In today' U.S. Navy the equivalent would be an ET3, or an Electronics Technician 3rd Class.
Navy Sonarman 3rd Class is an Petty Officer of the E4 pay grade equal to the Army Corporal E4. or E4 specialist
"HM" is the Navy rating for a Hospital Corpsman; the 3 means he/she is a 3rd Class Petty Officer.
Cook petty officer third class
fireman third class (lowest starting rank)
navy rating for radar operator
S-3 stands for seamen third class.
"REO" is the acronym for "Radar Electro/Optical", the radar unit ofmilitary aircraft.
CM3 MECHANIC PETTY OFFICER 3RD CLASS CM3 CONSTRUCTION MECHANIC PETTY OFFICER 3RD CLASS CM3 CARPENTER'S MATE THIRD CLASS
Made from a Composite Material. Strong light and not able to be detected by the radar.
air radar man
A radarman in the US Navy is responsible for operating and maintaining radar equipment used for detecting and tracking ships, aircraft, and other objects. They interpret and analyze radar data to provide situational awareness to the ship or aircraft they are assigned to. They may also be involved in troubleshooting and repairing radar systems.
SR Merchant Navy class was created in 1941.