Composite methodology to prevent ship propeller erosion

The jet flow generated by manoeuvring ships nearby vertical structures is known to erode the seabed sediment but is still difficult to predict the effects of a particular ship operating in a harbour basin. This paper presents a methodology to quantify the scouring action generated by ship's propellers combining field and real data with a manoeuvre numerical simulator testing some of the most commonly used formulas for maximum scouring depth prediction. From the real manoeuvres, analysed through Automatic Identification System (AIS) data, the manoeuvre patterns are identified to be later reproduced at the simulator, thus obtaining the propulsion system behaviour to apply the formulae and to estimate the maximum erosion depth expected in a harbour basin. The obtained results are validated with field data from bathymetries and Acoustic Doppler Velocimeter (ADV). Results show the arrival and departure manoeuvre sections where the vessel is potentially harmful. The different formulae applied yielded results in accordance with the provided bathymetry of the study area in terms of maximum erosion depth. Also, the areas of maximum expected seabed velocity are coincident with the areas where the maximum scour is observed in the bathymetry.