Patent Publication Number: US-6659034-B1

Title: Retractable mooring fitting assembly

Description:
GOVERNMENT LICENSE RIGHTS 
     This invention was made with Government support under U.S. Government contract N00014-01-C-0081 awarded by the Department of the Navy. The Government has certain rights in this invention. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to marine mooring hardware and, specifically, to mooring fittings. 
     BACKGROUND OF THE INVENTION 
     Mooring fittings are used in a variety of maritime applications. In some maritime applications, it is desirable that the mooring fitting be removable or retractable. However, some currently known removable or retractable mooring fittings require use of lifting devices powered by the marine vessel. Other currently known removable or retractable mooring fittings can present hazards to line-handling personnel. 
     For example, some marine vessels with a flat deck, such as barges, include bitts that are removable. Currently known removable bitts are typically attached to the deck with bolts. The bolts therefore present potentially weak load paths between the bitt and the marine vessel. Further, such removable bitts are typically heavy and require lifting devices to install and remove the bitts to and from the deck of the marine vessel. Power for such lifting devices is supplied from the marine vessel. 
     Some ocean-going tugboats have retractable towline guideposts. The retractable towline guideposts are typically hydraulically retracted below the deck of the tug and are hydraulically raised above deck for use. Again, hydraulic power for retracting and deploying the towline guideposts is supplied by the marine vessel. 
     Further, some naval submarines include retractable mooring cleats. The cleat rotates below the outer non-pressure hull to reduce surface drag. The retractable mooring cleats are bolted in a stowed or deployed position. Each half of the cleat is spring-loaded to rotate between the stowed and deployed positions. To change the position of the retractable mooring cleat between the stowed and deployed positions, the mooring cleat is unbolted and each half of the cleat is mechanically agitated to cause the spring to begin urging the cleat to its desired position. However, such operations are potentially dangerous and present hazards to line handling personnel. For example, extremities of line handling personnel may be subject to severe trauma if any of the extremities are in the vicinity of the cleat when the spring urges the cleat rapidly past an edge of the deck surface. 
     Thus, there is an unmet need in the art for a retractable mooring fitting that provides robust load paths between the mooring fitting and the marine vessel, does not require power from the marine vessel to retract or deploy the mooring fitting, and that minimizes potential hazards to line handling personnel. 
     SUMMARY OF THE INVENTION 
     The invention provides a retractable mooring fitting assembly that provides robust load paths between the mooring fitting and the marine vessel, does not require power from the marine vessel to retract or deploy the mooring fitting, and that retracts and deploys in a manner that minimizes potential hazards presented to line handling personnel. 
     According to one non-limiting embodiment of the invention, a retractable mooring fitting assembly for a marine vessel includes a mooring fitting that has a first end and a second end. A counterweight is disposed toward the second end of the mooring fitting. An axle is interposed between the counterweight and the first end, and the mooring fitting is pivotable about the axle. 
     According an aspect of the invention, at least a first bearing is attached to the mooring fitting. The at least first bearing is arranged to provide at least a first load path from the mooring fitting to the marine vessel. The at least first bearing is disposed intermediate the first end of the mooring fitting and the axle. 
     According to another aspect of the invention, a second bearing is attached to the mooring fitting. A second bearing is arranged to provide a second load path from the mooring fitting to the marine vessel. The second bearing is disposed toward the second end of the mooring fitting. If desired, the second bearing includes the counterweight. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
     FIG. 1 is a perspective view of a non-limiting marine vessel that includes the mooring fitting assembly of the present invention; 
     FIG. 2 is an exposed side view of the mooring fitting assembly of the present invention; and 
     FIGS. 3-10 are side views of the mooring fitting assembly of the present invention being rotated between a stowed position and a deployed position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a non-limiting example of a marine vessel  10 , such as a barge, that includes a retractable mooring fitting assembly  12 . According to the invention, the mooring fitting assembly  12  advantageously retracts below a deck surface  14  that is attached to the tops of sides of the marine vessel  10 . For example, the marine vessel  10  may be connected to a plurality of barges to form a floating platform or causeway for deployment during amphibious operations at unimproved beach locations. In such an application, the mooring fitting assembly  12  is suitably used to tie ships or other marine vessels (not shown) to the marine vessel  10  and to connect the combination of the barges to moorage systems, such as anchors. However, when the mooring fitting assembly  12  is not in use for tying up ships or other marine vessels or for connecting the barge to a moorage system, the mooring fitting assembly  12  may interfere with operations. Further, when the mooring fitting assembly  12  extends above the deck surface  14  in a deployed position, the mooring fitting assembly  12  prevents stacking the barge for stowage. Advantageously, the mooring fitting assembly  12  retracts and is stowed below the deck surface  14  when the mooring fitting assembly  12  is not in use or when it is desired to stack the barge for stowage. Alternately, the marine vessel  10  suitably includes a tug and the mooring fitting assembly  12  suitably includes a towline guidepost. 
     Referring now to FIG.  2  and by way of overview, the mooring fitting assembly  12  includes a mooring fitting  16 , such as without limitation a post bitt (showed in phantom). The mooring fitting  16  is shown deployed in a first position  18  and stowed in a second position  20  in an enclosure  22  that is disposed beneath the deck surface  14  of a marine vessel (not shown). The mooring fitting  16  has a first end  24  and a second end  26 . A counterweight  28  is disposed toward the second end  26 . An axle  30 , such as a rotational pin, is interposed between the counterweight  28  and the first end  24 , such that the mooring fitting  16  is pivotable about the axle  30 . 
     Further details of an embodiment of the invention are discussed below. In one presently preferred embodiment of the invention, the mooring fitting  16  suitably includes a bitt, such as without limitation a post bitt. Given by way of non-limiting example, the post bitt  16  includes a post member  32  and a cross member  34  that is disposed substantially normal to the post member  32  toward the first end  24 . The present invention advantageously accommodates mooring fittings  16  of various sizes. For example, the mooring fitting  16  may have a design capacity of up to 140,000 pounds or more, depending on a desired application. However, it will be appreciated that the present invention can accommodate mooring fittings  16  that are scalable up or down to sizes as large or small as desired for a particular application. It will further be appreciated that the present invention accommodates various mooring fittings, such as without limitation bitts such as post bitts, towline guideposts, cleats, double bitts, chocks, and the like. 
     The axle  30  is suitably any cylindrical member, such as without limitation a pivot pin, that provides a pivot point about which the mooring fittings  16  can pivotally rotate. Advantageously, the axle  30  can be the only component of the present invention to be lubricated. Further, as will be discussed in detail below, live loads do not pass though the axle  30 . That is, the axle  30  is not a live load path between the marine vessel and the mooring fitting  16 . 
     The counterweight  28  is attached to the second end  26  of the mooring fitting  16  in any acceptable, known manner. The size and weight of the counterweight is scalable according to a desired application. Advantageously, in one non-limiting example, when the mooring fitting  16  includes a bitt with a design capacity of around 140,000 pounds, the counterweight is sized such that the mooring fitting  16  deploys or stows by rotating about the axle  30  with an applied force of around 45 pounds or less. It will be appreciated that neither dedicated machinery nor a source of power from the marine vessel is necessary to deploy or stow the mooring fitting  16 . As a result, the mooring fitting  16  can be deployed or stowed quickly even in rough seas. 
     The present invention includes bearing surfaces that provide load paths for transmitting live loads between the mooring fitting  16  and the marine vessel. Advantageously, the live loads are transmitted via bearing surfaces instead of through the axle  30 . In one non-limiting embodiment, a section  36  of the deck surface  14  is fastened to the post member  32  intermediate the cross number  34  and the axle  30  to provide one or more upper bearing surfaces. In one present. non-limiting example three upper bearing surfaces are provided. It will be appreciated that the section  36  is fastened to the post member  32  such that the section  36  aligns with the deck surface  14  when the mooring fitting  16  is in the first position  18 . The section  36  is suitably fastened to the post member  32  in any acceptable known manner. A radius bearing  38  is fastened to the post member  32  beneath the section  36 . The radius bearing  38  defines a mating surface  40  that defines a finite radius. A lower bearing  42  is provided toward the second end  26 . In one present embodiment, the counterweight  28  provides the lower bearing  42 . 
     Advantageously, the present invention also provides the enclosure  22 , such as a vault, for rotatably mounting the mooring fitting  16 . The axle  30  is rotatably mounted to the enclosure  22 . Further, as will be discussed below, live loads are transmitted into the top and bottom of the enclosure  22  from the mooring fitting  16 . In turn, the live loads are transmitted from the enclosure  22  to the marine vessel in tension, sheer, and compression. As a result, live loads are not transmitted through the axle  30  as a load path. The enclosure  22  includes a mating radius bearing  44 . The mating radius bearing  44  includes a mating surface with a finite radius that is sized to mate with the surface  40 . As such, the bearings  38  and  44  both provide a load path and permit rotation to and from the first position  24 . 
     An upper retainer  46  is provided beneath the section  36  to prevent downward motion of the mooring fitting  16 . A lower retainer  48  includes a surface  50 . When the mooring fitting  16  is in the first position  18 , the counterweight  28  contacts the surface  50 . As a result, the lower retainer  48  prevents upward motion when the mooring fitting  16  is deployed in the first position  18 . 
     A latching mechanism  54  is provided to prevent rotation of the mooring fitting  16  while deployed in the first position  18 . In one present embodiment, the latching mechanism  54  includes a removable elongate member  56  that has a first end  58  and a second end  60 . The first end  58  is retained by the enclosure  22  beneath the deck surface  14 . The second end  60  abuts against the counterweight  28 . Other latching mechanisms may be used as desired for a particular application. 
     Advantageously, the enclosure  22  with the mooring fitting  16  received therein may be installed as one composite unit beneath the deck surface  14  of the marine vessel. The enclosure  22  is suitably installed in the marine vessel in any acceptable manner, such as bolting or welding. The enclosure  22  advantageously can serve as a storage container for the mooring fitting  16 . As a result, additional storage facilities for the mooring fitting  16  are avoided. 
     Removable covers (not shown) for the enclosure  22  are also provided. The removable covers cover the enclosure  22  and bridges deck live loads across the enclosure  22  when the mooring fitting  16  is stowed or deployed. In one non-limiting embodiment, the cover can support live loads of 12,000 lbs./sq. ft. or more. 
     The invention operates as follows. FIG. 3 shows the mooring fitting  16  stowed in the enclosure  22  in the second position  20 . The cross member  34  rests on a bottom surface  62  of the enclosure  22 . Referring now to FIG. 4, as the counterweight  28  is urged downwardly, the mooring fitting  16  rotates about the axle  30 . The cross member  34  begins to exit the enclosure  22 . Referring now to FIGS. 5 and 6, as the mooring fitting  16  continues to rotate about the axle  30 , the post member  32  begins to exit the enclosure  22 . 
     Referring now to FIGS. 7 and 8, the mooring fitting  16  continues to rotate about the axle  30 , and the radius bearing  38  approaches the mating radius bearing  44 . Referring now to FIG. 9, the radius-bearing surface  40  begins to mate with the surface of the mating radius bearing  44 . The section  36  approaches the upper retainer  46 , and the counterweight  28  approaches the first surface  50  of the lower retainer  48 . 
     Referring now to FIG. 10 the mooring fitting  16  is fully deployed in the first position  18 . The radius bearing  38  mates with the mating radius bearing  44  and the section  36  mates with the deck surface  14  to provide a load path to transfer live load from the mooring fitting  16  to the enclosure  22 . The counterweight  28  mates with the bottom surface  62  of the enclosure  22  to provide a load path from the bottom of the mooring fitting  16  to the enclosure  22 . Live loads are, in turn, transferred from the deck surface  14  and the mating radius bearing  44  and the bottom surface  62  of the enclosure  22  to the marine vessel (not shown). The counterweight  28  contacts the first surface  50  of the lower retainer  48 , thus preventing upward motion. The second end  60  of the elongate member  56  contacts the counterweight  28 , thus preventing rotation of the mooring fitting  16  about the axle  30  while the mooring fitting  16  is deployed in the first position  18 . 
     While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment.