Disclosed are a method and a virtual sensor system for determining the speed through water of a marine vessel. The method includes obtaining propeller revolutions per minute and at least one of torque at propeller, propulsion power, thrust and engine fuel flow, obtaining speed over ground or logged data from one or more speed through water logs of the vessel and using the obtained data and hydrodynamic modelling to determine the speed through water of the vessel.

Disclosed are a method and a virtual sensor system for determining the speed through water of a marine vessel. The method includes obtaining propeller revolutions per minute and at least one of torque at propeller, propulsion power, thrust and engine fuel flow, obtaining speed over ground or logged data from one or more speed through water logs of the vessel and using the obtained data and hydrodynamic modelling to determine the speed through water of the vessel.

This disclosure relates to a system for reducing cavitation at a surface that moves relatively with respect to a first fluid. The system comprises a degasser configured to at least partially degas a second fluid. The system also comprises a reservoir in communication with the degasser and configured to house the at least partially degassed second fluid, the reservoir having an outlet that is arranged for directing the second fluid towards the surface. The system is configured such that the directing of the at least partially degassed second fluid towards the surface forms a boundary layer at the surface. The boundary layer is adapted to at least partially increase the negative pressure required to initiate cavitation at the surface so as to reduce the occurrence of cavitation during such relative movement.

This disclosure relates to a system for reducing cavitation at a surface that moves relatively with respect to a first fluid. The system comprises a degasser configured to at least partially degas a second fluid. The system also comprises a reservoir in communication with the degasser and configured to house the at least partially degassed second fluid, the reservoir having an outlet that is arranged for directing the second fluid towards the surface. The system is configured such that the directing of the at least partially degassed second fluid towards the surface forms a boundary layer at the surface. The boundary layer is adapted to at least partially increase the negative pressure required to initiate cavitation at the surface so as to reduce the occurrence of cavitation during such relative movement.

A fluid-redirecting structure includes a rigid body having an upstream end, a downstream end, and an axis of rotation, the rigid body incorporating a plurality of troughs each spiralled from a tip at the upstream end to the downstream end about the axis of rotation, the troughs being splayed with respect to the axis of rotation thereby to, proximate the downstream end, direct incident fluid along the troughs away from the axis of rotation.

A fluid-redirecting structure includes a rigid body having an upstream end, a downstream end, and an axis of rotation, the rigid body incorporating a plurality of troughs each spiralled from a tip at the upstream end to the downstream end about the axis of rotation, the troughs being splayed with respect to the axis of rotation thereby to, proximate the downstream end, direct incident fluid along the troughs away from the axis of rotation.

In a rotating electrical machine apparatus, a rotor portion provided in a cylindrical portion and a stator portion provided in a recessed portion in which the rotor portion is housed are aligned along the rotation axis of a rim such that a force is generated in a direction opposite to the direction of a load that acts along the rotation axis of the rim of loads that act on the rim following rotation of a blade.

An exemplary method for a marine vessel having a propeller mounted to a rotatable shaft for converting rotative shaft power transferred from the shaft to the propeller into thrust to propel the marine vessel across water, includes obtaining measurement values that are descriptive of the shaft power, the thrust and speed through water of the marine vessel; separately estimating at least one of first excess shaft power caused by fouling of the propeller and second excess shaft power caused by fouling of the hull of the marine vessel; and issuing an indication of propeller cleaning in dependence of the first excess shaft power and hull cleaning in dependence of the second excess shaft power.

The invention relates to a blade component for a propeller. The blade component comprises a base which is attachable to a portion of a propeller hub to at least partially enclose the hub and form at least one open ended passage in the hub to permit flow there through. At least one propeller blade extends substantially radially outwardly from the base, and the at least one blade includes a blade face, a blade back, a leading edge, a trailing edge, and a root section connected to the base. An inlet opening is configured on the base which permits flow from the outside to the inside of the enclosed hub. The base or the hub further include a compartment which sub-divides the open ended passage and forms a further water flow passage when the base is attached to the hub, wherein the operatively forward end of the compartment is closed, and the opposing end is open such that water enters the water flow passage through the inlet opening and is directed to flow there through and exit the rear end of the enclosed hub. The inlet opening is configured to run substantially parallel to the axis of the hub, and the inlet opening is further located in register with the water flow passage there below and substantially adjacent to one side of the compartment.

An anti-biofouling method which suppresses biofouling in water includes a preparation step of using a copper alloy-made anti-biofouling object member immersed in the water as a cathode electrode, and immersing and arranging an anode electrode member serving as a counter electrode of the anti-biofouling object member in the water, and a current supplying step of supplying DC current between the anti-biofouling object member and the anode electrode member.