Distributed sensing of loads acting against the hull of a stationkeeping vessel in ice

This paper introduces the concept of distributed motion sensing for stationkeeping vessels in ice infested waters. During the SKT 2017 project, conducted in February and March 2017 in the Bay of Bothnia, five inertial measurement units were installed on the vessel Magne Viking. Four of the sensor units were installed at different positions inside the hull of the vessel, which enabled the system to locally measure ice-induced vibrations in the hull of the vessel. The fifth sensor unit was installed at a central position of the vessel and served as reference sensor for measuring the acting global load on the vessel. Under stationkeeping the global load measured on the ship should be close to zero, because the environmental load is equal to the force from the stationkeeping system. However the remaining four motion sensor units in the hull also measured locally induced vibrations. The study shows that this sensor configuration allows for the detection of changes in the acting load against the vessel. This is demonstrated with motion data obtained during the stationkeeping trials on the vessel Magne Viking.