Controlling the Roll Responses of PCTC's

Abstract: Modern Panamax Pure Car and Truck Carriers (PCTC) have become more vulnerable to critical roll responses as built in margins have been traded against increased transport efficiency. The research presented in this licentiate thesis aims at enhancing the predictability and control of these critical roll responses. The thesis presents the development of a new method for assessing the roll damping, which is a crucial parameter for predicting roll motions. The method involves a unique set up of full scale in-service trials and is straightforward, cost efficient and shows a good potential. The thesis also includes a demonstration of a new application for rudder control to be used for mitigation of parametric roll. This is performed by simulating real incidents that have occurred with PCTC’s in service. Simulations with rudder roll control show promising results and reveal that the approach could be very efficient for mitigation of parametric roll. Last but not least an approach for monitoring of roll induced stresses, so-called racking stresses in PCTC’s, is presented. The approach involves measurement of the ship motions and scaling of pre-calculated structural responses from global finite element analysis. Based on full scale motion and stress measurements from a PCTC in-service the approach is evaluated and demonstrated to be an efficient alternative to conventional methods.