DP in ice
Dynamic Positioning (DP) is designed to keep a vessel in place by using the ship’s own propellers, rudders and thrusters. A control system does this automatically several times a second, calculating the forces required to compensate for the surroundings and adjusting the vessel back to the desired position. DP in ice adds another layer of complexity, i.e., the existence of sea ice. Ice drift direction varies constantly and ice load varies significantly in both magnitudes and directions. SAMS is very good at calculating ice actions exerted on various structures in different ice conditions. To bring in the possibility of DP in ice simulations, SAMS implements a model that predicts the propeller-flow velocities, calculates the hydrodynamic forces on the ice and integrates the equation of motion of the ice cover, which is represented by an ensemble of rigid bodies that may interact with each other.
A simplified DP in ice simulation can be found below. In this simplified demonstration, a ‘manually controlled DP’ is simulated. However, SAMS can easily be linked up to your preferred control system to allocate needed thrusters in various ice conditions.