What is the officer in charge of a ship in the captain's absence called?

In my U.S. Navy experience (submarine force), the in-port officer that was on-duty and in charge of the ship in the CO’s absence was referred to as the Ship’s Duty Officer (SDO).

As previously noted, the SDO was also a qualified Officer of the Deck (OOD), and thus qualified to take the boat to sea.

The term “Command Duty Officer” (CDO) was a more generic term that was generally used only for shore commands. For example, the shore-based submarine squadron I was later assigned to had a daily CDO.

–robby (former qualified submarine OOD/SDO & sub squadron CDO)




What you are looking for has been noted. It’s the Command Duty Officer. Every ship has one and he acts for the Captain when he’s not onbaord.

It should also be noted that the position of SDO/CDO is a watch station, not a billet (i.e. job).

In other words, a duty officer stands the watch for a certain period of time (usually 24 hours), and his/her movement is limited. For example, when I stood watch as SDO on a submarine tied to the pier, I was limited to the pier. If I needed to go anywhere else, I needed to get someone to relieve me. When I stood watch as a squadron CDO, I was limited to the confines of the Navy base. This meant that when I stood watch as SDO, I didn’t go home that night. Instead, I slept on the boat. When I stood watch as CDO, I slept in the CDO bunkroom at squadron HQ.

The position of XO (Executive Officer) mentioned in Post #7 is different. It’s a billet (i.e. job) that an officer is assigned to for a much longer period of time (typically 2-3 years). The XO (and CO, for that matter) can go home at night when the ship is in port.