A General Approach for DP Weathervane Control: Experimental Results

Abstract

With oil exploration occurring at increasing distances from the shore, the use of DP vessels becomes economically attractive for oil transfer and transportation. This operation has some peculiarities, such as the possibility to change the DP vessel heading in order to reduce DP thrust utilization. However, calculation of the optimum heading is not simple, due to uncertainties at wave and current estimation. Moreover, these factors are not constant along time, and the system must adapt with the changes to keep the optimum position.This paper presents and test a new method to define the heading set-point based on the theory of Zero Power Control. This method has important advantages over traditional weathervane control method, such as an effective control of all horizontal movements and the possibility to define any reference-point, not only points located at the vessel bow.