Method and apparatus for passive mooring of vessels

Abstract

A method of passive mooring of vessels, and related apparatus, is disclosed. A plurality of primary mooring lines are anchored to a sea floor, with upper ends held at a desired depth in a waterbody by floats. Secondary mooring lines may be attached to the primary mooring lines. One or more tethers connect at least some of the primary mooring lines. Typically, at least two of the primary mooring lines are not joined together by tethers, leaving an access gap. A vessel can be moved into position within the primary mooring line arrangement, and onboard mooring lines carried from the vessel by remotely operated vehicles, to join the onboard mooring lines to the secondary mooring lines. The onboard mooring lines, secondary mooring lines, and ultimately primary mooring lines can then be brought onto the vessel and connected thereto, typically via bollards on the vessel.

Description

[0001] Method and Apparatus for Passive Mooring of Vessels

[0002] Billy Ballard, Justin Barrow, Jason Pasternak, John Shelton, Matthew Smith, and Chris Snelling, Inventors

[0003] Delmar Systems, Inc., Applicant

[0004] Cross reference to related applications

[0005] This United States non-provisional application claims priority to United States provisional patent application SN 63 / 691648, filed 09 / 06 / 2024, for all purposes. United States provisional patent application SN 63 / 691648 is incorporated herein by reference in its entirety. Background - Field of the Invention

[0006] Many floating vessels comprise on-board equipment to handle lines intended to secure the vessel to other structures, such as onboard capstans, bollards and the like. Floating vessels may be moored to the ocean floor with various types of anchors, with mooring lines attaching the floating vessels to the anchors. However, many floating vessels, by way of example certain drillships, cruise ships, barges, etc., do not have self-contained offshore mooring systems, at all, or have self-contained mooring systems of limited capability.

[0007] It would be advantageous to have an apparatus and related method(s) to moor such vessels using onboard existing equipment, including but not limited to remotely operated vehicles (ROVs), as applicable, and capstans, winches, davits, or cranes, existing on the vessels.

[0008] Summary of the Invention

[0009] The apparatus and method(s) embodying the principles of the present invention, permitting the mooring of a floating vessel without the desire and / or capabilities of selfmaintaining station and / or the ability to moor in deep or shallow water, comprise, in one embodiment:

[0010] • Mooring lines or tethers of various components (10) that connect some means of fixing the mooring lines to the sea floor, such as anchors or clump weights, on or in the sea floor, to surface or subsurface buoyancy elements (20),

[0011] • The mooring lines ( 10) preferably inter-connected via tethers (40) to maintain proximity of points for connection to the floating vessel; and

[0012] • Methods of connecting and disconnecting the floating vessel to the mooring lines (10), for example via tethers that are pulled onto the floating vessel (30) and / or active lines on the vessel.

[0013] Brief Description of the Drawings

[0014] Figs. 1 and 2 are simplified schematics showing an overhead view and side (viewed through the water column) of an exemplary arrangement of the method and apparatus for passive mooring of vessels, embodying the principles of the present invention.

[0015] Fig. 3 is a perspective view of an exemplary mooring line arrangement, with a floating vessel moved into position in preparation for mooring.

[0016] Fig. 4 is another perspective view of the exemplary mooring line arrangement of Fig. 3, with a floating vessel moved into position in preparation for mooring and a remotely operated vehicle (ROV) deployed from the floating vessel in preparation for bringing a primary mooring line onto the floating vessel, via an onboard mooring line.

[0017] Fig. 4A is a view substantially like Fig. 4, with a capture apparatus employed in lieu of an ROV. Figs. 5 and 6 are perspective views of a floating vessel, after connection to the primary mooring lines.

[0018] Note that the X-Y-Z axes notations in the drawings may assist in understanding orientation of the various elements.

[0019] Description of the Presently Preferred Embodiment(s)

[0020] While various mooring release systems can embody the principles of the present invention, with reference to the drawings some of the presently preferred embodiments can be described.

[0021] The primary mooring line installation

[0022] With reference to the drawings, a system embodying the principles of certain aspects of the invention can be described. The methods / apparatus described herein have particular, although not exclusive, applicability to floating vessels without the capability of self-maintaining station and / or the ability to moor in deep or shallow water, or that such methods are not desired.

[0023] Fig. 1 is an overhead view of a mooring line pattern in place in a waterbody, for example an ocean. Fig. 2 is a side view of the mooring line pattern of Fig. 1, viewed through the water column. Both Figs. 1 and 2 are relatively large scale, to show the general layout. A plurality of primary mooring lines 10, typically four or more, are shown in place. Primary mooring lines 10 are anchored to the waterbottom at a first end, with a second end suspended in the water column at a desired depth by surface or subsurface buoyant members, namely floats 20. Primary mooring lines 10 may be secured to the waterbottom by any form of anchor, clump weights or the like.

[0024] Referring to Figs. 3 - 6, secondary mooring lines 30 are attached to the second ends of primary mooring lines 10. Secondary mooring lines 30 are typically, but not necessarily, of smaller diameter than primary mooring lines 10.

[0025] Referring to Fig. 3, which is a perspective view of a mooring arrangement, tethers 40 join primary mooring lines 10 together at a desired depth in the water column, which may range from the surface of the water to some deeper depth. In some embodiments, each of primary mooring lines 10 are tethered together to another primary mooring line 10; this arrangement would form a “closed” configuration, in that tethers 40 would span all spaces between primary mooring lines 10. However, in other embodiments, as shown in Figs. 3 and 4, two of primary mooring lines 10, designated 10A and 10B, are not joined by tethers 40, leaving a gap between primary mooring lines 10A and 10B. Such a gap permits access to the central area defined by the first ends of primary mooring lines 10; this is important when a floating vessel with a deep draft and / or suspended equipment seeks to enter or exit the central area. By way of example, this situation may be posed by a floating drilling unit (drillship or semi-submersible drilling rig) which must move off location with the drilling riser at least partially extending downward into the waterbody, such as for storm relocation.

[0026] It is understood that any number of primary mooring lines may be employed. Further, any desired number of the primary mooring lines may be tethered together; as noted above, a single access gap, or multiple access gaps, may be provided.

[0027] Move in of floating vessel; connection to primary mooring lines An exemplary procedure of connection of a floating vessel to the primary mooring lines in a pre-set mooring line pattern can be described.

[0028] Referring to Fig. 3, which is a perspective view, floating vessel 100 is moved to a desired position within the central area of the second (upper) ends of primary mooring lines 10. As described above, two of primary mooring lines 10A and 10B are not tethered together, thereby leaving an opening for vessel movement. Floating vessel 100 may have its own propulsion, or may be moved into position by service vessels. The system and associated method of use disclosed herein may be used in conjunction with many different types of vessels, but typically would be used in conjunction with vessels without self-contained offshore mooring systems; examples would include, but not be limited to, drillships, cruise ships, barges, etc. Such vessels would typically have onboard Remotely Operating Vehicles (RO Vs), capstans, winches, and / or other means of tensioning / recovering lines, and associated lines, and would also have bollards to which mooring lines can be secured.

[0029] With floating vessel 100 moved into desired position, typically within the central, open area of the upper ends of primary mooring lines 10, an ROV 200 is launched from floating vessel 100, ROV 200 carrying an onboard mooring line 50. As noted above, floating vessel 100 would typically move into position through one of the access gaps in the tether connections, in Fig. 4 between primary mooring lines 10A and 10B. Referring to Fig. 4, onboard mooring line 50 is connected, via ROV 200, to a secondary mooring line 30; in Fig. 4, the arrow shows movement of ROV 200 toward secondary mooring line 30, for attachment thereto. Using the onboard capstan or winch, the onboard mooring line 50, then the attached secondary mooring line 30, is brought onboard floating vessel 100. Finally, second end (upper end) of primary mooring line 10 is brought onboard floating vessel 100, and primary mooring line 10 is attached to one or more bollards. It is understood that by attaching primary mooring line to multiple bollards, the working load limits of the bollards may be accommodated. In some embodiments, secondary mooring lines 30 may be connected to the bollards.

[0030] Although use of an ROV to connect onboard mooring lines 50 to primary mooring lines 10 is described above, particularly in connection with subsurface buoyancy of primary mooring lines 10, in other embodiments surface buoyancy of primary mooring lines 10 is used. In those embodiments, in lieu of an ROV, a capture apparatus 52, shown in schematical form on Fig. 4A, which may comprise lassos, hooks or other means known in the art can be used to connect onboard mooring lines 50 to on- vessel winch, crane, or davit lines, and bring in the onboard mooring lines 50 and primary mooring lines 10 (and, if appropriate, secondary mooring lines 30).

[0031] The above procedure is repeated for the remaining mooring lines.

[0032] Generally, a reverse sequence can be followed when floating vessel 100 disconnects from and leaves the mooring array. The connections to primary mooring lines 10 are disconnected, in a predetermined order. Primary mooring lines 10, with secondary mooring lines 30 and floats 20 attached, then moved overboard. It is understood that primary mooring lines 10 may be designed so as to move down in the water column to a desired depth, suspended at that depth by floats 20, or may be left at the surface for reconnection without an ROV. Once all mooring lines are disconnected, floating vessel 100 can then be moved out of the central area of the mooring line array through one of the access gaps. Conclusion

[0033] While the preceding description contains many specificities, it is to be understood that same are presented only to describe some of the presently preferred embodiments of the invention, and not by way of limitation. Changes can be made to various aspects of the invention, without departing from the scope thereof.

[0034] Therefore, the scope of the invention is to be determined not by the illustrative examples set forth above, but by the appended claims and their legal equivalents.

Claims

We claim:

1. A method of mooring floating vessels, comprising: a) providing an apparatus, comprising: a plurality of primary mooring lines having first and second ends, said first end anchored to a seafloor underlying a waterbody, said second ends suspended at a desired depth in said waterbody, by a float; and secondary mooring lines attached to said second ends of said primary mooring lines; b) moving a floating vessel into a desired position relative to said plurality of primary mooring lines, said floating vessel comprising one or more onboard mooring lines; c) with said floating vessel in said desired position, connecting said one or more onboard mooring lines to one of said secondary mooring lines; d) bringing said secondary mooring line and said primary mooring line onboard said vessel, by retraction of said onboard mooring lines; and e) securing said primary mooring line or said secondary mooring line to said vessel.

2. The method of claim 1 , wherein a plurality of tethers connect at least some of said primary mooring lines to one another at a desired depth.

3. The method of claim 1 , wherein in step (c) said onboard mooring lines are connected to said secondary mooring lines by use of a subsea remotely operable vehicle (ROV).

4. The method of claim 1, wherein two of said primary mooring lines are not connected to one another by said tethers, thereby leaving a gap in said tethers.

5. The method of claim 1, wherein said floating vessel comprises one or more bollards, and said primary mooring line or said secondary mooring line is secured to said vessel by attachment to one or more of said bollards.

6. The method of claim 1, wherein said primary mooring line or said secondary mooring line is secured to said vessel by attachment to multiple bollards.

7. The method of claim 1, wherein steps (c) through (e) are repeated until a final desired number of primary mooring lines or said secondary mooring lines are connected to said floating vessel.

8. A method of mooring floating vessels, comprising: a) providing an apparatus, comprising: a plurality of primary mooring lines having first and second ends, said first end anchored to a seafloor underlying a waterbody, said second ends suspended on the surface of said waterbody, by a float; and secondary mooring lines attached to said second ends of said primary mooring lines; b) moving a floating vessel into a desired position relative to said plurality of primary mooring lines, said floating vessel comprising one or more onboard mooring lines; c) with said floating vessel in said desired position, connecting said one or more onboard mooring lines to one of said secondary mooring lines, by use ofcapture apparatus to capture and pull in one of said secondary mooring lines; d) bringing said secondary mooring line and said primary mooring line onboard said vessel; and e) securing said primary mooring line or said secondary mooring line to said vessel.

9. The method of claim 8, wherein said capture apparatus in element (c) comprises a lasso.

10. The method of claim 8, wherein said capture apparatus in element (c) comprises a hook.

11. The method of claim 8, wherein said apparatus in element (a) further comprises a plurality of tethers connect at least some of said primary mooring lines to one another at a desired depth.

12. The method of claim 11, wherein two of said primary mooring lines are not connected to one another by said tethers, thereby leaving a gap in said tethers.

13. The method of claim 8, wherein in step (b) said floating vessel comprises one or more bollards, and said primary mooring line or said secondary mooring line is secured to said vessel by attachment to one or more of said bollards.

14. The method of claim 13, wherein said primary mooring line or said secondary mooring line is secured to said vessel by attachment to multiple bollards.

15. The method of claim 8, wherein steps (c) through (e) are repeated until a final desired number of primary mooring lines or said secondary mooring lines are connected to said floating vessel.

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