Seakeeper predictions for the heave and pitch response to regular head waves have been compared with towing tank results for a number of geometrically similar hullforms of differing length: displacement ratio at three different speeds; Fn = 0.20, 0.53, 0.80. For the hullforms tested (based on the NPL round bilge series, Bailey 1976) Seakeeper was able to adequately predict the heave and pitch response up to a Froude number of 0.53; predictions at higher speeds suffered from poor prediction of the resonant frequency, although the magnitude of the resonant peak was reasonably well calculated.
Catamaran results were obtained from Seakeeper by modelling a single demihull in isolation. Experiments show that the differences between the catamaran and isolated demihull configurations are most pronounced at slow Froude numbers (Fn = 0.20) and for catamarans with closely spaced demihulls and small length: displacement ratios.