Real Navigation Mod

[XLjedi]

Originally Posted by Hadrys

This is nothing, when transiting for 1000 km in bad weather I have to correct course all the time. Check out with ctrl+click in x1024 how fast the boat gets of the course... I really wonder how I did it for the first time, when my position after several direction changes, was quite accurate in the end (1 screen). Maybe x256 doesn't generate such a big error? All my observations are while doing 7-10 knots. This is a serious problem because small errors on longer distances add up very quickly... it might be realistic but for the gameplay - transit - its very annoying.

Could you make a WCA course adjustment?

[ichso]

Couldn't you just calculate the error in your heading for longer distances too ? Just try the following:
Under a certain and constant (bad) weather condition, with lots of wind, set a straight course in any direction and compare your drift from the estimated positions after 10km, 100km and 500km, perhaps even 1000km.
Even if this drift has some exponential rate of growth, one should be able to estimate it. Always assuming that the surrounding conditions do not change of course. It should be not too hard to take all that into account when planning course, even if bad weather disturbs it. At least one can minimize the error with that.

[XLjedi]

Originally Posted by ichso

Couldn't you just calculate the error in your heading for longer distances too ? Just try the following:
Under a certain and constant (bad) weather condition, with lots of wind, set a straight course in any direction and compare your drift from the estimated positions after 10km, 100km and 500km, perhaps even 1000km.
Even if this drift has some exponential rate of growth, one should be able to estimate it. Always assuming that the surrounding conditions do not change of course. It should be not too hard to take all that into account when planning course, even if bad weather disturbs it. At least one can minimize the error with that.

Unless you're going from calm winds to hurricane conditions there is no exponential growth in WCA (wind correction angle). As long as the wind vector is constant and your movement vector is constant it would be a steady WCA. Assuming constant wind and course hdg/spd your 10, 100, 500, 1000 km observations should yield a straight line.

Granted, WCA is a term more common in aero-navigation. In a naval sim, I haven't done any testing to see what would be required to offset a 15kt crosswind. I doubt they did any modelling of wind driven (or other) currents... but I dunno for sure.

[don1reed]

In real life navigation there is no way that mariners can quantify the errors of Tidal Current and Leeway caused by the wind.

Drift = speed of current
Set = Current's course
Leeway = Leeward motion of a vessel pushed by the wind.

Separately one can use vectoring to compensate on a course to follow; but, when both appear at the same time, the only way mariners can quantify their cumulative effect is by comparing simultaneous fix and DR positions.

-...-

Now, back to the ficticious world of SH3 & 4, sailing without dragging/dropping a course using the course icon.

The actual head of the sub is being sent off course during foul wx, it is not being pushed to leeward by wind or drifting due to current. Its as if the helmsman falls asleep, and the vessel takes another course. I guess its put in the game to resemble the effects of wind and current; but, the only known compensation so far has been to keep the High Speed TC around 128 or below, and be extremely vigilant trying to watch the miniature compass...which will drive one to drink.

Originally Posted by don1reed

The actual head of the sub is being sent off course during foul wx, it is not being pushed to leeward by wind or drifting due to current. Its as if the helmsman falls asleep, and the vessel takes another course. I guess its put in the game to resemble the effects of wind and current; but, the only known compensation so far has been to keep the High Speed TC around 128 or below, and be extremely vigilant trying to watch the miniature compass...which will drive one to drink.

I don't have any bright ideas how to compensate and the only way so far is to stick to the compass or constantly press = in peri or uzo view to check if we're on the exact course.

Eventually we could check out if that is possible to switch off in cfg that helmsman falling asleep (the error is enormous!) or reenable waypoint autonavigation just for transiting without any course shown, just the end point to keep it simple and start from there manually. Or if we figure out precise long/lats than it would make sense...

This game still requires imaging some things to keep it real but also I don't want to spend the whole time trying to keep my boat on course. Why me? What for do I have my crew?

Looks like mine from the first post

[ichso]

Ok, I finally installed the RealNavMod. I started my patrol out of St.Nazaire, my patrol area was commanded to be DT59. So I set course for the Southern Atlantic.
Weather is calm, wind speed is at 4km/h, some clouds but one can still see the stars.

So in the second night, I grabbed my sextant and wanted to do a quick latitude measurement. I found Polaris by finding Ursa Major and Cassoipeia, as described in the manual which came with the mod.
But strangely it really isn't at the amount of degrees it should be. I know that I am somewhere around 45°N because I can't have travelled so far yet. But when using the sextant as described I would get measurements of about slightly more than 60°N.
I made a screenshot which shows Cassiopeia. Ursa Major didn't fit on the screen.
As you can see, the horizon is even under this screen capture, so I would get an result definitly way more than 45°N if aligning the screen with the horizon.

Any Ideas what I'm doing wrong there ?

(At least the stop watch looks fine again, thx Hadrys )

Originally Posted by ichso

Ursa Major didn't fit on the screen.
As you can see, the horizon is even under this screen capture, so I would get an result definitly way more than 45°N if aligning the screen with the horizon.

Any Ideas what I'm doing wrong there ?

(At least the stop watch looks fine again, thx Hadrys

Happy to hear that.

Maybe this is the problem with the camera file Van was mentioning? What mods do U have except GWX? You have a different control panel...

BTW i'm using a modified version now which allows to plot course if you ask your helmsman - intended to help in ports and long distance transiting in bad weather. Once my boat went off course nearly 90 deg in under an hour, so this is ridiculous.

Still don't know how to remove navigation tracks just to have final end points only.

[ichso]

In one of the other threads I read something about GWX compatibility when using RealNav. Poor Sailor posted his NYGM version of the camera.dat which was changed by GWX and confused something with the camera angles and gave incorrect readings of Polaris.
SH3 is still running, was too lazy to install the file and reload the game + savegame yet.

The different panel comes from the 6_dials_nygm22 mod. Using this and RealNav together I had to read the detailled mod description of RealNav because both mods need essential changes in menu_1024_768.ini. 6_dials was already installed so I took the modified version of the menu[bla].ini and inserted the [G3F I320] by copy&paste to get the draggable sextant to work.

I don't use any further mods which should interfere with this stuff, just some sounds, textures, OpenHatch and the likes.

BTW i'm using a modified version now which allows to plot course if you ask your helmsman - intended to help in ports and long distance transiting in bad weather. Once my boat went off course nearly 90 deg in under an hour, so this is ridiculous.

This sounds nice too. In this first patrol using RealNav there is still good weather, so I have no problems but I experienced your problems before when setting some manual intercept courses for example. In bad weather you get way off track and it's hard to compensate, if you rely on precision because you don't get your own position displayed by the sim than it's even much worse.

So far I travelled in a straight line out of St.Nazaire to my first course change waypoint. The track was about 980km this far and I got off course by ~5km (using ctrl+LMouse).

Originally Posted by ichso

In one of the other threads I read something about GWX compatibility when using RealNav.

In bad weather you get way off track and it's hard to compensate, if you rely on precision because you don't get your own position displayed by the sim than it's even much worse.

So far I travelled in a straight line out of St.Nazaire to my first course change waypoint. The track was about 980km this far and I got off course by ~5km (using ctrl+LMouse).

Gut gemacht Her Kapitan! Manual plotting give a nice feel, but with those deviations it's impossible to keep on course.

I've mentioned that camera problem. I also have pure gwx + some skins, music etc and polaris is very precise. So I have no idea. We know so much by now but are still at the same point. I'll post thet assisted version later (just changed commands cfg).

[ichso]

Good. I will change something too. The RealNavMod disabled some features of the nav officer. In fact it disabled every status question he could gave you except for the current depht under keel. That's too bad because I miss the feature that he can tell you how far you can sail with your remaing fuel. I can't tell that by looking at the fuel gauge only so I will reenable this option.

But real navigation is nice. I finally have something to do, even if nothing happens in the game.
No clueless wandering in my room anymore while waiting for the SH3 days to go by

Originally Posted by ichso

I can't tell that by looking at the fuel gauge only so I will reenable this option.

I was thinking about, I'll reenable it in normal realnav and assisted. I could use it now... I'm going home, I'm just there. After hard beating (but the hunt was very fat) 20 knots in my VIIB and engines suck vast amounts of that black precious liquid.

I must admit that the problem with keeping course discouraged me, but lack of my sub on the map is good.

PS Flugzeug gesichtet, even didn't wonder just alarm, at 20 knots they disappeared under the surface in few seconds. 2 Huricanes 100km W from Brest?

Updated compilations, fixes some errors, added assisted mode, see readme. Check post #1.

[ichso]

I got the thing with the stars working. In one of the other threads about real navigation someone posted his NYGM version of the camera.dat. Now it seems to work allright for me.

My little patrol report using RealNav the first time so far:

Got out of St.Nazaire at Dec 16th 1940. Patrol area was ordered to DT59, West of Northern Africa. So I set course to 245°, 10.5kn.
Weather was fine till I reached the first waypoint 980km somewhere near the spanish coast. There we got into heavy fog and rain which kept going on for the next 10 days.

Course led me further southeast, had to go around Madeira, I took a safety course some kilometers further to the east then initially planned to not run into the ground because of the bad visibility.

Once I used Crtl + LMouse just to check my position, I will forbid me that on my next patrol Course was good, I just overestimated my speed a little bit, so I hang a little bit behind. Perhaps this is a issue of TC, I used 256x or 512x at max.

When I finally reached the patrol area I made another Ctrl+LMouse check, the same about the speed again, otherwise our position was suprisingly exact.
On our way I cut down the TC every ~4-8 hours to correct the course again which slightly slipped off track from time to time.

I decided not to reintegrate the Nav officer feature that he tells me how far I can got with my remaining fuel. I just count the travelled km's and add them up.
So far in this patrol I travelled ~4141,1km. I have to take into account that stormy weather and recharging batteries will increase the fuel consume.

When I thought our 24h patrol in DT59 was over I had to CTRL+LMouse again because it said I didn't patrol 24 hours in that sector yet. I saw that I got a little bit out of the DT59 so I headed back south, finished the patrol.
Again it was a matter of higher speed than I though although I already took even half or quarter knots into account when making my calculations.

Suddenly in this night the sky cleared completely up again wind turned on to 13km/h though.
I did a reading of the stars and Polaris' position seems to be dead on now. So I'm looking forward to some real celestial navigation on the rest of the patrol and the ones that are still to come
Here are 2 images of my current travelled course and the now functional sextant reading.

Originally Posted by ichso

I got the thing with the stars working. In one of the other threads about real navigation someone posted his NYGM version of the camera.dat. Now it seems to work allright for me.

This is wired. Why with nearly same mods (important for us files should be the same) the behavior is different? Maybe check if one of your mods doesn't modify camera.dat?

Originally Posted by ichso

Once I used Crtl + LMouse just to check my position, I will forbid me that on my next patrol Course was good, I just overestimated my speed a little bit, so I hang a little bit behind. Perhaps this is a issue of TC, I used 256x or 512x at max.

On our way I cut down the TC every ~4-8 hours to correct the course again which slightly slipped off track from time to time.

During high wave speed can drop by 20-30%, but I'm curious with such a small course correction required. It would be good to edit some cfg's so the error would be very small to simulate helmsman keeping eye on compass constantly.

Originally Posted by ichso

So I'm looking forward to some real celestial navigation on the rest of the patrol and the ones that are still to come

Gut gemacht!! All my sextant readings are well so far, but how do you deal with longitudes?

PS my friend got me 2 teaching books about astro and sea navigation. Also reading Das Boot gives a nice clue how they did that!

[ichso]

This is wired. Why with nearly same mods (important for us files should be the same) the behavior is different? Maybe check if one of your mods doesn't modify camera.dat?

Maybe that I installed an older version of this mod, which wasn't GWX 1.03 ready ? I know I downloaded the GWX version too but don't know which one I delete and which one was left. Doesn't matter as long at it works .

During high wave speed can drop by 20-30%, but I'm curious with such a small course correction required. It would be good to edit some cfg's so the error would be very small to simulate helmsman keeping eye on compass constantly.

there I observed the speed gauge for a few seconds in 1x and then a few seconds under 256x TC to get an impression of my average speed.
The thing with the course can become very annoying, that's right. Didn't had that bad weather yet but there will be little progress in time if you constantly have to go back to 1x and correct your course. It was acceptable with 9km/h wind speed.

Gut gemacht!! All my sextant readings are well so far, but how do you deal with longitudes?

I never saw the sun since I made my very first course change, the weather was just too bad. I saved and quitted in the night I made my first real sextant reading and planned about measuring the longitude at the next sunrise. I'm going to use vanjast's Sun Almanac and the time difference at first.

Also reading Das Boot gives a nice clue how they did that!

I read Das Boot nearly 10 years ago, must have jumped over the descriptions of navigational efforts as I don't remember any of them in that book

Originally Posted by ichso

I saved and quitted in the night I made my first real sextant reading and planned about measuring the longitude at the next sunrise. I'm going to use vanjast's Sun Almanac and the time difference at first.

I read Das Boot nearly 10 years ago, must have jumped over the descriptions of navigational efforts as I don't remember any of them in that book

I've just found on my HDD another almanac, don't know how I got it but it was a year ago. It gives SR/SS during war years but only for 51°N... It shows some diffs I think.

almanac39-45.pdf

I haven't read Das Boot yet but in the movie it was rather omitted, but here they often take star fix, plot course etc. Just like we do it

Also I've restored GWX weather to stock SH3 stock settings and now it's raining far less. Fog, overcast, heavy waves throwing your boat in all ways yes! but the visibility is far better, it became more playable but also very hard to recognize targets far away in those conditions (smoke on the dark horizon etc). Cool