on board, including divers, diving supervisors and superintendents, dive technicians, life support technicians and supervisors, ROV pilots, ROV superintendents, survey team, clients personnel, etc. For all these personnel to carry out their contracted job with an oil and gas company, a professional crew navigate and operate the vessel according to the contract requirements and instructions of project superintendents. However, ultimate responsibility lies on the master of the vessel for the safety of every person on board. In expanding the utility of the vessel, these vessels provide in addition to the usual domestic facilities. specialised diving mixed gas compressors and reclaim systems, gas storage and blending facilities, and saturation diving accommodation systems where the divers live under compression. These vessels are available to be hired by diving contractors or directly by oil and gas contractors who then will subcontract a specialist service-provider to use the vessel as a platform to carry out their activities. Special features Dynamic positioning Dynamic positioning (DP) is a computer-controlled system to automatically maintain a vessel's position and heading by using its own propellers and thrusters. Position reference sensors, combined with wind sensors, motion sensors and gyrocompasses, provide information to the computer pertaining to the vessel's position and the magnitude and direction of environmental forces affecting its position. Dynamic positioning is a great advantage for saturation diving operations as the risk to the divers and the work area from anchor patterns is reduced, and the vessel can be positioned more quickly. Saturation system The "saturation system", "saturation complex" or "saturation spread" typically comprises a surface complex made up of a living chamber, transfer chamber and submersible decompression chamber, which is commonly referred to in commercial diving and military diving as the diving bell, PTC (personnel transfer capsule) or SDC (submersible decompression chamber). The system can be permanently installed on the ship or can be capable of being moved from one vessel to another by crane. The entire system is managed from a control room ("van"), where depth, chamber atmosphere and other system parameters are monitored and controlled. The diving bell is the elevator or lift that transfers divers from the system to the work site. Typically, it is mated to the system utilizing a removable clamp and is separated from the system tankage bulkhead by a trunking space, a kind of tunnel, through which the divers transfer to and from the bell. At the completion of work