Originally Posted by NYGM_Tonnage_War_Manual 2.2a

The abstract changes are the permanent use of the magnetic pistol and a minimum depth restriction on the torpedoes. The real world result that we desire is to replicate through these are the early war high fail rate on the torpedoes as well as a more realistic use of the torpedo in heavy seas.

So why do it? Because the player knows that by disabling the magnetic pistol and setting the torpedo to a 1metre depth that they will not incur a realistic torpedo failure due to a premature detonation caused the torpedo slamming into the waves or a torpedo veering off course and/or heading towards the sea bed nor will the AI see a electric torpedo.