Abstract:
A pontoon system comprising a series of hollow plastic modular units held together in a string under a watercraft is disclosed. The string may be compressed so as to form a unitary pontoon. If the compression force holding the individual pontoon member is released, any individual pontoon member which has been damaged may be removed and replaced without having to remove the watercraft from the water.

Description:
This application claims the benefit under Title 35 U.S.C. §119 (e) of U.S. Application No. 60/258,491 filed Dec. 29, 2000. 
    
    
     FIELD OF INVENTION 
     This invention relates to a pontoon assembly for watercraft which comprises a series of modular pontoon assemblies (modules) which may be linked together to form an integrated pontoon. The modular components are similarly shaped (with the exception of the bow and stem modules) and each module is provided with a mating face surface profile which ensures that two adjacent modules may be easily assembled together in an interlocked relationship at the mating faces. When a series of such modules are assembled together with the mating faces interlocked together, the result is complete pontoon having all the floatation advantages associated with the prior art single unit pontoon assembly in common use today but in addition allows for fast and speedy replacement of any part of the pontoon assembly which might be damaged during use. It is not necessary to remove the entire pontoon assembly to replace one of the modular components. 
     Each module of this invention is preferably formed from a tough plastic material which is capable of undergoing substantial distortion without experiencing rupture. Such modules may be successfully formed through blow molding or by a centrifugal casting process. The result is a tough durable lightweight module which when assembled together with a series of like modules may ultimately be formed into an integral pontoon which is capable of replacing the standard metallic pontoons used on watercraft etc. The resulting pontoon composed of a plurality of interlocking modules is available at a fraction of the price of the elongated metallic cylindraceous pontoons of the prior art. Individual modules in the completed pontoon may be easily removed and replaced without the requirement of complete removal of the entire pontoon from the watercraft. The prior art pontoons either require complete removal of the pontoon or the raising of the watercraft with sophisticated lifting equipment to enable a repair to the pontoon whilst it is still attached to the watercraft. 
     BACKGROUND OF THE INVENTION 
     Pontoons have been used to supply floatation for houseboats, barges, docks, rafts, bridges, etc. for years. Prior art pontoons have usually taken the shape of an elongated, hollow metal cylinder and in instances where the pontoons are used as floatation devices for moving watercraft, etc. the leading and trailing portions of the pontoon are usually shaped to minimize the resistance to motion of the pontoon through the water. 
     Recently pontoons have been developed which are more of a modular nature and which have been used for docks, rafts and other stationary floating objects so that the floatation may be adjusted by adding more units to the floating raft or dock assembly. The versatility of the modular concept for floatation devices has led to wide acceptance of hollow plastic pontoon modules for docks and rafts etc. 
     Pontoons for houseboats and other moving watercraft have generally been fabricated from sheet metal stock to form a hollow, cylindrical, metallic vessel on which a superstructure is mounted. 
     Over the years, pontoon equipped houseboats have suffered from one serious deficiency. If the metallic pontoon suffered puncture damage anywhere along its length it is necessary to raise the pontoon out of the water in order to be able to carry out a repair. This necessitated that the houseboat be tipped in some fashion or other or that the entire craft be lifted out of the water to effect a successful repair. At times it will be found that if the damage to the pontoon is severe enough, the entire pontoon must be removed from the watercraft to effect a satisfactory repair. 
     It is well recognized that a large industry has evolved in which pontoon equipped houseboats are rented to vacationing persons who have had little or no experience in operating watercraft of this type and size. As a result, it is not unusual for a novice to damage the pontoons on such rented watercraft. Repairing damaged pontoons can be prohibitively expensive. 
     SUMMARY OF THE INVENTION 
     The modular pontoon assemblies of this invention may be ideally applied to applications such as houseboats and other types of watercraft such as barges, sightseeing craft, etc. which are not primarily intended for operation at high speeds, but where damage to the pontoon assemblies is an occupational hazard. The modular pontoon assembly of this invention is formed of a series of identically shaped hollow molded plastic modules which are quite resilient and which have the ability to distort upon impact without suffering puncturing damage. The material is resistant to tearing etc. when subjected to unintentional scraping or abrasive scrubbing on the pontoon surface. 
     The pontoons themselves are formed into a predetermined shape so as to keep the resistance low when the watercraft is in motion, and the sides of the pontoon are shaped to add increased resistance to impact damage during docking and mooring. 
     Each pontoon is provided with a pair of spaced apart upright parallel flanges at the upper surface thereof in which a series of spaced transverse bolt holes are formed. A pair of substantially “C” shaped pontoon rails are supplied on the mounting craft to engage the flanges on their outside surfaces for mounting the pontoons on a watercraft. The flanges of the pontoons are formed to be spaced apart sufficiently to thus fit between the “C” shaped pontoon rails. There is just sufficient clearance between the rails and flanges to allow the flanges formed on the top of each pontoon module to slide between the pontoon rails. When a pontoon is located in the desired position and location between the pontoon rails, one or more through bolts are passed through the matching holes in the rails and the upright flanges on the top of the pontoon module to fix the pontoon to the watercraft. 
     The complete pontoon for a watercraft may comprise several modules serially mounted on the pontoon rails to provide the desired floatation. The modules at each end of the pontoon assembly preferably have a curved water engaging surface (similar to a ski) to cut down losses when the craft is moving. The mounted modules are preferably maintained in a state of compression in the string. They are pressed together by a jacking means or a winch to ensure a tight fit between adjacent modules forming the complete pontoon. The through bolts passing through the pontoon rails may be tightened to secure each module in its “home” position on the pontoon rails after the modules have been pressed together. 
     PERTINENT PRIOR ART 
     U.S. Pat. No. 5,355,825 Oct. 18, 1994 
     This patent is directed to an aquatic float the primary purpose of which is to supply floatation for aquatic structures such as docks, rafts or platform boats etc. The float is of a modular type having a pair of upright longitudinal flanges formed in the top surface thereof embrace “standard dimensional lumber”. The longitudinal flanges are provided with moulded in place fastener receivers. 
     U.S. Pat. No. 4,768,456 Sep. 6, 1988 
     This patent describes a modular float system which is ideally suited for docks and rafts. The patent describes a floating platform, the buoyancy of which is provided by large hollow plastic floats, which are serially held in place by a raft assembly which is mated into grooves formed in the top of each module. In this instance, the mating plastic grooves are provided with ridges to tightly engage the mating members of the raft assembly. 
     Each module is provided with an interlocking surface of mating with the adjacent module so that the integrity of the float assembly is maintained. 
     This assembly which is directed to floating docks and rafts might be adaptable for use as a pontoon assembly for a houseboat etc. but the construction of the interlocking raft and float surfaces is such that each module tends to be “locked” in place one the raft members have been properly seated in the provided recesses in the top of the float surface. It would almost require a jacking device to separate a float module from the raft. The interlocking assembly (dove tail) shown in FIGS. 5 and 6 may yield further problems for separation of adjourning floats if one float must be removed from the system 
     U.S. Pat. No. 5,947,049 Sep. 7, 1999 
     This invention relates to a boat lift or a walkway which comprises a set of hollow plastic modules which are mounted on a pair of rails by means of through bolts. Because of the configuration of the device of this invention, it is not applicable to the pontoon assembly of this invention. 
     U.S. Pat. Re No. 24837 Jun. 4, 1960 
     U.S. Pat. No. 2,879,735 May 31, 1959 
     U.S. Pat. No. 3,448,709 Jun. 10, 1969 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a modular pontoon assembly of this invention. 
     FIG. 2 shows the pontoon module and its associated hardware used to mount the module to a watercraft. 
     FIG. 3 shows a perspective illustration of the pontoon and apparatus used to secure the module to the hardware of the watercraft. 
     FIG. 4 is a sectional view of the mating arrangement for a pontoon module into the mounting hardware of the watercraft. 
     FIG. 5 is an illustration of the method of replacement of a pontoon module from a pontoon assembly. 
     FIG. 6 is an illustration of a bow or stern pontoon module. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, a pontoon module  10  is shown, which is preferably formed of a tough plastic material manufactured and sold by Agri Plastic such as LLPE polyethylene. 
     Module  10  is shaped to have protruding bulging sides  12  and  14  which function as protective “bumpers” for the complete pontoon assembly during docking operations. 
     The lower surface  16  is supplied with a ribbed type corrugation type surface which adds additional strength to the bottom of the pontoon module. 
     Both ends  18  (only one of which is shown) are provided with a ridged surface comprising depressions  20  and upstanding ridges  22  which yield an interlocking surface having a substantial degree of robustness. This is necessary because adjacent modules are purposely made to interlock with each other in the final assembly of the complete pontoon assembly. 
     The top surface of the pontoon module  10  is provided with a pair of upstanding longitudinally extending flanges  24  and  26  which are used to mount each module on a designated watercraft. 
     Each flange has at least one cast-in-place sleeve such as  28  which is sealed in the flanges  24  and  26  of module  10 . 
     It is to be noted that other ribbing such as  30  is present on the side surfaces of module  10  to add increased strength to the module. 
     Each module is also provided with a removable seal plug  32  in the top surface thereof. 
     FIG. 2 shows how a watercraft  50  having a pair of metallic channel members  52  and  54  mounted thereon may receive individual pontoon modules  10  therebetween. The flanges  24  and  26  of module  10  are made to be received between channels  52  and  54  in a sliding fit. Channels  52  and  54  are provided with elongated matching mounting holes  56  for receiving a mounting bolt  58  therein (see FIG.  3 ). A hollow quill  60  is provided to receive bolt  58  and provide a spacer between the sleeves  28  in flanges  24  and  26 . 
     Bolt  58  is provided with a pivoting locking key  62  at one end and a threaded portion  64  at the remote end. 
     Key  62  when axially aligned with bolt  58 , allows the swift insertion of the bolt  58  into the mounting assembly comprising rails  52 ,  54  and flanges  24  and  26  containing sleeves  28 . A wing nut  66  is shown in FIG. 3 to mate with threaded portion  64  of bolt  58 . 
     FIG. 4 shows a sectional view of the method of attachment of module  10  to the rails  52  and  54  of watercraft  50 . 
     The presence of spacer quill  60  between sleeves  28  allows the nut  66  to be tightened securely and the predetermined constant spacing of the rails  52  and  54  is assured because of this construction. 
     Note that holes  56  are elongated so that there is a limited degree of freedom for modules  10  to move longitudinally along the rails  52  and  54 . This degree of freedom is provided so that the individual modules  10  of a complete pontoon assembly are free to move along rails  52  and  54  when supplied with a compressive force, so that the interlocking end surfaces  16  of adjacent modules are pressed together to form an integral pontoon assembly. 
     A winch assembly  70  operated by handle  72  is shown in FIG. 5 having cable  74  attached to a remote module is used for pulling the modules  10  together in the final assembly. 
     To remove a damaged module from an assembly winch  70  is released to relax cable  74 . Nuts  68  are loosened to allow the modules  10  to move apart slightly. The damaged module in all probability will have suffered a puncture and will have neutral or negative buoyancy. When the bolts  58  and spacers  60  have been removed from the mounting rails  52  and  54  the damaged module  10  may be easily removed by allowing it to slide downwardly from the pontoon assembly without the need of jacks or prybars, etc. The replacement module (which may be filled with water to establish neutral buoyancy) is lowered to a location below and between the two modules in the assembly (see FIG. 5) from where the damaged module was removed. When the interlocking surfaces  16  of the modules on either side of the replacement module are properly mated, the replacement module may be slid upwardly between the adjacent modules and mounted between rails  52  and  54  using bolts  58  and quills  60 . 
     Since all the nuts  68  of the pontoon assembly had previously been relaxed, the modules  10  of the pontoon assembly may now be compressed together by operating winch  70 . When the desired degree of compression of the modules has been achieved, nuts  68  are tightened to permanently lock the modules  10  in place on rails  52  and  54 . 
     The replacement module may now be emptied of its ballast water by pumping the contained water out of the module through the opening provided for the seal plug  32 . Normal buoyancy is thus restored without having to “dry-dock” the watercraft or lift the craft with a crane. 
     The advantages of the pontoon modules of this invention are many: 
     1. Because the pontoon assemblies of this invention are primarily intended for use on watercraft such as houseboats, the pontoon modules must be capable of withstanding severe side thrusts occurring during docking or other unintentional acts resulting from improper operation by persons not possessing true boating skills. The location of flanges  24  and  26  on each module  10  provides a significant degree of strength to the module to prevent twisting of the module when properly mounted between rails  52  and  54 . These modules will be subjected to impacts on the side of the module during a docking operation which apply torques to the individual modules which tend to twist the module in the mounting channels  52  and  54 . Because of the distance between the flanges  24  and  26 , the module is able to absorb the side thrust imposed on it without suffering damage. 
     2. Provision is made for “locking” the modules into an integral assembly by some form of compression means (winch  70 ) to provide a continuous surface uninterrupted by spaces between adjacent modules. This strengthens the completed assembly. 
     3. The pontoon modules may be easily replaced by unskilled personnel who have no access to cranes or other dry docking equipment. 
     4. The pontoon modules of this invention are capable of winter exposure in ice, thus watercraft so equipped do not have to be protected from the water freezing during the winter season. Thus the storage efficiency of the watercraft bearing these pontoons is significantly enhanced. 
     5. The modules of this invention may be ideally applied to pontoon floats for aircraft.