Automatic variable discrete pitch marine propeller

A self-actuating variable pitch marine propeller comprising a hub case, drive securing means designed to secure the propeller to a rotating drive shaft on a boat propulsion system such that the propeller rotates with the drive shaft;

• a plurality of blades extending radially outward from the hub case, each blade comprising a hydrodynamic surface and a blade shaft extending from the hydrodynamic surface along a blade axis extending transverse to the drive shaft axis, the center of pressure of the hydrodynamic surface being distant from the blade axis so as to generate a hydrodynamic force torque about the blade axis when the propeller is rotated, said blade shaft being both pivotally and linearly, along the blade axis, slidably connected to the hub case, such that rotation of the propeller by the drive shaft generates a centrifugal reaction force tending to cause the blades to move linearly outwardly along the blade axis;
• motion-directing means, operatively connected between the hub case and a blade shaft, and having at least two portions, a first portion designed to cause such blade to move pivotally about the blade axis, when the blade moves linearly along its blade axis, and a second portion designed to permit only linear movement of the blade and to prevent pivoting movement when the blade is in a first operational pitch position;
• whereby the second portion resists the hydrodynamic force torque generated by the blade surface, and thus tends to hold the blade in the first operational pitch position until the rotational movement of the propeller generates sufficient centrifugal force effect to cause radial linear movement of the blade.

A self-actuating variable pitch marine propeller comprising a hub case, drive securing means designed to secure the propeller to a rotating drive shaft on a boat propulsion system such that the propeller rotates with the drive shaft;

• a plurality of blades extending radially outward from the hub case, each blade comprising a hydrodynamic surface, and a blade shaft extending from the hydrodynamic surface along a blade axis extending transverse to the drive shaft axis, the center of pressure of the hydrodynamic surface being distant from the blade axis so as to generate a hydrodynamic torque about the blade axis when the propeller is rotated, said blade shaft being both pivotally and linearly, along the blade axis, slidably connected to the hub case such that rotation of the propeller by the drive shaft generates a centrifugal force effect tending to cause each blade to move radially linearly outward along the blade axis;
• first motion-directing means, operatively connected between the hub case and a blade, designed to cause such blade to move pivotally about the blade axis, when the blade moves linearly along its blade axis;
• and blade holding means comprising a second motion-directing means operatively connected between a blade and the hub case and designed to cause the blade to move radially linearly inward along its blade axis in response to the resultant hydrodynamic torque force generated by the blade, and acting along the blade axis, thus tending to hold the blade in a first position in opposition to the centrifugal reaction force until the rotational speed of the propeller increases sufficiently to generate a centrifugal force effect great enough to overcome such hydrodynamic torque force;
• whereby the blades are automatically movable between a first, smaller radial and lower angle of pitch, operational position, and a second, larger radial and higher angle of pitch, operational position, as the rotational speed of the propeller increases.