Sensitivity of Thrust Efficiency Loss in Dynamic Positioning Predictions

Existing strategies and proposed methods for optimal thrust allocation in dynamic positioning systems of floating objects are primarily focused on minimization of power consumption with treating of numerous limitations and conditions that should be satisfied at the same time. On the other hand, one can notice that thruster interaction effects such as axial and transverse current, thruster-hull interaction, thruster-thruster interaction and ventilation are rarely taken into account. These effects, whether they occur separately or in combinations, can cause significant thrust losses, which consequently degrade reliability of dynamic positioning systems, decrease accuracy, increase response time and power/fuel consumption, etc. The main goal of this paper is the quantification of the effects due to different allocation methods on the resulting DP capability predictions of the vessel. Application to an existing offshore vessel has been considered to highlight their sensitivity on the final result in terms of operational rosettes.