BTW, in the early days of the Mk1 Nimrod one of the most guarded secrets was it could prosecute a target but could not kill it.
The Mk30 torpedo was quiet and had a good endurance by even a submerged conventional could out run it. The Mk44 was faster but could still be evaded by a fast nuke but no sweat, even if it got a hit it wouldn't go bang. They didn't fix the fuzes until after the Mk46 came along. From 1980 it was a different game.
What was important was that it was thought it was deadly.