Senior officer is the second-highest rank a player can have in a crew. Senior officers have all the abilities of fleet officers. They can also assign rank (up to fleet officer) without requiring the captain to approve in autocratic crews, and vote on issues in oligarchic crews. Unlike lower ranking members of the crew, senior officers and the captain can expel or demote anyone of lower rank (a senior officer must first demote the pirate to be expelled). On doubloon oceans a player can not use the abilities of the rank unless they have purchased the appropriate badge (Senior Officer or above). On subscription oceans, a player can not use the abilities of the rank unless their subscription is active.
Depending on a crew's booty shares, senior officers may receive a different share than those of other ranks during booty division.
The requirements for promotion to senior officer differ with each crew. The rank is generally given after a long period of officership, during which they show considerable loyalty to the crew, recruit several new players to the crew, and show good leadership qualities.
Senior officers are recognized as leaders of their crew, often acting as interim captain when the captain is away. They are often considered the first mates of a crew.
The rank of senior officer was introduced with Beta release 2003-08-19.