I did as was suggested, I came in at angle behind the lead escort (an everts) and got into the convoy, passing just in front of a flower (curiously no arcs represented. (yes I was kinda cheating, I wanted to see if I was getting things right.
To make a long story short, I fired four torpedoes, one salvo at a factory whale ship close by and the other salvo, at another such ship. Then I just dived as deep as I could. On my way down I heard the crumph of the torpedoes going off.
A few minutes later someone dropped some cans, which did very minor damage.
forty five minutes later the whale ship sunk, and the escorts and convoy were far away.
I couldn't persue due to low fuel reserves so I set course for the nearest U-tanker.
Thanks for the hints fellas.
