[Gustav Schiebert]

The only real skill the commander bought during the attack was translating what was seen in a 2-3 sec glance of the periscope into an attack plan. It meant identifying target direction and speed, partly through AOB calculators and the like but more often than not though gut feeling.

The skilled commanders were the ones who manoeuvred their boats into position well; since most shots were taken at under 1,500m there was no 'marksmanship' to speak of. I suspect as computer game players with free torpedoes and save games we are more prepared to take longer shots, and have an unrealistic appreciation of how close real commanders got.

If you want a full-realism experience then I recommend the OLC Gold mod. It accurately reflects the role of other crewmen in doing the work for you, so that your job is just to assess the firing data (and plug it into the computer, as you have no-one to do that for you). Other players might be able to recommend more challenging and less realistic ways of doing the calculations yourself.