T-1's original diesels performed so poorly that they were replaced with MAN engines. Other interwar American submarine programs also adopted German or British machinery, sometimes building foreign designs under license. Those purchases helped overseas manufacturers preserve expertise while the United States struggled with dependable submarine propulsion. A large naval-industrial base could still have narrow technical dependencies.
Notable Point · 25:30-26:56
Foreign engines behind early US submarines
T-1's re-engining shows how the US Navy relied on German MAN and British technology when domestic submarine diesels proved unreliable.