Gun armament alone was unlikely to sink a destroyer or large merchant ship, so the Schnellboot needed torpedoes as its decisive weapon. Carrying four torpedoes also meant carrying two launchers, two reloads, and equipment capable of moving those heavy weapons. On a fast 100-ton craft, that burden competed directly with protection and other fittings. British boats that did not need torpedoes could devote that weight to other equipment. The Schnellboot combined formidable striking power with little room for armour, giving British countermeasures a vulnerability to exploit.
Notable Point · 27:36-29:08
Torpedoes impose a trade-off on E-boats
An E-boat needed torpedoes to threaten destroyers and large merchant ships, but tubes, reloads, and handling gear consumed weight that could not become protection.