I know you want to know more about what Garry told us about ships.
Garry wrote me another message.
The attached picture is of the Kootenay’s wheelhouse (post war Kootenay)
At the top of the picture you will see two voice pipes. One goes to the bridge, one goes to the flag deck.
This was for voice comms as well between bridge / flag deck and wheelhouse (as well as all other departments).
I’m not sure what was used most often as I saw both being used for comms.
Because the steamers has two shafts, which could operate independently, there were two telegraphs for the Ahead, Astern indication and two for the revolutions.
The reason for this is you could have the command, half ahead starboard and half astern port (or visa versa) … used for manoeuvring the ship off the jetty, and various other reasons I’m sure.
In order for this to happen quickly, you had a helmsman and the wheel and one guy at each set of repeaters.