The present invention relates to a device for optional activation of a vertical-axis propeller to be configured on the lower surface of a marine vessel, said device comprises a vertical-axis propeller; a sliding means associated with the lower surface of the marine vessel and sliding the vertical-axis propeller; at least one slider that is associated with the vertical-axis propeller and is in sliding relation with the sliding means; and at least one driving means for driving the vertical-axis propeller in upwards and downwards in the sliding direction.

A propulsion device for a ship is introduced. The propulsion device for the ship comprises a duct having a nose corresponding to the front vertex of a hydrofoil cross-section and a tail corresponding to the rear vertex of the hydrofoil cross-section, wherein the shape of the duct cross-section comprises: an outer surface formed upward in a convex shape at the front end of the duct and formed downward in a concave shape at the rear end of the duct; an inner front part of the duct formed downward in a convex shape at the front end of the duct; an inner rear part of the duct formed downward in a convex shape at the rear end of the duct; and a parallel part for connecting the inner forward part and the inner backward part in parallel to each other.

A propeller assembly is provided. The propeller assembly includes a central hub including a forward end, an aft end, and a hub body extending therebetween along an axis of rotation of the central hub. The propeller assembly further includes a first retention member including a first radial interference member, the first retention member coupled to the forward end of the central hub and a second retention member including a second radial interference member, the second retention member coupled to the aft end of the central hub. The propeller assembly also includes a fairing platform extending between the first retention member and the second retention member, wherein the fairing platform is retained by the first radial interference member and by the second radial interference member.

An apparatus and system for a marine propeller assembly are provided. An aft retention member that may be used with the marine propeller assembly includes a base, an opposing nose and a conic body extending therebetween along a centerline normal to the base. The aft retention member also includes at least one protuberance extending radially away from a surface of the conic body. The protuberance extends axially along a surface of the aft retention member from the base arcuately convergent to a predetermined point between the base and a tip of the nose.

An apparatus and system for a marine propeller assembly are provided. A forward retention member that may be used with the marine propeller assembly includes a planar base, a drive shaft engagement end opposite the planar base, and a conic body extending therebetween along a centerline normal to the planar base. The forward retention member also includes at least one protuberance extending radially away from a surface of the conic body, the protuberance extending axially from the planar base arcuately convergent to a predetermined point between the planar base and the drive shaft engagement end.

Barrel extension assemblies for structural modification of a propeller barrel on a marine propeller include a ring housing having a ring housing interior, the ring housing adapted to detachably engage an interior surface of the propeller barrel at a trailing barrel edge for structural modification of the propeller barrel. Barrel extension methods for modifying performance of a marine vessel are also disclosed.

This disclosure is related with propeller noise and cavitation abatement in applications like propulsion, ventilation, pumping or turbine systems on fluids by novel techniques that allows stronger propellers with improved laminar flow by means of a propeller which consists on a rotating cylindrical block or a truncated substantially conical block with one or more tunnels around it rotational axis, said block also may have flow-guiding structures at both ends that help to keep the fluid's laminar flow when it is mixing fluids with its environment, having the rotating block tunnels with either substantially circular shaped cross-section or variable shape cross-section from substantially circular to irregular oval measured in perpendicular plane to the rotational axis whereby it smoothly accelerates fluid or gas by means of either centrifugal or axial movement, also including Dynamic Balance or Imbalance or Torque Modulation Means that modulate specific vibrations which generates sound waves.