A ride control system for active damping of heave and pitch accelerati
ons of surface effect ships (SES) is presented. It is demonstrated tha
t distributed effects that are a result of spatially varying pressure
in the air cushion result in significant vertical vibrations in low an
d moderate sea states. In order to achieve high quality human comfort
and crew workability it is necessary to damp these vibrations using a
control system which accounts for distributed effects owing to spatial
pressure variations in the air cushion. To develop such a ride contro
l system a mathematical model describing the motion of the craft in th
e vertical plane is derived. This mathematical model accounts for acce
lerations induced by both the dynamic uniform and the spatially varyin
g air cushion pressure. Sensor and actuator placement is discussed, an
d the stability of the control system is analysed using the theory of
passivity. The performance of the ride control system is shown by powe
r spectra of the vertical accelerations and the pressure variations ob
tained from full-scale experiments with a 35 m SES.