Few random question about u-boats, both in game and in real life

[Thoth_already_in_use]

Originally Posted by Sailor Steve

No, it only takes two. The radioman on my ship draws a line on the chart showing the direction of the signal.

Originally Posted by LGN1

concerning 3: Look for 'High-frequency direction finding' or 'Huff-Duff'.
Short summary: It was not so easy to determine accurate positions in the beginning of the war due to technical limitations and short signals (<20s).

I wasn't aware that you can determine the direction only with one measurement point, but using the loops make sense. But still, the presence of uboat nearby (source of radio signal in coded german) should put the escort in some kind of alert state. At least to call an air support (if available) to investigate. Or I still missing something.

I remember that the important air operation are conducted in radio-silence just to avoid an early warning.

The question in the same vibe. Submarine can't send a message while submerged, but can it receive one? Probably not, so how the BdU orders are communicated to them -- are they repeated until the submarine acknowledge it?

Originally Posted by Pisces

9. x would be a scratch mark to help with the 2 magnification settings.
10. Can you show a screenshot? It's been a while since I looked at the Magui interface. I can imagine 2 wheel indicators with a time scale used for calculation (of speed).

Thanks. I will try when I get home.
Concerning the Zeit calculator, it is on backside of attack disk screenshot in this tread.
Speed and time estimations are a headache for me, so I'm really interested in everything with zeit written on it.

[Pisces]

Originally Posted by Thoth_already_in_use

...
Concerning the Zeit calculator, it is on backside of attack disk screenshot in this tread.
Speed and time estimations are a headache for me, so I'm really interested in everything with zeit written on it.

Yeah, that is used to calculate Time,speed, distance and angle problems. The scales works for multiplying and dividing numbers. A full loop around the scale multiplies by 10 (clockwise) or divides by 10 (counterclockwise). You have to keep a mental note of how the decimal mark moves as you multiply or divide with larger and smaller orders of magnitude.

From the inside out you have the following scales:

Inner moving disk, Time: scale in seconds (small font on peach background) going over in minutes-seconds (large font, white background). Personally I customized mine physical Attackdisk with marks for an hour scale. The placement of 1 hour is equivalent to 6(0) minutes and 36(00) seconds). The pointer (thin red line) is located at 1 second and is equivalent to 10 seconds, 100 seconds (1m40s) and 1000 seconds (16m40s)

Middle moving disk: distance and speed
inner scale: distance in meters (or speed in meters per second)
middle scale: distance in nautical mile (or speed in knots)
outer scale: same as inner scale

Outer/base disk: angle
This is the angle according to a sine curve. It shows angle values from 90 to about 6 degrees. But they also represent the same sine values for the complement of the angle (180 degrees -angle). The 90 degrees mark is unity (1), as sin(90)=1.0. However the same mark is equivalent to 5.74 degrees (when approached counterclockwise from the right), as sin(5.74) = 0.1 And would also be equivalent to 0.573 degrees (as sin(0.573)= 0.01) Unfortunately due to space limitations the scale from 5.74 to 0.573 and smaller isn't drawn. It could be very useful for certain calculations like torpedo lead angle which can result in such small angles.

As you can see on the screenshot of the Magui mod-thread the time arrow is pointing to 1.95 nautical mile or 1.95 knots. You can immediately see on the adjacent linked scale that this is equivalent to just over 1(.000) meter per second). 1.95nm*1852m /3600s= 1.003m

Similarly when you look at the 10 and 1-00 mark on the time disk you can see that such a speed makes 60-ish meters in 1 minute, and 600 meters in 10 minutes. Here is where keeping mind of the decimal point shifting becomes important. It takes 1 full turn clockwise to indicate distance in 10 seconds. Another 3/4 turn to multiplies by 6 to indicate the distance in 60 seconds (1-00). Another subsequent full turn adds another zero if you wanted to know the distance in 10 minutes. Or just look across whichever time interval you want to know the distance for.

There are a whole bunch of calculation techniques using these scales, by aligning certain values to one another and looking across to other scales. There should be several threads about this device. In the download section there should also be a sort of manual describing these calculations. I personally made a physical wheel out of cardboard pizza boxes. And added a free pointer across all scales. Once you get the hang of the order of motions required you'll do them quicker than with a digital calculator. Just be aware of those decimal point mess-ups.

[Pisces]

As for time-speed-distance calculator. There is another movable tool on the map screen above the officer commands. It's has the wider tab. It's called a 'nomograph'. Place it somewhere on the map.

You'll notice 3 scales in units of time, distance and speed. Make sure you know 2 out of 3 of those. The one you don't know is the one this tool wil calculate.

Use the line tool and draw a line completely across it. Do not make the line end on the tool initially. As you won't be able to grab it with the tool in the way.

Grab 1 endpoint of the line. Re-position it on either the outermost left or right scale at the value that you know.

Grab the other endpoint and drag it so that the other known scale is intersected at the 2nd known value.

The line should now cross the unknown scale of the time,distance,speed problem. Read that value.

The line is likely to end up diagonaly. This is correct for the calculation. It does not have to be perfectly horizontal.

BTW, this is not the second (circular) dial that I mentioned in my other post. That one is the stopwatch background with U-jagd on it. It is used to determine target speed: Put periscope vertical line in front of target and reduce speed to 0. Or if you want to keep moving forward turn the periscope to bow (or stern) and turn the boat to get the view in front of the target bow and stop the turn completely. Start the stopwatch when the target bow begins to cross the vertical periscope line. The time is stopped when the target finishes moving through the vertical periscope line with it's stern. (the precise point may be out of sight) One of the curves (green, blue, red, yellow) is chosen to match the target length (75m, 200m, 150m, 100m) as close as possible. The second hand points to the target speed for that curve. If the target length is between those of the curve then take the average of the speeds of the nearest ones. (in terms of length; be mindfull that the colors are in a strange order)

[Thoth_already_in_use]

Originally Posted by Pisces

As for time-speed-distance calculator. There is another movable tool on the map screen above the officer commands. It's has the wider tab. It's called a 'nomograph'. Place it somewhere on the map.

I know it, but I don't like it too much. Because of log scale and lack of fine graduation it is difficult to make fine measurement. And for approximative ones, the speed tables are much faster. Actually I use the discs around periscope ocular -- but still need to test how accurate it can be.
And I found my old notes about 4-bearing method -- so I don't really need these calculators (but they are fun to use).
And thanks for the manual)


Another 2 questions, now about the TDC. Does TDC takes into account the time that torpedo is expulsed from tube and the time needed to turn, or should I estimate this time manually?

The distance dial is there to correct the parallax. Does it updates when I move periscope like other dials? Imagine that I take measurement at 150* and estimated distance of 3 km. Then I want to shoot at 45* and 1.5km. Should I update distance or it would be done automatically? (I've just realized I dont't have degrees mark on keyboard, I will use *, sorry about this).

[Rhodes]

Distance is not updated in the sh3 and real life TDC used in u-boats. Contrasty of the TDC used in the fleet boats and in SH4.

But, I think, if the other variables are right, the distance will not matter per see, since if the target is 2km, torpedo time to get hit would be 2m (roughly speaking and for example), but if the distance is less or more, it would just take less or more for you see the hit.

[Sailor Steve]

Originally Posted by Thoth_already_in_use

I wasn't aware that you can determine the direction only with one measurement point, but using the loops make sense. But still, the presence of uboat nearby (source of radio signal in coded german) should put the escort in some kind of alert state. At least to call an air support (if available) to investigate. Or I still missing something.

Yes, the escorts should be at battle stations when they think a u-boat is in the area, and ready for action. That's one of the deficiencies of the game. There are quite a few places where it could be better.