockin Robbins

vanjast, you have used real celestial navigation and you know that even on dry land you're not going to get 100m accuracy (except by coincidence). At sea, 50 miles is considered a bullseye! That is why when navigating for a port, for instance, it is standard practice to know your expected error and aim to one side by a bit more than that. Then, when you encounter land, if you aimed south, for instance, you would know to turn right.

If you tried to hit the port dead on, you would be somewhere in the error cone and at landfall wouldn't know whether you were north or south of your destination. You'd have a 50% chance of turning the wrong direction!

Yes, I know that, I'm just repeating what somebody else claimed in the SH3 forum.

As an example when I first tried the Mod in SH3, I had my last clear night off the coast of Norway, from there dead reckoning (DR) to Scotland. Sighted land without having a clue where I exactly was - working out an approx position, plotted a course to the outer western island of Ireland. After 2 weeks of gale force seas the sky cleared enough for a quick fix - course adjustment of 10degrees and a few days later spotted the island about 5 NM off the port bow.

That was my first Nav attempt - Now I hoped to have improved the accuracy in SH4, having read volumes on navigation, which is quite interesting.