... or a manual solution through
ERMc where I draw a green line in the rec manual where the stadimeter will give the correct range to every ship in the game as shown bellow.
The beauty in this is that it gives a lot of room for errors. Closer you are, better values you get but also the risk to be spotted will increase dramatically, so it add a great level of realism. If the target is far away, you will have a hard time to measure the range and the chances to get a perfect shot are minimal. Also, in stormy condition you will need to work hard to get these values, no computer will do the job for you.
So, no more millions of tons sunk in 1 patrol, exactly as it was in real life. Work hard and be proud of your achievements.