Operability of the Visby class corvette with regards to sea conditions

Abstract

The project Operability of the Visby class corvette with regards to sea conditions is meant to accomplish two main tasks. First it is to investigate what a reasonable limit on ship motions on the Visby class corvettes should be to make sure that the crew remains able to perform their duties and that all systems are working as required. The second task is to investigate the operability at each main mission with regard to these limits, as well as the circumstances of the occasions where the ship fails with any of the criteria. The selected criteria focus on human performance. They include Motion Sickness Incidence (MSI) index to relate motion to cognitive performance in places such as the bridge, and Motion Induced Interruption (MII) index to quantify the effect on the ability to perform manual work. A slamming criterion is also used because of the negative effects on crew health and comfort. Criteria that focus on ship and system performance include roll and pitch limits to ensure the capability to launch missiles and torpedoes, and a submergence criterion for an exhaust pipe opening. Several relevant mission sets are considered, and one scenario of an escorting mission to Gotland is presented in a bit more detail, where the statistical distribution of wave directions for each sea state is taken into account. It is concluded that the operability, depending on mission and season, is around 90 %, higher for some missions, particularly when course deviations are allowed. Most of the criteria are limiting in some situation with none being obviously over represented.