Navigational stars in Silent Hunter 5

[Sean C]

AFAIK, they are only training officer cadets at Annapolis.

[CaptBongTrillion]

I'm not sure I understand how to apply the graphical method if I am west of the prime meridian. So far, I've been applying the method in places east of the prime meridian, and the starting point for the drawing is the bottom left corner of the 1 deg X 1 deg box. Do I still start in the bottom left corner if I am west of the prime merdian? Or do I start in the bottom right? Thanks.

If you mean the LOP transfer, then there is no fundamental difference which side of the prime meridian you are on - you can choose any point as the Dead Reckoning Position. You can give your example of drawing on the map so that I can check if you are wrong.

[CaptBongTrillion]

I don't have a specific example yet, but my assigned patrol area is pretty far out in the Atlantic so we'll see if I can actually find it I was also wondering about what happens if I don't know exactly which 1x1 box I'm in, but you answered that, and it sounds like it doesn't matter. You will just get LOP lines that place you in the correct box.

But to better explain my thought process, say I have a DR position of 56 N 4 W for example, and I am in fact inside this 1x1 box. Because longitude increases in absolute value going west, I think my assumed position is the bottom right corner of the 1x1 box. So is the bottom right corner supposed to be the origin of the LOP transfer lines? Or do I say that my DR position is 56N 5 W which is the bottom left corner of the box?

I guess another way to ask it might be: does it matter which corner I start in?

I don't know if I'm making any sense here

[CaptBongTrillion]

Ok I think I'm starting to see the flexibility of this method. I had a situation where I guessed the wrong DR position and still got a fix. Here's the map work below. I showed the island I found for proof My navigator gave me a position almost 50 km away (the random mark to the north) but I know this couldn't have been correct, otherwise I wouldn't have run into the island.

https://imgur.com/a/q8AYP7D

https://imgur.com/a/xCvSuKu

There are three things to keep in mind here:
1. It really doesn't matter which point is used as the Dead Reckoning Position. You can try to use for this each of the 4 vertices of the square, inside which your actual position is located, and performing the LOP transfer in all four cases you will get practically the same observed position.
2. It is not necessary to use coordinates rounded to the nearest degree as Dead Reckoning Position. It makes sense to take DRP into account to within minutes of arc.
3. The closer the Dead Reckoning Position is to your actual position, the more accurately you will determine your actual position using celestial navigation. In this case, the actual curvature of the LOP (which we depict as a straight line, even though it is a large arc) will not have a noticeable effect on the result.

I have compiled Nautisches Jahrbuch for 1939. I will continue to post Nautisches Jahrbuch as they become available.

https://drive.google.com/file/d/1RBC...ew?usp=sharing

[Ashikaga]

I know this is slightly off topic and has little to do with celestial navigation but I managed, when my navigator was severely wounded, to dead reckon my way back to base guestimating the time period traveled and course setting from the last DR fix. I then started setting new course lines from rhe guessed fix mark on the map and measured them and used the distance/time equation and started heading down my course lines at such and so speed for such and so time duration and at the end of that line changed course to the new heading I thought was good. When I figured I should almost be at my base and hit land which I then could follow, the Navigator recovered. I did a celestial fix and it turned out that I was 80-100 Nm from where Celestial said I was.

I did feel a little proud. Even with that much of a difference.

Ashi.

Indeed, it was not uncommon for the sky to be tightly covered for 5 or more days in a row and you had to rely only on DR.

Perhaps someday you will update TWoS to 2.2.24 and find yourself in a similar situation as Paul Pfaffinger with U-441, you can make a celestial fix yourself and feel just as proud about it.

[Ashikaga]

That might be sooner than later Alpheratz! I was just told that upgrading from version 2.2.7 does not endanger my savegames. Even though Vecko states at the upgrade that from 2.2.9 onwards it is no longer savegame compatible.

Yay! ;-)

Best,

Ashi.

https://drive.google.com/file/d/19o5...ew?usp=sharing

Updated Excel table for celestial navigation by the Sun, Moon and 58 navigational stars. Now U-boat position fix will be a couple of hundred meters more accurate:

https://docs.google.com/spreadsheets...f=true&sd=true

In the lines of the sun.txt file: 78-80, 267-269, 633, 634, 809-811, 998-1000, 1174-1176, 1363-1365, 1539-1541, 1728-1730, 1905, 1906, 2094, 2095 , 2270, 2271, 2459, 2460, there was no minus sign before the minutes of declination of the sun, which led to erroneous UT readings of the sextant. This error was quite difficult to spot in testing as it only affects a few days in each year: late September and late March. Link to updated sun.txt file, which fixes the above errors:

https://drive.google.com/file/d/1cw6...ew?usp=sharing

Replace with this file the corresponding file in the root folder with the game.

[derstosstrupp]

Thanks Alpheratz! Great work as always!