Effects of the Environmental Disturbances to the Ship’s Propulsion Dynamics

Propulsion of the majority of modern merchant ships (e.g. containerships, VLCCs and others) utilises the marine diesel engine as propeller mover. Typical marine propulsion plants include a single, long-stroke, slow-speed, turbocharged, two-stroke diesel engine directly coupled to the fixed-pitch propeller. Slow-speed diesel engines are usually built with a smaller number of cylinders and, consequently, a smaller number of moving parts, increasing thus the reliability of the ship's propulsion system. Safely sailing is crucially dependent of the propulsion system which is exposed to hard environmental conditions like sea waves, wind, sea currents, etc. so it’ s very important to investigate their effects on ship’ s propulsion system. In the paper, some investigation results of the environmental disturbances impact to the propulsion system dynamics during open sea sailing have been presented. The simulation was done using Full mission Engine Room Simulator with 2-stroke marine diesel engine of type MAN B&W 5L90MC on the VLCC ship. Analysis has been done simulating different sea wave conditions induced by wind and through observing relevant propulsion engine parameters and control system reaction to external disturbances.