One thing that is still missing (I think) is a good speed conversion chart for the various weather conditions.
I found that looking at the speed gauge and trying to estimate the average speed from that differs too much from the average speed unter 512x TC so this would still result in wrong position markings by tracking course.

A really complete chart would be to huge I think. Then one would have to write everything down for each uboat available and with each combination of speed effecting upgrades available for it.
Maybe there are just some factors by which the sub's maximum speed is reduced under certain wind strenghts, which wouldn't be all surprising.

For example: In early 1941 I travelled many days in my VIIC under wind speeds of 9. Some time I calculated a speed of 9,8kn from my course, which would be 18,47km/h. This was good enough to use to travel in any direction as long as the wind stayed at 9.

So it seems as this would really only depend on the wind and a little helpful table would be nice. So that one could just read the values he needs.

Van's sun almanac and SR/SS MR/MS tables on the right hand pages of the Nautical Almanac are in Local Mean Time, not GMT.

See:
http://www.irbs.com/bowditch/pdf/chapt18.pdf

section: 1809 Local Mean Time, paragraph 2

Today I'm testing my patience as not much to do at work, probably everybody's waiting for US Interest Rate Statement...

Stormy weather but managed to pick a brake in overcast. I'm halfway between Ponto Delgada and Lisbon CF65.

Trying to nav without that silly helmsman and correcting my course constantly at max x128... Calculated speed deviation and checking my positions every 9 hours by sending a report to BdU (it gives your grid) so it fits very nicely when I should enter next grid. Also did some math to calculate my lat at SR time (didn't catch SS though). As checking with the maps lat looks fine - 38°N. I like that part very much because lat fits very well, I'm on 215° course so my adjustment for lat was also not that simpe. Also I don't align my bottom of the screen but give it some space to precisely adjust sextant.

Now the hard part. SR was at 5:34 (4:34 local as I should be between 7,5°W and 22,5°W). Which value should I take, GMT? With GMT that gives 1h 6 minutes difference so 1,1x15= 16,5°W and it also looks fine! Impressive Ichso. Very simple method and probably you proved it to be right.

Thanks.
I agree with don1reed, that the SR SS tables give the SR/SS times for local time, not GMT. But then his older post can't be right that the clock in the rightmost low corner shows the local time. Otherwise the SR time you can calculate easily by knowing latitude and using the almanac would match the time which is shown by the clock in the right lower corner (white background).

I'm going to try this method of position marking only on my next patrol and won't rely on cheating. I want to see how far I get off course then.
It's a little annoying that you need very precise latitude measurements and at best very precise SR/SS times (calculated from almanac and measured) too in order to get a good longitude value. If one trys to intercept a convoy, reach a certain destination or something like this all those factors can lead easily to a failure. So some pratice is needed ;).

That's a nice idea, could make it easier. Will try that too.

But that's the whole point! We are that nasty kind of guys who love to make things harder. Check out this thread http://www.subsim.com/radioroom/showthread.php?t=117480.

Sextant: I didn't find any difference if aligning screen with horizon or not. if it is under bottom panel it's ok. Also I'm now using 1680x1050 and stock sextant works ok, it's stretched like it should.

Is my calculation right? Interpolated lat, (right corner game time - almanac ) in hrs * 15. Or am I missing something? You produced a lot of stuff with Don and it's quite confusing.

I'm still a little confused about that two clocks we got in the game.
But as it worked out so far I'm pretty sure that the lower right clock (white bg) gives GMT.
Don's suggestion (I think it was him) to interpolate between the latitudes from the almanac is necessary. The only thing we might have done wrong might be to take the wrong moment for the local SR so far. Your calculation looks good.

As an example:
Let's say your latitude is 46°N, your at Jan 1st, 1941.
- Looking in Van's almanac the SR times are 7:22 for 40°N and 7:58 for 50°N so
at your lat. the SR should be at ~7:43.
- You observe that red light gets turned off at 9:07 which means a difference of 84
minutes = 1.2333... hours.
- Multiply 1.233333... * 15 = 18.5 (°W). Your longitude.

I still need to print this cool thing. But it might make things even a little easier as there are no errors by marking something on the map when using the wiz-wheel.

The last time it felt (at wind speed 15) that at TC 128x I got more off course than traveling at higher TC: 256x and 512x. Perhaps my PC is to slow and drops computing course errors at higher TC's ? :hmm:

I'll just added vans map to check out more precisely in game and it looks like Vans longs and lats are fine but my lat readings are varied 2°S from my plotting. Just pressed ctrl+click which I wouldn't like to do but there was no other way. It turned out that after 600km in heavy storm and lots of diving. I'm ~7km to far mainly, because the weather got better for some time and I didn't compensate. My current long fix from last SR is precise despite 2°S lat reading... it couldn't be so much different or I'm measuring it in the wrong point of horizon? It's not that obvious. I'm gonna take a Polaris fix tonight as I'm patrolling (drifting) in CF91. I'm not gonna compensate for ctrl click, we'll see what happens next.

PS I'll try to redo the grid with much thinner lines, Vans are HUGE.

:rotfl:
Especially in the highly zoomed out views ;)

The thing about the latitude readings is one I dont trust that much yet either. There are many factors which can disturb the reading. If Polaris is port or starboard from your heading then it's sometimes really hard to align the horizon with your screen, it will always be leaning to one side. One other thing is that the view gets distorted by the projection of the sky texture if Polaris is not in the center of your screen.

I have to read something about shooting the sun with the sextant again. Was in some thread about the mod.

What I'm going to test later is at what point the sun has to be in order to be considered as high noon. Perhaps this is possible with the sextant too ?
This would give us an alternative possibility to measure longitude.

Would be useful.

Ok I seems that I can't do 2+2=4... Until I haven't clicked ctrl and turned on Vans map it was fine. I'm standing still. SS was at 20:15 (-1 local time). With sextant I've managed to measure Polaris an hour later at 36°N. At midnight we've got brown clouds and thunderstorms (looks cool) but not a single star arrrrgh!

Position from the map is 37°... I should probably even subtract 1° from my reading as Polaris is 1°N (?) so I would get 35°. I've calculated for 35,36,37 and getting results like 12° or 25° if I add 1 hrs. I should get 17,5°W!! 3 Juli 41, almanac 19:05 19:32 = 27*0.7 (37°N) = 19:24.

20:15 - 19:24 = 51' / 60 = 0,85 hrs * 15 = 12,75°W (already you know it's wrong as the value must be >1 and exactly 1,16666 hrs = 1h 10' difference = SS at 20:34.

So anything doesn't fit here. In game we're still -1hrs between 7,5 - 22,5°, IRL -2hrs between 15 - 30. I can't see any obvious compensation here. Maybe reloading the game messed up something with the clock??? Or am I blind? Either way I'm gonna continue my patrol with manual plotting.

Do u have skype guys? Maybe we could conference... BTW my name's Adam as we already produce those amounts of stuff here ;)

PS I could try to make timezones over the game map (7.5-22.5) as a little brighter areas. Just not to bother but might be useful??

Hm, I never tried that method with SS times. But I had issues measuring longitude with it too. It first was several degrees off and I tried to play around a bit with the values (latitude and time). Finally I used ctrl+click and saw that I was more off of my estimated position as I thought and using my cheated latitude everything fitted again.
This was frustrating and I planned to be more careful with my dead recogning the next time. I will test the sunset longitude too when I fire up SH3 in a few minutes.

Why not, sounds nice as long as they don't disturb the overview. But it can't get much worse than now with Van's huge long/lat lines :roll:

Nice, Thomas :)
I'm afraid Im a complete skype/teamspeak outsider though:oops:

I have tried to alter the sextant a bit. Im using it from the deckgun pos. as that one are stabilized (altered the AngularAngle to 75 to have 60° from bottom to the top of the screen - VALID FOR SH-4) and thus much easier to shoot stars from.

I then noticed (as the deckgun station unzoomed has a red cross in the center of the screen) that 30 degrees were 1 deg to high compared to the center of the screen. I have now made the Sextant centered on 30° and then similair on both sides of 30°'s.

The sextant I have altered can be found:

http://files.filefront.com/KF+Sextan.../fileinfo.html

It is correct that Polaris should have 1 deg. substracted from its sextant reading (or at least aproximatly 1°)

I stand corrected Don :oops: Allthough GMT is a Local Mean Time.....:|\\

Thanks! I recognized thist problem too yesterday.
I worked around it by holding the sextant a certain (and very specific) amount to the left. The slightly distorted view at that position seemed to produce correct polaris readings then. Here's a screenshot of how I did it:
http://cip.uni-trier.de/%7Eschmidt/sh3/ds.jpg

GMT converter
 

I've moved it even more to the left but still can't subtract 1° and not so sure about those numbers. Using flak camera doesn't change anything. Maybe I'll try 75° verstion. However getting my lat from ctrl-click and Vans map in SH3 i get 2,5°W instead of 4°W... so I'll just keep on plotting and enjoy flat sea, cloudless sky not worrying about sextant and try to sink something using slide ruler (great thing)!

Need to finally do my 14th patrol because from 2 weeks (?) I've been starting it all over again to try something, navigate, test mods etc and honestly I should restart it again as my crew needs still few fixes which can be done in port only.