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 arbitrarily set the DP vessel heading.
Setting the correct yaw angle brings advantages to the vessel such as reducing the fuel consumption and minimizing the DP system output. However, it is not trivial to calculate the optimum heading, due to uncertainties at wave and current estimation. Moreover, these factors are not constant along time, and to keep the optimum position, the system must adapt with the changes.
A method to update the heading Set-Point based on the theory of Zero Power Control was developed, which has advantages over other weathervane control methods, such as an effective control of all horizontal movements and the possibility to control any reference-point, not only points located the vessel bow.
A fully non-linear dynamic simulator was then used to carry out a complete analysis of the controller.