A fluid machine includes: a shaft portion; a shroud surrounding the shaft portion and including an inside surface that forms a flow path-forming surface defining a flow path with the shaft portion; a first propeller rotatably provided in the flow path; a second propeller rotatably provided on a downstream side of the first propeller in the flow path; and a motor including a rotor that is fixed to an outer circumferential portion of the second propeller and that is accommodated in the shroud, and a stator that surrounds the rotor via a clearance and that is fixed in the shroud. A portion of the flow path-forming surface on a downstream side of the second propeller decreases in diameter toward the downstream side, and the shroud includes an inlet flow path that is open at a portion between the first propeller and the second propeller of the flow path-forming surface.

A fluid machine includes: a shaft portion; a shroud surrounding the shaft portion and including an inside surface that forms a flow path-forming surface defining a flow path with the shaft portion; a first propeller rotatably provided in the flow path; a second propeller rotatably provided on a downstream side of the first propeller in the flow path; and a motor including a rotor that is fixed to an outer circumferential portion of the second propeller and that is accommodated in the shroud, and a stator that surrounds the rotor via a clearance and that is fixed in the shroud. A portion of the flow path-forming surface on a downstream side of the second propeller decreases in diameter toward the downstream side, and the shroud includes an inlet flow path that is open at a portion between the first propeller and the second propeller of the flow path-forming surface.

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 boat includes a propulsion device that generates, by driving of an engine, a propulsive force to propel a boat body, a trim changer that changes a trim angle of the boat body, a trim actuator that drives the trim changer, and a controller configured or programmed to control operation of the trim actuator based on a value corresponding to a change in a boat speed.

A jet pump assembly includes a marine engine, a jet drive and a shield adapted to be secured to a transom of a watercraft. The shield has arms to which the marine engine is secured and legs to which the jet drive is secured, the arms and legs extending in opposite directions. The shield has a flange adapted to be secured to the transom of the watercraft. The shield covers an opening in the transom through which the jet pump assembly is passed during assembly. A gasket between the shield and transom prevents water from entering the watercraft.

A jet pump assembly includes a marine engine, a jet drive and a shield adapted to be secured to a transom of a watercraft. The shield has arms to which the marine engine is secured and legs to which the jet drive is secured, the arms and legs extending in opposite directions. The shield has a flange adapted to be secured to the transom of the watercraft. The shield covers an opening in the transom through which the jet pump assembly is passed during assembly. A gasket between the shield and transom prevents water from entering the watercraft.

A boat includes a propulsion device that generates, by driving of an engine, a propulsive force to propel a boat body, a trim changer that changes a trim angle of the boat body, a trim actuator that drives the trim changer, and a controller configured or programmed to control operation of the trim actuator based on a value corresponding to a change in a boat speed.

Maintenance personnel need to be safely transferred to offshore structures from marine vessels in varying sea and weather conditions. Disclosed herein is a control system for a marine vessel (100) having a propulsion and steering system (101) and a fender arrangement (102) at the bow of the marine vessel to provide contact between the marine vessel and an external structure (103). The control system comprises force, pressure, torque or strain sensors and a controller. The force, pressure, torque or strain sensors measure force, pressure, torque or strain that are indicative of forces between the fender arrangement (102) and the external structure (103). The controller controls the operation of the propulsion and steering system (101) to substantially obtain or maintain desired forces between the fender arrangement (102) and the external structure (103) based on the force, pressure, torque or strain measurements from the force, pressure, torque or strain sensors.

Disclosed are an improved nozzle for an unmanned underwater vehicle (UUV), and a method for operating the same. The nozzle includes a first rigid member operatively coupled to a UUV steering mechanism. The nozzle also has a second rigid member, coupled to the first rigid member by a flexible bellows according to a configurable operating angle. The nozzle does not extend beyond a bounding surface when stored but does when deployed. Water traversing the first rigid member and contacting the second rigid member produces a reactive force according to the configurable operating angle. Simultaneous and independent control of the volume of fluid traversing several such nozzles in the UUV, and their respective orientations and operating angles, permits automatic station-keeping or navigation according to another guidance objective.

Disclosed are an improved nozzle for an unmanned underwater vehicle (UUV), and a method for operating the same. The nozzle includes a first rigid member operatively coupled to a UUV steering mechanism. The nozzle also has a second rigid member, coupled to the first rigid member by a flexible bellows according to a configurable operating angle. The nozzle does not extend beyond a bounding surface when stored but does when deployed. Water traversing the first rigid member and contacting the second rigid member produces a reactive force according to the configurable operating angle. Simultaneous and independent control of the volume of fluid traversing several such nozzles in the UUV, and their respective orientations and operating angles, permits automatic station-keeping or navigation according to another guidance objective.