Realistic attacks!

[melnibonian]

It depends on the target really. If the merchant is alone one torpedo was usually used to wound it or stop it before it was finished off by gun fire (early in the war). During convoy battles the usual practice was to fire a salvo of two torpedoes per target to ensure a hit and to maximise the chances of a kill. Generally speaking though each Captain had his own style and based on their experience they were taking the choice on how many torpedoes they would use.