A device for moving a watercraft comprises: —at least one propulsion chamber having a first inlet section for a liquid, referred to as the upstream edge, and a second outlet section for the liquid, referred to as the downstream edge; at least one flexible membrane housed in the chamber; and at least one actuator configured to produce thrust from the watercraft through undulation of the membrane between the upstream edge and the downstream edge.

A device, which is autonomous or which can be associated with another structure, for propulsion in a liquid environment, is described. The device has a bladder body made of a soft material, developing along and around a central longitudinal axis, defining an internal chamber between a dorsal wall and a ventral wall; in the bladder body, an inlet opening and an outlet opening of a liquid in and out of the chamber, arranged at a longitudinal end of the body; and drive means for driving a contraction of the bladder, arranged on the dorsal wall and having a mechanical connection with the ventral to cyclically attract the ventral wall to the dorsal wall, thereby causing a pulsed ejection of a propeller jet from the chamber through the outlet opening.

A device, which is autonomous or which can be associated with another structure, for propulsion in a liquid environment, is described. The device has a bladder body made of a soft material, developing along and around a central longitudinal axis, defining an internal chamber between a dorsal wall and a ventral wall; in the bladder body, an inlet opening and an outlet opening of a liquid in and out of the chamber, arranged at a longitudinal end of the body; and drive means for driving a contraction of the bladder, arranged on the dorsal wall and having a mechanical connection with the ventral to cyclically attract the ventral wall to the dorsal wall, thereby causing a pulsed ejection of a propeller jet from the chamber through the outlet opening.

A watercraft having a body with an opening for a user, a seat, at least one drive mechanism placed at least partially within the opening; an intake configured to allow a flow of water from a body of water surrounding the watercraft; a pump configured receive the flow of water and accelerate the flow of water, and a user controlled discharge configured to receive the flow of accelerated water from the pump and discharge the accelerated water to the water surrounding the watercraft such that the watercraft moves in a direction chosen by the user.

A watercraft having a body with an opening for a user, a seat, at least one drive mechanism placed at least partially within the opening; an intake configured to allow a flow of water from a body of water surrounding the watercraft; a pump configured receive the flow of water and accelerate the flow of water, and a user controlled discharge configured to receive the flow of accelerated water from the pump and discharge the accelerated water to the water surrounding the watercraft such that the watercraft moves in a direction chosen by the user.

A marine thruster includes a cylinder with a front opening and a rear opening; radial baffles positioned within an interior of the cylinder to separate the interior into equally divided water chambers; pistons positioned within a corresponding one of the equally divided water chambers; and an inner-ring rotary valve engaged with the cylinder to allow for side intake of water and the separation of each of the equally divided water chambers into a dry section and a wet section by pistons; the pistons engage with a power source, the power source providing axial reciprocating motion; and the pistons push water through the equally divided water chambers.

A marine thruster includes a cylinder with a front opening and a rear opening; radial baffles positioned within an interior of the cylinder to separate the interior into equally divided water chambers; pistons positioned within a corresponding one of the equally divided water chambers; and an inner-ring rotary valve engaged with the cylinder to allow for side intake of water and the separation of each of the equally divided water chambers into a dry section and a wet section by pistons; the pistons engage with a power source, the power source providing axial reciprocating motion; and the pistons push water through the equally divided water chambers.

A marine thruster includes a cylinder with a front opening and a rear opening; radial baffles positioned within an interior of the cylinder to separate the interior into equally divided water chambers; pistons positioned within a corresponding one of the equally divided water chambers; and an inner-ring rotary valve engaged with the cylinder to allow for side intake of water and the separation of each of the equally divided water chambers into a dry section and a wet section by pistons; the pistons engage with a power source, the power source providing axial reciprocating motion; and the pistons push water through the equally divided water chambers.

A Side-Intake piston water jet propulsor for marine vehicles employs a concept of Side-Intake of water and generates thrust through piston's reciprocating motion in cylinder. The concept of Side-Intake makes intake openings on the side and near the discharging end of the cylinder wall to achieve that the piston separates the cylinder into a dry and a wet compartment during its movement. The dry compartment is kept at atmospheric or ambient pressure. As a result, the piston confronts air or ambient pressure instead of water during its recovering stroke for water intake. From hydrodynamics point of view, this characteristic of piston's recovering stroke through air achieves the same function as an oarsman recovering his oar through air. However, said propulsor achieves that under water or a vessel's water line.

A Side-Intake piston water jet propulsor for marine vehicles employs a concept of Side-Intake of water and generates thrust through piston's reciprocating motion in cylinder. The concept of Side-Intake makes intake openings on the side and near the discharging end of the cylinder wall to achieve that the piston separates the cylinder into a dry and a wet compartment during its movement. The dry compartment is kept at atmospheric or ambient pressure. As a result, the piston confronts air or ambient pressure instead of water during its recovering stroke for water intake. From hydrodynamics point of view, this characteristic of piston's recovering stroke through air achieves the same function as an oarsman recovering his oar through air. However, said propulsor achieves that under water or a vessel's water line.