HMS Clyde

In the second half of June 1940, Lt.Cdr. DC Ingram, in the Clyde, see Miscellaneous Classes) brought his boat in through heavy seas to fire at a vessel which he could hardly see through the murk of rough and overcast weather.

He obtained a hit on the battle-cruiser Gneisenau as she was steaming south at high speed down the coast of Norway. It was a brilliant attack, made in conditions which would have daunted all but the most determined, and the Gneisenau was out of action as a result for several weeks.

The Clyde herself had a narrow escape. Because of the rough weather, she had been trimmed eight tons heavy to prevent her breaking surface during the attack. As soon as she fired she went deep and her heavy trim took her to 250 feet in her first dive. It was not the depth charges that worried her captain, but the great pressure of water at that depth, for the Clyde's stern was 50 feet lower than the bow and that class of submarine had a flattened section aft to give her increased speed on the surface. As it was, a four-inch steel pillar, supporting this section, was already bending under the pressure before the Clyde could be brought up to a safe depth.

from "H.M. Submarines" by Lt. Cdr. P.K. Kemp RN, 1952