The present invention discloses a method and an apparatus enabling the cleaning of a jack-up vessel, particularly the lower end portion of one of its legs. The method of the present invention discloses cleaning of a jack-up vessel having a hull, a leg that extends through a hull opening surrounded by a railing includes the steps of attaching a support to the railing, the support being selectively attachable to a desire location on the railing. A monitor is mounted upon the support, the monitor having a water blasting nozzle. Water is transmitted under the pressure to the monitor and the leg is water blasted using pressurized fueled that flows through the nozzle and is directed selectively to mudded or dirtied portion of the leg to be cleaned.