The US Navy's primary way of sending messages was via HF broadcasts from shore stations to ships  - the Fleet (FOX) Broadcast.

They ran experiments in late 1945 about converting from CW (Morse Code) to radioteletype.

I didn't realize that around-the-world echo was such an issue - I have heard "long-path" echoes sometimes but not often. Despite the "not-great" results from this experiment, they eventually addressed the issues and converted over to RTTY on HF (and then UHF Satellite).