Abstract: A wingsail for a powered watercraft comprising a first aerofoil element, a second aerofoil element, and a third aerofoil element, wherein each of the aerofoil elements is rotatable about an axis and has an aerofoil section with a centre of area which is closer to its leading edge than its trailing edge, and the aerofoil elements are movable to a configuration in which flow from the trailing edge of one of the first or third element is directed toward the leading edge of the second element, and flow from the trailing edge of the second element is directed toward the leading edge of the other of the first or third element.

Abstract: A motorised outrigger stabilised watercraft comprising a main hull extending in a fore-aft direction, a single outrigger arranged to stabilise the main hull, extending substantially parallel to the main hull and spaced laterally from the main hull, and at least one hydrofoil located at or proximate the stern of the main hull.

Abstract: A powerboat comprising a hull, a plurality of dynamically adjustable hydrofoils positioned below the waterline towards the rear of the hull, and a control system, wherein the cross sectional area of the hull below the waterline decreases towards the rear of the hull, and the control system is configured to adjust the hydrofoils in operation of the powerboat to control the running trim of the powerboat. The powerboat can operate efficiently at over a wide range of Froude numbers, in particular both low (displacement mode) speeds and high (planing mode) speeds.