In WWII movies, torpedoes always hit the target then explode. I understand now that torpedoes after WWII go under the ship then explode – is this correct?

Posted 3Sep2017.

Sorta.

This is one of the occasions where I will politely disagree with/clarify some of the previous answers.

First and foremost, I would have to ask which movies you are referring to. Off the top of my head, the ones from the 1940s and 50s – Destination Tokyo, Hellcats of the Navy, and Run Silent, Run Deep were limited in the ability of the special effects artists in accurately replicating the moment of impact of the prop torpedoes. These were movies, after all, and I am almost positive that the operational environment of the time was not swimming-pool clear for hundreds of feet with a wonderfully flat bottom (though Simon Lake’s first designs around a century ago actually equipped submarines with wheels for driving along the seabed… seriously… quit laughing.)

Both Lance and David have good points about the contact fuze; however, the issue of the Mark XIV during the Second World War was not a simple matter. Three problems… well, four contributed to the deactivation of the Mark VI magnetic detonator towards the middle of the war: faulty depth setting mechanisms, premature detonations due to shifts in the magnetic field of the launching submarines, a crummy firing pin design, and the mess that was the Bureau of Ordnance before and during the war. As much as I would like to digress on those points, the “official” stance of folks like Ralph Christie, due to the wonderfully optimistic Fleet Exercises during the interwar period, was to mandate the use of the Mark VI magnetic detonator until overruled by Chester Nimitz in June 1943.

So, the answers given by Lance and David are right in the theory of targeting the more vulnerable part of a ship – the keel – but there was a bit more to the employment of torpedoes in the Second World War. A good topic for a thesis, I found out…