http://en.wikipedia.org/wiki/Sextant

I think that the measurement is connected with the sun (at midday?). If we check the range between sun and horizon we can calculate the current ship's latitude from tables. (so the "0" should be located at horizon line).


The question: we have our current ship's position on map - should we extra check the lattitude or longitude?
:06:

I had a request for the Sextant because there were some who didn't want to ask the Navigator for current position (or if the Navigator was wounded) and they wanted to calculate position on their own (they want real real navigation). Want to play around with it Antar? I can send you v5.4.0 as it is now so you can see and test.

EDIT:

from reading the wikipedia on the Sextant it appears I need to be able to rotate the Sextant so horizontal measurements can be taken also. Have to add now.

:o
Lol...

I think that I know how to check a longitude (sorry I'm not sure - I'm no seamen):
You have tables with moon/sun rises/sets at GMT - different value with table and GMT shows you where you are:

Sun rises at 7.00 GMT, in "real" at 8.00 - you are at 15°W, between Portugal and Azores.
How does it implement... no idea...

letting you use the sextant in the horizontal plane turned out more difficult than I thought :shifty: Finally got it working correctly though. Now I just need someone who is familiar with this tool to see if it's working correctly in game or not. I have a feeling that the scaling isn't correct but I'm not sure.
http://www.subsim.com/radioroom/pict...pictureid=3356

Wikipedia says that an experienced navigator can make out position with an accuracy up to 460m and that normaly even during hazy days error is not more than several NM.

Ideally to fully simulate a sextant we would need a stadimeter with one picture always holding sun in the view and the other moving up and down with the mouse wheel so the horizon could be brought into view and the lower limb of the sun would be made to touch horizont. Then, providing you were also seeing degrees of the pictures' offset angle and the old good chrono on the screen, you could make out your lat and long simultaneously at noon, as a real navigator would do, hence fully simulating the sighting and navigation calculations (that are quite simple in fact) using a sextant. And for 100% simulation we would need to see the degrees in an inset depicting sextant's index arch.

But that is asking too much I guess the simple 'sextant' band from SH3 although not as convinient and precise still does the job.

There is one fundamental thing, however, to say that sextant is functional we need to prove that sun altitude is actually reflecting lat and long in the game. :)

That was about sextant.

To have full real navigation we also need dead reckoning simulated, i.e. navigator should continuosly draw and calculate the boat's track based solely on course and speed as he does already but with some error to simulate currents, approximations and non-precise instruments (especialy knots indication). Then it would be possible to intersect dead reckoning with sextant's fix and find your position. But that would require correcting the last line of the dead-reckoning path to fit the fix. Which I recon is impossible to do in SH.

I'm going for simple for now and thus have used the sextant 'tape'. Once we prove that the sun altitude does reflect lat and long in the game then I can look into a more functional sextant. But for now there's no use designing something that might not even work. So we go the simple route for now :yep: Quite frankly I don't know how to use the tool....just because I make something doesn't mean I fully understand it :haha:

I can add dead-reckoning to the game. I made a tremendous breakthrough while working on this part of the mod that let's me do things like my super marks idea and dead-reckoning :D

The feedback I'm getting from most is that they don't want dead-reckoning. They want to be the one putting the plots on the map (they want to be Captain and Navigator at same time).

Fully agree, we need to prove that it can function first. And even then it's probably won't worth the time invested - band will do just fine.

Great news about the dead-reckoning! As if I had any doubts that you are genius... :yeah:

:06:

To measure the lattitude check the range of sun (probably at midday?) over horizon line. If you check it you can calculate the current ship's latitude from tables (different sun max height for day and month).

http://damecarcass.blogspot.com/2009...l-horizon.html

You can do that with two measures:
1) when sun rises (to check the longitude)
2) max height of sun (to check the latitude)

The band itself is very easy to check - very quick and rough check is to check the height of the Polar star in degrees over the horizont that is the angle between the star and the horizon (not the bottom of the screen). And that will give you your latitude (providing you are in northen hemisphere where the star is visible). For example - if the star height is 30, then you are on the 30 latitude. Compare it to the actual posit.

To check the longitude you need to set your position exactly at Greenwich meredian, i.e. long = 0. Then the sun should stop rising (use band to check sun height) exactly at 12:00PM and after it should start to descent. If your posit is 15 degrees westerly - then the sun will be at its zenith at 1:00PM, i.e. every 15 degrees to the W give you +1 hour to the noon time as compared to GMT. 1 degree W gives +4 min.

We must also check if the sun's position corresponds to lat. It is slightly more difficult. I'll explain later.

I sent you the latest version of the real navigation mod (v5.4.0). I'm hoping you can test it out and provide feedback :yep: The Real navigation add-on mod has to be the LAST mod installed via JSGME. That is the only requirement.

Being that SH5 is based off of SH4 which is based off of SH3 and what you are talking about above is correct in SH3 then it should work in SH5.

Will do ASAP. :salute:

Report:
As I understand it now map centered in coordinates, the latter which gave the navigator after the start of the game or the latest calculations of the position. Now it is impossible to guess the real position of the boat:yeah:. That's good:up:. Hints positions in the message box no longer appear. The mod works well. :woot:
It now remains to check the sextant. Sun table - just what need.:yeah:
@Vanilla
Excellent comments on navigation. I, too little competence in matters of navigation. Thank you for your help.

Last update rus for 5.4.0
http://www.subsim.com/radioroom/down...o=file&id=2897

got a PM from sober asking if it was possible to choose your starting location for the historical missions. Before I had discovered the breakthrough when working on the real navigation it was not possible. But since discovering that breakthrough I've been able to make this happen (and discover another important breakthrough :rock:). So a new setting has been added to the mission settings dialog box:
http://www.subsim.com/radioroom/pict...pictureid=3357

when you click 'Change' a HUGE world map will become visible. It starts out allowing you to pan it with the mouse. It acts just like all draggable items (left click and hold and drag). When you have the world map in the general vicinity of where you want to start you press the 'Tab' key. This takes the world map out of pan mode and into click mode. Now whereever you click on the map will be your new starting location :rock: If you want to re-enable pan mode then press 'Tab' again. Once you click on the map to set your new location the map will hide. If you want to change your decision then click 'Change' again. If you decide you do not want to set a new location then press the 'Shift' key to exit.

In order for the change to persist you have to click 'Apply changes' as usual.

Start the game and you'll find yourself in a new location :D This is great for testing (especially for W_Clear's environment mod to see the different climate zones)
http://www.subsim.com/radioroom/pict...pictureid=3358

Absolutely fantastic :rock: