Surface vessel with motorised mechanical propulsion having a fusiform hull and ballasted keel

A mechanically propelled, wave piercing surface vessel (1) devoid of any sail, mast or rigging for propelling the vessel by wind, comprising:

• a fusiform hull (2) with a waterline;
• and
• a keel (3) in a lower part of the hull,
• the hull (2) being elongated in a longitudinal direction of the vessel, and
• the keel having a lower end, the keel (3) having at the lower end a bulb (6) linked to the hull by a linking part (5) of the keel, the linking part having a maximum width, the bulb having a maximum width, the maximum width of the linking part (5) being smaller than the maximum width of the bulb (6), the linking part having a maximum length, the bulb having a maximum length, the maximum length of the linking part (5) being smaller than the maximum length of the bulb (6), said lengths and widths being considered in the longitudinal direction of the vessel (1) and in a horizontal transverse direction perpendicular to the longitudinal direction, respectively,
• wherein the hull (2) has a total width to total length ratio of less than 0.2, and a maximum length of less than 20 metres, with a ratio of a hull height above the waterline and except possible appendices thereof to a hull height under the waterline lower than 0.8 and higher than 0.1,
• wherein a mechanical propulsion means of the vessel includes at least one electrical motor and/or internal combustion engine that operates one or more propellers or one or more turbines,
• wherein the vessel is configured to sail at speeds corresponding to a Froude number higher than 0.45 without planing,
• wherein the vessel is configured for acoustic measurements and contains acoustic measurement systems including acoustic wave transmission and reception transducers, and
• wherein at least the acoustic wave transmission and reception transducers are arranged inside the bulb (6) of the keel (3).