Abstract:
A pontoon boat has left and right pontoons extending longitudinally, a tunnel therebetween, and a deck supported thereon. Bow and stern ends, and a boat length therebetween, are defined by at least one of the pontoons and the deck. An opening of the deck communicating with a tunnel thereunder has an outboard engine mounted therein and a hatch disposed thereover. A longitudinal center plane is vertical and equidistant from the bow and stern ends. A drive unit of the engine has a driveshaft, a propeller shaft operatively connected thereto, and a propeller connected to the propeller shaft. A mounting bracket connects the drive unit to the deck. The engine is disposed forward of the stern end by a distance at least equal to one-fourth of the boat length. The engine is aligned with or rearward of a longitudinal center plane. A method of operating the pontoon boat is also disclosed.

Description:
CROSS-REFERENCE 
     The present application claims priority to U.S. Provisional Patent Application No. 61/759,038 filed on Jan. 31, 2013, the entirety of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to pontoon boats. 
     BACKGROUND 
     Pontoon boats, which typically range in length from 5-10 m (15-30 feet), are usually powered by one or more outboard engines mounted to a transom of the pontoon boat and therefore necessitate a barrier to prevent passengers from inadvertently getting too close to the outboard engine while it is in operation. Typically, the barrier is formed by a guardrail, a wall, a storage locker or a front facing-bench extending across at least a majority of the rear portion of the deck. With the driver stationed near the longitudinal center of the pontoon, typically along the starboard side, this rear barrier can block the driver&#39;s rearward line of sight. This is not a desirable configuration when the area surrounding the boat, especially behind the boat, is populated with people participating in water activities, such as swimming, skiing and the like. This configuration of a conventional pontoon boat is also inconvenient for a spotter when a water skier, wake-boarder, inflatable raft, and the like is being towed by the boat as the spotter has to hang over the transom in order to have adequate view of the towed object/persons. 
     This problem has sometimes been addressed by using an inboard/outboard motor (I/O motor), also referred to as a stern drive, mounted inside the vessel and not to the transom. In this arrangement, the propeller is positioned beneath the deck, a swim platform or the like, reducing the likelihood of accidental contact with the propeller. I/O motors are however heavier and relatively more complex to install compared to outboard engines as they require a watertight bilge area for housing the I/O motor. 
     There is a need for a pontoon boat powered by an outboard engine and having a configuration wherein the outboard engine is easily accessible for maintenance and installation without blocking visibility of the driver, and the propeller is located so as not to hamper the normal activities of people in the vicinity of the boat. 
     SUMMARY 
     It is an object of the present invention to ameliorate at least some of the inconveniences present in the prior art. 
     In one aspect, the present provides a pontoon boat having a left pontoon and a right pontoon. The left and right pontoons extend longitudinally. A central axis of the left pontoon is parallel to a central axis of the right pontoon. A longitudinal centerline is disposed in a plane containing the central axes of the left and right pontoons. The longitudinal centerline is equidistant from each of the central axes of the left and right pontoons. A deck is supported by the left and right pontoons. A tunnel extends longitudinally between the left and right pontoons below the deck. A bow end is defined by at least one of the left pontoon, the right pontoon and the deck. A stern end is defined by at least one of the left pontoon, the right pontoon and the deck. A boat length is defined by a distance between the bow end and the stern end. A longitudinal center plane of the boat is defined by a vertical plane normal to the longitudinal centerline and disposed longitudinally equidistant from the bow end and the stern end. An opening is defined in the deck and communicates with the tunnel. An outboard engine is mounted in the opening. A hatch is disposed over the opening and the outboard engine. The outboard engine includes a drive unit having a driveshaft. A propeller shaft is operatively connected to the driveshaft; and a propeller is connected to the propeller. A mounting bracket connects the drive unit to the deck. The engine is disposed forward of the stern end by a distance at least equal to one-fourth of the boat length in the longitudinal direction. The engine is one of: aligned with and rearward of the center plane in the longitudinal direction. 
     In an additional aspect, the boat length is one of equal to and less than twenty feet, and the outboard engine is disposed at a position about the longitudinal center plane in the longitudinal direction. 
     In a further aspect, the boat length is greater than twenty feet, and the outboard engine is disposed at a position at least equal to one foot behind the longitudinal center plane in the longitudinal direction. 
     In another aspect, the driveshaft is aligned with the longitudinal centerline in the lateral direction. 
     In yet another aspect, a deflector is mounted in the tunnel forward of the outboard engine. 
     In an additional aspect, the propeller is disposed lower than the deflector when the driveshaft is disposed in a vertical orientation. 
     In a further aspect, the deflector is attached to the deck. 
     In a further aspect, the mounting bracket is connected to the deflector. 
     In another aspect, the drive unit is pivotable with respect to the mounting bracket about a trim axis, the trim axis being horizontal and perpendicular to the longitudinal centerline. 
     In yet another aspect, the drive unit is fixed with respect to the mounting bracket about a vertical axis. 
     In an additional aspect, at least one rudder is connected to a rear portion of at least one of: the deck, the left pontoon and the right pontoon. 
     In an additional aspect, the rear portion is the rear end. 
     In a further aspect, the at least one rudder comprises a left rudder and a right rudder. 
     In another aspect, the left rudder is attached to the left pontoon and the right rudder is attached to the right pontoon. 
     In yet another aspect, at least one lateral thruster is included. Each of the at least one lateral thruster is supported by at least one of: the deck, the left pontoon and the right pontoon. For each of the at least one lateral thruster, a central axis of the lateral thruster is generally horizontal and generally transverse to the longitudinal centerline. 
     In yet another aspect, the at least one lateral thruster includes a left lateral thruster mounted to the left pontoon and a right lateral thruster mounted to the right pontoon. 
     In an additional aspect, the left lateral thruster is connected to a forward portion of the left pontoon, and the right lateral thruster is connected to a forward portion of the right pontoon. 
     In another aspect, the bow end is defined by the left pontoon and the right pontoon. The stern end is defined by the left pontoon and the right pontoon. The boat length defined by the distance between the bow end and the stern end is defined by the left pontoon and the right pontoon. 
     In another aspect, the present provides a method of operating a pontoon boat in water. The pontoon boat has a bow end and a stern end, at least two pontoons extending longitudinally beneath a deck, an outboard engine mounted to the deck along a longitudinal centerline of the pontoon at a position rearward of the bow end by a distance between half and three-fourths of the distance from the bow end to the stern end. The outboard engine includes a drive unit pivotally connected to a mounting bracket disposed forward of the drive unit. The drive unit is pivotable about a trim axis. The method includes hydrodynamically lifting the bow end of the pontoon boat by pivoting the drive unit towards the mounting bracket about the trim axis. 
     For purposes of the present application, terms related to spatial orientation when referring to a pontoon boat and components in relation to the pontoon boat, such as “forwardly”, “rearwardly”, “left”, “right”, “above” and “below”, are as they would be understood by a driver of the pontoon boat, with the pontoon boat in a straight ahead orientation (i.e. not steered left or right), and in an upright position (i.e. not tilted). The explanations provided above regarding the above terms take precedence over explanations of these terms that may be found in the document incorporated herein by reference. 
     Embodiments of the present invention each have at least one of the above-mentioned object and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present invention that have resulted from attempting to attain the above-mentioned object may not satisfy this object and/or may satisfy other objects not specifically recited herein. 
     Additional and/or alternative features, aspects, and advantages of embodiments of the present invention will become apparent from the following description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where: 
         FIG. 1  is a schematic top plan view of a pontoon boat with all components normally positioned on the deck, except for a hatch, removed for clarity; 
         FIG. 2  is a schematic partially cut-away left side elevation view of the pontoon boat of  FIG. 1 , showing an outboard engine mounted thereto; 
         FIG. 3  is a perspective view, taken from a rear, bottom, of the pontoon boat of  FIG. 1  showing the outboard engine of  FIG. 2  mounted in a tunnel; 
         FIG. 4  is a perspective view, taken from a front, right and bottom, of the pontoon boat of  FIG. 1  showing a deflector mounted in the tunnel forward of the outboard engine; and 
         FIG. 5  is a perspective view, taken from a front, bottom, of the pontoon boat of  FIG. 1  and showing the deflector mounted in the tunnel forward of the outboard engine. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1 and 2 , the pontoon boat  10  includes a deck or a platform  12  supported on a left pontoon  14  and a right pontoon  14 . The left pontoon  14  and the right pontoon  14  are bolted to the undersurface of the deck  12 . A tunnel  16  is defined by the space between the pontoons  14  below the deck  12 . It is also contemplated that the pontoon boat  10  could be constructed of more than two pontoons  14  which could form a single tunnel  16 , or multiple tunnels  16 . 
     The pontoons  14  are elongated tubular structures. The pontoons  14  are hollow and watertight so as to provide buoyancy. It is contemplated that the pontoon  14  could be filled with a low density material such as foam, for example. The left pontoon  14  is identical to the right pontoon  14 , and as such only the right pontoon  14  will be described herein. It is contemplated that the pontoons  14  could be mirror images of each other, or different from each other. The pontoon  14  has a front end  14   a  and a rear end  14   b . The pontoon  14  has a central cylindrical portion  18  with a diameter  22  and a central cylindrical axis  20 . The cylindrical portion  18  of the pontoon  14  ends in a conical frustum  24  at the front and rear ends. A central axis  25  of the front end conical frustum  24  extends forward and upward with respect to the central axis  20  of the cylindrical portion. A central axis  25  of the conical frustum  24  of the rear end extends rearward and upward with respect to the central axis  20  of the cylindrical portion  18 . The upper surfaces of the front conical frustum  24 , the cylindrical portion  18 , and the rear conical frustum  24  are disposed so that the pontoon  14  has a horizontal and continuous upper surface across the entire length thereof. A skeg  15  extends downward from the lower surface of the cylindrical portion  18  near the rear end  14   b  of the pontoon  14 . It is contemplated that the pontoons  14  could have a different configuration than as described above. 
     A bow end  5  of the boat  10  is defined by the front ends  14   a  of the left and right pontoons  14 . A stern end  6  of the boat  10  is defined by the rear ends  14   b  of the left and right pontoons  14 . The distance between the bow end  5  and the stern end  6  defines the length L of the boat  10 . It is also contemplated that the boat  10  could have a central pontoon between the left and right pontoons  14 , and that a front end of the central pontoon could extend forward of the front end  14   a  of the pontoons  14 , or that a rear end of the central pontoon could extend further rearward than the rear end  14   b  of the pontoons  14 . For a boat  10  having such a central pontoon between the left and right pontoons  14 , the boat length L would still be defined by the length of the pontoons  14  between their front and rear ends. In the illustrated embodiment, the front and rear ends  14   a ,  14   b  of the pontoons  14  extend beyond the deck  12 . It is contemplated that the deck  12  could be longer than the pontoons  14 , and bow and stern end  5 ,  6  and therefore the length of the boat  10  could be defined with respect to the deck  12  instead of the pontoons  14 . 
     The central cylindrical axes  20  of the left and right pontoons  14  are spaced apart by a distance larger than the diameter  22  of the cylindrical portion  18  so the tunnel  16  between the inward facing surfaces of the pontoons  14  has a width approximately twice the diameter  22  of the cylindrical portion. It is contemplated that the relative widths of the pontoons  14  and the tunnel  16  could be different than in the illustrated embodiment. 
     A longitudinal centerline  26  is defined equidistant from the axes  20  in a horizontal plane  28  ( FIG. 2 ) containing the axes  20 . A vertical plane  30  ( FIG. 1 ) containing the longitudinal centerline  26 , and therefore positioned at the lateral center of the pontoon boat  10 , forms the lateral center plane  30  of the pontoon boat  10 . A vertical plane  32  normal to the longitudinal centerline  26  and equidistant from the bow end  5  and the stern end  6  defines a longitudinal center plane  32  of the boat  10 . 
     A rudder  34  is pivotably attached to the rear end of each pontoon  14  for steering the boat  10 . Each rudder  34  is pivotable about a respective vertical axis  36 . Each rudder  34  is mounted so that the vertical axis  36  intersects the central cylindrical axis  20  of the pontoon  14 . The rudders  34  are operatively connected to a steering mechanism (not shown) at the helm (not shown). In the illustrated embodiment, the steering mechanism is a power steering mechanism in which a hydraulic linear actuator (not shown) is connected to one of the rudders  34 , and the two rudders  34  are connected to each other by a tie-rod  35 . Thus, the linear actuator directly controls one of the rudders  34  which moves the other rudder  34  via the tie-rod  35 . It is contemplated that the two rudders  34  could be connected to each other hydraulically, by a hydraulic tie-bar or a “liquid tie bar” instead of mechanically via the tie-rod. It is also contemplated that each rudder  34  could be connected to a separate linear actuator. It is contemplated that the rudders  34  could be attached to the pontoon  14  such that the vertical axes  36  are offset from the central axes  20  of the pontoon  14 . It is contemplated that each rudder  34  could be connected to a structure other than the corresponding pontoon  14 , for example the rudders  34  could be attached to the deck  12  between the pontoons  14 . It is also contemplated that the pontoon boat  10  could be provided with a single central rudder  34  with the corresponding vertical axis  36  intersecting the longitudinal centerline  26  of the boat  10 . It is further contemplated that the boat  10  could have more than two rudders  34 . 
     A lateral thruster  40  is connected to the pontoon  14  in a passage  42  extending laterally through a forward portion of the pontoon  14 . The lateral thruster  40  is disposed in the forward portion of the cylindrical portion  18  but it is contemplated that it could be disposed in other locations, including the front or rear conical frustum  24 . The lateral thruster  40  in the illustrated embodiment includes an impeller  43  having a central axis  44 . The impeller  43  provides a lateral thrust in the direction of the central axis  44  to the pontoon  14 , and thereby the boat  10 , when being operated. The central axis  44  of the impeller  43  is horizontal and perpendicular to the central cylindrical axis  20  of the pontoon  14 . The central axis  44  of the impeller  43  is disposed below the central axis  20  of the pontoon  14 . It is contemplated that the lateral thruster  40  could be positioned elsewhere along the pontoon  14 . It is contemplated that additional lateral thrusters  40  could be provided. For example, the pontoon  14  could have a fore lateral thruster  40  as shown in the figures, as well as an aft lateral thruster  40  in a rear portion of the pontoon  14 . It is contemplated that propeller-type lateral thrusters mounted to the outside of the pontoons  14  or deck  12  could similarly be used. The left and/or right lateral thruster  40  is/are selectively operated for providing thrust in a lateral direction. The lateral thrusters  40  are used primarily for docking, while the rudders  34  are used primarily for steering in open waters. 
     An opening  46  is formed in the deck  12  and a hatch  48  is positioned over the opening  46 . The lateral center plane  30  and the longitudinal center plane  32  pass through the opening  46 . The opening  46  is substantially rectangular but it is contemplated that the opening  46  could have a different shape. The opening  46  of the deck  12  communicates with the tunnel  16 . 
     The helm (not shown), from where the operation of the boat  10  is controlled, is positioned immediately behind the hatch  48 . It is contemplated that the helm could be positioned on a right side of the hatch  48 , or on a left side thereof. A driver&#39;s seat may also be provided behind the helm. A passenger seating area could be provided forward and/or rearward of the hatch  48 . A reboarding platform (not shown) is provided at the rear end of the deck  12 . It is contemplated that the reboarding platform could be pivotable to form a tailgate that swivels between an up (close) and down (open) position. The deck  12  supports other structures such as railings, seats, and the like, which have been omitted from  FIGS. 1 and 2  out of clarity, and will not be described herein. 
     With reference to  FIG. 2 , an outboard engine  100  is mounted in the opening  46  of the deck  12 . An engine mount  50 , extending from the deck  12  into the tunnel  16 , supports the outboard engine  100 . The engine mount  50  is welded or otherwise fixed to the deck  12  at the edge of the opening  46 . The engine mount  50  is in the form of a rectangular bracket. The engine mount  50  is slightly tilted from the vertical so that its lower end in the tunnel  16  is disposed slightly forward with respect to its upper end which is connected to the deck  12 . It is contemplated that the engine mount  50  could be constructed differently, or that the engine mount  50  could not be tilted with respect to the vertical direction. 
     The outboard engine  100  of the present embodiment is a conventional outboard engine, i.e. one that would typically be mounted to the stern end of the hull of a conventional watercraft having a transom. The outboard engine  100  includes a drive unit  112  and a bracket assembly  114 . The bracket assembly  114  connects the drive unit  112  to the engine mount  50 . The engine mount  50  is configured to be similar to the transom so that a stern-mounted outboard engine can be used without significant alterations to the bracket assembly  114 . U.S. Pat. No. 7,736,206, issued on Jun. 15, 2010 to McChesney et al., the entirety of which is incorporated herein by reference, provides additional details related to stern-mounted outboard engines. Other types of bracket assemblies are similarly applicable. 
     The drive unit  112  includes an upper portion  132  disposed above the deck  12 , and a lower portion  134  disposed below the deck  12  in the illustrated embodiment. The upper portion  132  includes an engine  136  (schematically shown in dotted lines in  FIG. 2 ) surrounded and protected by a cowling  138 . The lower portion  134  includes a gear case assembly  140 , a skeg portion  142 , and the midsection  141  which extends from the upper portion  132  to the gear case assembly  140 . The lower portion includes the propeller  120  mounted on a propeller shaft  146 . The midsection  141  includes an exhaust systern (not shown) that routes exhaust gases out through the propeller  120  and through an idle exhaust relief outlet (not shown) along the rear side of the lower portion  134 , as is known in the art. An idle exhaust conduit  150  ( FIG. 3 ) is connected to the idle exhaust relief outlet and extends rearward therefrom so as to route exhaust gases above the surface of the water away from the opening  46  when the outboard engine  100  is in idle operation. It is contemplated that the idle exhaust systern could also be provided with a blower for directing the exhaust gases during idle operation. 
     The engine  136 , housed within the cowling  138 , is an internal combustion engine, such as a two-stroke or four-stroke engine, having cylinders extending horizontally. It is contemplated that other types of engines could be used and that the cylinders could be oriented differently. The engine  136  is coupled to a driveshaft  144  (schematically shown in dotted lines in  FIG. 1 ). When the drive unit  112  is in the upright position as shown in  FIG. 2 , the driveshaft  144  is oriented vertically. It is contemplated that the driveshaft  144  could be oriented differently relative to the engine  136 . The driveshaft  144  is coupled to a drive mechanism (not shown), including a transmission  148  (shown schematically in dotted lines) and the propeller shaft  146 . The driveshaft  144  and the drive mechanism transfer the power from the engine  136  to the propeller  120  mounted on the rear side of the gear case assembly  140  of the drive unit  112 . In  FIG. 2 , the propeller shaft  146  is shown perpendicular to the driveshaft  44 , however it is contemplated that it could be at other angles. 
     Other known components of an engine assembly are included within the cowling  38 , such as a starter motor, an alternator and the like. As it is believed that these components would be readily recognized by one of ordinary skill in the art, further explanation and description of these components will not be provided herein. 
     The bracket assembly  114  includes a mounting bracket  116  pivotally attached to the drive unit  112 . The bracket assembly  114  could also include actuators, linear and/or rotary, for pivoting or otherwise adjusting the position of the drive unit  112  with respect to the engine mount  50 . The mounting bracket  116  attaches the drive unit  112  to the engine mount  50  such that the propeller  120  of the drive unit  112  is in a submerged position with the boat  10  resting relative to a surface of a body of water. At least a portion of the propeller  120  is disposed lower than the pontoons  14 . The mounting bracket  116  is similar to the stern bracket of a stern-mounted outboard engine. The engine mount  50  is configured to be similar to the transom so that a stern-mounted outboard engine can be used without significant alterations to the bracket assembly  114 . The mounting bracket  116  is bolted to the engine mount  50 . A series of holes  152  are provided on the mounting bracket  116  so that the vertical position of the outboard engine  100  can be adjusted with respect to the engine mount  50 . It is also contemplated that the engine mount  50  could be a jack plate that, as is known in the art, allows the vertical position of the outboard engine  100  to be varied with respect to the deck  12  and/or pontoons  14 . 
     With reference to  FIGS. 3 to 5 , a deflector  60  is disposed in the tunnel  16  forward of the outboard engine  10 . The deflector  60  is bolted to the undersurface of the deck  12 . It is contemplated that the deflector  60  could be fastened to the deck  12  by other means. It is also contemplated that the deflector  60  could be attached to the pontoons  14  instead of, or in addition to, being attached to the deck  12 . The deflector  60  is laterally centered in the tunnel  16  and spaced from the inner surfaces of the left and right pontoons  14  so that water can flow rearward through the tunnel  16  around the sides of the deflector  60 . The smoothly curved surface of the deflector  60  deflects water flowing in the tunnel  16  to either side of the lower portion  134  of the outboard engine  100 , excluding the gear case assembly  140 . The deflector  60  is positioned to be higher than the propeller  120  of the outboard engine  100  as can be seen in  FIG. 3 . 
     The deflector  60  is intended to minimize the drag caused the midsection  141  and as such is sized and shaped to shield as much of the lower section  134  as possible without negatively effect the thrust generated by the propeller  120 . The deflector  60  is an elongated hollow structure. The deflector  60  tapers from a central portion  64  having a large cross-section towards a nose  62  in the front end  62 . The rear end  66  of the deflector is positioned just forward of the engine mount  50 . The narrow front end  62  has a smaller lateral and vertical dimension than the central portion  64  and the rear end  66 . From the narrow front end  62 , the outer surface of the deflector  60  extends rearward, laterally outward and downward towards the central portion  64 . The outer surface of the deflector  60  extends rearward from the central portion  64  to the rear end  66 . Fins  68  extending rearward from the rear end  66  on each side of the engine mount  50  and the mounting bracket  116  of the outboard engine  100  help to deflect water in a rearward direction along the sides of the lower portion  134 . The deflector  60  encloses a closed volume within the nose  62 , central portion  64  and the rear end  66 , and as such is buoyant and functions like a central pontoon. It is also contemplated that another central pontoon could similarly be provided in the tunnel  16  rearward of the outboard engine  100 . It is contemplated that the deflector  60  not enclose a closed volume but merely provide surfaces, such as the fins  68 , to deflect the flow of water and spray around the midsection  141 . For example, the central and rear portions  64 ,  66  could be omitted, and deflector  60  could be formed by the nose  62  with fins  68  connected thereto. 
     The drive unit  112  is laterally centered with respect to the boat  10  such that the lateral center plane  30  passes through the driveshaft  144  (as can be seen by the position of the driveshaft  144  indicated in  FIG. 1 ). It is contemplated that the outboard engine  100  could not be laterally centered and the lateral center plane  30  could not pass through the driveshaft  144 . The driveshaft  144  is disposed rearward of the longitudinal center plane  32  as can be seen in  FIG. 2 . The propeller shaft  146  is parallel to the longitudinal centerline  26  when the drive unit  112  is in an upright position as shown in  FIG. 2 . It is also contemplated that more than one drive unit  112  could be provided. 
     Similar to a stern-mounted outboard engine, the drive unit  112  can be trimmed up (out) or down (in) relative to the mounting bracket  116  about a trim axis  124  extending generally horizontally thereby changing the angle of the propeller shaft  146  with respect to the mounting bracket  116 . The trim angle can be adjusted manually, hydraulically or by-wire, as is known in the art. The throttle and trim angle of the outboard engine  100  is controlled from the helm whichever actuation mechanism is used for adjusting the trim angle. Positioning an outboard engine  100  at or near the longitudinal center plane  32  of the boat  10  rather than at the stern  6  has an effect on the boat dynamics, as will be discussed in further detail below. 
     In a conventional stern-mounted application, the drive unit  112  would also be pivotable about a vertical steering axis for steering the boat. In contrast, in the illustrated embodiment of the pontoon boat  10 , steering is accomplished by the rudders  34  and/or by the lateral thrusters  40  as mentioned above. As such, the drive unit  112  of the pontoon boat  10  is not pivotable for steering. It is however contemplated that the drive unit  112  of the center-mounted outboard engine  100  shown herein could be connected to the mounting bracket  116  so as to be pivotable about a vertical steering axis. For example, the drive unit  112  could be pivotable about the vertical steering axis by an angle 100° to port and 100° to starboard (i.e. a total angle of 200°), with respect to a longitudinal plane containing the vertical steering axis, so as to propel the pontoon boat  10  in a lateral direction. 
     Positioning the outboard engine  100  near the longitudinal center plane  32  of the pontoon boat  10  changes the effect of trim angle adjustment on the boat  10  compared to a boat  10  having a stern-mounted outboard engine as in the prior art. The propeller  120  applies a thrust on the boat  10  in a direction coaxial with the propeller shaft  146 . When the drive unit  112  is trimmed in/out so that the propeller shaft  146  is not horizontal, the thrust applied to the boat  10  has a vertical (upward/downward) component. When the drive unit  112  is trimmed in, the propeller thrust has an upward component. When the drive unit is trimmed out, the propeller thrust has a downward component. As will be appreciated by one skilled in the art, trimming in and out a conventional, stern-mounted outboard engine has the effect of pushing the bow down and up, respectively. However, adjusting the trim angle of the drive unit  112  on the pontoon  10  has a different effect. More specifically, when the drive unit  112  is trimmed in, the main effect of the upward thrust from the propeller  120  is to lift the entire boat  10 , including both of the bow end  5  and the stern end  6 , upwards out of the water. Trimming in the drive unit  112  may also push the bow end  5  up slightly more than the stern end  6 . Trimming out the drive unit  112  reduces the upward thrust from the propeller  120  and reduces the lifting associated therewith. This is due at least in part to the propeller thrust being applied much closer to the center of gravity of the boat  10  and the buoyancy of the pontoons  14  that extend both in front of and behind the propeller  120 . These hydrodynamic effects could also vary with boat speed and based on whether or not the boat  10  is on plane. 
     With reference to  FIGS. 1 and 2 , the outboard engine  100  is mounted along the longitudinal centerline  26  such that the mounting bracket  114  is connected to the engine mount  50  at a position that is spaced from the longitudinal center plane  32  by a distance X. The distance X is determined based on the boat length L of the pontoon  14 . The length L of a boat can, in general be defined in various ways as mentioned above. For a pontoon boat such as the boat  10 , however, the length L is typically defined based on the length of the pontoons  14 . The distance X can be up to one-fourth of the boat length L. The longer the length L, the farther rearward the outboard engine  100  will be positioned, i.e. the distance X is a greater fraction of the boat length L. For smaller pontoon boats  10 , measuring up to 6 m (20 feet) in length, the outboard engine  100  may be positioned with the driveshaft  144  being up to 30 cm (one foot) behind the longitudinal center plane  32 . For a 7 m (23-foot) pontoon boat  10 , the outboard engine  100  could be positioned with the driveshaft  144  up to 60 cm (two feet) behind the longitudinal center plane  32 . The outboard engine  100  is mounted such that the driveshaft  144  is spaced from the stern end  6  by a distance at least equal to one-fourth of the boat length L. It is also contemplated that the distance X could be defined with respect to a center of gravity of the boat  10 , or the driveshaft  144 , or the propeller shaft  146  instead of the mounting bracket  114 . 
     The center of gravity (CG) of the boat  10  having the center-mounted outboard engine  10  described above is disposed further forwardly than that of a conventional boat of a comparable size which has a stern-mounted outboard engine. This positioning of the CG is also beneficial during transport of the boat  10  on a trailer having its front end attached to the rear of the transport vehicle, typically by a joint such as a ball and socket joint. The torque exerted on the joint depends on its distance from the CG of the boat being carried by the trailer. A center-mounted boat  10  exerts a smaller torque on the joint than a stern-mounted boat of a comparable dimension and weight since the CG of the center-mounted boat  10  is closer to the joint than the CG of the conventional stern-mounted boat. The joint used to connect the trailer to the transport vehicle could therefore be smaller, and would require less frequent replacement, for a center-mounted boat  10  than for a conventional stern-mounted boat. 
     The pontoon boat  10  shown herein, having the center mounted outboard engine  100 , can provide an unobstructed view from the helm of the pontoon boat  10  of the area in the vicinity of the boat  10 , especially the area behind the boat  10 , since the rear portion of the boat  10  does not need to be blocked by a guardrail, wall or other obstacle typical in boats having stern-mounted outboard engines. The unobstructed view of the area in the vicinity of the boat is also advantageous when a water skier, wake-boarder, raft, and the like, is being towed behind the boat  10 . In addition to the unobstructed view towards the rear, the pontoon boat  10  shown herein could also be configured to allow entry and exit of passengers and/or cargo from the stern end of the boat  10  leaving more space in the remaining areas of the deck for storage of cargo, seating of passengers, and the like. 
     Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.