Hull cleaning robot

A robot configured to clean a surface of a coating applied to a hull of a vessel whilst travelling over said hull, wherein the coating has a König pendulum hardness of less than 75 counts, the robot comprises a cleaning brush assembly that has a lamellar cleaning brush having a plurality of lamellas 403 extending outwardly from a brush core 404 and having a height, the lamellar cleaning brush arranged to rotate about its axis to apply a cleaning action to the surface when it is in contact with the surface. The robot is configured to apply a degree of compression of the brush on the surface such that the brush is held in a position a distance, towards the surface of the coating, away from an initial position at which the brush is in contact with, but not deformed by, the surface of the coating, wherein said distance is less than 56% of the height of the plurality of lamellas. Other robots are disclosed.