Propeller for boat

A propeller for a boat, comprising

• a propeller shaft carried in a body of a propelling device to project rearwardly of said body;
• a propeller boss disposed rotatably about said propeller shaft;
• a torque limiting device for connecting said propeller shaft and said propeller boss in such a manner that a slip is produced between said propeller shaft and said propeller boss, when a torque equal to or more than a predetermined value is received;
• and
• a plurality of propeller blades mounted to said propeller boss such that one of a diameter and a pitch angle of said propeller can be changed,
• said torque limiting device being constructed by detachably securing an extension shaft to said propeller shaft to extend rearwardly of said propeller shaft, by rotatably fitting said propeller boss to an outer periphery of said extension shaft over substantially an entire length of the extension shaft, by supporting said propeller blades on a front portion of said propeller boss, and by filling a damper rubber between an inner peripheral surface of a rear portion of said propeller boss and an outer peripheral surface of said extension shaft.

A propeller for a boat, comprising:

• a propeller shaft carried in a body of a propelling device,
• a propeller boss for mounting to said propeller shaft,
• a plurality of propeller blades mounted to said propeller boss through a plurality of blade shafts disposed parallel to an axis of said propeller boss, and which can be turned between a closed position in which a propeller diameter is minimized, and an opened position in which the propeller diameter is maximized,
• said propeller boss being formed around an outer periphery thereof with a plurality of recesses and a plurality of land portions in a circumferentially alternate arrangement,
• a boss of each of the propeller blades being supported on said blade shaft carried on longitudinally opposite end walls of the recess and being accommodated in the recess, and
• each of said land portions being provided with an exhaust passage which extends longitudinally through said land portion.