There are two distinct variants of bottom doors; single and double. Both are of hinged, closed box-type construction, complete with necessary lifting eyes. They are selected according to vessel configuration, discharge speed required and size of hopper. The bottom doors are operated by rods actuated by
hydraulic cylinders, generally mounted above the hopper. The cylinders can also be placed in the hopper or in void spaces. The design of the doors is such that surface smoothness ensures fast discharge and, if repairs are needed, they are relatively easy to remove from the ship.

 

Pre-dumping doors and self-suction channel doors can also be installed in the hopper bottom.