Question about Dud Torpedoes and detonation

[oche]

I've always played my campaigns on 92% realism, the only unrealistic feature i took the liberty of having was using the external camera. I've wasted several campaigns returning to base with no tonnage sunk, and basically most of the torpedoes do not hit the target's hull on angle between 45 and 90 degrees, either that or the torpedoes get trampled on the target's propeller when i attack from behind while chasing target. I don't how far this did this happened in the war, but in comparison to the allied torpedoes, specially the US torpedoes, how was the detonation efficiency of the german torpedoes?

What i have decided to do now is set the dud torpedoes off on the realism setting and turning off the external camera feature, having the realism settings at 96% instead of 92%. It's now my 12th patrol, July 1943, patrol zone is just a few hundred miles of the portuguese coast, been enjoying it so far, but haven't had the chance to fire torpedoes yet. Would it make a difference when attacking with torpedoes now, will it make a difference or will torpedoes fail to explode if it hits a target at a lesser angle of 45%?.