Abstract:
A stair assembly to enable easy boarding and deboarding of a watercraft includes one or more step members hingedly fixed within a cavity formed with the bow, side walls or transom of the watercraft to permit the step members to swing, in a rolling movement, from a compact stowed position to an extended, deployed position wherein the stair assembly extends outboard of the watercraft. The step members are specifically shaped and configured to conform with the bow, side walls and/or transom when in the stowed position to thereby fill the cavity and provide an integral, seaworthy structure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a stair assembly for a watercraft and, more specifically, to a stairway having hinged step members fitted within a cavity formed in the bow, side walls or transom of a watercraft, wherein the stair assembly is movable between a compact, stowed position within the cavity and a deployed, outboard extending position to thereby permit boarding and deboarding of the watercraft. 
     2. Discussion of the Related Art 
     Various stairways and ladders are well known in the marine industry to permit passage between a watercraft and a dock, body of water, adjacent vessel and the like. For instance, there are numerous types of gangways which are normally used on larger vessels to permit boarding and deboarding when the vessel is tied up along side a pier or dock. Furthermore, swim ladders are extensively used on boats of all sizes to enable passengers to climb aboard the boat from within the water. 
     While the various stair and ladder structures known in the industry are generally suitable for their intended purpose, there still exists a need for a stair assembly which is structured to permit easy passage when boarding and deboarding a watercraft. More particularly, there exists a need for a stair assembly which accommodates people of all ages and sizes, permitting easy boarding and deboarding from the watercraft into the water, onto a beach or onto an adjacent structure such as a dock or another vessel. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a stair assembly for use on a watercraft to permit easy boarding and deboarding between the watercraft and a body of water, a beach, or a rigid structure such as a dock or adjacent vessel. The stair assembly includes one or more step members hingedly fixed to one another and to the watercraft. The step members are collapsible into a compact, stowed position so that the assembly fits within a cavity formed in the bow, side walls or transom of the watercraft. When in the stowed position, the stair assembly is integral with the surrounding bow, side wall, or transom structure. A joint between the stair assembly and hull structure is watertight, thereby providing a seaworthy structure which prevents water from entering the watercraft when travelling on the water. 
     The stair assembly swings open, in a rolling movement, from the stowed position to an extended, deployed position. In the deployed position, the stair assembly extends outboard of the watercraft to expose step surfaces which may be provided with a non-skid texture or paint. In the deployed position, the stair assembly can be extended into the water so that a distal free end of the stair assembly is positioned below the surface of the water. In this manner, a person swimming in the surrounding water can easily climb aboard the watercraft by walking up the stairway. Likewise, the stairway can be extended to an adjacent shoreline, a dock, or another vessel. To assist a person travelling the stair assembly, handrails may be fitted along the opposite sides, extending the length of the stair assembly. 
     In one preferred embodiment of the invention, the stair assembly is specifically structured and configured for installation on a rigid hull inflatable watercraft. In this particular embodiment, the under side of the step members are provided with a radius so that when the stair assembly is collapsed to the stowed position, the assembly assumes a cylindrical configuration which is congruent with the inflatable tube sections surrounding the watercraft. Thus, the diameter of the formed cylinder of the stair assembly is the same as the diameter of the inflatable tubes of the watercraft thereby providing an integral structure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a side elevation, in partial cutaway, showing the stair assembly fitted to the bow of a rigid hull inflatable watercraft; 
     FIG. 2 is an isolated top perspective view of the stair assembly, shown in an extended position, and fitted to a rigid hull inflatable watercraft to be integral with the surrounding inflatable tube structure of the watercraft when the stair assembly is in a stowed position; 
     FIG. 3 is a side elevation showing the stair assembly extending to a dock structure to facilitate boarding and deboarding of the watercraft; 
     FIGS. 4A-4D illustrate a sequence of movement of the stair assembly from a compact, stowed position to a fully extended, deployed position; 
     FIG. 5A is a top plan view of a watercraft showing the stair assembly fitted to a surrounding wall structure of the watercraft at both the bow and the starboard side, wherein the stair assembly is in a stowed position; 
     FIG. 5B is a top plan view of the watercraft of FIG. 5A showing the stair assemblies at the bow and starboard side in the extended, deployed position; 
     FIG. 6 is an isolated view, in cross section, taken along the plane of the line  6 — 6  of FIG. 5A; 
     FIG. 7A is an isolated elevational view, in partial section, showing one preferred embodiment of a hinge and stop means for limiting hinged movement of the step members of the stair assembly; 
     FIG. 7B is an isolated view, in partial section, showing another embodiment of the hinge and stop means; and 
     FIG. 7C is an isolated view, in partial section, illustrating yet another embodiment of the hinge and stop means. 
    
    
     Like reference numerals refer to like parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the several views of the drawings, and initially FIGS. 1 and 2, the stair assembly of the present invention is shown and generally indicated as  10 . The stair assembly  10  includes one or more step members  12  that are hinged together. The uppermost step member  12  hinges to the hull structure  110  of a marine craft  100  along edge  15 . 
     It is contemplated that the stair assembly  10  be mounted to the hull structure  110  of the marine craft  100  within a cavity or opening formed in the bow, side walls, or transom of the marine craft  100 . In the instant embodiment, the stair assembly  10  is shown fitted to the bow of a rigid hull inflatable marine craft. In this particular embodiment, an opening is formed along a segment of the inflatable tubes  120  of the marine craft  100 , providing a cavity to accommodate the stair assembly  10  when the stair assembly is in its compact, stowed position and permitting passage through the cavity to traverse the stair assembly  10  when the stair assembly is in its extended, deployed position. 
     Referring to FIG. 2, each of the step members  12  include an upper portion having at least one top step surface  20 , opposite sides  22 ,  22 ′, and a bottom side  24 , and upper and lower transverse edges  14  between the top and bottom portions. The step surfaces  20  of each of the step members  12  may be provided with a non-skid texture and/or a non-skid paint or coating material. The bottom side  24  is specifically shaped and configured to conform with the structure of the bow, side walls, or transom of the marine craft  100 , in accordance with the location of installation. In the particular embodiment shown, the bottom sides  24  of the step members  12  are provided with a rounded configuration, in accordance with a specific radius, so that when the stair assembly  10  is rolled up in a compact, stowed position, as seen in FIGS. 1,  4  and  6 , the stair assembly  10  conforms generally with the configuration  106  of the hull structure  110 , as well as the tubes  120  on opposite sides of the stowed stair assembly. More specifically, the configuration of the stowed stair assembly  10  is at least partially cylindrical to conform to the configuration of the cradle configuration  106  of the hull and cylindrical shape of the inflatable tube sections  120  on each side of the stair assembly  10 . In one preferred embodiment, the stair assembly is mounted within cavity  125 , between the inflatable tubes  120  of the marine craft with the use of a mounting assembly  90 . The mounting assembly  90  includes cap means  91  mounted to an end of the tube  120 , facing the cavity, and including a first portion  94  and a second portion  96 . A shoulder  92  is formed between the first portion  94  and the second portion  96 , defining an abutment shoulder which mates with the top step surface  20  of the first step member when the stair assembly is folded into the stowed position. More specifically, the first and second step members collapse to form a semi-cylindrical configuration adjacent the first portion  96  of the cap means  91  and disposed in abutting engagement with the shoulder  92 . The third and fourth step members are narrower in width and collapse between the second portions  94  of the opposing cap means  91  facing inwardly towards the cavity. Thus, the abutment shoulder  92  serves to provide a water tight seal between the stair assembly and the cap means  91 . To further provide a water tight seal, the abutment shoulder  92  may be provided with a rubber strip or another type of sealing membrane material. Each of the cap means  91  are mounted to the cradle portion  106  of the hull  110  with through bolts  108 , as seen in FIG.  6 . The outer configuration of the cap means  91  is specifically structured to be congruent with the configuration of the cradle portion  106 , to provide mating, sealing engagement therewith. A silicone or other watertight sealing material should be placed between the mating surfaces of the cap means  91  and the cradle portion  106  to provide a watertight attachment thereto. 
     When the stair assembly  10  is opened to one of various deployed positions, as seen in FIGS. 1,  2 ,  3  and  5 , the stair assembly  10  extends outboard of the marine craft  100 . In FIG. 1, the stair assembly  10  is shown extending down below the surface  40  of the water, enabling a person  50  to walk up the stair assembly  10  and into the marine craft  100 . When in the deployed position, the cavity  125  formed through the bow, side walls or transom of the marine craft  100  provides a walk-through passage. This enables persons traversing the stair assembly  10  to board and de-board the marine craft  100  without having to climb over the gunwale  130  of the marine craft  100 . The lowermost step member may further be provided with a folding ladder  80  formed of aluminum, stainless steel, polyvinyl chloride, fiberglass, or other like corrosion resistant material. The folding ladder  80  is hingedly attached to the lowermost step member and is movable between a collapsed, stowed position against the bottom of the step member and an operable position (as shown in FIG. 1) extending beyond the lower transverse edge of the lowermost step member, and generally downward therefrom. 
     Referring to FIGS. 4A-4D, a sequence of movements of four step members  12  is shown, moving from the compact, stowed position to an extended, deployed position. As is seen in FIGS. 4A-4D, the movement of the step members  12  is in a generally rolling motion, wherein each of the step members  12  rotates through a predetermined arc (limited by rope  70 , stop members  60 , or articulated hinge  66 , as described more fully hereinafter) about the respective hinge  30  connecting adjacent step members  12  until reaching the desired deployed position. Referring to FIGS. 4A-4D, a sequence of movements of three step members  12  is shown and being deployed from a compact, stowed position to an extended, deployed position in a generally rolling motion. 
     In FIG. 3, the stair assembly  10  is shown extending outward above the water  40  to a dock  42 , thereby enabling persons to traverse the stair assembly  10  and board and de-board from the dock  42 . Means are provided for releasably locking the step members  12  into folded or unfolded positions as required. In the present embodiment, the upper most and lower most step members  12  are locked in an unfolded, extended position and the middle step member  12  is locked in a folded position against the upper most step member  12 , thereby creating a traversable bridge between the marine craft  100  and the dock  42 . 
     It should be noted that the step members  12  may be manufactured of many suitable composites such as fiberglass reinforced plastic, kevlar, carbon, plastic, PVC, aluminum, steel, or rubber (similar to the inflatable tubes of the illustrated marine craft). Furthermore, the interior of the step members  12  may be hollow and may utilize grates over the step surfaces to support the weight of a person  50  while also permitting water to fill the interior of the step members so that they sink when deployed overboard in the extended, operable position. 
     Hinges  30  are used for attaching adjacently positioned step members to one another along the upper and lower transverse edges  14  for permitting hinged movement of the step members in a generally rolling motion between the compact, stowed position, and the extended, deployed position as shown in FIGS. 1,  4  and  6 . Hinges  32  are utilized to attach the uppermost step member  12  along its upper transverse edge  14  to the deck  104  or the hull  110  of the marine craft  100 . Means are also provided for releasably locking the step members  12  into the stowed, compact position. 
     Various means are available for stopping the hinged movement of the step members beyond the extended, deployed position. The fully extended position is reached when the attached step members form a stairway that extends away from the marine craft with the step surfaces positioned and maintained horizontal. 
     One such means for stopping the hinged movement is shown in FIGS. 2 and 7A and uses ropes threaded through holes  72  in the step members  12  with knots  76  at fixed spaced intervals along the ropes  70 . Each of the knots  76  are structured and disposed to engage an under side surface of the respective step members  12  upon the respective step member  12  reaching the extended, deployed position, and thereby preventing further, hinged, opening movement of the respective step member  12  beyond the extended, deployed position. In the preferred embodiment, as shown in FIG. 2, an elastic cord  74  is attached between each respective step member  12  and a location on the rope  70  midway between the knot  76  engaging the respective step member  12  and the knot  76  engaged to the next lower step member  12 . The elastic cords  74  pull the rope  70  inside the step members  12  when the stair assembly  10  is retracted to a stowed position. The ropes  70  are further used as a means for lifting and retracting the step members  12  from the extended, deployed position to stowed position. 
     An alternate embodiment for stopping hinged movement of the step members is shown in FIG. 7B wherein opposing stop members  60  are positioned on the bottom  24  of the step members  12 . The stop members  60  are positioned and disposed to mate in abutting engagement upon adjacently positioned step members  12  reaching the extended, deployed position, thereby preventing further hinged, opening movement of the adjacently positioned step members  12  beyond the extended, deployed position. 
     While the instant invention has been shown and described in connection with a preferred and practical embodiment thereof, it is recognized that departures may be made from the instant disclosure which, therefore, should not be limited except as defined in the following claims as interpreted under the doctrine of equivalents. 
     Now that the invention has been described,