Why American awareness of British liquid loading lagged

Why did the United States Navy take so long to recognize British use of liquid-loaded torpedo protection?

The principle was visible but not being actively sought, so American adoption began before the full extent of British practice finally registered around 1943.

The Americans were not initially looking for the practice, even though its physical principle was straightforward. Water spreads impact force, just as a high-speed flat impact on water can be more damaging than its softness suggests. American designers began using related ideas before and during the war, but did not appreciate the full scale of British practice until roughly 1943. The delay is striking because British and American yards and naval constructors maintained extensive professional contact.