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CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/991,214 filed May 9, 2014. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to free-standing and other watercraft lifts and watercraft covers for use with watercraft lifts. 
     Description of the Related Art 
     The use of boat covers to protect boats is well known. A number of designs are currently known to perform this basic operation. Many boats have multi-section covers, often with one covering the bow section and another covering the aft section. The covers are typically shaped to cover at least portions of the three-dimensional shape of a boat and are manually spread out over the boat and then manually attached using snap or other fasteners. The bow section is attached with fasteners around the perimeter of the bow section especially when there is a bow opening. The aft section is attached to fasteners on the windshield, or in front of the windshield, as well with fasteners around the perimeter of the aft section. This common cover system has several negative aspects for the user. The large number of snaps or other fasteners used make the covers time consuming to install. The covers are often difficult to install after the material ages. The covers are large and awkward to store on-board. The covers can be dirty, and unpleasant to handle. The covers tend to lose shape, causing pockets of water, which further cause a loss of shape and pools of water. The covers do not cover a significant amount of hull surface surrounding the covers, and do not cover significant portions of the sides of the boat with which used, which causes fading in the sun and does not protect these areas from dirt. The covers provide no security, which makes the contents of the boat and the boat itself vulnerable to theft. 
     Several two-dimensional automatic cover designs are currently known. U.S. Pat. No. 3,549,198 uses a rotating arm to pull a flat cover over the top of a dump truck to secure the contents. This design would not be ideal for use with a boat lift since the cover is two-dimensional, non-adjustable and would be impractical to fit the three-dimensional shapes of various boat types with which the lift might be used. The torsional spring of the roller is also subject to over-tightening. 
     It is known to use a two dimensional cover design similar to U.S. Pat. No. 3,549,198 for application on a portable boat lift with a pontoon boat. Such a design does not provide protection to the sides of the boat. It also is more vulnerable to side wind, since it has exposed edges that catch the wind. Both designs use a roller fixed to the front, and a set of arms which pull the cover rearward like a window shade. This type of design is undesirable for an application on a boat, since the cover slides over parts of the boat, causing cover wear, and potential boat damage. The fixed cover in the front also blocks views and is not attractive since the roller remains visible at the front even when the cover is deployed. Pulling the cover from a fixed roller in the front also can cause damage to the cover and boat by dragging the cover on the boat. Further, the lift with the cover similar to that described in U.S. Pat. No. 3,549,198 does not provide any protection against operation of the lift when the cover is deployed, which can cause cover or boat damage, especially if installed on lifts that translate rearward when lowering, such as the lift of U.S. Pat. No. 5,908,264. Since the lift of this patent with the cover similar to U.S. Pat. No. 3,549,198 does not use the same remote control, another drawback is that the user is required to operate it separately from the automatic boat cover. It is also desirable to be able to manually adjust the cover when operating in case it is not seating correctly. 
     U.S. patents such as U.S. Pat. Nos. 4,019,212 and 6,786,171 describe a cover system that does not touch the boat. These systems have a fixed roof with structure and retractable sides that completely surround the watercraft. The tall sides of these systems block views and are more vulnerable to wind. For use on a free-standing boat lift, the fixed roof structure can make the lift vulnerable to tipping. Because of the fixed roof, these systems often require permitting and are highly regulated. 
     U.S. Pat. No. 4,019,212 is a device that attaches to a free-standing boat lift and lifts the cover off vertically. This design requires an external frame and overhead structure to lift the frame. The design is not conducive to covering the full sides of the watercraft. Since the cover still creates a shadow over the water when the boat is off the lift, this design would often be regulated as a canopy or covered moorage and not as a boat cover. 
     U.S. Pat. No. 8,911,174 solves the challenges above, but did not address some additional challenges. In U.S. Pat. No. 8,911,174 the starting and ending position of the roller is important for cover fit and cover storage position. In that patent, the starting and ending position of the swing arm is adjusted by moving the upper cylinder pivot position along the swing arm. This adjustment is complicated since an adjustment impacts both the forward and rear position at the same time. These adjustments are made underwater, making adjustments even more challenging. 
     The lift of U.S. Pat. No. 8,911,174 prevents lowering the boat with the cover on by using a hydraulic switching manifold that switches the operation from lift mode to cover mode, and will not switch to lift mode unless cover is fully off. 
     The U.S. Pat. No. 8,911,174 uses a torsion spring to roll up the cover and to apply tension on the cover, which is important for operating the cover in the wind. Since more cover tension can be perceived as beneficial, the operator can over tension the torsion spring and cause spring damage. 
     The automatic boat cover of U.S. Pat. No. 8,911,174 is costly, largely due to the hydraulic and control systems. 
     Applying U.S. Pat. No. 8,911,174 to a boat lift with a lifting cradle, lifted by cables, is challenging since the pivot position under the boat may limit minimum water depth. If the pivot position is raised, the loads applied to the swing arm get very high as the angle of the arm gets very shallow in the forward and rear positions. 
     The automatic boat cover of U.S. Pat. No. 8,911,174 uses a custom fit cover for the boat. The design of this cover is difficult for some boats that have protruding features such as antennas and/or fishing gear. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a side view of a boat on a lift in accordance with an embodiment of the present invention with the cover in an ‘Off’ position. 
         FIG. 2  is a side view of the boat on the lift with cover in a ‘Partially On’ position. 
         FIG. 3  is a side view of the boat on the lift with cover in an ‘On’ position. 
         FIG. 4  is an isometric view of the lift and cover without a boat. 
         FIG. 5  is an isometric view of the lift and cover showing inner handles. 
         FIG. 6  is an isometric view of the lift with a boat showing rear details of cover. 
         FIG. 7  is a side view of an adjustable arm of the lift. 
         FIG. 8  is an isometric view of a hydraulic powerpack of the lift. 
         FIG. 9  is a section view of the slip clutch side of the roller assembly. 
         FIG. 10  is an isometric exploded view of the slip clutch side of the roller assembly. 
         FIG. 11  is an isometric view of the clutch side of the roller assembly. 
         FIG. 12  is an isometric view of the adjustable length hydraulic cylinder. 
         FIG. 13  is an isometric view of the adjustable screw end of the hydraulic cylinder. 
         FIG. 14  is an isometric view of the hydraulic cylinder shown in a retracted position. 
         FIG. 15  is an enlarged isometric view of the retracted hydraulic cylinder end. 
         FIG. 16  is a side view of the swing arm actuated by the boat lift. 
         FIG. 17  is a front view of the swing arm actuated by the boat lift and the cover hoops. 
         FIG. 18A  is a side view of the lift of  FIG. 1  showing a limit switch. 
         FIG. 18B  is an enlarged aft, port side portion of the lift of  FIG. 18A . 
         FIG. 19  is an isometric view showing a cable actuated swing arm in rear position, with a guide track. 
         FIG. 20  is a side view of a cable actuated swing arm in forward position. 
         FIG. 21  is a portable boat lift with a cable actuated automatic boat cover. 
         FIG. 22  is an isometric view of a boat lift with a cable actuated automatic boat cover with a winch. 
         FIG. 23  is an isometric view of an automatic cover system used with a wheeled vehicle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention generally relates to a watercraft lift system generally used for lifting powerboats under 30 feet long, however, the design could be applied to other type boat and watercraft lift systems and other type boats and watercraft. U.S. Pat. No. 8,911,174 is incorporated herein by reference in its entirety. 
     The disclosed embodiments of the invention are illustrated for a watercraft lift system that allows for simple installation and removal of the cover, better protection for the boat or other watercraft being lifted, less view blockage, and better theft prevention. The combination of these features saves the boater time before and after boating, reduces hull cleaning, reduces hull fading, and allows the owner to store equipment, such as water skis inside the boat more securely. 
     According to the watercraft lift system disclosed herein, one may set the forward swing arm angle by fully extending the hydraulic cylinder, and fine-tune the swing arm angle by changing the length of the hydraulic cylinder with a screw end fitting on the cylinder shaft. To set the rearward angle, the cylinder shaft can be stopped by using shims on the cylinder shaft. 
     According to the watercraft lift system disclosed herein, the lift can also be disabled using a limit switch on the cover mechanism that prevents lowering when the cover is on the boat. 
     The hydraulics described in U.S. Pat. No. 8,911,174 can be eliminated if the swing arms are pulled rearward mechanically as the bunks of the lift are raised, and visa versa. If the torsional spring force is strong enough to retract the cover, a cable can be used to drive the swing arms rearward, and the roller can pull the swing arms forward by pulling on the cover. According to another embodiment, a rotational motor may be used to reel the cover in and out without using a torsion spring. 
     In another embodiment, a mechanical stop is fixed to push the cover arm rearward as the lift raises. 
     In a further embodiment, the high loads on the lifting cradle of U.S. Pat. No. 8,911,174 maybe reduced by actuating the swing arm using a cable on a track that guides the cable to a distance away from the pivot to get reduced loads. 
     To simplify cover design, multiple hoops are positioned over the boat, so the cover rests on the hoops for much of the boat instead of the boat. The cover can still hook on to the bow, and the cover may touch parts near the rear of the boat. In another embodiment, the cover attaches to another hoop instead of hooking on to the bow. 
     As shown in the drawings for purposes of illustration, a boat  50  is supported by a boat lift  32  using port and starboard (left and right side) boat lift bunks  48 . The boat lift  32  may use rollers or other means for supporting the boat thereon. The boat lift  32  includes port and starboard forward lift legs  47  and port and starboard rearward lift legs  49  which are telescopically connected directly or indirectly through cross-beams or otherwise to port and starboard side rails  30  of the frame of the boat lift  32 . 
     Port and starboard swing arms  26  are, respectively, pivotally connected to the port and starboard side rails  30  at port-side and starboard-side pivot locations  61  by a pivot channel, and are each simultaneously moved by operation of a corresponding port and starboard hydraulic cylinder  34 . Each of the port and starboard swing arms  26  includes a lower base arm portion  41  and an upper arm portion  42  telescopically disposed within the base arm portion and by which the length of the swing arm can be selectively adjusted to fit the boat  50  with which the boat lift  32  is being used. The length of swing arm  26  is adjusted by sliding the upper arm portion  42  farther out of the base arm portion  41  or farther into the base arm portion, then securing the upper arm portion in place within the base portion. 
     The port hydraulic cylinder  34  has a lower end pivotally connected to the port side rail  30  or another frame member of the boat lift  32 , and an upper end pivotally connected to the port swing arm  26 . The starboard hydraulic cylinder  34  has a lower end pivotally connected to the starboard side rail  30  or another frame member of the boat lift  32 , and an upper end pivotally connected to the starboard swing arm  26 . To deploy the cover  22 , the hydraulic cylinder  34  may move from an extended position (shown in  FIG. 1 ) to a retracted position (shown in  FIG. 3 ). The retracting movement of the hydraulic cylinder  34  causes the swing arms  26  to move from a forward position to a rearward position. The roller  24  allows the cover  22  to unwind and extend over the boat while the swing arms  26  move from the forward position to the rearward position. To retract the cover  22 , the hydraulic cylinder is moved from the retracted position (shown in  FIG. 3 ) to the extended position (shown in  FIG. 1 ). The extending movement of the hydraulic cylinder  34  causes the swing arms  26  to move from a rearward position to a forward position. The tension in the torsion spring  97  causes the roller  24  to wind the cover  22  back into the roller  24  when the swing arms  26  move from the rearward position to the forward position. A controller in the hydraulic powerpack  66  may send a control signal to the hydraulic cylinder  34  causing the hydraulic cylinder to extend or retract. 
     The starting and ending position of a roller tube  24  is adjusted by positioning the lower pivot  61  and lower cylinder pivot  62  along the side rail  30 , and the upper arm portion  42  of the swing arm  26  in the base arm portion  41  of the swing arm  26 . The forward position of the swing arm  26  is set by adjusting the end fitting cylinder shaft  102  of the hydraulic cylinder  34 . Screwing the end fitting cylinder shaft  102  inward to the hydraulic cylinder  34  increases the angle of the swing arm (see  FIGS. 12-15 ). Conversely, screwing the end fitting cylinder shaft  102  out of the hydraulic cylinder  34  decreases the angle of the swing arm  26 . The angle of the swing arm  26  in the rear position may be adjusted by stopping the full retraction of the cylinder shaft  101  using shims  104  on the cylinder shaft  101 , between the cylinder body  105  and the shaft plate  103  (see  FIGS. 14 and 15 ). 
     The roller tube  24  extends laterally between and is rotatable relative to the end portions of the upper arm portions  42  of the port and starboard swing arms  26 . As seen in  FIG. 9 , a torsional spring  79  is positioned within the roller tube  24  and applies adjustable rotation force to the roller tube and hence a pulling force to a cover  22  attached thereto. 
     In another embodiment, a motor (not shown) is mounted on one end of the roller  24  instead of the torsional spring  97 . A controller (in hydraulic powerpack  66 ) may send a control signal to the motor causing the motor to reel the cover  22  in or out as the swing arms  26  move. For example, when hydraulic powerpack  66  sends a control signal to the hydraulic cylinder  34  to retract (cover the boat) and move the swing arms  26  to the rearward position, the hydraulic powerpack  66  may also send a control signal to the motor causing the motor to unwind the cover  22 . Conversely, when hydraulic powerpack  66  sends a control signal to the hydraulic cylinder  34  to extend (uncover the boat) and move the swing arms to the forward position, the hydraulic powerpack  66  may also send a control signal to the motor causing the motor to wind the cover  22  back into the roller  24 . The motor and hydraulic cylinder  34  may be controlled in concert to ensure that the cover  22  is not ripped or otherwise damaged. Alternatively, an actuation member may apply a rearward load on the swing arm  26  so that when the motor lets the cover out, the swing arms  26  move rearward. The motor could be electric or hydraulic driven. 
     The front of the cover  22  has a pocket sized to accept therein the bow of the boat  50  when the cover is deployed to cover the boat (see  FIG. 2 ). A forward cover line  20  extends between the front of the cover and a forward end portion of a bow sprit  28  which has a rearward end portion attached to a forward transverse frame beam  46  of the boat lift  32  (see  FIG. 4 ). The forward cover lines  20  connect between the bowsprit  28  and the forward section of the cover. In the preferred embodiment, one forward cover line  20 A attaches to a port side forward wing  64  of the cover, and the other forward cover line  20 B attaches to a starboard side forward wing  65  of the cover. A spreader bar  54  separates the port and starboard cover lines  20 A and  20 B, and helps to prevent the cover from snagging on wide-bow boats. The forward cover lines  20  are depicted in the deployed position and the retracted position in  FIG. 1  (only cover line  20 A being visible). Another embodiment uses a line extending from port and starboard attachment points  44  and  45  on the cover to the boat lift frame directly, without using a bow sprit, such as to the forward transverse frame beam  46  of the boat lift  32  or to a bow stop accessory that mounts to the boat lift bunks  48 . Another embodiment uses a single line attaching the front of the cover  22  to the boat lift  32 . Another embodiment secures the front of the cover to a fixed point below the bow so a bow sprit  28  would not be needed. 
     The perimeter of the cover  22  has an edge pocket with an elastic cord  40  extending through the edge pocket (see  FIG. 6 ). When the cover  22  is fully deployed on boat  50 , the elastic cord is tightened by being wrapped around the roller tube  24  in the opposite direction than the cover for the first few wraps so that the elastic cord  40  is tensioned when the roller tube  24  is pulled aft, and is loosened when roller tube  24  moves forward and the cover  22  begins to be rolled up on the roller tube  24 . 
     The preferred embodiment of the cover  22  uses forward side wings  64  and  65  which are designed to better secure the cover to the sides of the boat (see  FIGS. 3 and 5 ). 
     As seen in  FIG. 6 , the aft end of the cover  50  is attached to the roller tube  24  with a multiplicity of elastic members  38  to assist to keep cover tight on boat  50 . 
     The cover  22  has a plurality of interior handles  52  which assist the operator in positioning the cover if needed. 
     The length of swing arm  26  is adjusted by sliding the upper arm portion  42  farther out of the base arm portion  41  or farther into the base arm portion, then securing the upper arm portion  42  in place within the base arm portion  41 . 
     The lower pivot of swing arms  26  can be adjusted fore and aft by where the base arm portion  41  is attached along the side rail  30  to change the position the pivot location  61  of each swing arm. 
     A hydraulic powerpack  66  operates the boat lift  32 . After the lift  32  is in a fully up position, the control system switches the control to the cover, and the cover  22  can be moved to the ‘On’ position. When the cover is fully retracted, the control shifts to operate the lift, allowing the lift  32  to lower. 
     The illustrated embodiment is a hydraulic lift. In this embodiment, the switching of control can be done hydraulically from the lift to the cover with sequencing valves which automatically switch the system from ‘Lift mode’ to ‘Cover mode’ when the lift reaches the fully up position. The system switches back to ‘Lift mode’ when the cover is fully removed when the cover cylinder is fully extended. 
     The hydraulic powerpack  66  includes a hydraulic power unit  68 , a control box  70 , a hydraulic switching manifold  72  and a battery. The hydraulic hoses  74  for the lift  32  and the hydraulic hoses  76  for the cover system  10  connect to the hydraulic switching manifold  72 . The battery  78  powers the hydraulic power unit  68 , and the control box  70  operates the hydraulic power unit  68 . The hydraulic switching manifold directs the flow to the hydraulic hoses  74  for the lift  32  or the hydraulic hoses  76  for the cover system  76 . The control box  70  can be operated by a manual two way switch or with a remote control. 
     The roller tube  24  is torsionally loaded by the torsion spring  79  that extends longitudinally within the roller tube, as shown in  FIG. 9 . The torsion spring  79  has a first end secured to a spring mount  95  attached to the roller tube  24 . A second end of the torsion spring  79  is attached to another spring mount  94 , which is connected to an end plate  90  via a friction clutch  80 , a centering puck  87  and a ratchet plate  86 . The ratchet plate  86  is constrained to rotate in one direction by a locking pawl  88 , as shown in  FIG. 11 . The torsion spring  79  is preloaded by turning a bolt  93 , which turns a pin  92 . The pin  92  turns the ratchet plate  86 , centering puck  87 , friction clutch  80  and spring mount  94 . The first end of the torsion spring  79  is restrained by the spring mount  95 . 
     The roller  24  is designed to prevent over-torqueing or overloading the torsion spring  79 . If the torque exerted on the torsion spring  79  exceeds a pre-set torque limit by either (i) excessive preloading by turning the bolt  93 , or (ii) rotating the roller tube  24  too many times during operation, the spring mount  94  will slip to relieve torque. That is to say, the spring mount  94  will slip (rotate) relative to the ratchet plate  86  and centering puck  87 , with the friction clutch  80  being between the relative rotating parts. This slip will relieve torque load on the torsion spring  79 , preventing damage. The pre-set torque limit (maximum torque limit) on the torsion spring  79  may be set by compressing a clutch spring  81  against the friction clutch  80 . The clutch spring  81  is positioned within and concentric with the torsion spring  79 . The compression of the clutch spring  81  against the friction clutch  80  is set using a double nut  96  on a threaded section of a longitudinally extending axle  91 . The axle  91  extends concentrically within the torsion spring  79  and the clutch spring  81 . This configuration effectively prevents over-tensioning of the torsion spring  79  by using the friction clutch  80  as slip clutch. 
     A spring sock  97  between the torsion spring  97  and the roller tube  24  reduces noise and wear, and separates the torsion spring  97  material from the roller tube  24  material. In the preferred embodiment, this roller assembly with slip clutch is used for an automatic boat cover system with swing arms  26 . Another embodiment would be for an automatic boat cover system that uses tracks to guide the positioning of the roller. Another embodiment uses a cover system having the roller assembly with slip clutch to cover a wheeled vehicle with an open-box top, such as a dump truck, pickup truck, or a trailer with an open-box frame. 
     The non-hydraulic version has the swing arm  26  mounted on a non-moving part of a boat lift  32 , or to the adjacent dock structure, or sea bed  36 . As the translating part of the boat lift  102  moves upward, the swing arm  26  is pulled rearward by a flexible actuation member  126 . By way of non-limiting example, if the actuation member  126  is a cable, the cover  22  may be reeled in on the roller as the lift is lowered, due to the torsion in the roller tube  24 , as seen in  FIG. 16 . 
     A preferred embodiment has a guide track  120  on the swing arm that accepts the actuation member  126 , as shown in  FIGS. 19 and 20 . This guide track  120  positions the actuation member  126  (cable) optimally relative to the swing arm pivot  61  to reduce peaks in loads in the cable as the swing arm  26  moves. The shape of the guide track support  121  allows for clearance if the swing arm pivot  61  is mounted on the boat lift cradle support  122 . In another embodiment, the cable actuated automatic cover system may be used in a portable  4  bar linkage boat lift, such as the boat lift  32  shown in  FIG. 21 . In this embodiment, the cable is pulled by moving parts, such as the bunks or lifting arms. In another embodiment, the swing arm  26  is pulled rearward with an actuation member  126  (cable), which is being pulled by a winch  128 , shown mounted on the boat lift  32 . Another embodiment has the winch  128  mounted on the dock or piling  127 . 
     Another method of preventing accidental lowering of the lift with the cover on is to include a limit switch  110 , as shown in  FIGS. 18A and 18B . The limit switch  110  detects when a swing arm  26  is in a certain position. For example, the limit switch may sense when at least one of the swing arms  26  are forward, and the cover  22  is on the boat. In  FIGS. 18A and 18B , the limit switch senses that one of the swing arms  26  are rearward and that the cover  22  is on the boat. A control system connected to the limit switch determines a position of the swing arms  26  based on a signal sent from the limit switch  110 . The control system prevents the boat from lowering unless the limit switch  110  senses that one or both of the swing arms  26  are forward and cover  22  is off. 
     In yet another embodiment, the cover  22  may extend over hoops  123  to cover the boat  32 , as seen in  FIG. 16 . When the cover  22  is moved from the forward position to the rearward position, the cover  22  covers the front of the boat  32 , extends over the hoops  123 , and covers the back of the boat  32 . Hoops  123  may attach to the top or sides of guide posts  122  of the boat lift  32 . When the cover  22  covers the boat  32  and the hoops  123 , the cover  22  is partially supported by the hoops  122  and guide posts  122 . The cover  22  may widen from the forward portion of the cover  22  to a middle portion of the cover  22  that covers the hoops  123 . The cover  22  may also widen from the rearward portion of the cover  22  to the middle portion of the cover  22  that covers the hoops  123 . The cover  22  is sized to fit around the hoops  123  so as to protect and cover a wide variety of boats without requiring custom fitting. Although two hoops  123  are illustrated in  FIG. 16 , the cover system may instead have only a single hoop  123 . Alternatively, more than two hoops  123  may be used to accommodate boats having a longer length or special needs. 
     The above described elements may be identified in the drawings as follows:
           10  Cover system     20  Forward cover line     22  Cover     23  Cover track     24  Roller tube     25  Anti-racking bar (not in text)     26  Swing arm     27  Arm stiffener (not in text)     28  Bow sprit     30  Side rail     32  Boat lift     34  Swing Arm Hydraulic Cylinder     36  Seabed     38  Aft cover elastic     40  Perimeter cord     41  Lower section of swing arm     44  Forward wing attachment (Port)     45  Forward wing attachment (Stbd)     46  Boat Lift transverse beam     47  Forward Lift Legs     48  Boat Lift bunks     49  Aft Lift Legs     50  Boat     52  interior handles     54  spreader bar     60  Upper cylinder pivot     61  Swing arm pivot     62  Lower cylinder pivot     64  Forward cover wing (Port)     65  Forward cover wing (Stbd)     66  Hydraulic Powerpack     68  Hydraulic power unit     70  Control box (RC)     72  Hydraulic switching manifold     74  Hydraulic hoses for lift     76  Hydraulic hoses for cover system     78  Battery     79  Torsion spring     80  Friction clutch     81  Clutch spring     82  Cylinder shaft     83  End fitting, cylinder shaft     84  Length Adjuster     85  Clip-on shims     86  Ratchet Plate     87  Centering puck     88  Locking pawl     89  Roller guide     90  End plate     91  Axle     92  Pin     93  Bolt     94  Spring mount (clutch side)     95  Spring mount (roller tube side)     96  Double nut     97  Spring sock     101  Actuation member     102  Translating part of boat lift     110  Limit switch     120  Guide track     121  Guide track support structure     122  Boat Lift cradle structure     123  Guide on     124  Hoop     125  Lifting cable     126  Actuation cable     127  Piling     128  winch     129  Pulley     130  Actuation cable end on translating part of lift     131  Actuation cable end on swing arm       

     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. 
     Accordingly, the invention is not limited except as by the appended claims.

Summary:
A boat lift with hydraulically or mechanically actuated arms which self-installs a fitted three-dimensional boat cover on a powerboat. The control logic of the system allows for cover operation only when the lift is raised. A spring-tensioned roller keeps the cover tight and self-rolls the cover on the roller when the actuated arms are pivoted forward. The roller is hidden behind the boat in ‘cover-on’ position. A slip clutch prevents the torsion spring from being over tightened. The forward position of the roller is adjusted by adjusting the hydraulic cylinder length. The rearward position of the roller is adjusted by limiting the retracted position of the hydraulic cylinder. A non-hydraulic embodiment actuates the cover when the lift is operated.