1. Francesco MAURO, University of Rijeka, University of Rijeka, Faculty of Engineering, Vukovarska 58, 51000 Rijeka, Croatia, franzmauro@gmail.com, +39 3287593321, the corresponding author.

2. Radoslav NABERGOJ, University of Trieste, Faculty of Engineering, Via Valerio 10, 34127 Trieste, Italy, nabergoj@univ.trieste.it, +39 040 676 3406


Abstract
To predict the capability of dynamic positioning systems on floating objects, the existing procedures and strategies are primarily focused on the power consumption minimisation, treating of numerous limitations and conditions that should be satisfied at the same time. On the other hand, when the extreme limits of the system must be predicted other factors are of primary importance istead of minimal power consumption. Thruster interaction effect such as axial and transverse flow acting on the propeller disc, thruster-hull interaction, thruster-thruster interaction and ventilation are relevant and are raraly taken into account. These effects, whether they occur separately or in combinations, can cause significant thrust losses, which can consequently degrade reliability of dynamic positioning systems.Different allocation strategies were studied to take the above mentioned effects into account.A smart thrust allocation strategy has been developed to maximise the DP capability of vessels during operations in heavy weather conditions.    The main goal of this paper is the quantification of the effects due to interaction effect on the resulting DP capability predictions of the vessel. Application to an existing offshore vessel has been considered to highlight different allocation strategies on the final result in terms of operational rosettes.

Keywords - dynamic positioning systems, thruster interaction, optimal thrust allocation