Abstract:
A watersports boat includes a hull having an underside defining a running surface that contacts water when the hull moves therein. An aft running surface section of the hull has (a) a trailing edge forming an aft-most point of the contact with water along any given buttock line of the hull when the hull is moving forward, (b) a non-repositionable aft running surface section forming a first portion of the trailing edge, and (c) a re-positionable aft running surface section forming a second portion of the trailing edge. The first portion of the trailing edge and second portion of the trailing edge meet substantially tangent to one another.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This claims priority to U.S. provisional application Ser. No. 61/788,025, filed Mar. 15, 2013, which is incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to the field of boats and, more particularly, to watersports boats for skiing and wake sports. 
     BACKGROUND 
     The shape of a boat&#39;s hull determines how it travels through the water and the activities for which it is suited. The shape is generally chosen to fit within desired load carrying, stability, speed, and hydrodynamic parameters for the boat&#39;s intended purpose. As a boat travels through the water, its motion is typically described by one of two general modes of operation: (1) pre-planing mode, including displacement mode and semi-planing or transition mode, and (2) planing mode. How a boat transitions between these operational modes and how it behaves within a particular operational mode is a function of the shape of the hull. 
     In displacement mode, when the boat is moving relatively slowly through the water, the primary force that keeps the boat from sinking is buoyancy. When operating in displacement mode, the bow of the boat is typically raised out of the water while the stern is pressed down into the water. 
     In semi-planing mode, the hull is traveling at sufficient speed to generate a moderate amount of hydrodynamic lift, but the primary force that supports the boat&#39;s weight is still buoyancy. 
     In planing mode, the hull generates even more lift so that the primary forces supporting the boat&#39;s weight are hydrodynamic rather than buoyant. These hydrodynamic forces tend to lift the running surface out of the water, thereby reducing drag. 
     Certain hull designs are specifically geared to perform in only one of these three operational modes. However, boats that are designed for skiing or wake sports water should be configured to operate well in all three modes so that the boat is adaptable to different activities such as cruising, waterskiing, wakeboarding, and/or wake surfing. For example, it may be best to operate in displacement or semi-planing mode when pulling a wakeboarder, because the wake produced in these modes is typically more substantial than the wake produced in planing mode. In contrast, for waterskiing, it may be best to operate in planing mode so that the wake is as small as possible. Often times, individual water sports performers will even prefer for the wake to be tuned to their particular preferences. Unfortunately, although many water sports boats operate well through all three operational modes, there are still very few boats that are capable of fine-tuning the wake pattern to meet each performer&#39;s personal preferences. 
     SUMMARY 
     We have overcome these drawbacks by inventing a boat hull having a re-configurable running surface. 
     An exemplary embodiment of the watersports boat includes a hull having an underside extending from a forward bow to an aft transom along a longitudinal centerline. The underside defines a running surface that contacts water when the hull moves therein. An aft running surface section of the hull includes (a) a trailing edge forming an aft-most point of the contact with water along any given buttock line of the hull when the hull is moving forward; (b) a non-repositionable aft running surface section forming a first portion of the trailing edge; and (c) a re-positionable aft running surface section forming a second portion of the trailing edge. The first portion of the trailing edge and second portion of the trailing edge meet substantially tangent to one another. 
     The non-repositionable aft running surface section may include port and starboard recesses formed in opposed corners of the aft running surface section and spaced outboard the centerline, each of the recesses extending from a respective step at a forward end thereof aft to a respective aft edge thereof, the step forming the first portion of the trailing edge. 
     The re-positionable aft running surface section may include an aft edge defining the aft-most point of water contact and opposed port and starboard edges extending longitudinally toward the aft edge and forming the second portion of the trailing edge. 
     The re-positionable aft running surface section may include opposed port and starboard longitudinal edges extending between a forward end and an aft end thereof and inwardly along the centerline from the forward end to the aft end. 
     The re-positionable aft running surface section may be substantially co-planar with the portion of the aft running surface immediately forward the re-positionable aft running surface. 
     The re-positionable aft running surface section may be a bottom surface of a running surface extension member mounted to the hull at a running surface extension member receiving area recessed into the aft running surface section. 
     The re-positionable section of the aft running surface may be repositionable about a pivot axis bisecting the centerline. 
     The re-positionable aft running surface section may be re-positionable between a first position and a second position for adjusting hydrodynamic lift at a stern of the hull. 
     The watersports may further include a keel member having an apex lower than the aft running surface section, inclining toward the aft running surface section aft the apex, and meeting the aft running section forward the transom. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a starboard side elevation view of a boat hull in accordance with an embodiment; 
         FIG. 2  is a port side elevation view of the hull of  FIG. 1 ; 
         FIG. 3A  is a bottom plan view of the hull of  FIG. 1 ; 
         FIG. 3B  is a bottom plan view of another hull embodiment; 
         FIG. 4  is a port and aft perspective view of the hull of  FIG. 1 ; 
         FIG. 5  is a partial enlarged starboard elevation view of the hull of  FIG. 1 ; 
         FIG. 6  is a front elevation view of the hull of  FIG. 1 ; 
         FIG. 7  is a back elevation view of the hull of  FIG. 1 ; 
         FIG. 8  is a partial enlarged starboard, aft, and topside perspective view of the hull of  FIG. 1 ; 
         FIG. 9  is a partially enlarged starboard, aft, and bottom perspective view of the hull of  FIG. 1 ; 
         FIG. 10  is a partial enlarged starboard cross-section view of the stern of the hull of  FIG. 1 ; illustrating an example of movement of the running surface extension member; 
         FIGS. 11 and 12  are partial enlarged starboard side elevation views of the stern of the hull of  FIG. 1 , showing the boat at different angles of attack; and 
         FIG. 13  is a block diagram illustrating a control system embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the Summary and in the Detailed Description of Embodiments, reference is made to particular features, including method steps. Where a particular feature is disclosed in the context of a particular aspect or embodiment, that feature can also be used, to the extent possible, in combination with and/or in the context of other aspects and embodiments. 
     In this section, embodiments will be described more fully. These embodiments may, however, take many different forms and should not be construed as limited to those set forth herein. 
     An exemplary embodiment of the watersports boat is generally shown in  FIGS. 1-4 . As best seen from  FIGS. 1 and 2 , the boat&#39;s hull  12  extends longitudinally between a bow  22  and a stern  24  and laterally between a starboard hull side  26   a  and a port hull side  26   b . The hull  12  also extends vertically from a topside  28  downwardly to a hull underside  29 , which defines a running surface  14  that contacts the water as boat moves across it. The running surface  14  is advantageously designed to provide small wakes for waterskiing, medium wakes for wakeboarding, and large wakes for wake surfing. As shown in  FIGS. 3A and 3B , the port and starboard sides are separated by an imaginary axis A, or hull centerline, longitudinally dividing the hull  12  in half from stem to stern. A keel  34  runs along the axis A. 
     A propulsion mechanism such as a boat engine, preferably an inboard engine with a propeller  31  extending outwardly and aft from the hull underside  29 , will generally be used to propel the boat  10  through the water. A rudder R and bottom fin F may also be included for boat control. 
     As best shown in FIGS.  3 A,B- 6 , the hull underside  29 , includes a starboard side reverse chine  36   a  and port side reverse chine  36   b  that extend longitudinally beneath their respective hull sides  26   a ,  26   b  and between the bow  22  and a midship section  38 . The chines  36   a ,  36   b  stabilize the hull  12  by allowing air to channel down the starboard and port sides to provide an equal and stable lift along both side of the hull  12  at slower speeds. At slower speeds, the reverse chines  36   a ,  36   b  creates a higher bow lift, which presses the stern  24  into the water and increases size of the wake the hull  12  produces. 
     The reverse chines  36   a ,  36   b  gradually terminate at the midship section  38  at respective reverse chine terminal ends  40   a ,  40   b . The reverse chines  36   a ,  36   b  taper outwardly towards the respective port or starboard hull side  26   a ,  26   b  as they approach the terminal ends  40   a ,  40   b  and gradually flatten where the terminal ends  40   a ,  40   b  meet port and starboard side midship running surfaces  42   a ,  42   b . More conventional port and starboard chines  43   a ,  43   b  extend aft to the transom  32 . 
     Respective starboard and port side aft running surfaces  48   a ,  48   b  extend aft from the midship section  38  and taper inboard as they approach the transom  32 . 
     As best shown in  FIGS. 3A ,  3 B,  4 ,  8 , and  9 , a pair of opposed aft hull side surfaces  50   a ,  50   b  are vertically positioned between the hull sides  26   a ,  26   b  and the hull underside  29 . The aft hull side surfaces  50   a ,  50   b  angle inwardly and downwardly toward the axis A and the transom  32 . 
     A pair of opposed substantially vertical walls  52   a ,  52   b  are positioned between the aft hull side surfaces  50   a ,  50   b  and the hull bottom  29 . The aft hull side surfaces  50   a ,  50   b , respectively, from a common boundary with the port and starboard variable planing surface  82   a ,  82   b  recesses. 
     At the bow  22 , as best shown in FIGS.  3 A, 3 B and  6 , a pair of opposed starboard and port-side strakes  54   a ,  54   b  extend outwardly and aft about the keel  34  towards the midship section  38 . The strakes  54   a ,  54   b  terminate at respective strake terminating ends  56   a ,  56   b . Between the bow  22  and the strake terminating ends  56   a ,  56   b , the strakes  54   a ,  54   b  substantially form a V shape. The strakes  54   a ,  54   b  are further defined by longitudinal strake edges  58   a ,  58   b  and longitudinal strake walls  60   a ,  60   b.    
     A V-shaped keel member  62  is positioned about the midship section  38  and extends longitudinally towards the stern  32  and essentially protrudes from the hull underside  29  symmetrically about the axis A. The keel member  62  includes a starboard side forward keel member surface  64   a  and a port side forward keel member surface  64   b . Both forward surfaces  64   a ,  64   b  extend from their respective forward surface edges  66   a ,  66   b  at an angle downward from the hull bottom  29  and meet at an apex at the keel  34 . The apex is lower than the aft running surface sections  48   a ,  48   b . The keel member  62  inclines toward the aft running surface sections  48   a , 48   b  aft the apex. 
     The keel member  62  separates port and starboard midship running surface sections  42   a , 42   b , which gradually flatten moving aft from the V-shaped bow running surface section  45  to meet the aft running surface sections  48   a ,  48   b.    
     The forward keel member surfaces  64   a ,  64   b  terminate at corresponding lateral edges  68   a ,  68   b  from which rearward keel member surfaces  70   a ,  70   b  extend. The rearward keel member surfaces  70   a ,  70   b  extend from their respective rearward keel member surface edges  72   a ,  72   b  and angle downwardly from the hull underside  29  and meet at an apex at the keel  34 . The rearward protrusion surface edges  72   a ,  72   b  angle inwardly towards the keel  34  and terminate at a lower edge  74 , defining a lower edge of a step  76  formed between the lower step edge  74  and an upper step edge  78 . The step  76  vertically offsets the rearward keel member surfaces  70   a ,  70   b  from the portion of the hull underside  29  that extends the remainder of the distance to the transom  32 . 
       FIG. 3B  shows an alternate embodiment of the hull  10  where the running surface extension member  30  is a static integral piece of the running surface  14 . The recesses  82   a ,  82   b  are also not present. 
     Forward of the upper step edge  78  the rearward keel member surfaces  70   a ,  70   b  split apart from the keel  34  to define outer longitudinal edges of a substantially triangular surface  80 , which angles upwardly towards the stern  24 . 
     An enlarged view of the hull  12  at the position of the keel member  62  is provided in  FIG. 5  so that one possible shape of the keel member  62  in this embodiment is clearer. In  FIG. 5 , the apex of the keel member  62  along the keel  34  defines a portion of the lower silhouette of the hull underside  29 . Moving aft, the keel  34  along the keel member  62  angles upwardly between the midship section  38  and the stern  24 . 
     Although it is not always necessary, in this embodiment, the keel  34  angles upwardly at three distinct vertices V 1 , V 2 , V 3  characterized by angles α 1 , α 2 , and α 3  relative to horizontal, which is represented by the broken line. The degree of angles A 1 , A 2 , and A 3  successively increases moving aft. 
     The keel of a conventional powerboat used for tow-based water sports is typically more or less horizontal along the midship and stern sections. These horizontal keels are not optimal for producing the larger wakes preferred by wakesurfers, for example, because the horizontal rear portion of the running surface creates lift as the boat travels through the water with a bow up attack angle. The keel member  62 , more particularly the upwardly angled keel  34  on the V-shaped keel member  62 , presents a lower attack angle to the water for the same attitude as the conventional hull. Thus, the upwardly angled keel  34  reduces the lift created by this section of the running surface  14 , thereby allowing the stern  24  to sit lower in the water for producing a larger wake relative to a conventional boat. 
     Aft of the V-shaped keel member  62 , the hull underside  29  includes a pair of variable planing surfaces  82   a ,  82   b  respectively positioned on starboard and port sides of the axis A. The variable planing surfaces  82   a ,  82   b  are recesses in the hull underside  29 . The forward boundary of the variable planing surfaces  82   a ,  82   b  is a leading edge  84   a ,  84   b  which extends inboard from the respective starboard or port side towards the axis A. The leading edges  84   a ,  84   b  also extend aft towards the transom  32  as shown. The leading edges  84   a ,  84   b  are vertically offset from their respective variable planing surfaces  82   a ,  82   b  by a variable planing surface vertical wall  86   a ,  86   b  that spans between the leading edges  84   a ,  84   b  and the variable planing surfaces  82   a ,  82   b.    
     Each variable planing surface  82   a ,  82   b  extends aft from the leading edge  84   a ,  84   b  to a trailing edge  88   a ,  88   b  formed along the transom  32 . 
     The variable planing surfaces  82   a ,  82   b  and their corresponding leading  84   a ,  84   b  and trailing edges  88   a ,  88   b  provide several advantageous functions. The variable planing surfaces  82   a ,  82   b  form a pair of air channels along the running surface  14 . As shown in  FIGS. 11 and 12 , when the boat  10  is travelling in pre-planing mode the stern  24  is relatively low such that the water flowing through the recesses loses contact with the hull at the trailing edges  88   a ,  88   b , which are also referred to as the pre-planing mode trailing edges. This operational mode creates larger wakes that are geared for wakeboarding and/or wakesurfing. In contrast, when the boat  10  is operating in planing mode, the angle of attack is relatively low such that the water flowing through these channels loses contact with the hull underside  29  at the leading edges  84   a ,  84   b , which are also referred to as planing mode trailing edges. During planing mode, the trailing edges  88   a ,  88   b  are above a planing waterline of the hull  12 . This allows air to ventilate the recesses preventing water from reattaching to the variable planing surfaces  82   a ,  82   b  as the boat is planing. 
     Details associated with the running surface extension member  30  are best shown in  FIGS. 7-10 . The running surface extension member  30  is positioned about the axis and extends about a medial section of the aft running surface sections  48   a ,  48   b  rearwardly from the stern and, preferably, beyond the transom  32 . The running surface extension member  30  may be fixed or pivotable relative to the axis A. In the embodiment, shown, the running surface extension member  30  is pivotable for added boat control. 
     The running surface extension member  30  is pivotably coupled to the hull  12  adjacent the transom  32  and extends aft relative to the leading edges  84   a ,  84   b . The extension member  30  includes a forward terminal edge  90  that is aligned with and intersects each leading edge  84   a ,  84   b  and aft terminal edge  92 . An extension member top surface  94  and an extension member bottom surface  96  extend generally parallel between the forward terminal edge  90  and aft terminal edge  92 . A pair of opposed longitudinal extension member edges  98   a ,  98   b  define lateral edges of the extension member  30 . 
     In the embodiment shown, the extension member  30  has a generally trapezoidal shape so that the leading edges  84   a ,  84   b  and longitudinal extension member edges  98   a ,  98   b  are substantially aligned and co-linear and so that the angle between the extension member&#39;s forward terminal edge  90  and longitudinal extension member edges  98   a ,  98   b  is substantially complementary to the angle between the extension member&#39;s forward terminal edge  90  and the leading edges  84   a ,  84   b . In other words, the leading edges  84   a ,  84   b  and longitudinal extension member edges  98   a ,  98   b  meet substantially tangent to one another. If the shape of the variable planing surface  82   a ,  82   b  is changed, however, it may be desirable to change the shape of the extension member  30  such that the longitudinal extension member edge  98   a ,  98   b /forward terminal edge  90  angle and forward terminal edge  90 /leading edge  84   a , 84   b  angles are complementary. This arrangement is particularly advantageous as it allows the extension member bottom surface  96  to function as part of the running surface  14 . 
     The extension member  30  may be coupled to the hull  12  about the stern  24  or transom  32  and adjacent or against the hull underside  29 . In the embodiment shown, the forward terminal edge  90  is received in a extension member receiving area  100  that is recessed into the underside  29  and continues to transom  32 . The receiving area  100  has a generally rectangular shape, which is substantially centered along the axis A and is recessed further into the underside  29  than the variable planing surfaces  82   a ,  82   b.    
     The extension member is positioned symmetrically about the axis A and is configured to pivot at an angle relative to the axis A. The extension member  30  is pivotably coupled to the hull  12  by a hinge  102 . 
     Suitable means for moving the extension member  30  include actuators such as motors, servos, or the like. In the exemplary embodiment, the actuator  104  is a hydraulic ram. The actuator  104  is positioned in an actuator receiving area  106  that is recessed into the transom  32  and is attached to the hull  12  at a first bracket  108 . The actuator  104  is attached to the running surface extension member  30  at a second bracket  110 . 
     The actuator  104  is configured to move the extension member  30  from a retracted position to an extended position. As best shown in  FIG. 10 , in the retracted position, the bottom surface  96  is substantially co-planar with a medial section of the aft running surfaces  48   a ,  48   b . In the extended position, the bottom surface  96  extends below the underside  29  of the hull  12  as illustrated by the dashed lines to interrupt water flowing past the stern  24  and generate lift. The angular displacement between the retracted position and the extended position may be, for example, between 0 to 90 degrees, 0 to 45 degrees, and/or, 0 to 30 degrees. 
     The extension member  30  essentially functions as a re-positionable portion of the running surface  14  at the medial position of the stern  24 . As mentioned, it may alternatively be a fixed piece of the same shape, but the fixed piece would not provide as many options for boat control. By extending the extension member  30  from the retracted position, the operator is able to add lift to the stern  24 , helping shape the wake and achieve planing mode faster. 
     The operator may control the position of the extension member  30  incrementally to achieve the desired performance. Aspects of the extension member control system are shown in  FIG. 13 , the actuator  104  is in signal communication with an electronic control system  120  for adjusting the angle of the extension member  30 . 
     The control system  120  includes a controller  122  coupled to the extension member  30  via the actuator  104 . The controller  122  may be configured as a computer processor, for example, and includes an operator setting input unit  124 , a boat operating parameters input unit  130 , and an extension member movement determination unit  140 . 
     The operator setting input unit  124  receives inputs from the operator of the boat  10  via an operator input device  150  coupled thereto. The operator setting input unit  124  includes a speed control on/off input  126 , an extension member set point input  128 , an extension member auto deploy on/off input  129 , and an intensity level setting input  132 . 
     The speed control on/off input  126  is used to turn on and off speed control of the boat  10 , and when turned on, sets the boat  10  to a desired speed via an engine speed control device  156  coupled to the boat engine  158 . 
     The extension member set point input  128  corresponds to an extension member set point operational mode, where the extension member  30  is set to an operator defined position once the desired speed of the boat has been reached. 
     The extension member  30  auto deploy on/off input  130  determines whether an extension member auto deploy mode is on or off. In extension member auto deploy mode, the control system  120  automatically adjusts the of the extension member  30  as the boat accelerates to assist with planing. 
     The intensity level setting input  132  determines how quickly the position of the extension member  30  is adjusted while in the auto deploy mode. 
     The boat operating parameters input unit  130  receives inputs on the different operating parameters of the boat  10 . For example, speed and position of the boat are received via inputs  132  and  134  and engine RPMs are received input  136 . A level of the ballast tanks  160  is also received via input  138  from a level sensor associated with the ballast tanks  160 . Speed and position of the boat  10  may be provided by a global positioning system (GPS), for example. Display of the various settings and operating modes is provided to the operator via a display  152  coupled to the operator setting input unit  124  and to the boat operating parameters input unit  130 . 
     The extension member movement determination unit  140  is for controlling movement of the extension member  30 . The extension member movement determination unit  140  receives inputs from the operator setting input unit  124  and the boat operating parameters input unit  130 . In particular, the extension member  30  is moved to pre-determined percentages of the rotation range of the extension member  30  as the speed of the boat  10  increases to a desired boat speed setting. 
     The two different operating modes of the control system  120  will now be discussed in greater detail. When the auto deploy on/off input  129  receives an input signal via the input device  150 , the auto deploy mode is activated. The auto deploy mode is primarily used to adjust the position of the extension member  30  when the boat moves from displacement mode to planing mode to help the boat reach planing mode and stay in planing mode. In auto deploy mode, the control system  120  automatically adjusts the position of the extension member  30  so that the operator does not have to do so manually. 
     In auto deploy mode, the position of the extension member  30  is moved to a predetermined percentage of the rotation range of the extension member  30  based on the speed of the boat  10 , the intensity level setting  132  and the ballast tank level threshold of the ballast tanks  160 . As the speed of the boat  10  increases to the desired boat speed setting, the extension member  30  is moved to at least one next predetermined percentage of the full rotation range. By way of example, the extension member  30  may move within a range of 30 degrees so that a position target of 50% corresponds to 15 degrees. 
     One way this can be accomplished is by programming different sets of position targets, where the predetermined percentages of the rotation range of the extension member  30  are different for each set. The boat speed is thus separated into boat speed interval ranges. The predetermined percentages of the rotation range of the extension member  30  may be different for each set because of the different combinations of the intensity level and the ballast tank level threshold. The intensity level setting may include a high intensity level setting that increases the predetermined percentage of the rotation range, and a low intensity level setting that decreases the predetermined percentage of the rotation range. If the level of the ballast tanks  160  is less than the ballast tank level threshold, then the predetermined percentage of the rotation range may be decreased. If the level of the ballast tank  160  is greater than the ballast tank level threshold, then the predetermined percentage of the rotation range may be increased. By way of example, the ballast threshold may correspond to a percentage, 50% for example, of the total allowable sum of the ballast tanks  160 . If the ballast tanks  160  hold 1900 pounds of water, for example, then the ballast threshold level is 950 pounds at the 50% setting. 
     The control system  120  automatically transitions from auto deploy mode to set point mode once the desired set speed of the boat  10  is reached. After the boat  10  has reached the desired boat speed setting, the extension member  30  is moved to a desired position based on an extension member set point value. The operator provides the set point value to the extension member set point input  128  via the input device  150 . The set point value corresponds to one of several possible inputs between a minimum and a maximum. 
     The entered set point value corresponds to the final position of the extension member  30  once the desired speed of the boat  10  is reached. This set point value is manually entered, or alternatively, may be entered based on a user profile. Each set point value corresponds to an extension member  30  position that is somewhere between the fully retracted position and fully extended position. 
     The interface between the extension member movement determination unit  140  and the actuator  104  is based on an electronic signal sent to the actuator  104  that corresponds to a specific extension member  30  position. The electronic signal can either be in the form of a continuous signal or a pulsed signal. In either case, the total duration of the continuous signal or the sum of the duration of the pulse signals determine how far the actuator extends and, therefore, the extension member  30  position. 
     The set point input  128  may have again value associated with the set point values to allow the extension member  30  to be adjusted by larger or smaller increments, depending on the boat&#39;s speed. For example, if the speed is less than a boat speed threshold, such as 13.0 mph for example, the electronic signals corresponding to the different set point values cause the extension member  30  to be moved less. Once the boat speed is greater than a certain desired value then no adjustments are made to the electronic signal durations. 
     The same is true for when the speed control is off. In other words, if the desired boat speed setting is less than the boat speed threshold, then the controller  122  may be further configured to move the extension member  30  to a position less than the desired position after the boat  10  has reached the desired boat speed setting. 
     In addition, if the speed of the boat  10  is reduced after reaching the desired boat speed setting after the extension member  30  has been moved to a desired position, then the controller  122  is further configured to move the extension member  30  to a predetermined percentage of the full rotation range between the fully retracted and fully extended positions. In other words, auto deploy mode may be re-activated if the boat drops below the desired boat speed setting. 
     The operator of the boat  10  can also interact with the control system  120  in an indirect way by turning off the speed control. Here, the control system  120  uses an artificial set speed as a replacement for all extension member set point values. The artificial set speed is determined by the condition of intensity level setting and the ballast tank level threshold. 
     A method of operating the boat  10 , which associated with using the control system  120  is now described. From the start the method includes receiving as input a desired boat speed setting and at least one extension member set point value corresponding to a desired extension member position. The extension member  30  is moved to a predetermined percentage of the rotation range based on a ballast tank level threshold of the ballast tanks  160  and based on a current speed of the boat  10 . As the current speed of the boat  10  increases to the desired boat speed setting, then the extension member  30  is moved to at least one next predetermined percentage of the rotation range. The method further includes moving the extension member  30  to the desired extension member position based on the at least one entered extension member set point value after the boat  10  has reached the desired boat speed setting. 
     As discussed, the boat  10  has a reconfigurable running surface  14  designed to provide an optimized wake for many different water sports such as skiing, wakeboarding and/or wakesurfing. The running surface  14  is reconfigurable because water attaches to different parts of it depending on the boat&#39;s angle of attack, which is essentially an acute angle formed between the water and the bow  22 . In displacement mode, the angle of attack will generally be larger than in planing or preplanning mode. 
     According to this principle, a method of modifying the wake produced by the boat  10  includes imparting to the boat a first angle of attack wherein water attaches to the aft running surface sections  48   a ,  48   b  and breaks off at the transom  32  and imparting to the boat a second angle of attack wherein water breaks off the respective leading edges  84   a ,  84  of the port and starboard side recesses of the variable planing surfaces  82   a ,  82   b . The second angle of attack may be achieved by lowering the bow  22  relative to the water&#39;s surface, which in turn raises the stern. In this case, the first angle of attack would produce a higher wake than the second angle of attack. 
     Various modifications of the embodiments described here can be made without departing from the spirit and scope of the invention as described above and as defined in the appended claims.