Why not use a semi-automatic torpedo turret if a ship can store shells and has power available?
Short answerEarly torpedoes were large and required manual preparation and firing settings; unlike modern networked weapons, they could not rely on an integrated data link, so rapid automated handling was heavy and slow.
NotesMechanical assistance is possible, but torpedoes are large and require firing settings before launch. Modern systems can pass those settings through a data link, while early weapons needed manual input. That preparation makes a rapid automatic cycle much harder than shell handling. A recalled Soviet rotating-carousel submarine arrangement shows that mechanized handling existed, although moving and preparing the weapons remained difficult.