Handheld Propulsion Assembly

Abstract

A handheld propulsion assembly includes at least one propulsion subassembly. In the propulsion subassembly, pivot and hinge mounts are disposed respectively on upper and lower surfaces of a floatable board member, a crank shaft is pivotably mounted on the pivot mount about a pivot axis, a crank arm extends radially from the crank shaft, and a blade is hinged to the hinge mount. When a driven portion of the crank arm is driven to swing back and forth, the floatable board member is correspondingly moved forward and backward. The blade is angularly movable about a hinge axis between an unfolded position, where the blade has a maximized propelling force, and a folded position, where the blade has a minimized propelling force.

What is claimed is: 
     
         1 . A handheld propulsion assembly for watercraft, comprising:
 at least one propulsion subassembly including:
 a floatable board member which is elongated in a forward-rearward direction, and which has upper and lower surfaces; 
 a pivot mount which is disposed on said upper surface of said floatable board member, and which has a pivot bearing surface defining a pivot axis; 
 a crank shaft having a pivoted end which is pivotably mounted on said pivot mount about the pivot axis, and which is in frictional engagement with said pivot bearing surface, and a connected end opposite to said pivoted end; 
 a crank arm extending from said connected end in a radial direction relative to said crank shaft, and having a driven portion opposite to said connected end such that when said driven portion is driven to swing back and forth, said floatable board member is correspondingly moved forward and backward due to the frictional engagement between said pivot bearing surface of said pivot mount and said pivoted end of said crank shaft; 
 a hinge mount disposed on said lower surface of said floatable board member, and defining a hinge axis; and 
 at least one blade which is hinged to said hinge mount, and which is angularly movable about the hinge axis between an unfolded position, where said blade has a maximized propelling force, and a folded position, where said blade has a minimized propelling force. 
   
     
     
         2 . The handheld propulsion assembly according to  claim 1 , wherein the pivot axis is oriented transverse to the forward-rearward direction. 
     
     
         3 . The handheld propulsion assembly according to  claim 2 , wherein the hinge axis is parallel to the pivot axis. 
     
     
         4 . The handheld propulsion assembly according to  claim 3 , wherein said blade has a free side edge and a hinged side edge which is opposite to said free side edge, and which is hinged to said hinge mount about the hinge axis such that when said blade is in the unfolded position, said free side edge is disposed remote from said lower surface of said floatable board member to permit said blade to have the maximized propelling force, and such that when said blade is in the folded position, said free side edge is disposed close to said lower surface of said floatable board member to permit said blade to have a minimized propelling force. 
     
     
         5 . The handheld propulsion assembly according to  claim 4 , wherein said at least one propulsion subassembly further includes a stop member which is connected to said hinged side edge of said blade, and which extends along a lengthwise axis that is oriented perpendicular to said blade such that said stop member abuts against said lower surface of said foldable board member once said blade is moved to the unfolded position. 
     
     
         6 . The handheld propulsion assembly according to  claim 4 , wherein said blade has left and right lateral edges which are opposite to each other in a direction of the hinge axis, said at least one propulsion subassembly further includes left and right side brackets each connecting said lower surface of said floatable board member and a corresponding one of said left and right lateral edges, and each being configured to be collapsible such that when said blade is displaced to the folded position, said left and right side brackets are displaced to a collapsed position, where each of said left and right lateral edges is substantially parallel to said lower surface of said floatable board member. 
     
     
         7 . The handheld propulsion assembly according to  claim 2 , wherein the hinge axis is oriented transverse to both a direction of the pivot axis and the forward-rearward direction. 
     
     
         8 . The handheld propulsion assembly according to  claim 7 , wherein said at least one propulsion subassembly further includes a fin member which extends downwardly from said lower surface of said floatable board member, and which extends forwardly from said hinge mount in the forward-rearward direction to terminate at a front end edge. 
     
     
         9 . The handheld propulsion assembly according to  claim 8 , wherein said blade has two blade halves each having a free side edge and a hinged side edge which is opposite to said free side edge, and which is hinged to said hinge mount about the hinge axis such that when said blade is in the unfolded position, said free side edges of said blade halves are disposed remote from each other to permit said blade to have the maximized propelling force, and such that when said blade is in the folded position, said free side edges of said blade halves are disposed close to each other to permit said blade to have a minimized propelling force. 
     
     
         10 . The handheld propulsion assembly according to  claim 1 , wherein said at least one propulsion subassembly includes a plurality of said blades which are displaced from each other in the forward-rearward direction. 
     
     
         11 . The handheld propulsion assembly according to  claim 1 , wherein said crank arm has upper and lower segments which are telescopically connected to each other. 
     
     
         12 . The handheld propulsion assembly according to claim  11 , wherein said lower segment has a tubular end portion distal from said connected end, and said upper segment has a connected end portion which is distal from said driven portion, and which is slidably fitted into said tubular end portion so as to permit telescopic connection between said connected end portion and said tubular end portion. 
     
     
         13 . The handheld propulsion assembly according to  claim 12 , wherein said tubular end portion has a plurality of through holes that are linearly displaced from each other, and said connected end portion has a spring-loaded ball configured to be snapped into a selected one of said through holes for adjusting the length of said crank arm. 
     
     
         14 . The handheld propulsion assembly according to  claim 12 , wherein said lower segment further has an impact absorbing portion proximate to said connected end. 
     
     
         15 . The handheld propulsion assembly according to  claim 1 , comprising two of said propulsion subassemblies, each further including:
 a bearing lug which is adapted to be mounted on a gunwale of the watercraft, and which has a bearing lug surface; and   an auxiliary crank member having a handle segment extending in a direction of the pivot axis to terminate at a grip portion and a juncture portion, an arm segment extending from said juncture portion in the radial direction to terminate at an arm end, and an actuating segment which is disposed to connect said arm end and said driven portion of said crank arm, and which is rotatably mounted on said bearing lug surface.   
     
     
         16 . The handheld propulsion assembly according to  claim 15 , further comprising:
 a post adapted to be mounted on a deck of the watercraft; and   a bearing member which is supported by said post, and which has left and right bearing surfaces,   wherein each of said propulsion subassemblies further includes a coupling rod extending from said grip portion to terminate at a journal end which is journaled on a corresponding one of said left and right bearing surfaces.