Torpedoes detonate at closer ranges

[irish1958]

Originally Posted by Reece

These are the standard type with pistol detonators, I do have dud torpedoes but this is like 100% of the time, using manual TDC.
Is there a setting? don't think I've noticed a timer setting, if there is it's always been default, this might be the answer, the only thing I've ever adjusted is the speed, distance and angle.

Yesterday, I had three torpedoes hit and bounce off at 450 meters on manual TDC settings. Settings were "fast" and "magnetic." The forth torpedo was set to go off 1.5 meters under the boat, and passed under without exploding.
How do the torpedoes arm? Is it time or distance?