A conventional air-dropped torpedo tended to dive on water entry before returning to its set depth, risking a strike on the harbour bottom. Other navies added temporary fins to reduce that dive. The British arrangement placed fins at one end and a tension cable at the other so the weapon would belly-flop into the water. That shallow entry allowed Swordfish to deliver torpedoes effectively at Taranto, regardless of the aircraft's old-fashioned appearance.
Notable Point · 2:07:25-2:08:56
How Swordfish torpedoes attacked in shallow harbours
Fins and a tension cable made British aerial torpedoes belly-flop into the water for attacks in Taranto's shallow harbour.