A propulsion system for a marine vessel in a body of water includes an water intake formed in the hull, a impeller disc rotatable about a vertical axis for raising water and increasing the momentum of water in a plenum chamber, and a plurality of control gates located around the periphery of the hull. The impeller disc has a large outer diameter and is formed to enable efficient rotation by an electric motor. One or more of the water intake, the plenum chamber, the impeller disc and the control gates is designed to reduce acoustic noise generated by the marine vessel, direct the acoustic noise to avoid broadband acoustic noise, increase efficiency of the propulsion system and provide additional safety to passengers on the marine vessel and marine life in the body of water.

An underwater propulsion unit including a propeller, a motor, and a housing. The motor is disposed further forward in a propulsion direction than the propeller and drives the propeller into rotation. The housing that accommodates the motor and the propeller includes a first portion and a second portion. In the second portion disposed further rearward in the propulsion direction than the first portion, an introduction inlet and a spout outlet are provided. The introduction inlet introduces water into the housing, and water introduced from the introduction inlet and delivered by the propeller is spouted out of the housing. When viewed in a direction parallel to the propulsion direction, the introduction inlet is disposed further outward than the first portion and introduces water into the housing in a direction parallel to the axis of the propeller.

An underwater propulsion unit including a propeller, a motor, and a housing. The motor is disposed further forward in a propulsion direction than the propeller and drives the propeller into rotation. The housing that accommodates the motor and the propeller includes a first portion and a second portion. In the second portion disposed further rearward in the propulsion direction than the first portion, an introduction inlet and a spout outlet are provided. The introduction inlet (21) introduces water into the housing, and water introduced from the introduction inlet and delivered by the propeller is spouted out of the housing. When viewed in a direction parallel to the propulsion direction, the introduction inlet is disposed further outward than the first portion and introduces water into the housing in a direction parallel to the axis of the propeller.

Described herein are paddlecraft such as kayaks modified to include a motor to assist the paddling action of a user of the paddlecraft. The paddlecraft has a motor driven propeller located in an elongated channel within a paddlecraft base which drives water flow from an inlet side to an outlet side of the motor driven propeller via the elongated channel to drive movement of the paddlecraft. At least one movement sensor may be located on the paddlecraft and motor driven propeller actuation is driven by a user when the at least one movement sensor senses paddling movement by the user. A network comprising multiple paddlecraft and movement sensor communication is also described along with a method of assisting a paddlecraft user to generate motion.

A vessel (2) which floats on water (4) and which generates electricity, which vessel (2) comprises: (i) a hull (6); (ii) at least one water inlet (8) at a front part of the vessel (2); (iii) at least one water outlet (10) at another part of the vessel (2); and (iv) apparatus (12) for generating electricity comprising at least one stator (16) and at least one rotor (18),
and the vessel (2) being such that: (v) water (4) passing from the water inlet (8) to the water outlet (10) causes the rotor to rotate and thereby the apparatus (12) to generate the electricity.