Numerical and experimental analysis of a typical DP shuttle tanker operating in Brazilian waters

Brazilian academic and offshore industry communities are developing numerical and experimental tools for the analysis of Dynamic Positioned (DP) vessels. One of the main reasons is the construction of several DP shuttle tankers (DP-ST) for operating in Campos Basin and in the new oilfields of Santos Basin. The DP-ST specifications include the limiting environmental condition and heading angle in which the DP system must be able to keep position. Proper numerical and experimental verification must be performed in order to assure that the vessel will satisfy the specifications. In the present paper, the complete dynamic and DP-holding analysis of a ST is detailed. Initially, experimental model-scale tests were carried out, considering the limiting environmental conditions. A dynamic-simulation tool was then used, and extensive comparisons between numerical and experimental results were done. Good agreement between them was verified for several cases. Some simplifications of the numerical model related to thrusters’ behavior may explain the differences between simulation and experiments for same extreme cases, when saturation of several thrusts are verified. A critical analysis of the validity of simulation tools for DP analysis is done.