Patent Publication Number: US-2023150632-A1

Title: Propulsion devices and methods of making propulsion devices that align propeller blades for marine vessels

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/378,371, filed Jul. 16, 2021, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure generally relates to stowable propulsors for marine vessels. 
     BACKGROUND 
     The following U.S. patents provide background information and are incorporated by reference in entirety. 
     U.S. Pat. No. 6,142,841 discloses a maneuvering control system which utilizes pressurized liquid at three or more positions of a marine vessel to selectively create thrust that moves the marine vessel into desired locations and according to chosen movements. A source of pressurized liquid, such as a pump or a jet pump propulsion system, is connected to a plurality of distribution conduits which, in turn, are connected to a plurality of outlet conduits. The outlet conduits are mounted to the hull of the vessel and direct streams of liquid away from the vessel for purposes of creating thrusts which move the vessel as desired. A liquid distribution controller is provided which enables a vessel operator to use a joystick to selectively compress and dilate the distribution conduits to orchestrate the streams of water in a manner which will maneuver the marine vessel as desired. 
     U.S. Pat. No. 7,150,662 discloses a docking system for a watercraft and a propulsion assembly therefor wherein the docking system comprises a plurality of the propulsion assemblies and wherein each propulsion assembly includes a motor and propeller assembly provided on the distal end of a steering column and each of the propulsion assemblies is attachable in an operating position such that the motor and propeller assembly thereof will extend into the water and can be turned for steering the watercraft. 
     U.S. Pat. No. 7,305,928 discloses a vessel positioning system which maneuvers a marine vessel in such a way that the vessel maintains its global position and heading in accordance with a desired position and heading selected by the operator of the marine vessel. When used in conjunction with a joystick, the operator of the marine vessel can place the system in a station keeping enabled mode and the system then maintains the desired position obtained upon the initial change in the joystick from an active mode to an inactive mode. In this way, the operator can selectively maneuver the marine vessel manually and, when the joystick is released, the vessel will maintain the position in which it was at the instant the operator stopped maneuvering it with the joystick. 
     U.S. Pat. No. 7,753,745 discloses status indicators for use with a watercraft propulsion system. An example indicator includes a light operatively coupled to a propulsion system of a watercraft, wherein an operation of the light indicates a status of a thruster system of the propulsion system. 
     U.S. Pat. No. RE39032 discloses a multipurpose control mechanism which allows the operator of a marine vessel to use the mechanism as both a standard throttle and gear selection device and, alternatively, as a multi-axes joystick command device. The control mechanism comprises a base portion and a lever that is movable relative to the base portion along with a distal member that is attached to the lever for rotation about a central axis of the lever. A primary control signal is provided by the multipurpose control mechanism when the marine vessel is operated in a first mode in which the control signal provides information relating to engine speed and gear selection. The mechanism can also operate in a second or docking mode and provide first, second, and third secondary control signals relating to desired maneuvers of the marine vessel. 
     European Patent Application No. EP 1,914,161, European Patent Application No. EP2,757,037, and Japanese Patent Application No. JP2013100013A also provide background information and are incorporated by reference in entirety. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. 
     The present disclosure generally relates to propulsion devices for marine vessel. In one example, a base is configured to be coupled to the marine vessel, the base having sides that extend downwardly from the marine vessel. A propulsor is pivotally coupled to the base and pivotable into and between a deployed position and a stowed position. The propulsor comprises a propeller having a hub with blades extending away therefrom. The propulsor is configured to propel the marine vessel in water when in the deployed position by rotating the propeller. An alignment device aligns the blades of the propeller between the sides of the base when the propulsor is in the stowed position. 
     The present disclosure further relates to methods for making a propulsion device for a marine vessel. The method includes configuring a base for coupling to the marine vessel, the base having sides that extend downwardly from the marine vessel. The method further includes pivotally coupling a propulsor to the base, the propulsor being pivotable into and between a deployed position and a stowed position, where the propulsor comprises a propeller having a hub with blades extending away therefrom, and where the propulsor is configured to propel the marine vessel in water when in the deployed position by rotating the propeller. The method further includes coupling an alignment device between the propeller and the base, where the alignment device is configured to align the blades of the propeller between the sides of the base when the propulsor is in the stowed position. 
     Various other features, objects and advantages of the disclosure will be made apparent from the following description taken together with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is described with reference to the following Figures. 
         FIG.  1    is an isometric bottom view of a propulsion device coupled to a marine vessel and having a propulsor; 
         FIG.  2    is an exploded isometric view showing the propulsor from  FIG.  1    in a stowed position; 
         FIG.  3    is a sectional side view of the propulsion device shown in  FIG.  2   ; 
         FIG.  4    is a rear view of the propulsion device shown in  FIG.  2   ; 
         FIG.  5    is a sectional view taken along the line  5 - 5  of  FIG.  2   ; 
         FIG.  6    is an isometric bottom view showing the propulsor from  FIG.  2    in a deployed position; 
         FIG.  7    is a sectional side view taken along the line  7 - 7  in  FIG.  6   ; 
         FIG.  8    is a rear view of the propulsion device as shown in  FIG.  6   ; 
         FIG.  9    is an isometric view of an alternate embodiment of propulsion device coupled to a marine vessel and having a propulsor; 
         FIG.  10    depicts an exemplary control system for controlling propulsion devices according to the present disclosure; 
         FIG.  11    depicts an isometric bottom-right view of a propulsion device with one embodiment of alignment device for aligning blades of a propulsor within a mounting base according to the present disclosure; 
         FIG.  12    is close-up of the device of  FIG.  11    with the propulsor pivoted further toward the stowed position and the blades now aligned; 
         FIG.  13    shows the device of  FIG.  12    with the propulsor in the stowed position; 
         FIG.  14    is an isometric view of a propeller for another embodiment alignment device according to the present disclosure; 
         FIGS.  15 - 16    are side views of an embodiment of alignment device incorporating the propeller of  FIG.  14    showing the propulsor progressively pivoting toward the stowed position; 
         FIGS.  17 - 18    are isometric views of another embodiment of alignment device before and after aligning the blades according to the present disclosure, respectively; 
         FIG.  19    is a front isometric view of another embodiment of alignment device according to the present disclosure; 
         FIG.  20    is a sectional view taken along the line  20 - 20  in  FIG.  19   ; 
         FIGS.  21 - 22    are sectional side views of another embodiment of alignment device according to the present disclosure showing the propulsor progressively pivoting into the stowed position; 
         FIG.  23    is a process flow diagram of one method for aligning blades of a propulsor according to the present disclosure; 
         FIG.  24    is a process flow diagram of another method for aligning blades of a propulsor according to the present disclosure; 
         FIG.  25    is an isometric right view of another arm for aligning blades of a propulsor according to the present disclosure; and 
         FIG.  26    is an isometric left view of the arm of  FIG.  25   . 
     
    
    
     DETAILED DISCLOSURE 
     The present inventors have recognized a problem with bow thrusters presently known in the art, and particularly those that are retractable for storage. Specifically, within the context of a marine vessel having pontoons, there is insufficient clearance between the pontoons to accommodate a propulsive device, and particularly a propulsive device oriented to create propulsion in the port-starboard direction. The problem is further exacerbated when considering how marine vessels are trailered for transportation over the road. One common type of trailer is a scissor type lift in which bunks are positioned between the pontoons to lift the vessel by the underside of the deck. An exemplary lift of this type is the “Scissor Lift Pontoon Trailer” manufactured by Karavan in Fox Lake, Wis. In this manner, positioning a bow thruster between a marine vessel&#39;s pontoons either precludes the use of a scissor lift trailer, or leaves so little clearance that damage to the bow thruster and/or trailer is likely to occur during insertion, lifting, and/or transportation of the vessel on the trailer. This can also be an issue with bunk trailers and/or shore stations having guides that go on the inside of the pontoons. As such, the present inventors have realized it would be advantageous to rotate the propulsor in a fore-aft orientation when stowed to minimize the width of the bow thruster. Additionally, the present inventors have recognized the desirability of developing such a rotatable propulsor that does not require additional actuators for this rotation, adding cost and complexity to the overall system. 
       FIG.  1    depicts the underside of a marine vessel  1  as generally known in the art, but outfitted with an embodiment of a stowable propulsion device  30  according to the present disclosure. The marine vessel  1  extends between a bow  2  and a stern  3 , as well as between port  4  and starboard  5  sides, thereby defining a fore-aft plane FAP, and port-starboard direction PS. The marine vessel  1  further includes a deck  6  with a rail system  8  on top and pontoons  12  mounted to the underside  10  of the deck  6 . The marine vessel  1  is shown with a portion of a scissor type lift  20 , specifically the bunks  22 , positioned between pontoons  12  to lift and support the marine vessel  1  for transportation over land in a manner known in the art. As is discussed further below, embodiments of a novel stowable propulsion device  30  have a propeller  284  that faces the underside  10  of the deck  6  when stowed, in contrast to during use to propel the marine vessel  1  in the water as a bow thruster. This is distinguishable from propulsion devices known in the art, in which the propeller faces the pontoons. In prior art configurations, there typically is insufficient room between the propulsion device and the pontoons to fit the bunks of the scissor type lift without risking damage to the propulsion device while inserting the bunks, lifting the marine vessel, and/or traveling on the road. 
       FIGS.  2 - 3    depict an exemplary stowable propulsion device  30  according to the present disclosure, here oriented in a stowed position. The stowable propulsion device  30  includes a base  40  having a top  42  with sides  44  extending perpendicularly downwardly away from the top  42 . The sides  44  include an inward side  46  and outward side  48  and extend between a first end  65  and second end  67  defining a length  66  therebetween. A width  64  is defined between the sides  44 . A stop  80  having sides  82  and a bottom  84  is coupled between the sides  44  of the base  40 . A leg  68  having an inward side  70  and outward side  72  extends between a top end  74  and a bottom end  76 . The leg  68  is coupled at the top end  74  to the top  42  of the base  40  and extends perpendicularly downwardly therefrom. A stationary gear  92  having a mesh face  96  with gear teeth and an opposite mounting face  94  is coupled to the leg  68  with the mounting face  94  facing the inward side  70  of the leg  68 . As shown in  FIG.  4   , one or more support rods  140  may also be provided between the sides  44  and received within support rod openings  143  defined therein to provide rigidity to the base  40 . In the example shown, the support rod  140  is received within a bushing  144  and held in position by a snap ring  146  received within a groove defined within the support rod  140 . 
     Returning to  FIGS.  2 - 3   , the base  40  is configured to be coupled to the marine vessel  1  with the top  42  facing the underside  10  of the deck  6 . The base  40  may be coupled to the deck  6  using fasteners and brackets presently known in the art. A mounting bracket  60  is coupled via fasteners  62  (e.g., screws, nuts and bolts, or rivets) to the outward sides  48  of the sides  44  of the base  40 . The mounting bracket  60  is receivable in a C-channel bracket or other hardware known in the art (not shown) that is coupled to the deck  6  and/or pontoons  12  to thereby couple the stowable propulsion device  30  thereto. 
     As shown in  FIGS.  2 - 4   , the stowable propulsion device  30  includes a shaft  230  that extends between a proximal end  232  and distal end  234  defining a length axis LA therebetween. The proximal end  232  of the shaft  230  is non-rotatably coupled to a moving gear  100 . The moving gear  100  has a proximal face  102  and mesh face  104  having gear teeth, where the mesh face  104  engages with the mesh face  96  of the stationary gear  92  to together form a gearset  90  as discussed further below. The moving gear  100  further includes a barrel  106  that extends perpendicularly relative to the proximal face  102  and is coupled to the shaft  230  in a manner known in the art (e.g., via a set screw or welding). In this manner, the moving gear  100  is fixed to the shaft  230  such that rotation of the moving gear  100  causes rotation of the shaft  230  about the length axis LA. 
     With reference to  FIGS.  2  and  5 - 6   , a pivot rotation device  150  is coupled to the shaft  230  near its proximal end  232 , below the moving gear  100 . The pivot rotation device  150  includes a main body  152  extending between a first end  154  and a second end  156  with an opening  153  defined therebetween. The shaft  230  is received through the opening  153  between the first end  154  and second end  156  of the main body  152  and rotatable therein. In the embodiment shown, a bushing  155  is received within the opening  153  of the main body  152  and the shaft  230  extends through an opening  157  within the bushing  155 . The bushing  155  provides for smooth rotation between the shaft  230  and the main body  152 . The shaft  230  is retained within the main body  152  via first and second clamp systems  210 ,  220 . The first clamp system  210  includes two clamp segments  212  coupled together by fasteners  216  received within openings and receivers therein, for example threaded openings for receiving the fasteners  216 . The clamp segments  212  are configured to clamp around the shaft  230  just above the main body  152 , in the present example with a gasket  213  sandwiched therebetween to provide friction. Likewise, clamp segments  222  of the second clamp system  220  are coupled to each other via fasteners  226  to clamp onto the shaft just below the main body  152 , which may also include a gasket sandwiched therebetween. In this manner, the shaft  230  is permitted to rotate within the main body  152 , but the first and second clamp systems  210 ,  220  on opposing ends of the main body  152  prevent the shaft  230  from moving axially through the main body  152 . 
     As shown in  FIGS.  2 - 3  and  5   , the shaft  230  is pivotable about a transverse axis (shown as pivot axis PA) formed by coaxially-aligned pivot axles  120 ,  121 . The pivot axles  120 ,  121  are received within pivot axle openings  52  defined within the sides  44  of the base  40 , with bushings  122  therebetween to prevent wear. Snap rings  126  are receivable within grooves  128  defined within the pivot axles  120 ,  121  to retain the axial position of the pivot axles  120 ,  121  within the base  40 . The interior ends of the pivot axles  120 ,  121  are received within the main body  152  of the pivot rotation device  150  coupled to the shaft  230 . The pivot axle  120  is received within a pivot axle opening  162  of the main body  152  such that the outer surface of the pivot axle  120  engages an interior wall  159  of the main body  152 . In the embodiment of  FIG.  5   , a gap  164  remains at the end of the pivot axle  120  to allow for tolerancing and bending and/or movement of the sides  44  of the base  40 . 
     With continued reference to  FIG.  5   , the pivot rotation device  150  further includes an extension body  170  that extends away from the main body  152 . The extension body  170  defines a pivot axle opening  178  therein for receiving the pivot axle  121 . The pivot axle  121  has an insertion end  129  with threads  127  defined thereon, which engage with threads  173  of the pivot axle opening  178  defined in the extension body  170 . A slot  123  is defined in the end of the pivot axle  121  opposite the insertion end  129 . The pivot axle  121  is therefore threadably received within the extension body  170  by rotating a tool (e.g., a flathead screwdriver) engaged within the slot  123  defined in the end of the pivot axle  121 . A snap ring  126  may also be incorporated and receivable within grooves  128  defined in the pivot axle  121  to prevent axial translation of the pivot axle  121  relative to the sides  44  of the base  40 . 
     As shown in  FIG.  2   , a face  176  of the extension body  170  defines a notch  177  recessed therein, which as will become apparent provides for non-rotational engagement with a pivot arm  190 . The pivot arm  190  includes a barrel portion  192  having a face  198  with a protrusion  179  extending perpendicularly away from the face  198 . The protrusion  179  is received within the notch  177  when the faces  176 ,  198  abut each other to rotationally fix the pivot arm  190  and the extension body  170 . It should be recognized that other configurations for rotationally fixing the pivot arm  190  and extension body  170  are also contemplated by the present disclosure, for example other keyed arrangements or fasteners. 
     The barrel portion  192  of the pivot arm  190  further defines a pivot axle opening  199  therethrough, which enables the pivot axle  121  to extend therethrough. The pivot arm  190  further includes an extension  200  that extends away from the barrel portion  192 . The extension  200  extends from a proximal end  202  coupled to the barrel portion  192  to distal end  204 , having an inward face opposite an outward face  208 . A mounting pin opening  209  is defined through the extension  200  near the distal end  204 , which as discussed below is used for coupling the pivot arm  190  to an actuator  240 . 
     As shown in  FIGS.  2  and  4   , the pivot arm  190  is biased into engagement with the main body  152  of the pivot rotation device  150  via a biasing device, such as a spring  134 . In the example shown, the spring  134  is a coil or helical spring that engages the outward face  208  of the extension  200  of the pivot arm  190  at one end and engages a washer  124  abutting a snap ring  126  engaged within a groove of the pivot axle  121  at the opposite end. In this manner, the spring  134  provides for a biasing force engaging the pivot arm  190  and the main body  152  such that the faces  176 ,  198  thereof remain in contact during rotation of the pivot arm  190 , but also provides a safeguard. For example, if the shaft  230  experiences an impact force (e.g., a log strike), the presently disclosed configuration allows the protrusion  179  (shown here to have a rounded shape) to exit the notch  177  against the biasing force of the spring  134  to prevent the force from damaging other components, such as the actuator  240  coupled to the pivot arm  190  (discussed further below). 
     Referring to  FIGS.  2 - 4   , the stowable propulsion device  30  further includes an actuator  240  (presently shown is a linear actuator), which for example may be an electric, pneumatic, and/or hydraulic actuator presently known in the art. The actuator  240  extends between a first end  242  and second end  244  and has a stationary portion  246  and an extending member  260  that extends from the stationary portion  246  in a manner known in the art. The stationary portion  246  includes a mounting bracket  248  that is coupled to the base  40  via fasteners  252 , such as bolts, for example. At the opposite end of the actuator  240 , a mounting pin opening  261  extends through the extending member  260 , which is configured to receive a mounting pin  262  therethrough to couple the extending member  260  to the pivot arm  190  of the pivot rotation device  150 . The mounting pin  262  shown extends between a head  264  and an insertion end  266 , which in the present example has a locking pin opening  268  therein for receiving a locking pin  269 . The locking pin  269 , for example a cotter pin, is inserted or withdrawn to removably retain the mounting pin  262  in engagement between the actuator  240  and the pivot arm  190 . In the embodiment of  FIGS.  2 - 4   , it should be recognized that actuation of the actuator  240  thus causes pivoting of the shaft  230  about the pivot axis PA. 
     Referring to  FIG.  2   , the stowable propulsion device  30  further includes a propulsor  270  coupled to the distal end  234  of the shaft  230 . The propulsor  270  may be of a type known in the art, such as an electric device operable by battery. In the example shown, the propulsor  270  includes a nose cone  272  extending from a main body  274 . The main body  274  includes an extension collar  276  that defines a shaft opening  278 , whereby the shaft  230  is received within the shaft opening  278  for coupling the shaft  230  to the propulsor  270 . The propulsor  270  includes a motor  282  therein, whereby control and electrical power may be provided to the motor  282  by virtue of a wire harness  290  ( FIG.  9   , also referred to as a wire) extending through the shaft  230 , in the present example via the opening  108  defined through the moving gear  100 ; however, it should be recognized that the wire harness  290  may enter the shaft  230  or propulsor  270  in other locations. In some configurations, the wire harness  290  also extends through a gasket  291  ( FIG.  9   ) that prevents ingress of water or other materials into the shaft  230 , for example. The propulsor  270  further includes a fin  280  and is configured to rotate the propeller  284  about a propeller axis PPA. The propulsor  270  extends a length  286  ( FIG.  3   ) and provides propulsive forces in a direction of propulsion DOP. With reference to  FIG.  4   , the propulsor  270  has a width PW that is perpendicular to the length  286 , in certain embodiments the width PW being less than the width  64  of the base  40 . 
     As shown in  FIG.  6    and discussed further below, the propulsor  270  is configured to propel the marine vessel  1  through the water in the port-starboard direction PS when the shaft  230  is positioned in the deployed position. It should be recognized that, for simplicity, the propulsor  270  is described as generating propulsion in the port-starboard direction, and thus that the marine vessel moves in the port-starboard direction. However in certain configurations, the propulsor  270  may accomplish this movement of the marine vessel in the port-starboard direction by concurrently using another propulsor coupled elsewhere on the marine vessel  1 , for example to provide translation rather than rotation of the marine vessel  1 . 
     It should be recognized that when transitioning the shaft  230  and propulsor  270  from the stowed position of  FIG.  3    to the deployed position of  FIG.  6   , the shaft  230  pivots 90 degrees about the pivot axis PA from being generally horizontal to generally vertical, and the propulsor  270  rotates 90 degrees about the length axis LA of the shaft  230  from the propeller axis PPA being within the fore-aft plane FAP ( FIG.  1   ) to extending in the port-starboard direction PS. The present inventors invented the presently disclosed stowable propulsion devices  30  wherein pivoting of the shaft  230  about the pivot axis PA automatically correspondingly causes rotation of the shaft  230  about is length axis LA without the need for additional actuators (both being accomplished by the same actuator  240  discussed above). With reference to  FIGS.  2 - 3   , this function is accomplished through a gearset  90 , which as discussed above is formed by the engagement of the stationary gear  92  and moving gear  100 . 
     As discussed above, the stationary gear  92  is fixed relative to the base  40  and the moving gear  100  rotates in conjunction with the shaft  230  rotating about its length axis LA. In this manner, as the shaft  230  is pivoted about the pivot axis PA via actuation of the actuator  240 , the engagement between the mesh face  96  of the stationary gear  92  and the mesh face  104  of the moving gear  100  causes the moving gear  100  to rotate, since the stationary gear  92  is fixed in place. This rotation of the moving gear  100  thus causes rotation of the moving gear  100 , which correspondingly rotates the shaft  230  about its length axis LA. Therefore, the shaft  230  is automatically rotated about its length axis LA when the actuator  240  pivots the shaft  230  about the pivot axis PA. It should be recognized that by configuring the mesh faces  96 ,  104  of the gears accordingly (e.g., numbers and sizes of gear teeth), the gearset  90  may be configured such that pivoting the shaft  230  between the stowed position of  FIG.  4    and the deployed position of  FIG.  6    corresponds to exactly 90 degrees of rotation for the shaft  230  about its length axis LA, whether or not the shaft  230  is configured to pivot 90 degrees between its stowed and deployed positions. It should be recognized that other pivoting and/or rotational angles are also contemplated by the present disclosure. 
     The present inventors invented the presently disclosed configurations, which advantageously provide for stowable propulsion devices  30  having a minimal width  64  ( FIG.  2   ) when in the stowed position, clearing the way for use of a scissor type lift  20  or other lifting mechanisms for the marine vessel  1 , while also positioning the propulsor for generating thrust in the port-starboard direction PS when in the deployed position. 
     As shown in  FIG.  6   , certain embodiments include stop  80  within the base  40  for stopping, centering, and/or securing the shaft  230  in the stowed position. In the embodiment shown, a centering slot  86  is defined within the bottom  84  of the stop  80 . This centering slot  86  is configured to receive a tab  308  that extends from a clamp  306  positioned approximately at a midpoint along the shaft  230 . When the shaft  230  is pivoted and rotated into its stowed position as shown in  FIG.  2   , the tab  308  of the clamp  306  is received within the centering slot  86  of the stop  80 , whereby the bottom  84  of the stop  80  itself prevents further upward pivoting of the shaft  230 , and whereby the centering slot  86  prevents lateral movement of the propulsor  270  when in the stowed position. 
     The embodiment of  FIG.  6    further depicts a positional sensor  300  configured for detecting whether the stowable propulsion device  30  is in the stowed position. The positional sensor  300  shown includes a stationary portion  302  and a moving portion  304 , whereby the stationary portion  302  is a Hall Effect Sensor positioned adjacent to the centering slot  86  of the stop  80 , which detects the moving portion  304  integrated within the tab  308 . In this manner, the positional sensor  300  detects when the shaft  230  is properly in the stowed position, and when it is not. 
     It should be recognized that other positional sensors  300  are also known in the art and may be incorporated within the systems presently disclosed. For example,  FIG.  3    depicts an embodiment in which the positional sensor  300  is incorporated within the actuator  240 , such as a linear encoder, that can be used to infer the position of the shaft  230  via the position of the extending member  260  of the actuator  240  relative to the stationary portion  246 . An exemplary positional sensor  300  is Mercury Marine&#39;s Position Sensor ASM, part number 8M0168637, for example. 
     The present disclosure contemplates other embodiments of stowable propulsion devices  30 . For example,  FIG.  9    depicts an embodiment having two pivot arms  190  coupled directly to the main body  152  of the pivot rotation device  150 . The actuator  240  is pivotally coupled to the two pivot arms  190  in a similar manner as that discussed above. In certain examples, the two pivot arms  190  are integrally formed with the clamp segments  212  of the first clamp system  210 , for example. The gearset  90  of the embodiment in  FIG.  9    also varies from that discussed above. Specifically, the mesh face  96  of the stationary gear  92  includes openings  97  rather than gear teeth. These openings  97  are configured to receive fingers  105  that extend from the mesh face  104  of the moving gear  100 , generally forming a gear and sprocket type system for the gearset  90 . The embodiment shown also includes a stop rod  81  for preventing the shaft  230  from rotating too far, or in other words past the deployed position. 
       FIG.  10    depicts an exemplary control system  600  for operating and controlling the stowable propulsion device  30 . Certain aspects of the present disclosure are described or depicted as functional and/or logical block components or processing steps, which may be performed by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, certain embodiments employ integrated circuit components, such as memory elements, digital signal processing elements, logic elements, look-up tables, or the like, configured to carry out a variety of functions under the control of one or more processors or other control devices. The connections between functional and logical block components are merely exemplary, which may be direct or indirect, and may follow alternate pathways. 
     In certain examples, the control system  600  communicates with each of the one or more components of the stowable propulsion device  30  via a communication link CL, which can be any wired or wireless link. The control system  600  is capable of receiving information and/or controlling one or more operational characteristics of the stowable propulsion device  30  and its various sub-systems by sending and receiving control signals via the communication links CL. In one example, the communication link CL is a controller area network (CAN) bus; however, other types of links could be used. It will be recognized that the extent of connections and the communication links CL may in fact be one or more shared connections, or links, among some or all of the components in the stowable propulsion device  30 . Moreover, the communication link CL lines are meant only to demonstrate that the various control elements are capable of communicating with one another, and do not represent actual wiring connections between the various elements, nor do they represent the only paths of communication between the elements. Additionally, the stowable propulsion device  30  may incorporate various types of communication devices and systems, and thus the illustrated communication links CL may in fact represent various different types of wireless and/or wired data communication systems. 
     The control system  600  of  FIG.  10    may be a computing system that includes a processing system  610 , memory system  620 , and input/output (I/O) system  630  for communicating with other devices, such as input devices  599  and output devices  601 , either of which may also or alternatively be stored in a cloud  602 . The processing system  610  loads and executes an executable program  622  from the memory system  620 , accesses data  624  stored within the memory system  620 , and directs the stowable propulsion device  30  to operate as described in further detail below. 
     The processing system  610  may be implemented as a single microprocessor or other circuitry, or be distributed across multiple processing devices or sub-systems that cooperate to execute the executable program  622  from the memory system  620 . Non-limiting examples of the processing system include general purpose central processing units, application specific processors, and logic devices. 
     The memory system  620  may comprise any storage media readable by the processing system  610  and capable of storing the executable program  622  and/or data  624 . The memory system  620  may be implemented as a single storage device, or be distributed across multiple storage devices or sub-systems that cooperate to store computer readable instructions, data structures, program modules, or other data. The memory system  620  may include volatile and/or non-volatile systems and may include removable and/or non-removable media implemented in any method or technology for storage of information. The storage media may include non-transitory and/or transitory storage media, including random access memory, read only memory, magnetic discs, optical discs, flash memory, virtual memory, and non-virtual memory, magnetic storage devices, or any other medium which can be used to store information and be accessed by an instruction execution system, for example. 
     The present disclosure further relates to propulsion devices and methods for making propulsion devices that provide for alignment of propeller blades for stowable propulsion devices such as those discussed above. For example, the propulsion devices  30  of  FIGS.  2  and  3    provide for rotating the propulsor  270  to be as narrow as possible when in the stowed position. Moreover, this propulsion device  30  is receivable at least partially inside the mounting base  40 , specifically between the sides  44  and above the bottom  45  thereof. The portion receivable inside the mounting base  40  may be limited to a portion of the propeller  284 , or also include a portion of the main body  274  for the propulsor  270 . 
     However, the present inventors have recognized that the propulsor  270  being receivable at least partially within the mounting base  40  depends upon the blades  287  of the propeller  284  being aligned within the width  64  of the mounting base  40 . Moreover, the present inventors have recognized that failure to align the propeller  284  before pivoting the propulsor  270  into the stowed position may not only prevent the propulsor  270  from fully pivoting into this stowed position, but may also damage the propeller  284  and/or other components of the propulsion device  30 , such as the actuator  240 . As such, the present inventors have identified that it would be advantageous to automatically align the propeller  284  within the mounting base  40  as the propulsor  270  pivots into the stowed position. 
       FIGS.  11  and  12    show a first example of a propulsion device  700  providing automatic alignment of the propeller  284  as its propulsor  270  pivots into the stowed position within the mounting base  40 . As discussed above, the mounting base  40  is coupled to the deck  6  of the marine vessel  1  and has sides  44  extending downwardly there from. The sides  44  include an inward side  44  and outward side  48 , with an inner width IW defined between the inward sides  46 . The sides  44  terminate at a bottom  45 . An end cap  710  is coupled to the mounting base  40  at mounting ends  712  and extends forwardly to a forward end  714 . The end cap  710  protects the propeller  284  from damage when in the stowed position, for example when navigating the marine vessel  1  onto the bunks  22  of a scissor type lift  20 . 
     The propulsion device  700  incorporates a pivot rotation device  150  such as that described above, which rotates the propulsor  270  about the shaft  230  as the shaft  230  is pivoted (here by the actuator  240 ) between deployed and stowed positions. The propulsor  270  includes a propeller  284  having a hub  285  with blades  287  extending radially outwardly therefrom. The blades  287  have tips  289  at the points radially farthest from the hub  285 . A blade span BS thereby extends between the tips  289  of the two opposing blades  287 . The propeller  284  and particularly its blades  287  also have contoured blade faces  281  extending between edges  283 , whereby the blades  287  are configured to propel the marine vessel  1  in water when rotated in a conventional manner. 
     The propulsion device  700  of  FIG.  11    further includes a position sensor  300 , in this example a rotational sensor incorporated within the pivot rotation device  150 , which measures the angular position of the shaft  230  (and thus the propulsor  270 ) while pivoting between the deployed and stowed positions. A current sensor  720  is also provided, here integrated within the actuator  240 , which measures an amount of electrical current drawn by the actuator  240  during operation thereof. The current sensor  720  and position sensor  300  are each operatively coupled to a control system  600  such as that previously discussed. The control system  600  may further include a timer  740  therein, which is discussed further below. 
     The propulsion device  700  of  FIG.  11    incorporates an alignment device  750  for automatically aligning the blades  287  of the propeller  284  between the sides  44  of the mounting base  40  as the propulsor  270  pivots toward the stowed position. The alignment device  750  is particularly an arm  760  that extends between a first end  762  and second end  764 . As shown in  FIG.  12   , the arm  760  has an inside  763  and outside  765 , as well as an upper edge  772  and a lower edge  774  with a height  776  defined therebetween. In the example shown, the height  776  progressively increases from the first end  762  to the second end  764 ; however, other configurations are also contemplated by the present disclosure (such as arcs having a constant height  776  or configurations having a smallest height  776  at a midpoint between the first end  762  and second end  764 , for example). The first end  762  is pivotally coupled to the mounting base  40  via fasteners  768 , which may be pins, rivets, nuts and bolts, and/or the like. The second end  764  is therefore moveable relative to the bottom  45  of the mounting base  40  with a second distance  770  defining a distance therebetween. Exemplary materials for the arm  760  include plastics, rubber, aluminum, or other materials known in the art. 
     In certain examples, the arm  760  also varies in width between the inside  763  and outside  765 . For example, the width may progressively increase between the first end  762  and second end  764 . 
       FIGS.  11 - 13    depict the propulsor  270  pivoting progressively toward the stowed position, being fully stowed in  FIG.  13   . As the propulsor  270  pivots toward the stowed position, the arm  760  engages one of the blades  287 , initially at the second end  764  of the arm  760 . This contact may occur while the propeller  284  is stationary, or rotating. If the propeller  284  is not aligned within the mounting base  40 , the position of the arm  760  on the inside of one of the sides  44  is such that the mass of the arm  760  acting on the curvature of the blade face  281  causes the propeller  284  to rotate until the second end  764  of the arm  760  drops off the blade  287  (the blade  287  thereby being aligned within the mounting base  40 . If the propeller  284  were rotating while the propulsor  270  is pivoting upwardly, engagement may occur between the edge  283  of the blade  287  and the inside  763  of the arm  760 , thereby stopping the rotation. In each case, engagement between the arm  760  and the propeller  284  thereby causes and maintains alignment of the blade span BS within the sides  44  of the mounting base  40 . 
     As discussed above, the propulsion device  700  further includes a position sensor  300  and current sensor  720 . In certain examples, the control system  600  causes the propeller  284  to rotate as the propulsor  270  pivots toward the stowed position. Rotation of the propeller  284  may be particularly controlled via measurements from the position sensor  300 , for example starting rotation of the propeller  284  after the shaft  230  has been pivoted to be a first angle R from being stowed (see  FIG.  11   ), and discontinuing rotation at a second angle R as shown in  FIG.  12   . This prevents unnecessary rotation of the propeller  284  when the arm  760  is not in close proximity thereto, and thus cannot yet provide alignment of the propeller  284  within the mounting base  40 . 
       FIG.  23    shows an exemplary process  900  for controlling the propulsion device  700  using a position sensor  300 . Step  903  begins with pivoting the shaft  230  towards the stowed position without rotating the propeller  284 . Once the shaft  230  is determined to be 95% of the way towards the stowed position, for example, step  905  provides for operating the motor  282  at the lowest possible RPM in step  907 . A timer  740  is also started in the control system  600  when the motor  282  begins rotating. The motor  282  continues rotating in step  909  until the timer  740  is determined in step  911  to exceed a predetermined threshold XA (e.g., 2 seconds, 1 second, or 200 ms, depending on the rotational speed) corresponding to the propeller  284  being aligned within the mounting base  40 . For example, it may be empirically determined that once the shaft  230  is 95% of the way to pivoting in the stowed position, rotating the propeller  284  at a given rotation for 1 second corresponds to alignment with the mounting base  40  (steps  913  and  915 ). Use of the timer  740  may also be advantageous in the context of also or alternatively using a propeller position sensor  730  (discussed further below), which provides insight as to a starting point for the rotation of the propeller  284  before rotating for a given time. For example, it may be determined that when the propeller position sensor  730  indicates alignment of the propeller  284  as it rotates, an additional 1 second of rotation will return the propeller  284  to alignment again. 
     In addition or in the alternative, the current sensor  720  may be provided as an input to the control system  600  rotating the propeller  284  as the propulsor  270  pivots to the stowed position. For example, an increase in the current drawn by the motor  282  occurs when the arm  760  stops the propeller  284  from rotating, which can be detected by the current sensor  720 . This increased current is detected by the control system  600 , which then stops supplying electricity to the motor  282  to prevent damage to the motor  282 , propeller  284 , and/or arm  760 . In particular, the control system  600  determines when to discontinue rotating the motor  282  by comparing the current measured by the current sensor  720  to a predetermined threshold XA (e.g., 0.1A, 0.3A, 0.5A, 1A, or others, depending on the hardware being used) corresponding to the arm  760  resisting rotation of the propeller  284 . 
     An exemplary process  950  for using the current sensor  720  is shown in  FIG.  24   , which may mirror that of  FIG.  23    but for the step  960  comparison of the current drawn from the motor  282  as determined by the current sensor  720  to a predetermined threshold XA. In this example, the current exceeds the predetermined threshold XA when the propeller  284  is prevented from further rotation, thereby indicating that the automatic alignment process has completed. 
       FIGS.  25  and  26    depict another embodiment of an arm  760 , which may be incorporated into the alignment device  750  of  FIG.  11   , for example. The arm  760  extends from a first end  762  to a second end  764  and has an inside  763  and an outside  765 , as discussed above. An opening  766  extends through the arm  760  near the first end  762 , which receives a fastener therethrough to pivotally couple the arm  760  to the base  40  ( FIG.  11   ). As shown in  FIG.  25   , the arm  760  extends from an upper edge  772  and a lower edge  774  defining a varying height  776  therebetween. From the outside  765 , the height  776  generally has a first section  902  that is relatively constant, which then increases in a generally linear manner after a point  926  in a second section  904  until a bottom  940 . The present inventors have identified that an angle  928  between the first section  902  and the second section  904  is advantageous for allowing the propeller to pivot the arm  760  upwardly (into the base  40 , see  FIG.  11   ) if the arm  760  does not contact the propeller in the right position, allowing the next blade of the propeller to be caught instead. In the example shown, the angle  928  is approximately 45 degrees; however, other ranges of angles are also contemplated by the present disclosure, including between 40-50 degrees, 30-60 degrees, and 20-70 degrees, for example. 
     With continued reference to  FIGS.  25 - 26   , the contour of the lower edge  774  has a generally rounded shape  924  at the bottom  940 , which the present inventors have identified to be advantageous in that if the bottom  940  catches the propeller in the middle of the blade, the rounded contour allows the propeller to slide past to catch the next blade. 
     Likewise, a thickness  922  between the inside  763  and the outside  765  varies between the upper edge  772  and the lower edge  774 . The thickness  922  is greatest at a shelf  916  that extends away from the inside surface  763  by a distance  918  (here at an angle  942  of 90 degrees, though other angles are contemplated by the present disclosure). The thickness  922  then decreases in a generally linear manner after a point  932  until reaching a minimum thickness  922  near the bottom  940 . The area  938  formed by this decreasing thickness  922  is where the propeller blade contacts the arm  760  to slowly stop the propeller from rotating and gently ease the propeller into position aligned with the base. In certain examples, the area  938  is generally flat and at a 30-60 degree angle to the outside  765  (e.g., 45 degrees), but other angles are also contemplated by the present disclosure. 
     With continued reference to  FIGS.  25 - 26   , a length of the arm  760  between the first end  762  and second end  764  is divided into a first section  906  where the opening  766  is located, a second section  910  where the shelf  916  is located, and a third section  908  that transitions therebetween. In the example shown, the third section  908  begins with a thickness  914  that is less than the distance  918  of the shelf  916 , but that then decreases generally linearly after a point  936  to a minimum thickness  912  near the opening  766 . This design, and the third section  908  in particular, includes ribs and/or lattice structures to ensure strength for the arm  760  between the first section  906  and second section  910 . 
     The shelf  916  is configured to be lifted by the blade of the propeller (when the propeller is properly aligned) as the shaft pivots towards the stowed position. In other words, the arm  760  is lifted at least partially into the base  40  ( FIG.  11   ) via the shelf  916  by the propeller. In certain examples, the shelf  914  has a transition  934  from the point  936  where the third section  908  meets the second section  910  to the full distance  918  of the shelf  916 , which helps position the propeller and avoid sharp corners for the arm  760 . The present inventors have recognized that the length of the second section  910  must be long enough that the shelf  916  does not fall off the blade of the propeller, which would allow the arm  760  to pivot downwardly out of the base  40  when the propulsor is stowed. In certain examples, the length of the second section  910  is approximately half of the length of the first section  906  and third section  908  combined (though other ranges such as 40%, or anything greater than 0%, are also contemplated by the present disclosure). 
       FIGS.  14 - 16    depict another example of alignment device  750  for aligning a propeller  284  within a mounting base  40 . This alignment device  750  functions similarly to the alignment device  750  of  FIGS.  11 - 13   , but now engages the propeller  284  near its hub  285  rather than engaging the blades  287 . As shown in  FIG.  14   , an opening is provided through a face  782  of the hub  285 , through which the propeller  284  is coupled to the motor  282  via fastening hardware  271  as conventionally known in the art. A hub ramp  780  extends away from the face  782  of the hub  285 . The hub ramp  780  has an aligning face  786  that rises from a lower height  788  above the face  782  to an upper height  790  above the face  782  (here between two lower heights  788  and two upper heights  790  in one rotation of the propeller  284 ). A stop wall  792  is defined between an upper height  790  and the lower height  788  adjacent thereto, which again increases to an upper height  790  in a ramped manner. 
     As shown in  FIG.  15   , a guide  800  is coupled to the mounting base  40  and engages with the ramp hub  780  to align the propeller  284  (and/or stop rotation when aligned) within the mounting base  40  similar to the arm  760  and current sensor  720  described above. The guide  800  has a first end  802  and second end  804 , the second end  804  having a distance  806  from the first end  802 . The guide  800  has a base  810  coupled to the mounting base  40 , as well as a member  812  near the second end  804  that is resiliently coupled to the base  810  via resilient members, for example springs  814 . Fingers  816  extend downwardly from the member  812  to tips  818 , which in the present example have inwardly tapering sides  820  going down to the tips  818 . The fingers  816  are configured to engage with the hub ramp  780  of the propeller  284 . 
       FIG.  15    shows the guide  800  in a neutral position with the propeller  284  not aligned within the mounting base  40 . The guide  800  is non-rotatable relative to the mounting base  40 . As the propulsor  270  continues to pivot upwardly toward the stowed position, the fingers  816  and particularly the tips  818  thereof contact the aligning face  786  of the hub ramp  780 , here with the tips  818  contacting the aligning face  786  substantially near the upper height  790 . As the propulsor  270  continues to pivot upwardly, the engagement between the fingers  816  and hub ramp  780  cause the propeller  284  to rotate such that the fingers  816  slide along the aligning face  786  of the hub ramp  780  toward the lower heights  788  thereof, which are configured to coincide with the propeller  284  being aligned within the mounting base  40 . As shown in  FIG.  16   , the rotation of the propeller  284  by the guide  800  stops when the fingers  816  contact the stop walls  792  of the hub ramp  780 . Specifically, the stop walls  792  are substantially steep such that the fingers  716  do not jump upwardly from the aligning face  786  to permit further rotation of the propeller  284 . 
     In the example shown in  FIG.  16   , further pivoting of the propulsor  270  upwardly no longer causes rotation of the propeller  284 , but now causes compression of the springs  814  coupling the fingers  816  coupled to the member  812  to the base  810  of the guide  800 . This provides that the propeller  284  is aligned within the mounting base  40  before the propeller  284  could potentially contact the bottom  45  of the sides  44  of the mounting base  40 . This further provides that, once aligned, the propeller  284  is maintained in alignment while the propulsor  270  is permitted to be further retracted within the mounting base  40  through compression of the springs  814 . 
       FIGS.  17  and  18    depict another example of an alignment device  750  according to the present disclosure. In this example, the alignment device  750  includes a guide  800  having similarity to that described for  FIGS.  15  and  16   , but wherein the member  812  and finger  816  are replaced with blade catchers  830 . Each of the blade catchers  830  extends from a first end  831  to a second end  833 , and a top  832  to a bottom  834 . An opening  836  is provided in each second end  833 , which extends inwardly to a backstop  838 . In the present example, the opening  836  converges in a “V” shape such that the backstop  838  has a shorter height (in the top  832  and bottom  834  direction) than the opening  836  at the second end  833 . 
     The blade catchers  830  are shaped to engage with the blades  287  of the propeller  284  as the propeller  284  rotates, specifically with the edges  283  of the blades  287  being caught within the openings  836 . The propeller  284  rotates while the propulsor  270  pivots toward the stowed position until the blades  287  are captured and retained within the openings  236  of the blade catchers  238 , thereby ceasing rotation of the propeller  284  (e.g., through use of the current sensor  720  discussed above). Further pivoting of the propulsor  270  toward the stowed position after the blades  287  are retained within the blade catchers  830  is permitted by the blade catchers  830  being coupled to the guide  800  via springs  814 , which compress until the propulsor  270  finally reaches the stowed position (similar to the example of  FIGS.  15 - 16   ). 
       FIGS.  19  and  20    depict another alignment device  750  for aligning a propeller  284  within a mounting base  40 . This alignment device  750  includes an arm  850  that extends between a first end  851  and second end  853 , here with a bend  864  therebetween. An opening  856  is defined near the first end  851 , which receives a fastener  858  for retaining the arm  850  between the sides  44  of the mounting base  40 . A member  860  extends downwardly from the arm  850  near the first end  851  and is configured to pivot with the arm  850  about the opening  856  such that the arm  850  is a ridged component. A member  861  is also provided between the sides  44  of the mounting base  40 , coupled thereto via fasteners  862  such as screws, bolts, or other fastening techniques known in the art. As shown in  FIG.  20   , the arm  850  is permitted to pivot in the upward direction, but is limited from pivoting further clockwise (or downward) via contact between the member  860  and the member  861 . 
     A plate  870  is coupled near the second end  853  of the arm  850 , for example via fasteners  872  such as bolts or screws. It should be recognized that other fastening techniques are also suitable, including welding, adhesives, and/or the like. A pin  874  extends downwardly from the plate  870  between a base  876  and a tip  878 . In certain examples, the pin  874  is rigidly coupled to the plate  870 . In other examples, the pin  874  extends through an opening in the plate  870  and is biased downwardly by a spring positioned between the base  876  of the pin  874  and the plate  870 . 
     As shown in  FIGS.  19 - 20   , an opening  784  is provided within the face  782  in the hub  285  of the propeller  284 , in this example two openings  784  generally aligned with the midpoint of the blade faces  281  of the blades  287 . The alignment device  750  is configured such that as a propeller  284  rotates while the propulsor  270  is pivoted toward the stowed position, the tip  878  of the pin  874  extending downwardly from the arm  850  skates along the face  782  of the hub  285  until coming into alignment with the opening  784 . Once aligned, the pin  874  enters the opening  784  in the hub  285 , either through the mass of the arm  850  or the biasing of the pin  874  downwardly. In this manner, the arm  850  is permitted to pivot in the counterclockwise direction relative to that shown in  FIG.  20    while the pin  874  skids along the face  782  of the hub  285 , but returns to the position shown in  FIG.  20    once the pin  874  is received within the opening  784  of the hub  285 . Once the pin  874  is received within the opening  784  (corresponding to alignment of the propeller  284 ), the motor  282  is stopped, for example using the current sensor  720  discussed above. 
     It should be recognized that while the description above includes examples of alignment devices  750  in which physical contact is made with the propeller  284 , other configurations of the elements that make this physical contact are also contemplated by the present disclosure. For example, the arm  760  of  FIGS.  11 - 12   , fingers  816  of  FIG.  15   , blade catcher  830  of  FIG.  18   , pin  874  of  FIG.  20    (for example) may be provided in differing qualities, have a different shapes, be mounted in a different positions, be configured to have resilient or flexible properties, and/or the like. 
       FIGS.  21  and  22    depict another alignment device  750  for aligning the propeller  284  within the mounting base  40 . The guide  800  is similar to that previously shown in  FIGS.  15  and  16   , including a member  812  coupled to a base  810  via springs  814  and separated by a variable distance  806 . In this alignment device  750 , base magnets  892 A and  892 B extend downwardly from the member  812  in a similar manner to the fingers  816  of  FIGS.  15  and  16   . Similarly, hub magnets  894 A and  894 B are retained within hub recesses  896  defined in the face  782  of the hub  285 . The hub magnets  894 A and  894 B are aligned with the blades  287  such that when the polarities of the base magnets  892 A and  892 B and hub magnets  894 A and  894 B are oppositely aligned (in other words, a north pole is aligned with a south pole, and vice versa), the propeller  284  is aligned within the mounting base  40 . 
     The base magnets  892 A and  892 B and hub magnets  894 A and  894 B are coupled to a control system  600  and serve as a propeller position sensor  730  (for example, a Hall-effect sensor presently known in the art). In other words, by knowing the geometry and placement of the guide  800  and it&#39;s base magnets  892 A and  892 B, the base magnets  892 A and  892 B and hub magnets  894 A and  894 B may be used to determine the rotational position of the propeller  284  relative to the mounting base  840 . In this manner, the propeller  284  may be stopped from rotating when the propeller position sensor  730  determines that the blades  287  are in alignment with the mounting base  840 . 
     In certain examples, the current generated by the hub magnets  894 A and  894 B passing by the base magnets  892 A and  892 B can be read as a propeller position sensor  730 , and/or the attraction and repulsion therebetween sensed as changes to the current drawn by the motor  282  to overcome the magnetic forces. As discussed above, this can be detected by the current sensor  720  to command the motor  282  to stop rotating. 
     Once the propeller  284  is aligned within the mounting base  840 , the springs  814  permit the member  812  to be compressed toward the base  810 , allowing the propeller  284  to be further retracted into the mounting base  40  as shown in  FIG.  22   . 
     In this manner,  FIGS.  21  and  22    exemplifies that the alignment devices and methods for aligning the propeller according to the present disclosure are not limited to having elements that come into physical contact with the propeller  284  (such as the examples of  FIGS.  11 - 20   ). In other words, the alignment device may be comprised of a control system using one or more sensors, with or without elements that physically contact the propeller. In addition to the sensors described above, the alignment device may also or alternatively include limit switches, capacitive and/or resistive sensors, encoders (e.g., in conjunction with the actuator  240  or within the pivot rotation device  150 ), optical sensors, and/or other positional detection mechanisms presently known in the art to detect the position of the shaft  230  and propulsor  270  and/or control rotation of the propeller  284  as the propulsor  270  moves towards the stowed position, for example. 
     The functional block diagrams, operational sequences, and flow diagrams provided in the Figures are representative of exemplary architectures, environments, and methodologies for performing novel aspects of the disclosure. While, for purposes of simplicity of explanation, the methodologies included herein may be in the form of a functional diagram, operational sequence, or flow diagram, and may be described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance therewith, occur in a different order and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology can alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all acts illustrated in a methodology may be required for a novel implementation. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. Certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have features or structural elements that do not differ from the literal language of the claims, or if they include equivalent features or structural elements with insubstantial differences from the literal languages of the claims.