Existing comment:
Before 1943, the sonar school taught only how to operate and maintain the equipment. No one knew enough about sound in the ocean to teach how to best use the sonar gear in combat.
The maximum effort and greatest contributions of both NRSL and UCDWR between 1941 and 1943 were in research. The physics of sound in the sea was not well understood. Sound propagation can be greatly affected by currents, marine organisms, water temperature, salinity, depth, and the structure of the ocean bottom. The San Diego Laboratory carried out studies and experiments on sound propagation, sound scattering, total strengths, and ambient noise. A brand-new science, entirely related to oceanography, had to be invented on a "crash basis."
This effort led to knowledge that the sonar schools and the Fleet used to teach personnel how to operate sonar to detect and attack submarines. This knowledge was also used to teach US submariners how to evade enemy sonar. Information was also acquired for harbor defense, and an extensive series of charts of the Pacific was prepared by Laboratory oceanographers.
The broad knowledge in such new categories then allowed development of equipment in 1944 to 1945 that enabled the Fleet to achieve important victories at sea.
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