Vessels and floating structures are subject to wave induced motions affecting and often even preventing their operation. A system to predict short periods of quiescent vessel motions a few minutes in advance could reduce the costly ‘Waiting on Weather’. The Joint Industry Project ‘On board Wave and Motion Estimator (OWME)’ developed a system capable of predicting the vessel motions on board in real time up to two minutes in advance. It measures remote wave profiles by means of nautical radar, uses linear wave theory to propagate the waves in time and space and estimates the ship response to the predicted wave field. This paper describes the concept and shows results of a first field trial aboard an offshore support vessel in mild sea conditions.
The Offshore industry employs many vessels and floating structures which are subject to wave induced motions. Several offshore operations such as the float over installation of a platform topside, connect operations for LNG-offloading or the landing of a helicopter only need a short period of quiescent vessel motions to be conducted safely. These kind of operations would benefit from a deterministic real time prediction of such quiescent periods. The Joint Industry Project ‘On board Wave and Motion Estimator (OWME)’ aimed to develop, demonstrate and validate a system capable of predicting the vessel motions on board in real time. The system is designed to predict the vessel motions at zero forward speed in mild to moderate sea states. Regardless of the actual design, a real time motion prediction system has to solve three principle tasks:
The actual directional sea state and weather conditions have to be obtained.
The sea state at the vessels location has to be predicted for the time horizon of the motion prediction.
