Thanks a bunch, your answers clarify things.
By the way, do you know how large is the angle that the torpedo can turn when launched? Is it something like 45 degrees?
I thought it's handy that a torpedo can turn a bit, for example when attacking a convoy and you want to destroy multiple targets. In that case wouldn't it be very slow to start turning your whole u-boat towards the next target and shooting and again towards the next target and shooting... well I don't know yet how to deal with convoys. But in that case it could be handy and fast to 'point and shoot'.
But yeah when hunting a single ship it is arguably the best solution to shoot a 'direct' torpedo (gyroangle 000).