Compressible accommodation ladder and related methods

An accommodation ladder includes a body having opposite sides, an upper, and rear and bottom surfaces. The body is formed of a compressible material, such as dense foam material, and the upper surface of the body forms a staircase with a plurality of steps. Spaced stanchions extend upwardly from the staircase and stanchion pipes extend through the body and receive lines therethrough to secure the body to a marine structure. The spaced stanchions are adapted to accommodate a plurality of releasable safety lines therebetween. A method of facilitating access between adjacent first and second marine structures includes arranging the staircase accommodation ladder between the structures, the accommodation ladder being a fender between such structures.

FIELD OF THE INVENTION

The present invention relates to apparatus and methods for facilitating access between adjacent marine structures, and more particularly, to accommodation ladders.

BACKGROUND OF THE INVENTION

Facilitating access between wharves, piers and the like and adjacent marine vessels, as well as between two or more adjacent marine vessels, can be a complicated endeavor. Changes in adjacent vessels, draft, tides, wake and wave action, among other factors, result in an ever-shifting relationship in all three dimensions. Existing accommodation ladders, gangways and the like can be insufficient to easily allow for such changes.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention to provide an improved accommodation ladder and related methods. According to an embodiment of the present invention, an accommodation ladder includes a body having generally opposed first and second sides, an upper surface, a rear surface and a bottom surface. The body is formed of a compressible material, such as foam, and the upper surface of the body forms a staircase with a plurality of steps, each step having a riser portion and a tread portion.

To secure the body to the marine structure, one or more pipes can extend through the body between the riser portion of one of the plurality of steps and the rear surface, such that a line can be passed therethrough. A “marine structure” as used herein includes marine vessels as well as shore- or seafloor-mounted structures against which marine vessels are brought. Non-limiting examples of shore- or seafloor-mounted structures include piers, wharves, docks, dry docks, and platforms. A “marine vessel” as used herein includes any waterborne structure, whether powered or unpowered. Non-limiting examples of marine vessels include ships, barges, floating platforms and hulks.

For the enhanced ease of use, the accommodation ladder can further include a plurality of spaced stanchions extending upwardly from the staircase, the stanchions being adapted to accommodate a plurality of safety lines therebetween.

According to a method aspect of the present invention, a method of facilitating access between adjacent first and second marine structures includes arranging the accommodation ladder in the form of a staircase between the first and second structures, the accommodation ladder also acting as a fender between the first and second structures.

Arranging the accommodation ladder between the first and second structures preferably includes securing the accommodation ladder to the first structure. In response relative level changes between the first and second structures, safety lines can be selectively removed and replaced between stanchions of the accommodation ladder proximate the second structure to allow easy access to different levels of the accommodation ladder.

The present invention is particularly well suited for facilitating access between a dredge and a succession of fleeting barges during dredging operations.

These and other objects, aspects and advantages of the present invention will be better appreciated in view of the drawings and following detailed description of a preferred embodiment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring toFIGS. 1-4, according to an embodiment of the present invention, an accommodation ladder10includes a body12, having generally opposed first and second sides14,16, an upper surface18, a rear surface20and a bottom surface22. The upper surface18extends between the first and second sides, and forms a staircase24having a plurality of steps. Each step includes a riser portion26and a tread portion28. The body12is formed of a compressible material, allowing the accommodation ladder10to compress between the first and second sides14,16of the body, thereby also functioning as a fender.

The accommodation ladder10is preferably adapted for securing to a marine structure. To this end, the accommodation ladder10can further include first and second pipes30,32extending through the body12between the rear surface20and riser portions26of respective steps of the staircase24. To help retain the first and second pipes30,32within the body12, flanges34are located as respective ends thereof.

Lines can be passed through the first and second pipes30,32to secure the body12to the marine structure hereinafter more fully described with respect toFIG. 5. As used herein, “line” is not necessarily limited to any particular material or construction thereof. Non-limiting examples of lines include ropes and chains.

For the convenience and safety of users, restraints are preferably provided on the staircase24. For example, the accommodation ladder10can advantageously include a plurality of spaced stanchions40extending from tread portions28of the steps of the staircase24. The stanchions are adapted to accommodate a plurality of safety lines42therebetween. Preferably, the safety lines42are selectively removable between adjacent stanchions40, for reasons described in detail below. Additionally, each stanchion40preferably includes a flange44on a lower end thereof.

To facilitate secure attachment of the stanchions40to the body12, a plurality of stanchion pipes50extend into the body12below each of the stanchions40. Preferably, each stanchion pipe50extends between the tread portion28of its respective stanchion40and the bottom surface22(an exemplary one of the stanchion pipes50is shown in broken lines inFIG. 3; it will be appreciated that stanchion pipes50for stanchions on higher steps would be longer to extend between their respective steps and the bottom surface22).

To help retain each stanchion pipe50within the body12, each stanchion pipe50has flanges52at opposite ends thereof. Additionally, at upper ends thereof, each flange52is releasably connected to a corresponding flange44on the lower end of the respective stanchion40. In an alternate configuration, the stanchions40could extend into and/or through the body12without a separate stanchion pipe50.

Referring toFIG. 5, in use, the accommodation ladder10is secured to a first marine structure60, such as a dredging barge, by lines62. Stanchions40and safety lines42are arranged to allow access to the staircase24from the first side14, while minimizing inadvertent falls and offering support along the second side16and at the top and bottom of the staircase24. The presence of the marine structure60generally prevents falls from the first side14, although additional stanchions40and safety lines42can be provided on the first side14, depending on user preferences and/or the physical characteristics of the first marine structure. In such construction, stanchion pipes50are also provided along the first side14for this purpose (seeFIG. 1).

Referring toFIG. 6, a second marine structure70, such as a fleeting barge for receiving dredged material from the dredging barge, is brought alongside the first marine structure60with the accommodation ladder10therebetween. The compressibility of the accommodation staircase ladder10will allow it to double as a fender, and will help prevent damage to the ladder10and adjacent marine structures60,70by absorbing impact energy.

InFIG. 6, the deck of the second marine structure70sits higher than the deck of the first marine structure60. To allow access from the staircase24to the second marine structure, the safety lines42are removed or dropped at one end thereof from between the upper two stanchions40on the second side16. In one possible scenario, the draft of the second marine structure70increases, lowering its deck level relative to the deck level of the first marine structure60.

As the level lowers, the safety lines42are replaced or reconnected at one end thereof between the uppermost two stanchions40on the second side and removed between an appropriate lower pair of stanchions. InFIG. 7, for example, the safety lines42are removed between the lowermost two stanchions40on the second side16, allowing access therebetween to the second marine structure70.

It will be appreciated that the foregoing is only one of many scenarios in which the accommodation ladder10can be advantageously employed. For example, referring toFIG. 8, access between the first marine structure and another second marine vessel80, such as a crew boat, can be facilitated by the accommodation ladder10. Additionally, the accommodation ladder10could be readily secured to another marine structure, such as a wharf or pier to facilitate access thereto from a ship or other marine vessel.

As noted, the body12of the accommodation ladder is made from a compressible material. Dense plastic foam material or rubber material are preferred materials, although the present invention is not necessarily limited thereto. For example, the staircase can be fabricated from thick slabs of such materials and joined together and resulting in the staircase depicted.

Where foam material is used, a preferred assembly method is the bonding of a plurality of foam slabs to form the body, with the height of each slab equal to the riser height of the staircase24(except for the riser of the bottom step, which is preferably made thicker—for instance, about twice the height of the other risers). The various pipes30,50are inserted and bonded to the foam. The foam assembly is coated in a polymer material, such as polyurethane on all sides. A hot plate can be used to rough up the coating on the tread portions28of the steps to form a non-skid surface.

Advantageously, the compressible accommodation staircase ladder10is positively buoyant, so that the accommodation ladder10will not sink if it comes loose from an associated marine structure. Additionally, the accommodation ladder10can be moved and secured to marine structures in the absence of crane support by towing it through the water to a desired location for installation.

Referring toFIGS. 9 and 10, according to another embodiment of the present invention, an accommodation ladder10′ has a ladder extension100′. Except as described below, the accommodation ladder10′ is substantially identical to the accommodation ladder10, with a body12′, having generally opposed first and second sides14′,16′, an upper surface18′, a rear surface20′ and a bottom surface22′. The upper surface18′ extends between the first and second sides, and forms a staircase24′ having a plurality of steps. The body12′ is formed of a compressible material, allowing the accommodation ladder10′ to compress between the first and second sides14′,16′ of the body, thereby also functioning as a fender.

The ladder extension100′ is formed similarly to the accommodation ladder10′. The extension100′ includes a body112′ having generally opposed first and second sides114′,116′, an upper surface118′, a rear surface120′ and a bottom surface122′. The upper surface118′ extends between the first and second sides, and forms a staircase extension124′ having a plurality of steps. Like the body12′, the body112′ is formed of a compressible material, also allowing the extension100′ to compress between the first and second sides114′,116′ of the body112′. Advantageously, stanchions40′ are also secured to stanchion pipes150′ extending through the body112′, allowing the safety lines42′ to be continued upward along the staircase extension124.

The body112′ is removably secured to the body12′. In the depicted embodiment, a pair mating pipes190′ extending through the body112′ are releasably connected to a pair of mating pipes192′ extending through the body12′. Accordingly, the staircase extension124′ effectively continues and lengthens the staircase24′, allowing the accommodation ladder10′ to permit access to and from taller marine structures. Also, when detached, the ladder extension110′ can function independently as a smaller accommodation ladder.

Referring toFIG. 11, a connection assembly200′ for connecting the mating pipes190′,192′ includes a central shaft202′ inserted therethrough. The central shaft202′ can be hollow or solid, and is preferably formed of a corrosion resistant metal. An expanded diameter head204′ is located at a first end of the shaft202′ and threads206′ are formed along a second end thereof. Once the shaft202′ is inserted through the mating pipes190′,192′, a nut210′ is threaded on the threads206′ of the shaft202′ to securely connect the bodies12′,112′, take up any clearances therebetween and place the shaft202′ in tension. Preferably, washers220′ are arranged around the shaft202′ between ends of the mating pipes190′,192′ and the head204′ and nut210′. Although only one connection assembly200′ is shown for clarity and brevity, it will be appreciated that a pair of connection assemblies200′ would be used in each of the pairs of mating pipes190′,192′.

Referring toFIG. 12, an alternate connection assembly300′ for connecting mating pipes190′,192′ is used, including a central shaft302′. The central shaft302′ has first and second flanges304′,306′ welded or otherwise secured to first and second ends thereof. It will be appreciated that at least one of the flanges304′,306′ is not secured to the shaft302′ until after insertion through the mating pipes190′,192′. The first flange304′ includes a plurality of threaded bores therein through which a plurality of jacking bolts312′ are threaded to securely connect the bodies12′,112′, take up any clearances therebetween and place the shaft202′ in tension. To inhibit unthreading of the jacking bolts312′, each bolt312′ can be threaded through a corresponding locking nut314′ abutting the flange304′. Again, washers320′ can be arranged on the shaft302′ between ends of the mating pipes190′,192′ and the flanges304′,306′. Although only one connection assembly300′ is shown for clarity and brevity, it will be appreciated that a pair of connection assemblies300′ would be used in each of the pairs of mating pipes190′,192′.

In general, the foregoing description is provided for exemplary and illustrative purposes; the present invention is not necessarily limited thereto. Rather, those skilled in the art will appreciate that additional modifications, as well as adaptations for particular circumstances, will fall within the scope of the invention as herein shown and described and the claims appended hereto.