[Pisces]

Did you apply any mods to the game? And did you do this while the campaign was already started with a patrol? Or under what conditions did your game crash? (there are some savegame condition guidelines to deal with bugs)

There is an entire guide in the back of the GWX3 mod manual (in documentation folder) dedicated to manual targeting. Did you follow that?

The recognition manual in game is the one you need. (N-key or clicking ESB that is hiding on the side of the screen) But instead of the warships you should be able to cycle with arrow buttons on the manual to a chapter for civilian ships. Then cycle with the arrows in the book to the page that matches the type. Lock to the ship in the view and place the checkmark. (it's been too long since I used it. my memory may be off on what it looked like)

I don't know exactly what measurements or calculations are done in the videos that you saw. The notepad procedure provided in the game and described in the manual doesn't really need calculation by you. But it may be tricky to get correct TDC settings with it. If your range calculation is off to begin with, so will the speed of the target be off later down the line.

Other userinterface mods provide tools on the screen to calculate AOB based on how large the target looks in the view. If you don't have those then you need to estimate by eye. The angle on the bow is the angle the target captain needs to turn his head (from his bow) to you. Some specific angles have tell-tale signs. An angle of 30 degrees will look halve as wide as it would look when side-on. Smaller angles are proportionally narrower, 15 degrees looks like a 1/4th of the width. Beyond 30 degrees the relation isn't so straight anymore. 45 degrees looks like it's 70% of the width. AOB 65 degrees is about 90% of the width. This reaches 100% of the width as you get closer to 90 degrees. You may see side-by-side masts or walls on it begin to hide to indicate when you are looking exactly side on 90 degrees AOB. With practice your ability and accuracy in this will improve.

What may have been calculated in the video is the speed of the target based on knowing only its length. If you are not moving, or if you are moving then only looking along your 0 or 180 bearing to the target (requires to be turned), then it takes the target a certain time to pass the wire based on it's length. This works best if you can look at the target from it's side as you can clearly see the beginning of the bow and stern and not have it occluded. Then a simple calculation can be done to determine it's speed: divide the target length from the manual, by the time of it's passage in seconds. This is speed in meters per seconds. If you multiply that by 1.94 (or just 2 accurate for government work) then you get the speed in knots. You can do that with a hand held calculator if you want.

The same calculation may have been done to calculate distance moved between plotted points on the map over a certain time. For this a specific time interval between plots is handy. 3 minutes and 15 seconds.In that time the target moves a couple of times 100m equal to it's speed in knots. So if it moved around 600m in that timeframe, then it's speed is 6 knots (give or take). The exact time interval is 194.4 seconds, but 3m 15s is very close and is easily marked on the stopwatch. And adds up nicely to 6m30s, 9m45s and 13m where you can average out the distance moved between plots. And divide accordingly by 2,3 or 4 to get the proper speed in 1 interval with a bit more precision.