The present invention relates to a motorization
system for a
watercraft with electric assistance intended to carry a user on water, the invention being used in particular in the field of surfboards, paddleboards or windsurfing boards, as well as in the field of kayaks or canoes. The motorization
system is adapted to be connected to a source of
electric energy and comprises, on the one hand, a watertight
enclosure (1) intended to be integrated in or on the
hull of a
watercraft, in which a rotor (2) and a
stator (3, 7) are arranged, and, on the other hand, a shaft (4) connected at a first end to the rotor (2) and projecting in a watertight manner outside the
enclosure (1) by a second end opposite the first end. At its second end, the shaft (4) can be connected to a propulsion means of the
watercraft, such as a
propeller, and when the
system is supplied with
electric energy, the rotor (2) rotates and drives the shaft (4) with this rotation. The system also comprises cooling means (5), which itself comprises at least one first elongated
assembly (5) at least partially made of
metal, a first end of which is arranged inside the
enclosure (1) and which protrudes in a watertight manner outside the enclosure (1) at a second end opposite the first end, allowing the conduction of heat from the inside to the outside of the enclosure (1) along the first elongated
assembly (5).