Patent Publication Number: US-11661163-B1

Title: Outboard motors having steerable lower gearcase

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 16/796,388, filed Feb. 20, 2020, now U.S. Pat. No. 11,130,552, which &#39;388 application is a continuation of U.S. application Ser. No. 16/171,490, filed Oct. 26, 2018, now U.S. Pat. No. 10,800,502, issued Oct. 13, 2020. Both applications are hereby incorporated by reference in their entirety. 
    
    
     FIELD 
     The present disclosure relates to outboard motors, and more particularly to outboard motors having a lower gearcase that is steerable with respect to a powerhead. 
     BACKGROUND 
     The following U.S. Patents are incorporated herein by reference in entirety: 
     U.S. Pat. No. 5,224,888 discloses a boat outboard propulsion assembly having an engine mounted on an engine support which, in turn, is secured to a swivel bracket adapted to be secured to a transom of a boat. Between the engine support and the engine, a steering bracket is provided which is attached to a propulsion unit that is pivotally supported by the engine support such that steering of the boat is accomplished by pivoting of the propulsion unit while the engine remains fixedly secured relative to the swivel bracket. The output drive shaft of the engine extends through the steering bracket and is connected to the propulsion unit. Engine exhaust gases are channeled through the steering bracket and the propulsion unit. 
     U.S. Pat. No. 5,487,687 discloses an outboard marine drive having a midsection between the upper powerhead and the lower gear case and having a removable midsection cowl assembly including first and second cowl sections. The midsection housing includes an oil sump in one embodiment and further includes an exhaust passage partially encircled by cooling water and partially encircled by engine oil for muffling engine exhaust noise. The midsection housing also has an oil drain arrangement providing clean oil draining while the outboard drive is mounted on a boat and in the water. 
     U.S. Pat. No. 6,183,321 discloses an outboard motor having a pedestal that is attached to a transom of a boat, a motor support platform that is attached to the outboard motor and a steering mechanism that is attached to both the pedestal and the motor support platform. A hydraulic tilting mechanism is attached to the motor support platform and to the outboard motor. The outboard motor is rotatable about a tilt axis relative to both the pedestal and the motor support platform. A hydraulic pump is connected in fluid communication with the hydraulic tilting mechanism to provide pressurized fluid to cause the outboard motor to rotate about its tilting axis. An electric motor is connected in torque transmitting relation with the hydraulic pump. Both the electric motor and the hydraulic pump are disposed within the steering mechanism. 
     U.S. Pat. No. 6,402,577 discloses a hydraulic steering system in which a steering actuator is an integral portion of the support structure of a marine propulsion system. A steering arm is contained completely within the support structure of the marine propulsion system and disposed about its steering axis. An extension of the steering arm extends into a sliding joint which has a linear component and a rotational component which allow the extension of the steering arm to move relative to a moveable second portion of the steering actuator. The moveable second portion of the steering actuator moves linearly within a cylinder cavity formed in a first portion of the steering actuator. 
     U.S. Pat. No. 7,244,152 discloses an adapter system provided as a transition structure which allows a relatively conventional outboard motor to be mounted to a pedestal which provides a generally stationary vertical steering axis. An intermediate member is connectable to a transom mount structure having a connector adapted for mounts with central axes generally perpendicular to a plane of symmetry of the marine vessel. Many types of outboard motors have mounts that are generally perpendicular to this configuration. The intermediate member provides a suitable transition structure which accommodates both of these configurations and allows the conventionally mounted outboard motor to be supported, steered, and tilted by a transom mount structure having the stationary vertical steering axis and pedestal-type configuration. 
     U.S. Pat. No. 8,246,398 discloses an outboard marine motor including an upper case enclosing an engine and a lower case fitted with a propeller and connected to a lower end of the upper case. The lower case is configured to be turned relative to the upper case around a vertical axial line. The power of the engine is transmitted to the propeller via a vertical drive shaft which is coaxial with the vertical axial line. Thereby, the outboard marine motor can be steered simply by turning the lower case. 
     U.S. Pat. No. 9,475,560 discloses an outboard motor having an internal combustion engine, and an adapter plate having an upper end that supports the engine and a lower end formed as a cylindrical neck. A driveshaft housing has an integral oil sump collecting oil that drains from the engine and through the adapter plate neck. One or more bearings couple the adapter plate neck to the oil sump such that the driveshaft housing is suspended from and rotatable with respect to the adapter plate. A driveshaft is coupled to a crankshaft of the engine, and extends along a driveshaft axis through the adapter plate neck, bearing(s), and oil sump. A steering actuator is coupled to and rotates the oil sump, and thus the driveshaft housing, around the driveshaft axis with respect to the adapter plate, which varies a direction of the outboard motor&#39;s thrust. 
     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. 
     In certain examples disclosed herein, an outboard motor has a powerhead that causes rotation of a driveshaft; a steering housing located below the powerhead, wherein the driveshaft extends from the powerhead into the steering housing; and a lower gearcase located below the steering housing and supporting a propeller shaft that is coupled to the driveshaft so that rotation of the driveshaft causes rotation of the propeller shaft. The lower gearcase is steerable about a steering axis with respect to the steering housing and powerhead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The present disclosure is described with reference to the following Figures. The same numbers are used throughout the Figures to reference like features and like components. 
         FIG.  1    is a perspective view of a driveshaft housing, steering housing and lower gearcase of an outboard motor according to a first embodiment of the present disclosure. 
         FIG.  2    is a perspective view looking down at a steering housing of the first embodiment. 
         FIG.  3    is an exploded view showing the steering housing, steering actuator, and a steering column according to the first embodiment. 
         FIG.  4    is a view of section 4-4, taken in  FIG.  2   . 
         FIGS.  5  and  6    are top views of the first embodiment, via section  4 - 4 , showing steering motions of the lower gearcase with respect to the steering housing. 
         FIG.  7    is a perspective view looking down at a steering housing of an outboard motor according to a second embodiment. 
         FIG.  8    is an exploded view looking showing the steering housing, steering actuator and a steering column according to the second embodiment. 
         FIG.  9    is a view of section 9-9, taken in  FIG.  7   . 
         FIG.  10    is a view of section 10-10, taken in  FIG.  1   , showing flow of exhaust gas and cooling water through the lower gearcase and steering housing of the first embodiment. 
         FIG.  11    is a partial sectional view showing flow of the exhaust gas and cooling water through the steering housing of the first embodiment. 
         FIG.  12    is an exploded view showing a lower side of the steering housing and a top side of the lower gearcase, and showing flow of the exhaust gas and cooling water from the lower gearcase to the steering housing. 
         FIGS.  13  and  14    are top views showing flow of the exhaust gas and cooling water between the lower gearcase and steering housing. 
     
    
    
     DETAILED DESCRIPTION 
     Conventional outboard motors typically are steerable about a steering axis with respect to a marine vessel so as to change the direction of thrust produced by the outboard motor and thereby vary the direction of travel. In addition, conventional outboard motors typically are tilt-able (trim-able) about a horizontal trim axis so as to redirect the direction of thrust upwardly or downwardly and thereby vary the attitude of the marine vessel in the water. Examples of such configurations are disclosed in the above-incorporated U.S. patents. 
     During research and development, the present inventors have identified that a current trend in the marketplace is to provide outboard motors having a relatively large size, particularly in the area of the powerhead. This is to meet consumer demand for more power. This trend presents challenges for boat designers and boat owners because the available design-space for mounting outboard motors on marine vessels is relatively small. When installing new larger-sized outboard motors on a marine vessel, designers and owners often want to use existing mounting locations on the transom of the marine vessel. However the distance between the centerlines of these mounting locations is often only about twenty-six inches, which may not provide enough room for turning, tilting, and trimming movements of larger-sized outboard motors, especially in multiple-outboard-motor configurations. When an operator of a marine vessel steers two or more adjacent larger-sized outboard motors about their steering axes, the outboard motors may collide. Such interference can also be incurred when the outboard motors are tilted or trimmed about their horizontal trim axes. 
     Additionally, some consumers wish to install four or more outboard motors on a marine vessel. Marine vessels are generally limited in overall width for a number of reasons, and fitting this many outboard motors on a single transom can be difficult, especially when their respective powerheads are large. Other cases where outboard motors have the potential to interfere with one another include marine vessels having less than twenty-six-inch mounting centerlines, or in cases where V-shaped engines (especially in the two hundred-plus horsepower range) are used. V-Shaped engines are often significantly wider than inline engines. Additionally, it would be desirable to be able to mount smaller engines (such as inline six-cylinder engines) on centerlines that are less than twenty-six inches from one another. 
     Further, the present inventors have identified that as outboard motors are designed with larger size, the distance of the larger mass and center of gravity of the outboard motor from the transom, and more importantly from the steering axis, can have a negative effect on handling. In outboard motor configurations, the mass of the powerhead is attached to the steering rudder by which steering is controlled. Any compliance and/or unwanted motion in the steering through the steering components, structure, and isolation mounts is magnified by the attached mass. 
     The present inventors determined that the above-described problems could be overcome by providing outboard motor configurations wherein the powerhead remains stationary while the gearcase and associated rudder is steered. This permits less powerhead motion during steering, allows closer mounting of the outboard to the transom, and maintains a large portion of the mass separated from steering motions. This allows the steering axis to be ideally positioned with respect to the gearcase and rudder, independent of the center of gravity of the outboard motor. The present disclosure is a result of the present inventors&#39; efforts to overcome design challenges related to these configurations. 
       FIGS.  1 - 6  and  10 - 14    depict a first embodiment of an outboard motor  20  having a powerhead (shown schematically at  22  in  FIG.  1   ), which for example can include an internal combustion engine and/or any other conventional mechanism for causing rotation of an axially extending driveshaft  24 . The driveshaft  24  extends into a driveshaft housing  26  located below the powerhead  22 . Optionally, the driveshaft housing  26  contains a sump for containing oil or similar lubricant for the noted internal combustion engine. Optionally the driveshaft  24  is connected to a transmission for engaging forward, reverse and neutral gear positions of the outboard motor  20 . Optionally, the driveshaft housing also includes mounting locations  23  for mounting the outboard motor  20  to a supporting cradle that is coupled to a transom bracket and/or the like, for supporting the outboard motor  20  with respect to the transom of a marine vessel. The type and configuration of the driveshaft housing  26  is merely exemplary and can vary from what is shown. 
     Referring to  FIGS.  1  and  2   , a novel steering housing  28  is located below the driveshaft housing  26 . The steering housing  28  is a generally oblong member having a main body  29  and upper and lower perimeter mounting flanges  30 ,  31  (see  FIG.  2   ). The upper perimeter mounting  30  is fixed to the lower perimeter of the driveshaft housing  26  by bolts (not shown) engaged in bolt holes  34 . The bolts and bolt holes  34  are spaced apart around the upper perimeter mounting  30 , as shown, so that the steering housing  28  and driveshaft housing  26  remain securely fixed together. A center-column  35  defining a through-bore  36  (see  FIG.  3   ) axially extends from top to bottom through the steering housing  28 . The driveshaft  24 , itself or via an extension member, axially-extends through the through-bore  36 . In the illustrated example, the center-column  35  and through-bore  35  are generally cylindrical and contain a bearing arrangement for supporting steering of the outboard motor  20 , as will be further described herein below. 
     Referring to  FIGS.  1  and  10   , the outboard motor  20  also has a lower gearcase  38 , which is located below the steering housing  28  and supports one or more laterally extending propeller shafts (the location of which is shown via dashed lines  40  in  FIG.  10   ). The illustrated example requires a pair of counter-rotating propeller shafts; however arrangements with only one propeller shaft could also be employed. The propeller shafts are coupled to the driveshaft  24 , for example directly thereto or via an axial extension thereof, by a conventional angled gearset (the location of which is also shown by dashed lines  42 ). The angled gearset is configured in the usual way so that rotation of the driveshaft  24  about its own axis causes counter rotation of the propeller shafts about their own laterally extending axes. Counter-rotating propellers  43  are mounted on the pair of propeller shafts, respectively, so that rotation of the propeller shafts  40  causes rotation of the propellers  43 . Rotation of the propellers  43  generates thrust forces in water, all as conventional. 
     Referring to  FIGS.  1 ,  3 ,  5  and  6   , the lower gearcase  38  is a housing that is steerable about a steering axis  44  with respect to the steering housing  28  and powerhead  22 . In the illustrated example, the steering axis  44  is coaxial with the driveshaft  24 . A steering column  46  ( FIG.  3   ) is fixed to the top of the lower gearcase  38  and extends upwardly into the bottom of the steering housing  28 . The steering column  46  is an elongated member having a center column  48  that extends upwardly from a lower perimeter mounting flange  50 . A through-bore  52  extends through the center column  48  and defines an open interior in the center column  48 . The driveshaft  24  extends through the open interior of the center column  48 , into the lower gearcase  38 , and into engagement with the noted propeller shafts via the noted angle gearset. 
     Referring to  FIGS.  1 ,  10 , and  12   , a gearcase cover  54  is fixed to the top of the lower gearcase  38 . Optionally, the gearcase cover  54  is a plate member that is separate component from the lower gearcase  38 . The lower perimeter mounting flange  50  of the steering column  46  is coupled to the gearcase cover  54  via bolts (not shown). The bolts extend through bolt-holes  53  ( FIG.  3   ) formed through the lower perimeter mounting flange  50  on the steering column  46  and through the gearcase cover  54 , respectively, and fix the gearcase cover  54  with respect to the lower gearcase  38  so that the lower gearcase  38 , gearcase cover  54  and steering column  46  rotate together with respect to the steering housing  28 . The manner in which the steering column  46  is fixed to the top of the lower gearcase  38  can vary from what is shown and described. 
     Referring to  FIGS.  3  and  4   , a steering actuator  56  is configured to rotate the steering column  46  together with lower gearcase  38  with respect to the steering housing  28  and powerhead  22 . The type and configuration of the steering actuator  56  can vary, as will become apparent from the second embodiment described herein below with reference to  FIGS.  7 - 9   . In the example shown in  FIGS.  3  and  4   , the steering actuator  56  is a hydraulically-actuated mechanism which is controlled by a supply of hydraulic fluid from a conventional hydraulic pump  58 . The steering actuator  56  has an elongated cylinder  60  to which the pump  58  provides a pressurized supply of hydraulic fluid. In this example, the elongated cylinder  60  is formed in the main body  29  of the steering housing  28  and particularly through opposing sidewalls  19  on opposite sides of the steering housing  28 , as shown. The steering actuator  56  further has an elongated piston  62  that is located in the cylinder  60 . The piston  62  has radially outer seals  63  that seal with the radially inner sidewalls of the cylinder  60  so as to define opposing fluid chambers  67  in the cylinder  60 . The piston  62  is movable (i.e., slide-able) back and forth in the cylinder  60  under pressure from the hydraulic fluid provided by the pump  58 . End caps  64  are mounted on sidewalls  19  of the steering housing  28  contain the hydraulic fluid in the respective fluid chambers  67  of the cylinder  60 . Opposing inlets  66  are formed in the cylinder  60  and couple the fluid chambers  67  to the pump  58  so that the pump  58  can supply the hydraulic fluid under pressure to opposite sides of the cylinder  60  and thereby cause the piston  62  to forcibly move back and forth in the cylinder  60 . 
     In the example shown in  FIGS.  3  and  4   , the steering actuator  56  is operably coupled to the steering column  46  by a rack and pinion  68 , which in this example includes sets of teeth  70 ,  72  on the piston  62  and the center column  48  of the steering actuator  56 , respectively. The sets of teeth  70 ,  72  are meshed together so that back-and-forth movement of the piston  62  within the cylinder  60  causes the teeth  70  on the piston  62  to move teeth  72  on the center column  48 , which in turn causes corresponding back-and-forth rotational movement of the center column  48  about the steering axis  44 . Thus, operation of the steering actuator  56  causes the rack and pinion  68  to rotate the steering column  46  together with the lower gearcase  38  about the steering axis  44  with respect to the steering housing  28  and powerhead  22 . The supply of pressurized hydraulic fluid from the pump  58  to the cylinder  60  can be controlled by a conventional valve arrangement and a conventional operator input device for controlling steering movement of an outboard motor, such as a steering wheel, joystick, and/or the like, all as is conventional. 
     Referring to  FIGS.  3 ,  8 , and  10   , upper and lower bearings  74 ,  76  facilitate smooth rotational movement of the steering column  46  and lower gearcase  38  with respect to the steering housing  28 . The upper bearings  74  are located above the rack and pinion  68  between a top end cap  82  having an outer perimeter seal  99  and outer upper bearing surface  69  ( FIG.  3   ) on the steering column  46 , and an inner upper bearing surface  81  ( FIG.  10   ) on the center-column  35  in the steering housing  28 . The lower bearings  76  are located below the rack and pinion  68  and between a lower outer bearing surface  71  ( FIG.  3   ) on the steering column  46  and a lower inner bearing surface  85  ( FIG.  10   ) in the on the center-column  35 . Outer perimeter seals  97  are disposed on a lower sealing surface  97  on the steering column  47 . A seal cap  93  ( FIG.  3   ), is disposed on top of the top end cap  82 . The upper and lower bearings  74 ,  76  surround the steering column  46  and are located radially between the steering column  46  and the inner perimeter of the through-bore  36  in the steering housing  28 . The type and configuration of the upper and lower bearings  74 ,  76  can vary from what is shown. In the illustrated example, the upper and lower bearings  74 ,  76 , each comprise inner and outer races containing tapered roller bearings that extend transversely (angular) with respect to the steering axis  44 . The top end cap  82  is coupled to the top of the steering column  46  by bolts  83  ( FIG.  3   ) and retains the upper bearings in place. 
       FIGS.  5  and  6    depict steering motions of the lower gearcase  38  with respect to the steering housing  28 . In  FIG.  5   , the noted operator input device controls the pump  58  to supply pressurized hydraulic fluid to the port side chamber  67 , which forces the piston  62  to slide to the starboard side, as shown by arrows. Starboard movement of the piston  62  causes the rack and pinion  68  to rotate the steering column  46  and lower gearcase  38  with respect to the steering housing  28 , as shown by the arrow. In  FIG.  6   , the noted operator input device controls the pump  58  to supply pressurized hydraulic fluid to the starboard side chamber  67 , which forces the piston  62  to slide to the port side, as shown by the arrow. Port movement of the piston  62  causes the rack and pinion  68  to rotate the steering column  46  and lower gearcase with respect to the steering housing  28 , as shown by the arrow. 
       FIGS.  7 - 9    depict a second embodiment of the outboard motor  20 . Many features that are the same or similar to the first embodiment have like reference numbers in the figures. The second embodiment differs from the first embodiment in that the steering actuator  56  is mounted to an outer surface of the main body  29  of the steering housing  28  by bolts  59 , rather than being formed with the main body  29 . Mounting flanges  57  outwardly extend on top and bottom of the outer surface and help retain the steering actuator  56  in place. Further, the steering actuator  56  is coupled to the steering column  46  by a yoke  100  and trunnion  102  instead of the rack and pinion  68 . The yoke  100  is coupled to the steering column  46  via mated radially-oriented and axially-extending splines  104  disposed on the outer diameter of the steering column  46  and around an inner perimeter of the body  106  of the yoke  100 . The yoke  100  has an arm  108  that protrudes from the body  106  via a through-bore in the outer surface of the steering housing  28  and into a rotatable cylinder  110  of the trunnion  102 . The body  101  of the trunnion  102  is located in the middle of opposing piston halves  62   a ,  62   b . Referring to  FIG.  9   , movement of the piston  62   a ,  62   b  in the cylinder  60  (as described herein above) causes movement of the trunnion  102 , via the arm  108  and rotatable cylinder  101 , movement of the trunnion  102  causes rotation of the steering column  46 , which in turn causes rotation of the lower gearcase  38 , as shown. Thus, operation of the steering actuator  56  causes the yoke  100  and trunnion  102  to rotate the steering column  46  and lower gearcase  38  about the steering axis  44  with respect to the steering housing  28  and powerhead  22 . 
     The above-described embodiments thus provide novel outboard motor configurations in which the powerhead remains stationary during steering motion of the lower gearcase and associate rudder. 
     During further research and experimentation, the present inventors have determined that outboard motor configurations having a steerable lower gearcase present challenges with respect to conveyance of cooling water from the lower gearcase to the powerhead and conveyance of exhaust gas from the powerhead to the lower gearcase. Particularly, the present inventors have identified challenges with respect to how to efficiently and effectively convey the cooling water and the exhaust gas between two components that rotate relative to each other. The present disclosure provides results of the present inventors&#39; efforts to overcome these challenges. 
     Referring now to  FIGS.  10 - 13   , an elongated exhaust conduit  200  conveys exhaust gas from the powerhead  22  through the steering housing  28  and into the lower gearcase  38  for discharge from the outboard motor  20 , for example via passageways  17  in the hubs of the propellers  43 . Referring to  FIG.  10   , the exhaust conduit  200  has a first exhaust conduit portion  202  that conveys the exhaust gas through the steering housing  28 , a second exhaust conduit portion  204  that conveys the exhaust gas from the steering housing  28  to the lower gearcase  38 , and a third exhaust conduit portion  206  that conveys the exhaust gas through the lower gearcase  38  for discharge from the outboard motor  20 . The exhaust gas flows from upstream to downstream, and more specifically from the first exhaust conduit portion  202  to the second exhaust conduit portion  204 , and then to the third exhaust conduit portion  206 . The configuration of the first, second and third exhaust conduit portions  202 ,  204 ,  206  can vary from what is shown and described. 
     In the illustrated example, the first exhaust conduit portion  202  is integrally formed with the steering housing  28  but is located aftwardly of the main body  29  so that a gap  201  exists there between. The first exhaust conduit portion  202  has an upstream end  207  that receives the exhaust gas from an exhaust tube  209  ( FIG.  1   ) located aftwardly of the driveshaft housing  26  (see  FIG.  1   ), a transversely extending middle portion  211  that curves forwardly from the upstream end  207  towards the main body  29 , and a downstream end  208  that discharges the exhaust gas to the second exhaust conduit portion  204 . Thus, via the first exhaust conduit portion  202 , the exhaust gas flows downwardly and forwardly relative to the main body  29  of the steering housing  28 , as shown by arrows. 
     The second exhaust conduit portion  204  annularly extends all the way around the steering column  46  (see  FIG.  12   ). Generally, the second exhaust conduit portion  204  has an upstream end  210  (see  FIG.  10   ) that receives the exhaust gas from the first exhaust conduit portion  202  and a downstream end  212  (see  FIG.  12   ) that discharges the exhaust gas to the third exhaust conduit portion  206 . As further described herein below and shown in  FIGS.  13  and  14   , the downstream end  208  of the first exhaust conduit portion  202  and the upstream end  210  of the second exhaust conduit portion  204  advantageously remain connected as the lower gearcase  38  is steered about the steering axis  44  with respect to the steering housing  28 . 
     As shown in  FIGS.  10  and  11   , the downstream end  208  of the first exhaust conduit portion  202  axially overlaps with the upstream end  210  of the second exhaust conduit portion  204 . Referring to  FIG.  12   , the bottom of the steering housing  28  has concentric radially inner and outer annular sidewalls  213 ,  215  that extend downwardly from a bottom face  217  of the steering housing  28  and around an entire periphery of the through-bore  36 . Corresponding concentric radially inner and outer annular sidewalls  219 ,  221  extend upwardly from the gearcase cover  54  and around an entire periphery of the through-bore  36 . The annular sidewalls  219 ,  221  radially overlap and rotate with respect to the annular sidewalls  213 ,  215  (see e.g.,  FIG.  10   , reference numbers omitted) during steering of the lower gearcase  38  with respect to the steering housing  28 . Thus, the second exhaust conduit portion  204  forms an annular channel  216  around the steering column  46 , through which the exhaust gas can travel as the exhaust gas is conveyed to the third exhaust conduit portion  206 , and as the lower gearcase  38  is steered about the steering axis  44  and with respect to the steering housing  28 . The upstream end of the  210  of the second exhaust conduit portion  204  is defined by the annular open top end of the annular channel  216  (see  FIG.  12   ). The annular channel  216  is defined by the annular sidewalls  213 ,  215 , bottom face  217 , and an opposing top face  218  of the top of the gearcase cover  54 . 
     Referring to  FIGS.  10  and  11   , O-ring seals  214  are radially disposed between the annular sidewalls  213  and  219  and  215  and  221 , respectively. The O-ring seals  214  advantageously maintain a fluid tight seal between the respective sidewalls, and thus between the first and second exhaust conduit portions  202  and  204 , and between the second and third exhaust conduit portions  206  and  206 , as the lower gearcase  38  is steered with respect to the steering housing  28 . During steering movements, the downstream end  208  of the first exhaust conduit portion  202  advantageously rotates peripherally along the annular channel  216  (see  FIGS.  13  and  14   ) so that the exhaust gas is discharged to the second exhaust conduit portion  204  at a peripheral location along the annular channel  216  that varies depending upon the steering position of the lower gearcase  38  with respect to the steering housing  28 . The downstream end  212  of the second exhaust conduit portion  204  is defined by a bore  222  (see  FIG.  12   ) axially extending through the top face  218  along the aftward side of the driveshaft  24 . The bore  222  conveys the exhaust gas to the third exhaust conduit portion  206  for discharge from the outboard motor  20 , as shown in  FIG.  10   . 
     Thus, exhaust gas is conveyed from the powerhead  22  and for discharge from the outboard motor  22  via the exhaust conduit  200  as follows: The exhaust gas is discharged from an exhaust manifold on the powerhead  22  to the exhaust tube  209 . The exhaust gas is discharged from the exhaust tube  209  to the first exhaust conduit portion  202 . From the first exhaust conduit portion  202 , the exhaust gas is discharged downwardly into the annular channel  216  at a location that will vary depending upon the steering position of the lower gearcase  38  with respect to the steering housing  28 . The exhaust gas can travel about the annular channel  216  to the bore  222  through which the exhaust gas is discharged to the third exhaust conduit portion  206 . From the third exhaust conduit portion  206 , the exhaust gas is laterally discharged via the passageways  17  in the propellers  43 . 
     Referring to  FIGS.  10  and  11   , a cooling water conduit  300  conveys cooling water from the lower gearcase  38  through the steering housing  28  and to the powerhead  22  for cooling of the powerhead  22  and/or other components of the outboard motor  20 . In general, the cooling water conduit  300  includes a first cooling water conduit portion  302  ( FIG.  10   ) that conveys the cooling water through the lower gearcase  38 , a second cooling water conduit portion  304  that conveys the cooling water out of the lower gearcase  38  and into the steering housing  28 , and third cooling water conduit portion  306  (see  FIG.  11   ) that conveys the cooling water through the steering housing  28  and for subsequent conveyance to the powerhead  22  and/or the other components of the outboard motor  20 . A cooling water pump  308 , which can be a conventional electrically-driven pump or mechanically-driven pump, generates a pumping force which, as described further herein below, draws the cooling water into the outboard motor  20  from the surrounding body of water in which the outboard motor  20  is being operated and pumps the cooling water upwardly in the outboard motor towards the powerhead  22 . The cooling water pump  308  thus causes the cooling water to flow from upstream to downstream through the cooling water conduit  300 . The location and configuration of the cooling water pump  308  can vary from what is shown. In the illustrated example, the cooling water pump  308  is located in a pump cavity  310 , which is defined in the steering housing  28 , alongside the center-column  35  of the steering housing  28 , and more particularly in direct fluid connection with the third cooling water conduit portion  306 . 
     Referring to  FIGS.  10  and  11   , the first cooling water conduit portion  302  has an upstream end  312  ( FIG.  10   ) that receives cooling water from the surrounding body of water via intake ports  314  located on opposite sides of the lower gearcase  38 . The first cooling water conduit portion  302  has a downstream end  316  located at the top of the lower gearcase  38  and configured to discharge the cooling water to the second cooling water conduit portion  304 , as further described herein below. The second cooling water conduit portion  304  has an upstream end  318  ( FIG.  11   ) that receives the cooling water from the downstream end  316  of the first cooling water conduit portion  302 , and a downstream end  320  that discharges the cooling water to the third cooling water conduit portion  306 . As further described herein below and shown in  FIGS.  13  and  14   , the downstream end  316  of the first cooling water conduit portion  302  and the upstream end  318  of the second cooling water conduit portion  304  advantageously remain connected as the lower gearcase  38  is steered about the steering axis  44  with respect to the steering housing  28 . 
     Referring to  FIGS.  10 - 14   , the downstream end  316  of the first cooling water conduit portion  302  axially overlaps with the upstream end  318  of the second cooling water conduit portion  204 . More particularly, as shown in  FIG.  12   , the bottom of the steering housing  28  has concentric radially inner and outer annular sidewalls  313 ,  213  that extend downwardly from the bottom of the steering housing  28  and around an entire periphery of the through-bore  36 . The annular sidewalls  313 ,  213  radially overlap and rotate with respect to sidewalls  219 ,  315  on the lower gearcase  38 , during steering of the lower gearcase  38  with respect to the steering housing  28 . Thus, the second cooling water portion  304  forms an annular channel  316  around which the cooling water can travel as it is conveyed by the second cooling water conduit portion  304  to the third cooling water portion  306 , and as the lower gearcase  38  is steered about the steering axis  44  and with respect to the steering housing  28 . The downstream end  316  of the first cooling water conduit portion  302  is defined by the annular open end  317  of the first cooling water conduit portion  304 . The annular channel  316  extends around an entire periphery of the driveshaft  24 . The downstream end  320  of the second cooling water conduit portion  304  is defined by a bore ( FIG.  11   ) on an aftward side of the driveshaft  24 . 
     Seals  214  advantageously maintain a fluid tight seal between the respective sidewalls, and thus between the first and second cooling water conduit portions  302  and  304  as the lower gearcase  38  is steered with respect to the steering housing  28 . Referring to  FIGS.  13  and  14   , during steering movements, the downstream end  316  of the first cooling water conduit portion  302  advantageously rotates along the annular channel  316  as that the cooling water is discharged to the second cooling water conduit portion  304  at a radial location along the annular channel  316  that varies depending upon the steering position of the lower gearcase  38  with respect to the steering housing  28 . 
     Thus, the cooling water conduit  300  extends from the lower gearcase  38  towards the powerhead  22 , and particularly around an entire periphery of the driveshaft  24 . Between the lower gearcase  38  and the powerhead  22 , the exhaust conduit  200  and the cooling water conduit  300  are concentric about the driveshaft  24 . Between the powerhead  22  and the lower gearcase  38 , the exhaust conduit  200  circumscribes the cooling water conduit  300 . 
     Optionally, the configurations shown and described herein above can have steering angular travel limited, for example to ±30°, via for example adjustable hard stops or electronic means. In certain examples, the gearcase can have the ability to turn up to ±47°. This permits the manufacturer of the outboard motor to produce and ship a single outboard motor from the factory to the boat builder, giving the boat builder flexibility to program the outboard motor to steer a certain amount of degrees that is required based on the particular application. 
     In the present description, 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.