A braking system for waterborne propeller driven vessel which, upon activating a brake pedal or similar actuation device causes the vessel to almost immediately stop its forward movement. The system initiates a burst of highly amplified horsepower and torque, created by a controlled pulse of electrical power released from a bank of fully charged ultracapacitors. This pulse of electrical power is sent directly to AC induction-driven motors, causing oversized propellers to immediately rotate astern, thereby generating a reverse thrust in opposition to the vessel's forward movement sufficient to stop the vessel. The horsepower and torque produced by the braking system and operation of the present invention will also cause the oversize propellers to transmit this tremendous power into the water, without cavitation, to assist in stopping vessel movement.

A water drone capable of navigating on the surface, or below the surface, of a body of water. In some embodiments such a vehicle is light-weight, electric-powered, and propeller-driven, and may be operated by remote control from the shore and guided with simple autopilot commands. The vehicle may have two actuators at the rear of the vehicle, each including a motor and a propeller, and each capable of producing forward or reverse thrust. The vehicle may be capable of travelling horizontally through the surf zone and diving vertically through the water column to the seafloor. The vehicle may monitor its own location and depth and may measure environmental conditions such as water temperature; such measurements may be communicated back to the operator using a telemetry system.

Disclosed is a method of decreasing pressure fluctuation induced on a surface of a hull due to propeller cavitation by adjusting a relative rotation angle of propellers of a twin-propeller ship.

Disclosed is a method of decreasing pressure fluctuation induced on a surface of a hull due to propeller cavitation by adjusting a relative rotation angle of propellers of a twin-propeller ship.

Disclosed is a method of decreasing pressure fluctuation induced on a surface of a hull due to propeller cavitation by using real-time vibration information and adjusting rotation angles of two propellers of a twin-propeller ship.

Disclosed is a method of decreasing pressure fluctuation induced on a surface of a hull due to propeller cavitation by using real-time vibration information and adjusting rotation angles of two propellers of a twin-propeller ship.

A vessel including a hull, an upper deck, an accommodation structure extending above the upper deck, a propulsion system powered by ammonia as a fuel, and a tank for storing ammonia for supplying the propulsion system, wherein the tank is located aft of the accommodation structure.

A marine propeller combination for a marine propulsion unit includes a first propeller and a second propeller arranged to rotate simultaneously in opposite directions about a common rotational axis. The marine propeller combination is configured such that the first and second propellers are angularly positioned such that during one revolution one of the blades of the first propeller is aligned with a drive leg of the marine propulsion unit when a blade gap of the second propeller is aligned with the drive leg, or one of the blades of the first propeller is aligned with the drive leg when one of the blades of the second propeller is aligned with the drive leg. The disclosure further relates to a marine vessel and to a method of operating a marine propeller combination.

Disclosed is a method for determining an effect of varying a propulsor characteristic on vessel propulsor performance, the method comprising: obtaining information indicative of a performance property of a first propulsor of a vessel based on operation of the first propulsor for a first time period with a first variation of the propulsor characteristic; obtaining information indicative of the performance property of a second propulsor of the vessel based on operation of the second propulsor, simultaneous with the first propulsor, for the first time period with a second variation of the propulsor characteristic, wherein the second variation is different from the first variation; and determining a difference between the performance property of the first propulsor and the performance property of the second propulsor. Apparatus for determining an effect of varying a propulsor characteristic, and non-transitory computer-readable storage media, are also disclosed.

Disclosed is a method for determining an effect of varying a propulsor characteristic on vessel propulsor performance, the method comprising: obtaining information indicative of a performance property of a first propulsor of a vessel based on operation of the first propulsor for a first time period with a first variation of the propulsor characteristic; obtaining information indicative of the performance property of a second propulsor of the vessel based on operation of the second propulsor, simultaneous with the first propulsor, for the first time period with a second variation of the propulsor characteristic, wherein the second variation is different from the first variation; and determining a difference between the performance property of the first propulsor and the performance property of the second propulsor. Apparatus for determining an effect of varying a propulsor characteristic, and non-transitory computer-readable storage media, are also disclosed.