It was known that the Soviet Navy had acquired the German Type XXI U-boat and other advanced submarines, and was expected to rapidly put derivatives of them into production.

It was hoped that this would allow them to be cheaply mass-produced in the large numbers it was thought would be needed to combat the growing Soviet Type XXI-derived submarine fleet.

The primary innovation created by Kayo was a low-frequency passive bow sonar system, the BQR-4, which was originally to be wrapped around the submarine's conning tower.

Testing on Grampus showed that self-noise would greatly reduce detection range, and the sonar was relocated to the bow.

[4] The advent of nuclear power, with USS Nautilus (SSN-571) entering service in 1955 and the Soviet Navy responding with the first November-class submarine only three years later, created a revolution in ASW.

In 1958, Bonita was used as a nuclear weapons testing target at Eniwetok in the South Pacific, part of Operation Hardtack I.