A suspension system for a water craft, the water craft including a chassis which is at least partially suspended above or relative to at least a first hull and a second hull. The suspension system includes a first hull locating arrangement for at least partially constraining the first hull in a lateral, a yaw, a roll and a longitudinal direction relative to the chassis, the first hull locating arrangement comprising a first, a second, a third and a fourth link arranged to directly or indirectly connect between the hull and the chassis. The first, second and third links each extend in at least a lateral direction relative to the chassis and contribute to a lateral constraint on the first hull relative to the chassis. The second link is longitudinally spaced from the first link relative to the chassis to contribute to a hull yaw constraint on the first hull relative to the chassis. The third link is vertically spaced from the first and/or second link to contribute to a hull roll constraint on the first hull relative to the chassis. The fourth link extends in at least a longitudinal direction relative to the chassis to at least contribute to a longitudinal constraint on the first hull relative to the chassis and may be adjustable in length to vary the lateral spacing between the first and second hulls and thereby vary the overall width of the vessel.