[DelphiUniverse]

I have never actually tried to perform an exact T-shape attack, I usually send away my fish when the target is at some comfortable angle that I know it will hit more or less at 90 degrees.

If you are at 800 metres, you don't have to do this, it is so close that the time spent doing that is a waste.

If you are at 3000 or 4000 metres, it will become more relevant to try to make a T-shape attack. When you have plotted the target ship's course and measured its speed, you can plot a point on the line when to fire when the ship will be straight ahead, by using the ship's speed and the torpedo speed setting.

The calculation is straight forward, what method to use is unknown to me, there is probably a method to do it easily, I don't know any at this moment.

If you are using the Steinbarsch torpedo with a speed setting of 45 knots and the ship is travelling at half of that speed at 22.5 knots, then you need to fire the torpedo when the ship is half the distance between the middle point and your uboat's distance to the middle point. If your uboat is at 4000 metres then you need to fire when the target is 2000 metres from the middle point.

Target Speed / Torpedo Speed * Uboat-distance-to-middle-point

If your uboat is 8000 metres away from the crossing intersection of the target, the torpedo speed is 45 knots and the target ship is travelling at 10 knots, then the calculation becomes:

10 / 45 * 8000 = 1777,7 metres. When the target is 1777 metres from the center point you should fire. (This works only if the torpedo course and target course are perpendicular at impact time)