Coho

Chinook II reused the hull from Chinook, but made significant upgrades to the hydrodynamics to increase efficiency. The kort nozzle from Chinook was eliminated, as it found that the increase in propeller efficiency gained by the nozzle was negated by the amount of drag that the nozzle created. The control surfaces were also redesigned to implement tubercles on their leading edges in order to decrease flow separation over the control surface. Chinook II also featured automatic depth control, with the submarine's depth being controlled electronically via a linear actuator that controlled the pitch of the dive planes according to a pressure sensor.

​The UVSRC attended the 15th International Submarine Races (ISR 15) at the Carderock Naval Warfare Center in Washington D.C. in 2019, with Chinook II. Chinook II took the prize for Most Reliable Submarine. Even though there were some technical difficulties such as a crash causing the main dome to shatter and broken props, Chinook II placed 5th overall. Additionally the electrical system, four-part hull design and tubercles were acknowledged with the Best Use of Technology award.