Jim mentioned a “comparing watch”, and shared some images to me. Here is one.
An explanation follows the image.
Prior to LORAN and GPS, navigation at sea depended on precise time for celestial position measurements. The ships
chronometer was the onboard time standard, kept in a gimbal mounted double box on the bridge.
About once a week a Quartermaster would come to radio and obtain a time tick from WWV,
CHU, JGY, or similar source. (Navy Quartermasters were navigators, not supply clerks.). Using the “comparing watch”, he’d compare that with the ships chronometer and record any deviation noted.
Additionally, on a daily basis in late morning he’d use the “comparing watch” to compare
all the other important ships clocks against the chronometer. That daily comparison would be noted in the ships log by the OOD and reported to the Skipper by messenger.
"Good morning sir, officer of the deck sends his respects and wishes to report the approach of the hour 1200. All
daily reports have been submitted, ships chronometers have been wound and compared. All magazine temperatures measured and are normal. Request permission to strike 8 bells on time sir.”
73, de Hans, KØHB
“Just a Boy and his Radio”™
Master Chief Radioman, US Navy (Ret)