American Counterparts Like the Porpoises the Oberons were far quieter than their American counterparts It s not clear what American counterparts this unreferenced statement would be referring to The Tang or Tench classes They were introduced 10 years before the Oberon boats so it doesn t seem valid to regard them as counterparts If it s referring to the roughly contemporary 1958 vs 1960 Permit class it s basically just saying that diesel electric submarines are quieter than nuclear propelled boats of the same era They re also slower can not stay submerged indefinitely and have shorter unrefueled range That s why they were typically assigned different missions in Navies such as the Royal Navy that operated both types So again they re not really a valid counterpart