Commercial shipping routes on the world's oceans pass through remote areas often with limited support infrastructure and severe met-ocean conditions. One such route, the great circle route between Asia and the North American West Coast, happens to be one of the busiest commercial shipping routes in the world. It passes directly through the Aleutian Archipelago and the southern portion of the Bering Sea. Electrical and mechanical system failures, loss of propulsion, and other issues experienced on large ocean-going vessels can and have resulted in significant marine casualties and oil spills in this area. A need exists for a safe means of attachment to disabled vessels for towing. Given its remoteness and the density of marine traffic in the area, the need is especially pronounced in the offshore waters of Alaska and the Bering Sea.
An emergency vessel towing system may be deployed to a disabled vessel that is in a free drift state to control the motion of the vessel. The system provides a safe method of attaching to the vessel. The system also distributes and equalizes a towing load over multiple connection points on the vessel's foredeck. Vessel as used herein means any ocean-going ship such as a commercial tank vessel, a container vessel, and a bulk carrier. Ocean as used herein means any ocean, sea, or any other body of water. Towing as used herein refers to any process involving attachment of ropes, cables, or any other line to a vessel in water to change, adjust, or control the position or location of the vessel, including pulling the vessel from one location to another, rotating the vessel, and docking the vessel.
The emergency vessel towing system may include a vessel attachment system configured to attach to a foredeck of the disabled vessel, and a retrieving system configured to connect to the vessel attachment system in a setup position.
Hawser assembly 18 may include hawser line 30 extending from proximal end 32 to distal end 34. Hawser line 30 may a length in the range of 50 to 300 meters, or any subrange therein, and an outer diameter in the range of 24 to 152 millimeters, or any subrange therein. Hawser line 30 may be formed of a light weight, high-strength material, with high pliability and positive buoyancy in seawater, such a line constructed of ultra-high-molecular-weight polyethylene fibers or other synthetic fibers. For example, hawser line 30 may be formed of 68 mm Samson Amsteel®-Blue. Proximal end 32 may include proximal eye 36 that engages distal eyes 24 of first and second bridles 14 and 16. Proximal eye 36 may include Samson DC Gard to protect against chafing due to friction with distal eyes 24 of distal ends 22 of bridles 14 and 16. Distal end 34 of hawser line 30 may include distal eye 38. Hawser assembly 16 may also include floats 40 and hawser thimble 42. Floats 40 may provide buoyancy and visibility of hawser line 30. Any number of floats 40 may be connected to hawser line 30. For example, between 1 and 10 floats 40 may be connected to hawser line 30. Hawser thimble 42 may include central opening 43. Hawser thimble 42 may be disposed in distal eye 38 of hawser line 30. Hawser thimble 42 may be formed of an Orkot® thimble or any other thimble capable of providing the strength necessary for the described connections.
Retrieving system 12 may include retrieving line 44 extending from proximal end 46 having proximal eye 48 to distal end 50 having distal eye 52. Retrieving system 12 may also include pilot anchor 54 with canopy 56 and a plurality of shrouds 58. A central portion of canopy 56 may be attached to retrieving line 44. Each of the plurality of shrouds 58 may extend from a perimeter of canopy 56 (i.e., outer edge or outer surface of canopy 56) to retrieving line 44. Retrieving system 12 may further include marker buoys 60 attached to retrieving line 44, and strobing buoy 62 attached to distal eye 52. Proximal end 46 of retrieving line 44 may be disposed through central opening 43 of hawser thimble 42 with retrieving shackle 64 engaging proximal eye 48. In this way, retrieving system 12 is connected to vessel attachment system 10 in the setup position. In other embodiments, retrieving system 12 may be connected to vessel attachment system 10 by connecting retrieving shackle 64 to a strap or rope grommet secured to hawser line 30 near distal end 34. Retrieving line 44 may have a length in the range of 10 to 300 meters, or any subrange therein. Retrieving shackle 64 may be formed of any shackle having a load capacity sufficient to allow recovery of retrieving system 12, such as a screw-pin or bolt-type shackle formed of a durable material such as stainless steel. Retrieving shackle 64 may provide a mechanism for quickly disconnecting retrieving system 12 from vessel attachment system 10.
Vessel attachment system 10 may be secured to the foredeck of a disabled vessel. Ship foredeck arrangements vary, but generally include a pair of forward and aft bitts, each pair including one port bitt and one starboard bitt. Foredeck arrangements may also include roller or pedestal type fairleads and other fittings that may be used to align bridles 14 and 16 with the orientation of bitts. First and second bridles 14 and 16 may be secured to any fittings on the foredeck of a disabled vessel, preferably with first bridle 14 engaging two or more fittings on the port side and with second bridle 16 engaging two or more fittings on the starboard side of the disabled vessel.
After first and second bridles 14 and 16 are connected to foredeck 138, retrieving system 12 and hawser assembly 18 in the setup position may be routed through one or more chocks of disabled vessel 126 and into the water, beginning with distal end 50 of retrieving system 12. In one embodiment, retrieving system 12 and hawser assembly 18 may be routed through chock 160 in bow 162 of disabled vessel 126 and into the water (as shown in
As shown in
It should be understood that the specific arrangement illustrated in
In one embodiment, bridles 14 and 16, hawser line 30, and retrieving system 12 may be configured to position distal end 50 or strobing buoy 62 some distance from disabled vessel 126 to allow safe recovery of distal end 50. In one embodiment, hawser thimble 42 is positioned a distance from disabled vessel 126 that is about one half the length of the disabled vessel when hawser line 30 is completely extended. For example, if disabled vessel 126 has a length of about 300 meters, bridles 14 and 16 may extend about 4 meters beyond chock 160 and hawser line 30 may have a length of about 146 meters.
As shown in
With reference to
First and second bridles 14 and 16 of vessel attachment system 10 distribute the line load from hawser line 30 to foredeck fittings, such as bitts 140, 142, 144, 146, fairleads 148, 150, and chock 160. Each of bridles 14 and 16 may attach to two sets of bitts or similar foredeck fittings to effectively distribute a line load applied to hawser line 30, such as from towing line 168. This configuration provides for improved load sharing over conventional methods and systems for emergency towing.
Numerical modeling demonstrated that wrapping each of bridles 14 and 16 once around forward bitts 140 and 142, respectively, and fully belaying each of bridles 14 and 16 on aft bitts 144 and 146, respectively, distributes 50-75% of the line load to forward bitts 140 and 142 and 25-50% of the line load to the aft bitts 144 and 146. This distribution is dependent upon the coefficient of friction of the bridle material and other factors. With bridles 14 and 16 formed of Samson Rope Quantum®-12 having a coefficient of friction of 0.13, about 69% of the line load was distributed to forward bitts 140 and 142 and about 31% of the line load was distributed to aft bitts 144 and 146.
Continuous bridle 202 may extend from first end 206 to second end 208 (sometimes referred to as proximal ends 206, 208). First and second ends 206, 208 may each include an eye configured to allow connection to an extension line. Continuous bridle 202 may have a length between 20 and 300 meters, or any subrange therein. In one embodiment, continuous bridle 202 may have a length between 140 and 170 meters, or any subrange therein. Continuous bridle 202 may include protected sections in high stress and high friction areas, such as first and second ends 206, 208.
Hawser assembly 204 may include hawser line 30 extending from proximal end 32 to distal end 34. Hawser assembly 204 may also include hawser bushing 210 disposed in proximal eye 36 of hawser line 30. Continuous bridle 202 may be slidingly disposed through central opening 212 of hawser bushing 210 to detachably secure continuous bridle 202 to hawser assembly 204. Continuous bridle 202 may include chafe protection on the section disposed through central opening 212 of hawser bushing 210.
Hawser assembly 204 may further include strap 214. A first end of strap 214 may be attached to hawser line 30 near distal end 34. A second end of strap 214 may include strap eye 216. Strap 214 may be formed of a small synthetic strap or loop, spliced or otherwise attached to hawser line 30 at the base of distal eye 38. In one embodiment, hawser assembly 204 includes a rope grommet instead of strap 214. The rope grommet may be attached to hawser line 30 near distal end 34 by tucking a bight of the rope grommet through the body (braid) of hawser line 30, and passing it over the standing part, effectively choking the rope grommet onto hawser line 30. The rope grommet may be formed of a high strength synthetic material, such as high strength polyethylene fibers.
With reference to
With reference to
Referring now to
Optionally in this embodiment, a high-strength synthetic line having a small diameter may be used as a safety line for a controlled initial deployment of retrieving system 12 and vessel attachment system 200 from foredeck 230 of the disabled vessel. The safety line features a spliced eye on one end and a bitter end on the other. After securing the eye splice over a cleat or other fitting on the vessel's foredeck, the bitter end may be reeved through central opening 212 of hawser bushing 210 and, after taking up slack, fully belayed on a cleat or deck fitting. This secures the hawser bushing 210 in the bight of the safety line. Upon deployment of retrieving system 12 and vessel attachment system 200 into the water, the safety line takes the initial load and prevents vessel attachment system 200 from being pulled overboard under its own weight. The safety line can then be used to slip hawser bushing 210 to its intended operating position forward of the bow, by removing wraps from the cleat or deck fitting. The ends of continuous bridle 202 can then be secured to the bitts on each side of the foredeck (port and starboard) and the safety line removed.
An emergency vessel towing system including vessel attachment system 200 may be deployed in generally the same manner as described above in connection with vessel attachment system 10. Vessel attachment system 200 and retrieving system 12 may be delivered to a disabled vessel by aircraft or boat using a line-throwing appliance. First and second ends 206 and 208 of continuous bridle 202 may be attached to the foredeck of a disabled vessel as shown in
Each connection disclosed herein may include any combination of thimbles, bushings, grommets, shackles, line eyes, and quick release mechanisms providing the described connection. Each apparatus, system, and assembly described herein may include any combination of the described components, features, and/or functions. Each method described herein may include any combination of the described steps in any order, including the absence of certain described steps. Any range of numeric values disclosed herein shall be construed to include any subrange therein.
While preferred embodiments have been described, it is to be understood that the embodiments are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalents, many variations and modifications naturally occurring to those skilled in the art from a review hereof.
This application is a continuation of U.S. patent application Ser. No. 15/611,384, filed on Jun. 1, 2017, which claims the benefit of and priority to U.S. Provisional Patent Application No. 62/351,610, filed on Jun. 17, 2016, and U.S. Provisional Patent Application No. 62/447,520, filed on Jan. 18, 2017, all of which are incorporated by reference herein in their entireties.
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Number | Date | Country | |
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20190118910 A1 | Apr 2019 | US |
Number | Date | Country | |
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62447520 | Jan 2017 | US | |
62351610 | Jun 2016 | US |
Number | Date | Country | |
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Parent | 15611384 | Jun 2017 | US |
Child | 16222298 | US |