[UnderseaLcpl]

If the convoy course change allows you to make a hard turn and get yourself perpendicular to ships that have not yet passed you (assuming they are viable, big, targets) you should attempt to attack them instead. Don't bother calculating anything or inputting info into the tdc. Impact fuses, 2 or 3m.
Set the gyro angle at 0 and fire from as close to perpendicular as possible, leading the target by 1 degree for each knot of speed. (with a fast G7a) For electrics you should multiply your lead with a G7a by about 133%, as electrics are about 33% slower.
The torpedo should strike very close to where the centerline of your periscope was when you fired if you remember to open the tube first.


IMO, taking a hasty shot at the BB with a mag is a potential waste. Especially at 1000m and growing if the angle is extreme. If you're wrong in your calculations you waste torpedoes. Mags can also predetonate. I never use them against targets that are more than 500m away, and I still get a few failures.

You can always end-around and hit the BB later, unless you are being beset by aircraft and/or are late in the war.


Your judgement and the circumstances of your current campaign are the ultimate factors. A little more elaboration would help with suggestions, though.

What kind of torpedoes? What is your course? What is the convoy's course? What is the convoy speed? What kind of U-boat are you in? How many escorts? How are the escorts positioned? What year in the war? Where are you?
The more detail the better.