A configuration, not a universal specification
Somerville’s account records the first force’s torpedoes set to run at 30 feet and fitted with Duplex pistols. In the second strike, it records contact pistols and a 22-foot setting. Here, “pistol” means the weapon’s firing mechanism. B04
Those numbers describe the reported settings. They are not measurements of every torpedo’s actual underwater path, nor do they identify the precise torpedo mark by themselves.
A change prompted by experience
The report links the second configuration to failures in the earlier attack. It also records new instructions to contact Sheffield first. Weapon reliability and target identification were separate problems that both demanded attention. B04
Somerville records eleven torpedoes dropped at Sheffield. Two were seen to explode on entering the water and three on crossing the cruiser’s wake. These five observed premature explosions explain the urgency of changing the firing mechanism; they do not establish the behaviour of every torpedo carried by the force, or a universal failure rate for the weapon. B04
A Japanese example at Midway
Hiryū’s second-counterattack table names the Type 91 modification 3 aerial torpedo. It records nine weapons expended by a formation of ten attack aircraft, noting that the aircraft from Akagi did not release its torpedo. Here the document establishes a particular weapon modification and a release count. It does not give the weapon’s full performance envelope or prove nine hits. M41
The British and Japanese records answer different questions. Somerville describes changes in configuration between attempts; the Japanese table identifies a modification and expenditure. Neither is a technical manual from which every release limit or warhead characteristic can be reconstructed.
From release to damage
A torpedo had to enter the water, run towards the target and function on arrival. A premature explosion, a miss and a failed detonation are different failures. The British report’s observed explosions during the Sheffield attack should not be converted into a general failure rate for every torpedo of an assumed mark. B04
Comparing three experiences
The British example shows a change in firing mechanism between attacks on the same day. The American Mark 13 profile examines problems with water entry and running. The Japanese Type 91 profile connects a dated expenditure record to the exact modification described in a later technical investigation.
These are different kinds of evidence. A specification, a test result and a battle observation should not be placed side by side as though each measured the same thing. Individual loads, precise British weapon marks and complete malfunction counts remain subjects for further checking.
Read the Swordfish profile or return to the carrier attacks.