[Spraug]

Very nicely explained by all the guys, I cannot contribute anything except a warning/addendum on Sniper's post: careful with 90° approaches in the first half of the war. The detonators didn't like it and often produced duds. An approach like 60° will give you a better chance of explosion, but then you can't do a Dick O'Kane attack (see videos and explanations elsewhere), which is (one of) the best way(s) to attack multiple targets in a convoy.

Good hunting!

(Cool, didn't know about the "=", I really need to read the manual).