Abstract:
A non-self-propelled, floatable structure for supporting people, animals, machinery or other loads is disclosed, having a floatable body designed to float on water, and a retention skirt that protrudes downwardly from a peripheral edge of the floatable body. The retention skirt is designed to extend underwater, delimiting an internal space between the retention skirt, the floatable body, and the water. The retention skirt is airtight, preventing air passing through the skirt and towards said internal space. Thus, when a downward force is applied on an edge of the floatable body causing the opposite edge to start rising from the water, skirt airtightness beneath the rising edge creates a vacuum effect that stops the edge from rising and prevents the floating structure from swaying excessively and eventually turning over or capsizing. The retention skirt also limits or prevents lateral and transverse motion across the water surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation-In-Part claiming benefit of U.S. Non-Provisional patent application Ser. No. 13/297,448, filed on Nov. 16, 2011, which is a Continuation-In-Part and claims the benefit of U.S. Non-Provisional patent application Ser. No. 12/952,686, filed on Nov. 23, 2010, now abandoned, which is a Continuation-In-Part and claims the benefit of U.S. Non-Provisional patent application Ser. No. 12/104,824, filed on Apr. 17, 2008, now issued as U.S. Pat. No. 7,837,526, which is a Continuation-In-Part of and claims priority to U.S. Non-Provisional patent application Ser. No. 12/050,725, filed on Mar. 18, 2008, now issued as U.S. Pat. No. 7,867,049, which claims priority to U.S. Provisional Patent Application Ser. No. 60/951,491, filed on Jul. 24, 2007, all of which are incorporated herein in their entireties. 
    
    
     FIELD OF INVENTION 
     The present invention relates to floating structures, and more particularly to a non-self-propelled floating structure, raft, dock, deck, platform, barge, marine hazard marker, marine navigational marker, life raft, commercial marine craft, recreational marine craft or the like having a bottom perimetric skirt that increases the structure&#39;s stability in the water, greatly reducing the risk of the structure tilting excessively, turning over or capsizing, and limiting or preventing lateral or transverse movement of the floating structure along the water. 
     BACKGROUND OF THE INVENTION 
     Floating structures may come in a myriad of shapes and sizes, depending on their function. Some floating structures, such as boats and ships, are self-propelled and thus capable of providing a means of transportation on water. Other floating structures such as floating docks, decks, platforms, rafts, landing crafts or the like, are generally not self-propelled, and are conceived to provide a static horizontal surface on which to carry out a wide variety of tasks or actions, depending on the type of structure. Many non-self-propelled floating structures are either inflatable, or are constructed from durable buoyant materials both of which are designed to support the weight of one or more individuals, heavy machinery or extreme loads, and to remain afloat. Such floating structures come in a variety of shapes, and sizes, and are generally used in recreational and utility activities such as swimming, boating, construction, repair or marine operations. Some floating structures comprise floating rafts or platforms that provide a base structure for swimmers to utilize. Still other floating structures comprise floating docks or decks that are fixedly positioned in one location on the surface of the water, and are used for walking upon, for water sports, or for securely attaching a boat or vessel in place. 
     Self-propelled floating structures are normally provided with a hull, which is a relatively complex watertight body designed to be arranged partially underwater and to render the structure hydrodynamic, stable, floatable and capable of sustaining a load. Static, non-self-propelled structures need not be as hydrodynamic but, instead, must be as stable and secure as possible to provide a safe environment for the person(s) standing or carrying out an activity on the structure, and for the load that is supported on the structure. 
     For instance, floating workstations are known in the art that are capable of providing a floating platform near a ship hull for a person to stand on and carry out repair, cleaning or other maintenance operations of the hull surface. Floating workstations are capable of easily changing positions relative to the vessel, allowing the person carrying out maintenance of the vessel to conveniently access and work on different zones of the hull, in comparison to carrying out the maintenance operations from a dock. Floating workstations of the sort must be as stable as possible to ensure safety of the persons and load supported on the workstation. In the event that such floating workstations are not adequately stable, inappropriate movement of the load or persons on the structure could cause the workstation to sway excessively, and even turn over, putting the person at risk of falling and suffering severe or fatal injuries, for instance in the event that the person impacts the ship hull, or marine structures, a seawall, hazardous waters or a hazardous sub-surface (seabed or riverbed). 
     In order to increase stability, some floating structures are provided with poles that are stuck into the underwater floor surface. While effective, such a solution is cumbersome to carry out, and requires the provision of lengthy and/or bulky hardware. In addition, it is not applicable when the floating structure is floating in deep waters. 
     The present invention seeks to provide a system for stabilizing a non-self-propelled floating structure, which is effective in preventing that the floating structure turns over relative to the water surface in both deep and shallow waters, and yet presents a reasonable cost that will allow the system to be successfully installed in a wide variety of non-self-propelled floating structures. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the deficiencies of the known art and the problems that remain unsolved by providing a non-self-propelled, floatable structure comprising a floatable body designed to float on water, and a retention skirt provided about a perimeter of the floatable body, the retention skirt being configured to extend into the water a predetermined distance and to prevent air from entering in the space delimited by the skirt, the body and the water surface. In the event that, while the structure is floating in water and supporting a load, the floatable structure is unstabilized by an undue movement of the load or an external force, a vacuum effect is created in the aforementioned space that prevents the structure from separating from the water, and thus from eventually turning over. In addition, the skirt also reduces, and in some cases prevents, the lateral or transverse movement of the floatable structure, further increasing stability of the load supported on the structure. The stabilizing retention skirt is equally valid and effective in both deep and shallow waters. 
     In accordance with a first embodiment of the invention, the present invention consists of a non-self-propelled, floatable structure for supporting a load, comprising: 
     a floatable body, configured to float on water, said body comprising a first side for remaining over the water, and a second side for contacting the water, wherein said second side is arranged opposite to said first side; 
     a retention skirt, protruding from said second side of said floatable body and configured to extend underwater, an internal space being delimited between said retention skirt said the second side, wherein 
     said retention skirt is airtight for air passing in an inward direction, said inward direction corresponding to air passing through the skirt and towards said internal space. 
     In a second aspect, the skirt protrudes vertically downwards from the second side. 
     In another aspect, the retention skirt is at least partially flexible. 
     In another aspect, the retention skirt is at least partially rigid. 
     In another aspect, the floatable structure comprises at least one one-way air valve mechanism allowing air to exit the internal space and preventing air from entering the internal space. 
     In another aspect, at least one one-way air valve mechanism is comprised in the floatable body, allowing air to exit the internal space through the floatable body. 
     In another aspect, the one-way air valve mechanism comprised in the floatable body communicates the internal space with the first side of the floatable body. 
     In another aspect, the one-way air valve mechanism comprised in the floatable body comprises a one-way check valve. 
     In another aspect, the one-way air valve mechanism comprises a first end of the skirt and an opposed second end of the skirt, wherein said first end is externally overlapped over said second end, the first end being movable with respect to the second end, said first end being configured to separate from the second end responsive to an increase in air pressure in the internal space, and to rest against the second end responsive to a decrease in air pressure in the internal space. 
     In another aspect, the retention skirt is an entirely flexible skirt having overlapped first and second ends forming said one-way valve mechanism. 
     In another aspect, the retention skirt is removably attached to the floatable body. 
     In another aspect, the height of the retention skirt is manually or mechanically adjustable. 
     In accordance with another embodiment of the invention, the present invention consists of a non-self-propelled, floatable structure for supporting a load, comprising: 
     a floatable body, configured to float on water, said body comprising a top surface for supporting a load, and a bottom surface for facing the water; 
     a retention skirt, protruding downwards from a peripheral edge of said floatable body, an internal space being delimited between said retention skirt and said bottom surface, wherein said retention skirt is airtight for air passing in an inward direction, said inward direction corresponding to air passing through the skirt and towards said internal space; 
     at least one one-way air valve mechanism allowing air to exit the internal space and preventing air from entering the internal space in the event that the structure is placed on water and the internal space is enclosed between the bottom surface, the retention skirt, and the water. 
     In another aspect, at least one one-way air valve mechanism is comprised in the floatable body, allowing air to exit the internal space through the floatable body. 
     In another aspect, the one-way air valve mechanism comprises a first end of the skirt and an opposed second end of the skirt, wherein said first end is externally overlapped over said second end, the first end being movable with respect to the second end, said first end being configured to separate from the second end responsive to an increase in air pressure in the internal space, and to rest against the second end responsive to a decrease in air pressure in the internal space. 
     In another aspect, the retention skirt is an entirely flexible skirt having overlapped first and second ends forming said one-way valve mechanism. 
     In another aspect, the retention skirt is removably attached to the floatable body. 
     In accordance with yet another embodiment of the invention, the present invention consists of a non-self-propelled, floatable structure for supporting persons, animal or cargo, comprising: 
     a floatable body, configured to float on water, said body comprising a downward facing side for facing the water; 
     a retention skirt, protruding from said downward facing side of said body and configured to be arranged inside the water when the floatable structure is placed in the water, said retention skirt encircling an internal space, said internal space being delimited between said retention skirt and said downward facing side, wherein said retention skirt is airtight for air passing in an inward direction, said inward direction corresponding to air passing through the skirt and towards said internal space; 
     at least one one-way air valve mechanism allowing air to exit the internal space and preventing air from entering the internal space in the event that the structure is placed in the water and the internal space is enclosed between the bottom surface, the retention skirt, and the water. 
     In another aspect, at least one one-way air valve mechanism is comprised in the floatable body, allowing air to exit the internal space through the floatable body. 
     In another aspect, the one-way air valve mechanism comprises a first end of the skirt and an opposed second end of the skirt, wherein said first end is externally overlapped over said second end, the first end being movable with respect to the second end, said first end being configured to separate from the second end responsive to an increase in air pressure in the internal space, and to rest against the second end responsive to a decrease in air pressure in the internal space. 
     In another aspect, the retention skirt is an entirely flexible skirt having overlapped first and second ends forming said one-way valve mechanism. 
     These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  presents a top perspective view of an exemplary floatable structure provided by a flexible perimetral skirt, according to one embodiment of the present invention; 
         FIG. 2  presents a partial bottom perspective view of the floatable structure of  FIG. 1 , showing the skirt overlap area in a partially open position; 
         FIG. 3  presents a transverse cross-sectional view of the floatable structure of  FIG. 1 , placed in a rest position on the water, where the section has been carried out according cross-sectional plane  3 - 3  indicated in  FIG. 1 ; 
         FIG. 4  presents the floatable structure of  FIG. 3 , in a situation in which a load is being applied on an edge of the floatable body, causing the floatable structure to tilt; 
         FIG. 5  presents the floatable structure of  FIG. 3 , in a situation in which a lateral force is being applied on the floatable body; 
         FIG. 6  presents a transverse cross-sectional view of a second embodiment of a floatable structure in accordance with the invention, provided with a one-way check valve. 
     
    
    
     Like reference numerals refer to like parts throughout the various views of the drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. For purposes of description herein, the terms “upper”, “lower”, “left”, “rear”, “right”, “front”, “vertical”, “horizontal”, and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     One or more embodiments of the present invention are disclosed herein. It will be understood that the claims and embodiments of the present invention are intended to be coextensive with each other, and that the embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. It is noted that, according to common practice, the various features, elements and dimensions of particular embodiments are not to scale, and may be expanded, exaggerated or minimized for clarity. Thus, specific structural and functional details, dimensions, shapes, or configurations disclosed herein are not limiting but serve as a basis for teaching a person of ordinary skill in the art the described and claimed features of embodiments of the present invention. 
     Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in  FIGS. 1 through 3  an exemplary floatable assembly or structure  100  according to one embodiment of the present invention. As best shown in  FIG. 1 , the floatable structure  100  of the present embodiment is essentially flat and rectangular in shape, and includes an inflatable floatable body  110  configured to float on water. For this purpose, the floatable body  110  of the present embodiment comprises a raft-like plastic inflatable body  120  on which a platform  130  is arranged. The inflatable body  120  is a flexible bladder provided with one or more internal chambers  122  (as best shown in  FIG. 3 ) that can be filled with gas in order to render the structure  100  floatable; in the event of there being more than one internal chamber  122 , the chambers  122  will be separated by internal partitions (not shown in the figures as they are not of relevance to the present invention). Turning again to  FIG. 1 , several inflation/deflation valves  124  are provided in gaseous communication with the floatable body internal chamber or chambers  122  for filling, retaining, and removing gas from within each respective internal chamber  122 . In addition, a series of handles  126  facilitate manipulation of the floatable body  110 , and a series of side corner fastening members  128  to which ropes, straps or chains can be secured for pulling the structure or securing it to a dock or the like. The platform  130 , in turn, provides a firm standing surface or floor for stably supporting a load, such as cargo, tools, machinery, people or animals; said surface is preferably non-slip to ensure that the worker retains solid footing while standing thereon, and to ensure that load in general does not slide along the platform when wet. The platform  130  is composed of a plurality of panels  132  in parallel alignment, adequately connected to form a joint assembly. The platform  130  can be attached to the inflatable body  120  by various means well known by those skilled in the art, such as an adhesive material arranged between the platform  130  and the inflatable body  120 , by a dense hook and loop attachment, by rubber cement, by heat welding, by high-frequency electrical welding techniques, by mechanical fitting of the platform  130  into the inflatable body  120  so that the platform  130  is partially embraced by the inflatable body  120 , or by a combination thereof. 
     As shown in  FIGS. 1 and 2 , the floatable body  110  of the present embodiment presents a top surface  140 , sidewalls  142 , and a bottom surface  144 . The top surface  140  is provided by the platform  130 . The sidewalls  142  and the bottom surface  144  are provided by the inflatable body  120 . The top surface  140  and sidewalls  142  are arranged on a first side  150  of the floatable body  110 , whereas the bottom surface  144  is arranged on a second side  152  of the floatable body  110 . In the present embodiment, as shown in  FIG. 3 , the first side  150  is configured to remain above water level when the floatable structure  100  is placed in the water  500 , whereas the second side  152  is configured not only to face but also to contact the water  500 . In the embodiment shown, the bottom surface  144  of the second side  152  rests entirely and flatly on the water  500 . However, alternative embodiments are contemplated in which the bottom surface  144  of the second side  152  is not a simple flat surface but has a more complex design, featuring recesses and/or protuberances, in such a way that some air spaces can be defined between the bottom surface  144  and the water  500  surface. 
     The floatable structure  100  is not self-propelled, i.e., is not designed to provide an autonomous means of transportation, but rather to provide a static support for a person to stand on and carry out an activity (such as repairing a vessel hull outer surface) or for holding cargo. 
     In accordance with the invention, the floatable structure  100  further comprises a retention skirt  160  that protrudes downwardly from the second side  152  of the floatable body  110 . As shown in  FIGS. 2 and 3 , an internal space  170  is delimited between the retention skirt  160  and the second side  152  of the floatable body  110 . The retention skirt  160  is sized and shaped to extend underwater. In a non-limiting example, a floatable structure  100  having a width and depth of 6-10 feet could be provided with an 8-inch high retention skirt  160 . It is contemplated that, in general, the retention skirt can have any applicable height or length. 
     The retention skirt  160  forms a continuous wall capable of extending downwardly into a body of water. The retention skirt  160  is airtight for air passing in an inward direction, towards the internal space  170 . In other words, the retention skirt  160  material(s) and construction provide inward airtightness. For instance, the retention skirt can be manufactured as a flexible sheet of PVC material. Or, in another non-limiting example, the retention skirt can be manufactured from a metallic sheet. 
     The illustration of  FIG. 4  shows the floatable structure  100  of  FIG. 3  in a situation in which a sudden force F is applied in a downward direction near an edge of the floatable body first side  150 . For instance, the downward force F could be the weight of a load or person suddenly being exerted on the edge of the platform  130 . Because the force F is exerted near the edge of the floatable body  110 , the force F tends to cause a rotation movement of the floatable body  110  and, thus, the opposite edge of the floatable body  110  is pushed upwards as shown in the figure, and begins to rise upwards. In this situation in which the opposite edge of the floatable body  110  has begun to rise upwards, the retention skirt  160  is still partially underwater, thereby enclosing the internal space  170  between the water  500  and the second side  152  of the floatable body  110 . In this scenario, the inwardly airtight retention skirt  160  prevents air from entering from the outside of the retention skirt  160  into the enclosed internal space  170 . In consequence, as the floatable body  110  begins to rise, a vacuum or negative pressure effect is created in the internal space  170 , causing the rising floatable body  110  to suction water  500  upwards as indicated schematically by arrows  180 . The weight of the water  500  that is lifted upwards counteracts force F and prevents the floatable body  110  from rising further, thus stabilizing the floatable body  110 . Thus, as has been demonstrated, the retention skirt  160  as per the invention delivers an automatic and very effective stabilizing effect at reasonable cost. 
     In addition, the retention skirt  160  provides a dragging or stopping effect for displacement of the floatable structure  100  along the water surface, due to the fact that the retention skirt  160  is submerged in water  500  either vertically or with a strong vertical component, and poses a strong resistance to water moving relative to the retention skirt  160  in a lateral direction (indicated by arrow  190  in  FIG. 1 ), a transverse direction (indicated by arrow  192  in  FIG. 1 ) or a combination thereof, i.e. in any horizontal direction. The drag effect contributes to stability and safety of the persons and load standing on the floatable structure  100 . In order to illustrate this drag effect,  FIG. 5  shows the floatable structure  100  of  FIG. 3  in a situation in which a lateral force L is being applied on the floatable structure  100 , for instance by an external mass or body  510 . The external body  510  has been depicted only schematically as its precise shape or nature is not relevant. As can be observed, when lateral force L is applied on the floatable structure  100 , retention skirt  160  exerts a drag or fluid resistance to lateral water movement (water movement indicated by arrows  160 ) and thus reduces or prevents lateral movement of the floatable structure  100  along the water  500 . This drag effect is dependent on the velocity of water and thus increases when the lateral force L increases. The drag effect is also stronger if the retention skirt  160  is entirely rigid. 
     Preferably, the retention skirt  160  protrudes vertically downwards from the second side  152  of the floatable body  110  when the floatable structure  100  is in a rest position as shown in  FIG. 3 , for a more integrated and compact configuration of the floatable structure  100 . However, alternative embodiments are contemplated in which the retention skirt extends at a non-square angle from the bottom surface  144  of the floatable body  110  or is arranged non-vertically with respect to the water  500  surface level. 
     It is contemplated that the retention skirt can be partially or entirely flexible, or partially or entirely rigid. 
     As has been mentioned, the retention skirt  160  is inwardly airtight, i.e., prevents air from passing through the retention skirt  160  towards the internal space  170 . Optionally, the floatable structure can comprise at least one one-way air valve mechanism allowing air to exit the internal space  170  while also preventing air from entering the internal space  170 . Such a solution allows one-way expelling of air from the internal space  170  to outside the retention skirt  160 . Thus, when the floatable structure  100  is placed in the water, the floatable body  110  presses the air in the internal space  170  and the compressed air is gradually expelled from the internal space  170  though the at least one one-way air valve mechanism until the bottom surface  144  contacts and rests on the water  500  surface. Thus, having at least one one-way air valve mechanism allowing outward airflow promotes initial stability of the floatable structure  100 . 
     The embodiment shown in  FIGS. 1 through 5  shows a first example of a one-way air valve mechanism preventing inward airflow and allowing outward airflow from the internal space  170 . Specifically, the one-way air valve mechanism comprises a first end  162  of the retention skirt  160  and an opposed second end  164  of the retention skirt  160 , wherein the first end  162  is externally overlapped over the second end  164  as best shown in  FIGS. 1 and 2 . In addition, the first end  162  is movable with respect to the second end  164 , and is configured to separate from the second end  164  responsive to an increase in air pressure in the internal space  170  relative to the air pressure outside the retention skirt  160 , and to rest against the second end  164  responsive to a decrease in air pressure in the internal space  170  relative to the air pressure outside the retention skirt  160 . When the floatable structure  100  is placed in the water  500  and the internal space  170  becomes enclosed between the water  500 , the retention skirt  160  and the bottom surface  144  of the floatable body  110 , causing air pressure to rise due to the floatable structure  100  weight, air pressure pushes the first end  162  outwards and opens a gap  166  between the first end  163  and the second end  164 , as best shown in  FIG. 2 ; the gap  166  provides a passageway for air to exit the internal space  170  as has been explained. Such an arrangement of overlapping ends or portions of the skirt provides an automatic one-way valve effect that is constructively simple and inexpensive to manufacture, yet extremely effective. 
     The retention skirt can be provided with a variable number of one-way air valve mechanisms. However, in a preferred embodiment, the retention skirt  160  is an entirely flexible band of flexible material, as shown in  FIGS. 1 and 2 , the band having overlapped first and second ends  162 ,  164  forming a single one-way valve mechanism. Such a construction provides optimum cost-effectiveness and performance. It is understood that the position of the valve mechanism(s) along the retention skirt may vary in different embodiments of the invention. 
     The invention further contemplates that the retention skirt  160  can be removably attached to the floatable body  110 , to facilitate displacement of the floatable structure  100  along the water in the event that the structure needs to be transported or pulled to a different location. Thus, a detachable retention skirt  160  not only serves the purpose of the present invention (i.e. stabilizing the floatable body  110 ) but also does not prevent the floatable body  110  from being pulled along the water  500  if need be. 
     In addition, it is further contemplated that the retention skirt  160  can be manually or mechanically raised or lowered, in order to adjust the retention skirt height. Vertical adjustability allows regulating the degree to which the skirt penetrates in the water body, and thus regulating the intensity of both the rotational and transverse stabilization effects of the retention skirt. In the event that the floatable structure is to remain static in the body of water, the skirt can be lowered to provide maximum stability; if, however, the floatable body is to be pulled and transported along the water, the retention skirt can be raised to reduce its lateral and transverse drag effect. 
     The illustration of  FIG. 6  shows an alternative embodiment of the invention, consisting in a non-self-propelled, floatable structure  200  for supporting a load, comprising a floatable body  210 , configured to float on water, said body comprising a top surface  240  for supporting a load, and a bottom surface  244  for facing or contacting the water. The floatable body  210  of the present embodiment is a single, solid piece of foam. As in the previous embodiment, the floatable structure  200  comprises a retention skirt  260  protruding downwards from a peripheral edge of said floatable body  210 . An internal space  270  is delimited between the retention skirt  260  and the bottom surface  244 . The retention skirt  260  is airtight for air passing in an inward direction, the inward direction corresponding to a direction in which air were to pass through the retention skirt  260  and towards the internal space  270 . In addition, the floatable structure  200  includes several one-way air valve mechanisms preventing air from entering the internal space  270  in the event that the structure is placed on water and the internal space  270  is enclosed between the bottom surface  244 , the retention skirt  260 , and the water, and allowing air to exit the internal space  270  in the event of a pressure increase in the internal space  270 . In this alternative embodiment, the one-way air valve mechanisms through which air can exit the internal space  270  are comprised in the floatable body  210 . Such an arrangement allows, for instance, for the retention skirt  260  to be rigid and lacking movable portions and ends. Specifically, the one-way air valve mechanisms comprised in the floatable body  210  communicate the internal space  270  with the first side top surface  240  of the floatable body  210 , producing a very fast and efficient air evacuation. In this specific embodiment, the one-way air valve mechanisms comprised in the floatable body  210  are one-way check valves  280 . 
     In addition, weights  290  can be included along the retention skirt  260  to retain the skirt in a desired configuration, in order to guarantee its stabilizing and braking effect in the event of disturbed waters. 
     In the embodiments shown, the retention skirt  160 ,  260  protrudes downwards from a peripheral edge of the floatable body, in order to maximize the internal space  170 ,  270  enclosed within the retention skirt  160 ,  260 . However, alternative embodiments are contemplated in which the retention skirt  160 ,  260  is arranged differently, for instance along an intermediate portion of the bottom surface  144 ,  244  of the floatable body  110 ,  210 , and not along a peripheral edge. In addition, alternative embodiments are contemplated in which the floatable structure comprises more than one retention skirt, in order to include separate internal spaces. 
     The floatable structure and floatable body could present various configurations other than that of the illustrated embodiment. In general, the floatable structure can be a raft, dock, deck, platform, barge, marine hazard marker, marine navigational marker, life raft, commercial marine craft, recreational marine craft, or the like. In turn, the floatable body may comprise a variety of different shapes and sizes, including square, round, or elliptical. The floatable body may be fabricated from any one of hyperlon, PVC, a plastic, a synthetic, vinyl, rubber, foam rubber, fabric, mesh, or nylon material coated or laminated with a polymer, polymeric, or polyurethane material, wood, fibers, wood derivatives, cork, lightweight metal, heavyweight metal or any combination thereof. It will be noted that the floatable body may include internal beams, supports, ribs or reinforcement materials that are structurally integrated within or about the floatable body to provide structural strength, stability and rigidity. 
     Since many modifications, variations, and changes in detail can be made to the described preferred embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalence.