I posted this infromation a while back. Since we have a whole bunch of new guys I thought I would post it again.
There IS a method to use PT boat torpedos accurately that does not use luck or Kentucky windage (guessing).
First, you have to understand the concept of the collision course. If your moving, and something else is moving, and the other guy doesn't seem to be moving left or right in view, your on a collision course. He isn't flying straight at you, but is growing larger and his bearing from you is constant.
Second, your torpedo is slightly slower than your boat.
So, if you slow down to match the torpedo's speed, and deliberatly run an intercept course, your torpedos will likewise run an intercept course.
I found 2400 RPM setting for the engines will duplicate the speed of the torpedos. I paced them offline to get that number. The speed indicator isn't sufficently acurate enough to get a good match, but the RPM indicator was.
I also aim using the gun turrets. You can swing the guns around on the target, zoom in to max zoom level, and use the rudder controls to turn the boat left or right to get on the intercept course.
The only other advice is to drop all four torpeods, but none on the same course. Fire off a spread. The first one should be on that intercept course you ran, and the other three should be at slight angles to that so you get a spread. There is no point in saving the torpedos for a second run. You probably won't live that long.
Hans.