Experimental study on hydrodynamic performance of SWATH vessels in calm water and in head waves

•Four SWATH hull forms have been tested in calm water and in regular waves.•Dynamic instability peculiar for SWATH at higher relative speed is investigated.•Active stabilisation was developed and fitted to SWATH #5 and tested in calm water, regular and irregular waves.•Active stabilization made possible to reach higher speed and very low vertical motions.•Comparison of different hull forms assures significant database for small craft SWATH design and research.