You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/828,296, filed May 29, 2013, the entire content of which is herein incorporated by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     (Not applicable) 
     BACKGROUND OF THE INVENTION 
     The invention relates generally to a door/window for a boat and, more particularly, to a sliding door assembly for a boat. 
     A powered door assembly is a desirable feature for a boat windshield including a pass-through. A boat passenger can press a button on either side of the door/window to activate a motor that opens or closes the door assembly. Challenges in the design relate to positioning the drive components, accommodating the weight of the door, providing for a safety release, enabling component access for repair or replacement if necessary, etc. 
     BRIEF SUMMARY OF THE INVENTION 
     It would be desirable for a powered door/window assembly to address the noted design challenges. The door/window assembly according to preferred embodiments includes strategically positioned drive components that are hidden from view but are accessible from inside the structure in the event that one or more components need service or repair. Additionally, the assembly incorporates a counter balance such as a gas spring that assists the optional motor (or manual operation) in opening the door/window. The assembly also includes a safety release in the event of motor failure. Additionally, the counter balance is connected to the door/window via a block and tackle that amplifies a stroke output of the gas spring. 
     In an exemplary embodiment, a sliding window assembly is provided for a boat including a boat roof with a basin for receiving the sliding window assembly. The sliding window assembly includes a window frame secured in the basin, a component box housing operating parts for the sliding window assembly, and a window cooperable with the window frame and displaceable on the window frame between an open position and a closed position. The operating parts are cooperable with the window to facilitate displacement of the window. The operating parts include a carriage assembly connected to the window and engaged with the window frame and a counterbalance, such as a gas spring or the like, connected to the carriage assembly and biasing the window toward the open position. 
     The operating parts may include a motor driving a main cable to which the carriage assembly is connected. The main cable may include a spiral wound wire, and the operating parts may further include a gear engaging the spiral wound wire. The motor engages the gear to drive the main cable in forward and reverse directions. The carriage assembly may include a safety release that detaches the main cable from the window. 
     The counterbalance may be connected to the carriage through a block and tackle. In this context, the block and tackle may include a fixed pulley secured to the window frame, a movable pulley displaceable in or on a track, and a pulley cable wound over the fixed pulley and the movable pulley and secured at an end to the window. The counterbalance may act between the fixed pulley and the movable pulley and may be configured to bias the fixed pulley and the movable pulley apart. The pulley cable may be wrapped in multiple loops over the fixed pulley and the movable pulley. The movable pulley may be coupled with a bearing car displaceable in the track. The operating parts may include a motor driving a main cable to which the carriage assembly is connected. 
     In another exemplary embodiment, a boat includes a boat roof with a basin, and the sliding window assembly disposed in the basin. The operating parts may be configured such that they are accessible from inside the boat. A cover may be installed over the window frame that covers at least a portion of the window frame including the operating parts, where the cover is generally coplanar with the boat roof. 
     In yet another exemplary embodiment, a sliding window assembly includes a window frame, a window cooperable with the window frame and displaceable on the window frame between an open position and a closed position, and operating components including a counterbalance connected between the window frame and the window and a motor that drives a cable connected to the window. The counterbalance may be biased to assist the motor in displacing the window relative to the window frame toward the open position. 
     In still another exemplary embodiment, a sliding window assembly is provided for a boat including a boat roof with a basin for receiving the sliding window assembly. The sliding window assembly includes a window frame secured in the basin; a component box housing operating parts for the sliding window assembly; and a window cooperable with the window frame and displaceable on the window frame between an open position and a closed position. The operating parts are cooperable with the window to facilitate displacement of the window. The operating parts include a carriage assembly connected to the window and engaged with the window frame and a motor driving a gear engaged with a cable to which the carriage assembly is connected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of the door/window assembly cooperable with a boat roof and incorporated as part of a windshield assembly; 
         FIG. 2  is a top plan view of the assembly; 
         FIG. 3  is a front view of the assembly; 
         FIG. 4  shows the motor box assembly; 
         FIG. 5  shows the main cable and the carriage assembly; 
         FIG. 6  is a side view of the counterbalance and the block and tackle; and 
         FIG. 7  is a sectional view of the carriage assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Throughout the description, references to the assembly will be described in the context of a window assembly. The assembly is equally applicable to a door or pass-through construction, and the invention is not meant to be limited. For purposes of this description, any reference to a window, window frame, window assembly or the like is intended to encompass equivalent structures associated with a door. 
       FIG. 1  is a perspective view of the assembly  10  cooperable with a boat roof  12  and incorporated as part of a windshield assembly  14 .  FIG. 2  is a top plan view, and  FIG. 3  is a front view. Generally, the boat roof  12  is formed of fiberglass and includes a basin or depression  16  in which the window assembly  10  is installed. The window assembly  10  includes a window frame  18 , a component box  20 , which houses the driving mechanisms, and a glass door/window  22  supported on a subframe  23 . The window  22  and subframe  23  are displaceable between a closed position (shown in  FIG. 1 ) over the component box  20  and an open position in which the window  22  is disposed over an upper part  24  of the frame  18 . After the assembly  10  is installed in the basin  16 , a cover  26  (shown partially in  FIGS. 2 and 3 ) is installed over the frame  18  generally coplanar with the boat roof  12 . With the cover  26  in place, the window  22  and subframe  23  appear to open by sliding up into the roof. 
     The window assembly  10 , the basin  16 , the roof  12  and the cover  26  are fluid sealed to prevent water from entering the cabin. Sealed tracks on either side of the door assembly  10  may direct water to drains  28  adjacent a bottom of the door assembly  10 . Alternatively, as shown in  FIG. 5 , a bottom  54  of the assembly may be formed at an angle so that the assembly sits flush on the boat deck. A foam seal  56  prevents water leakage. 
     The component box  20  is shown disposed in a middle of the frame  18 . Preferably, the component box  20  is welded into the center of the frame  18 . Although the component box  20  can be positioned anywhere in the frame  18 , the middle section can be covered by the cover  26  while being accessible from inside the cabin in the event that any of the drive components requires repair or replacement. 
     Any suitable components for driving the glass window  22  and subframe  23  between open and closed positions can be provided, and the invention is not meant to be limited to the described/illustrated structure.  FIG. 4  shows the component box  20  with an exemplary drive system. The view in  FIG. 4  is from inside the cabin looking up into the component box  20  with a component box cover removed. 
     With reference to  FIGS. 4 and 5 , the window assembly is powered by a motor  30  that drives a steel cable  32  ( FIG. 5 ) attached to a two-piece block  48 , which can slide in a track extrusion  19  (discussed in more detail below). The cable  32  in the component box  20  is housed in a cable tube  33  that directs the cable from the component box  20  into a track in the track extrusion  19 . In an exemplary embodiment, the steel cable  32  is wrapped with a metal wire that is secured to the cable, defining a rack gear. The spiral wound cable  32  can be seen in  FIG. 5 , which shows the track extrusion  19 . The motor  30  drives a gear (disposed in a gear housing  58 ) that engages the spiral wound metal wire wrapped on the steel cable  32 . The motor  30  is operable in forward and reverse directions to drive the cable  32  and thereby open and close the window  22 . 
     From the component box  20 , the spiral wound cable  32  extends down a track in the track extrusion  19  into engagement with the two-piece block  48 . Specifically, the cable  32  is secured in an upper block  62  (preferably formed of plastic). A lower block  64  (preferably formed of plastic) is cooperable with the upper block  62  and is displaceable in a channel in the track extrusion  19  (see  FIG. 7 ). A connecting plate  66  (preferably formed of aluminum) is fixed (e.g., welded) to the subframe  23 . The connecting plate  66  acts to secure the upper and lower blocks  62 ,  64  together. The connecting plate  66  includes a knob  68  that extends through a threaded opening in the plate  66  and engages a hole  70  in the upper block  62 . Two connectors  72  such as screws or the like extend through the connecting plate  66  into threaded holes  74  in the lower block  64 . The block  48  including the upper block  62  and the lower block  64  along with the connecting plate  66  together define a carriage assembly. As the motor  30  drives the spiral wound cable  32 , the cable  32  displaces the carriage assembly to open or close the window  22 . A cross-section of the carriage assembly is shown in  FIG. 7 . In the event of motor failure or if it is otherwise desirable to displace the window manually, the window assembly can be released from the cable  32  by disconnecting the knob  68 . The knob  68  thus acts as a safety release for the window. 
     With continued reference to  FIG. 4  and with reference to  FIG. 6 , the drive components also include a block and tackle  34  with a counterbalance  36  that serves to counterbalance the weight of the window  22  and subframe  23 . The counterbalance  36  may be any suitable structure, and in a preferred embodiment is a gas spring. Other structures including various spring configurations may be contemplated, and the invention is not meant to be limited. A cable  38  is wound over a series of pulleys  40 ,  42  and over a turning pulley  60  before extending into a track in the track extrusion  19  and being secured in a slot in the lower block  64  (see  FIG. 5 ). The pulleys  40 ,  42  are displaceable relative to each other and serve to increase the stroke of the counterbalance  36 . In a preferred arrangement, the pulley  40  on the right in  FIG. 4  is attached to a movable carriage  43  such as a linear bearing or the like, and the pulley  42  on the left in  FIG. 4  is fixed in the frame  18 . The counterbalance  36  is biased open, that is, pushing the pulleys  40 ,  42  apart. The cable  38  is wrapped in multiple loops/spans to multiply the stroke of the counterbalance  36 . For example, with five loops, a  10 ″ stroke on the counterbalance  36  results in  50 ″ of window displacement. The number of loops needed is dependent on the stroke and width of the window. Additionally, the multiple loops of cable  38  serve to distribute the load such that a fraction (depending on the number of loops) of the counterbalance force is supported on each of the loops. With the counterbalance  36  biased open, the motor power required to open the window  22  is lower than the motor power required to close the window  22 . In this manner, the weight of the window can be used to facilitate closing, and closing the window can be more easily controlled by controlling amperage to the motor  30 . 
     As an alternative to the motor  30  and steel cable  32 , a cable drum (not shown) may be used. Still other alternatives may be suitable. Additionally, the sliding window assembly can be installed without the motor  30  and operable only in a manual mode with the counterbalance  36  and the pulley/cable assembly  38 ,  40 ,  42 . The sliding window assembly may also be constructed with a motor and without a counterbalance. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Summary:
A sliding window assembly includes a window frame and a window cooperable with the window frame and displaceable on the window frame between an open position and a closed position. Operating components of the assembly include a counterbalance connected between the window frame and the window and an optional motor that drives a cable connected to the window. The counterbalance is biased to assist the motor in displacing the window relative to the window frame toward the open position.