DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of a transfer system attached to a front portion of a hull with a cradle being lowered onto a transfer frame, according to an exemplary embodiment of the present disclosure.
FIG. 2 is an isometric view of the transfer system shown in FIG. 1 after insertion of the cradle onto the transfer frame, according to an exemplary embodiment of the present disclosure.
FIG. 3 is a bottom isometric view of the transfer system shown in FIG. 1 without the cradle, according to an exemplary embodiment of the present disclosure.
FIG. 4 is a bottom isometric close-up view of a thruster well opening under the hull shown in FIG. 3.
FIG. 5 is an isometric close-up view of tension rod assemblies installed on the side of a hull using deck fitting assemblies, according to an exemplary embodiment of the present disclosure.
FIG. 6 is a top view of a transfer system with long and short deck fitting assemblies attached to sides of the hull shown in FIG. 1.
FIGS. 6A and 6B are close-up top views of the long and short deck fitting assemblies shown in FIG. 6 with support flanges installed.
FIGS. 6C and 6D are close-up top views of the long and short deck fitting assemblies shown in FIG. 6 without support flanges installed.
FIGS. 7A and 7B are front and side views of a tension rod assembly installed on the side of a hull, according to an exemplary embodiment of the present disclosure.
FIGS. 7C, 7D, and 7E are additional fragmentary enlarged views of parts of the tension rod assembly shown in FIGS. 7A and 7B.
FIG. 7F is an isometric close-up view of the tension rod assembly shown in FIGS. 7A and 7B attached to a track system, according to an exemplary embodiment of the present disclosure.
FIG. 7G is a side close-up view of a hydraulic pre-tensioning ram attached to the tension rod assembly shown in FIGS. 7A and 7B, according to an exemplary embodiment of the present disclosure.
FIGS. 8A and 8B are top and bottom isometric views, respectively, of a track system, according to an exemplary embodiment of the present disclosure.
FIG. 9 is an isometric view of a transfer frame, according to an exemplary embodiment of the present disclosure.
FIGS. 10A, 10B, and 10C are front, side, and top views, respectively, of a hoist system in a retracted position, according to an exemplary embodiment of the present disclosure.
FIGS. 10D, 10E, 10F, and 10G are front, side, and bottom isometric views, respectively, of a hoist system in an extended position, according to an exemplary embodiment of the present disclosure.
FIGS. 11A and 11B are bottom isometric and side views, respectively, of a hoist system, according to an exemplary embodiment of the present disclosure.
FIG. 12 is a top isometric view of a transfer frame attached to a track system via a hoist system, according to an exemplary embodiment of the present disclosure.
FIG. 13 is an isometric view of a cradle, according to an exemplary embodiment of the present disclosure.
FIGS. 13A, 13B, 13C, and 13D are additional fragmentary enlarged views of parts of the cradle shown in FIG. 13.
FIG. 14 is an isometric view of a carriage assembly, according to an exemplary embodiment of the present disclosure.
FIG. 15 is a bottom isometric view of the carriage assembly shown in FIG. 14 positioned under a thruster well opening in an extended position, according to an exemplary embodiment of the present disclosure.
FIG. 16 is a bottom isometric view of the carriage assembly shown in FIG. 15 raised to a retracted position towards the thruster well opening, according to an exemplary embodiment of the present disclosure.
FIG. 17 is a bottom isometric view of a thruster being lowered into the carriage shown in FIG. 16, according to an exemplary embodiment of the present disclosure.
FIG. 18 is a bottom isometric view of the carriage and enclosed thruster shown in FIG. 17 being lowered into an extended position, according to an exemplary embodiment of the present disclosure.
FIG. 19 is a bottom isometric view of the carriage and enclosed thruster shown in FIG. 18 positioned at an end of the track system, according to an exemplary embodiment of the present disclosure.
FIG. 20 is an isometric view of a cradle and enclosed thruster being raised from a transfer system attached to a hull, according to an exemplary embodiment of the present disclosure.
DESCRIPTION OF EMBODIMENTS
Current vessel thruster maintenance is inefficient and costly. Thruster maintenance may be done while a vessel is dry docked or in water. Both of these options present several disadvantages. First, thruster maintenance performed at a dry dock requires the use of expensive dock space that includes using large tracts of ocean front real estate and highly customized equipment. Additionally, thruster maintenance performed at a dry dock results in lost vessel operating time. Removal and repair of a thruster in water can be difficult and dangerous for those attempting to perform the removal and repair. Systems performing underwater removal and repair of thrusters have involved the use of underwater divers manually moving the thruster out of a thruster channel, and then attaching cables to raise the thruster to the water surface.
Apparatuses and methods for mounting and dismounting thrusters to and from the hull of a vessel are disclosed in U.S. Pat. Nos. 4,066,034, 4,066,035, and WIPO Patent Application No. WO 2014/091063, which are incorporated herein by reference. U.S. Pat. Nos. 4,066,034 and 4,066,035 disclose mounting and dismounting using a plurality of cables suspended from a crane or other similar lifting/lowering device. WIPO Patent Application No. WO 2014/091063 discloses mounting and dismounting using lifting wires and crane wires connected to a supporting cradle containing the thruster unit. Divers are used to fasten and loosen the crane wires and lifting wires. Utilizing lifting wires and/or cables place the divers (and thrusters) at risk because they may lead to unbalancing or unhinging of the thruster while being manually moved and raised to the water surface with the attached cables, or even worse, breaking of the cables when raising the thrusters—a potentially life-threatening situation for the divers. Additionally, due to their particular size and construction, cranes and/or similar systems can only perform mounting and dismounting of thrusters in deep waters further offshore (i.e. not in shallow waters), leading to additional costs and inefficiencies in thruster operation.
Embodiments of the present disclosure relate to transfer systems, apparatuses, and methods, and in particular though non-limiting embodiments, to systems, apparatuses, and methods for the removal and reinsertion of thrusters from a hull using a transfer system.
Embodiments provide apparatuses and methods for the underwater removal and insertion of thrusters using a transfer system. Embodiments include a transfer system having deck fitting assemblies configured to be mounted to a hull of a marine vessel, tension rod assemblies secured to the deck fitting assemblies, a track system secured to the hull by the tension rod assemblies, a transfer frame movably secured to the track system via a hoist system, and a cradle removably secured to the transfer frame. The cradle and transfer frame may be collectively referred to herein as a “carriage” or “carriage assembly.” The carriage may be vertically movable and horizontally traversable along a portion of the hull.
Embodiments provide methods for removing, and subsequently reinserting, a thruster from, and into, a thruster well opening under a hull of a marine vessel using the transfer system described herein. According to an exemplary embodiment, a method includes installing the transfer system on the hull, moving the carriage across the track system towards a position directly under an opening of the hull via a hoist system, raising the carriage towards the opening via the hoist system, lowering the thruster from inside the hull through the opening and into the carriage, lowering the carriage and enclosed thruster away from the opening via the hoist system, moving the carriage and enclosed thruster across the track system towards an end of the track system, and removing the cradle and enclosed thruster from the transfer system. Once the thruster is removed and repaired/replaced, the method further includes lowering the cradle and enclosed repaired/new thruster onto the transfer frame, moving the carriage and enclosed thruster across the track system towards the position directly under the opening of the hull via the hoist system, raising the carriage and enclosed thruster towards the opening via the hoist system, and raising the thruster from the carriage towards and into the opening.
Embodiments of the present disclosure can take several forms and may be used with various different marine vessels. In instances, the marine vessel may be a cargo, container, or tanker ship. In other embodiments, the marine vessel may be a remote drilling or space launch platform, submarine, warship, tug, or any other vessel that utilizes underwater thrusters. The present disclosure may be used to remove and replace various different types of objects/equipment from the bottom of a vessel, including various types of thrusters. In example embodiments, thrusters may be any commercially available azimuth thrusters or tunnel thrusters from suppliers such as Wärtsilä®, Rolls-Royce®, or Masson Marine.
Embodiments of the present disclosure allow for the safe and efficient mounting and dismounting of thrusters from vessels in shallow waters using the transfer system described herein. Doing so is in shallow waters is an improvement over existing crane systems that can only perform mounting and dismounting in deep waters.
Turning to FIG. 1, a transfer system 100 is shown. The transfer system 100 includes deck fitting assemblies 102 configured to be mounted to a surface of a hull 101, tension rod assemblies 200 secured to the deck fitting assemblies 102, a track system 300 secured to the hull 101 by the tension rod assemblies 200, a transfer frame 500 movably secured to the track system 300 via a hoist system 400, and a cradle 600 removably secured to the transfer frame 500. In an exemplary embodiment, the transfer system 100 includes two tension rod assemblies 200 secured to two deck fitting assemblies 102, respectively, on each opposing side of the hull 101. As shown in FIG. 1, the cradle 600 is lowered down along direction A. Cradle 600 may be lowered via any known lifting and/or lowering device, including a crane. Once fully lowered, the cradle 600 fits snugly on the transfer frame 500. FIG. 2 is an isometric view of the cradle-transfer frame structure, also referred to as a carriage/carriage assembly 650. In embodiments, the carriage 650 is movable along multiple axes. Particularly, the carriage 650 is vertically movable, and also horizontally traversable along an underside portion of the hull 101 across track system 300. As seen in FIG. 2, the carriage 650 is horizontally movable in the direction, B. FIG. 3 is a bottom isometric view of the transfer frame 500 attached to track system 300 installed under the hull 101. As shown, the bottom of the hull 101 includes a thruster well opening, O, for removal and insertion of a thruster. FIG. 4 is a bottom isometric close-up view of opening, O. Once the carriage 650 is moved along the track system 300 in the direction, B, towards a position directly under opening, O, the carriage 650 is raised towards opening, O, to facilitate removal and insertion of a thruster.
FIG. 5 is an isometric close-up view of tension rod assemblies 200 installed on the side of a hull 101 using deck fitting assemblies 102. Each deck fitting assembly 102 includes a deck block 103 mounted onto a deck plate 105 and a support flange 104 installed onto the deck block 103. Support flange 104 is configured to support and attach tension rod assembly 200 to a side of hull 101. In exemplary embodiments, deck block 103 is welded to deck plate 105. However, any other attachment mechanisms may be used to attach deck block 103 to deck plate 105. Deck block 103 includes a plurality of holes/openings 103a configured such that the support flange 104 may be easily adjustable along different positions on the deck block 103, thereby allowing for pure vertical alignment of a tension rod assembly 200 with reference to a track system 300 installed under the side of a hull. See, e.g., FIGS. 1 and 2.
Deck fitting assemblies 102 may be long 102a and/or short 102b deck fitting assemblies 102. FIG. 6 is a top view of a transfer system with long and short deck fitting assemblies 102a, 102b attached to sides of a hull 101. FIGS. 6A and 6B are close-up top views of the long and short deck fitting assemblies 102a, 102b with support flanges 104 installed. FIGS. 6C and 6D are close-up top views of long and short deck fitting assemblies 102a, 102b without support flanges 104 installed. In exemplary embodiments, the long deck fitting assembly 102a is installed on a side of the hull 101 supporting a cradle 600 and/or thruster, and the short deck fitting assembly 102b is installed on an opposing side of the hull 101. As shown in FIG. 6C, the long deck fitting assembly 102a includes a deck block 103 positioned on a center of the deck plate 105 to account for installation of a long support flange 104. Long support flange 104 may be attached onto deck block 103 via nuts and/or bolts or other attachment mechanisms. In exemplary embodiments, the long support flange 104 and a tension rod assembly 200 are installed onto the deck block 103 by screwing/inserting a torque heavy duty hex nut 104a, as well as a bolt 104b. See FIG. 6A. As shown in FIG. 6D, the short deck fitting assembly 102b includes a deck block 103 positioned on an end-facing side of the deck plate 105 to account for installation of a short support flange 104. Short support flange 104 may be attached onto deck block 103 via nuts and/or bolts or other similar attachment mechanisms. In exemplary embodiments, the short support flange 104 and a tension rod assembly 200 are installed onto the deck block 103 by screwing/inserting a torque heavy duty hex nut 104a, as well as a bolt 104b. See FIG. 6B. In exemplary embodiments, hex nut 104a of long and short deck fitting assemblies 102a, 102b is capable of achieving a preload of 32,000 lbs to meet a 66,000 lb payload limit. Bolt 104b may be a 1¼″ diameter bolt. Bolt 104b may be tightened to 1400-1500 ft-lbs of torque tension.
Turning to FIGS. 7A and 7B, front and side views of a tension rod assembly 200 installed on the side of a hull 101 are shown. FIGS. 7C, 7D, and 7E are additional fragmentary enlarged views of parts of the tension rod assembly 200 shown in FIGS. 7A and 7B. FIG. 7F is an isometric close-up view of tension rod assembly 200 attached to a track system 300. Tension rod assembly 200 is configured to attach to and securely hold in place a track system 300 underneath a hull 101. In exemplary embodiments, two tension rod assemblies 200 are used on each opposing side of a hull 101. See, e.g., FIG. 1; FIG. 6.
Tension rod assembly 200 includes three tension rods 201a 201b 201c removably secured to each other. See FIGS. 7A and 7B. Link plate 204 is used to secure tension rod 201a to tension rod 201b via upper clevis fastener 202 and lower clevis fastener 203. A clevis is a U-shaped or forked metal connector within which another part can be fastened by means of a bolt or pin passing through the ends of the connector. Clevis pin 207 and a cotter pin are used to fasten lower clevis fastener 203 to link plate 204, which connection is further secured via backing/jam nuts 212. See FIGS. 7A and 7C. As shown in FIGS. 7A and 7C, sensor cable 205 is attached to upper clevis fastener 202 via load sensor pin 206. Sensor cable 205 and load sensor pin 206 are configured to measure and perform load readings. Although shown in FIGS. 7A and 7B as a shortened cable, the sensor cable 205 is substantially long and extends up and into, for e.g. a strain indicator box on a deck, or to any other system or configuration that may convert measured load signals into direct mode load output readings. In exemplary embodiments, sensor cable 205 is 80 feet long.
As shown in FIG. 7D, tension rod 201b is secured to tension rod 201c via two backing/jam nuts 212 and sleeve nuts 209. Each backing/jam nut 212 locks each sleeve nut 209 onto each rod 201b 201c to secure the two rods 201b 201c together. FIG. 7E shows an example embodiment of a connection to secure tension rod 201c to track system 300 that includes a backing/jam nut 212, clevis fastener 211, and clevis pin 210, which connection may be further secured via a cotter pin. In an exemplary embodiment, as shown in FIG. 7F, clevis fastener 211 is fastened to a gusset plate 302 attached to a longitudinal I-beam 301 of track system 300. Particularly, clevis fastener 211 is placed over the gusset plate 302 so that apertures in fastener 211 line up with an opening in gusset plate 302, such that it may be attached to gusset plate 302 via clevis pin 207 and a cotter pin and further secured via a backing/jam nut 212.
FIG. 7G is a side close-up view of a hydraulic pre-tensioning ram 220 attached to tension rod assembly 200 via hydraulic lines 221. In some embodiments, hydraulic pre-tensioning ram 220 may be installed with tension rod 201a over deck fitting assembly 102. See FIG. 7G. Since tension rod assembly 200 is attached to the I-beams 301 of track system 300, a special pre-load must be applied to ensure the entire system 100 stays in place during operation. To that end, a hydraulic pre-tensioning ram 220 may be used to allow for/apply a simultaneous pre-load to each I-beam 301. Pressure gauges may also be located on the deck that correlate to real-time readings obtained from the sensor cables 205/load sensor pin 206, and that are configured to measure the load within the various assemblies and overall system 100. In some embodiments, the readings may also be obtained via a direct readout on a computer screen located on the deck. Pressure gauges may contain various pressure control valve settings to control the pressure and estimated tension load of the system 100. For example, a reading of 100 psi on a pressure gauge may show up to 1313 lbs of tension load, thus indicating to a reader/user topside whether to increase or decrease the pressure settings for the system 100 as needed. A reading of 400 psi on a pressure gauge may show up to 5250 lbs of tension load. A reading of 800 psi on a pressure gauge may show up to 10,500 lbs of tension load. A reading of 1150 psi on a pressure gauge may show up to 15,100 lbs of tension load. Finally, a reading of 1450 psi on a pressure gauge may show up to 19,000 lbs of tension load. Tension rod assembly 200 is configured to have a functional operating range of 0 to 75,000 lbs, but components of the assembly 200 may withstand tension loads of 100,000 lbs without yielding any structural degradation. In exemplary embodiments, system 100, including a thruster and cradle 600, has a load capacity (dry condition) of 66,000 lbs. System 100, including a thruster and cradle 600, also has an overload capacity (without yielding dry condition) of 80,000 lbs. Beam 301 tension loads are continuously measured and monitored using the calibrated load cell instrumentation described herein. In exemplary embodiments, this load cell instrumentation can reliably operate at approximately 50 feet of water depth.
Referring to FIGS. 8A and 8B, top and bottom isometric views of track system/beam track weldment 300 are shown. Track system 300 is configured to be attached to the surface of a hull 101. In a particular embodiment, track system 300 is installed under and proximate to a bottom surface of the hull 101, parallel to a deck surface of the hull 101. See, e.g., FIG. 3. Track system 300 includes two longitudinal I-beams 301 connected together via stiffeners 304305. Stiffeners 304305 include lateral I-beam stiffeners 304 and/or angled I-beam stiffeners 305 configured to act as secondary tie beams or sections attached to the beams 301 to stiffen them against any deformations. Track system 300 further includes a gusset plate 302 installed on top of an end of each I-beam 301. See FIG. 8A. Each gusset plate 302 has openings 302a configured for insertion of connections to tension rod 201c and/or tension rod assembly 200. Each longitudinal I-beam 301 may constitute one solid beam. In other embodiments, each beam 301 may include multiple beams/beam subassemblies attached to each other via bolting or other attachment mechanisms. I-beams 301, I-beam stiffeners 304, 305, and gusset plates 302 may be attached to each other via fasteners, bolts, or any other mechanisms.
Track system 300 further includes a hoist rack 303 installed under/to a lower flange of each I-beam 301. See FIG. 8B. In exemplary embodiments, hoist rack 303 is made of steel and welded to each I-beam 301. Hoist rack 303 is configured to assist a hoist system 400 to move/drive along the track system 300. Particularly, hoist rack 303 functions as a gear rack having teeth equally spaced along the rack 303 such that when a pinion gear of a motor is placed on top of the rack 303, the linear nature of the rack 303 converts the pinion's rotary motion into linear motion. Track system 300 is further configured such that the center of track system 300 has a substantially square shape to coincide with positioning under thruster well opening, O, for removal and insertion of a thruster. Track system 300 further includes thruster well positioning posts 308 on each I-beam 301 constituting part of the substantially square shaped center of track system 300. Thruster well positioning posts 308 help guide, align, and install track system 300 to the hull 101 by insertion and placement into sides of opening, O. See, e.g., FIG. 4. Once positioned/secured within opening, O, posts 308 help stabilize/keep in place the track system 300 during operation of the system 100. In an exemplary embodiment, thruster well positioning posts 308 are square tubings made of steel.
Track system 300 includes triangular shaped plates 310 at an opposing end to the end having the gusset plates 302. See FIG. 8A. Triangular shaped plates 310 have openings 310a, similar to openings 302a in gusset plates 302, for insertion of connections to tension rod 201c and/or tension rod assembly 200. In some embodiments, track system 300 may include beam extensions 306 installed external and adjacent to the triangular shaped plates 310 and configured for supporting floatation rigging to position track system 300 under the hull 101. In various embodiments, beam extensions 306 may be attached to parachute lift bags configured to lift and lower, and move from side to side, track system 300 prior to installation under hull 101. In exemplary embodiments, parachute lift bags may be 10 foot diameter air bags. In exemplary embodiments, I-beams 301, including beam extensions 306, have a total length of approximately 742 inches, and a width of approximately 175 inches. In other embodiments, I-beams 301 without beam extensions 306 have a total length of 567 inches.
Since beams 301 are aligned and braced against a bottom surface of the hull 101, bottom surface of the hull 101 may have a flatness achieved by using compliant rubber or wood dunnage strips corresponding to each I-beam 301 at critical hull 101 locations. Load carrying I-beams 301 may be sized to support thruster weight and support equipment with a Safety Factor of +2.5. Corrosion resistant materials, epoxy coatings, and/or other protections may be used on the track system 300 where needed to prevent corrosion of the track system 300 while underwater. In various embodiments, beams 301 may be fabricated from alloy steel or carbon fiber composite materials.
Referring to FIG. 9, an isometric view of a transfer frame 500 is shown. Transfer frame 500 includes multiple opposing beams and/or plates attached to each other via bolting or other attachment mechanisms to form a substantially square or rectangular shaped structure. However, transfer frame 500 may have any shape suitable to allow for attachment of transfer frame 500 to a hoist system 400, as well as for attachment to a cradle 600. In an exemplary embodiment, hoist system 400 attaches to transfer frame 500 at a center position, C. As shown in FIG. 9, transfer frame 500 includes multiple padeyes at its center position, C, for connection to the hoist system 400. However, transfer frame 500 may have any other attachment mechanism for connection to hoist system 400. Transfer frame 500 is designed for a Safety Factor of +2.5. End plates 500a of transfer frame 500 are configured to act as contact pad locations for placement of crane 600 onto transfer frame 500. Transfer frame 500 further includes tip mass stabilizers 501 mounted on its sides. Tip mass stabilizers 501 are vertical rods configured to assist transfer frame 500 and cradle 600, i.e., carriage 650 in maintaining proper balance and stability/prevent carriage 650 from tipping, particularly when a payload is placed on transfer frame 500.
FIGS. 10A, 10B, and 10C are front, side, and top views of a hoist system 400 in a retracted position 400b. FIGS. 10D, 10E, 10F, and 10G are front, side, and bottom isometric views of hoist system 400 in an extended position 400a. FIGS. 11A and 11B are bottom isometric, and side, views of another embodiment of hoist system 450. FIG. 12 is a top isometric close-up view of a transfer frame 500 attached to a track system 300 via hoist system 400. Hoist system 400 is movably attached to track system 300 at a first end and secured to transfer frame 500 at a second end. Particularly, the connection at the first end includes multiple structural plates 408 positioned on either side of I-beam 301 and secured together via rods, as well as drive and lifting motors 402403 secured to the plate whereby the pinion gear of the drive motor 402 interacts with the teeth of hoist rack 303 to facilitate horizontal movement of hoist system 400. Hoist system 400 attaches to transfer frame 500 at the second end via a lifting block structure. Lifting block structure includes multiple structural plates 404 attached to a block and pin type arrangement 401 that pins into a center padeye lug of transfer frame 500. See FIGS. 10A, 10B, and 12. However, lifting block structure (and hoist system 400) may be attached to transfer frame 500 via any other attachment mechanisms. In exemplary embodiments, block and pin type arrangement 401 is clevis shaped. As shown in FIGS. 10B and 10E, lifting block structure is a substantially rectangular shaped structure. In other embodiments, lifting block structure and block and pin type arrangement 401 may have any other shape suitable for performing their functions.
Hoist system 400 is driven via by pneumatic power. Particularly, drive motor 402 and lifting motor 403 of hoist system 400 are connected to pressurized air lines that are routed down across side of the hull 101 from connections located topside/deck. Compressed air for the pneumatic power may be provided via an air compressor or from a pressure storage vessel or air receiver (i.e., a storage tank containing pressurized air). Drive motor 402 and lifting motor 403 may be manually controlled by control levers/valves/tethered control pendants 410 operated by divers underwater. See FIG. 10D. However, drive motor 402 and lifting motor 403 may be controlled remotely. In other embodiments, hoist system 400 may be driven by hydraulic power, electrical power, or any combination of pneumatic, hydraulic, and/or electrical power. Other power systems, as would be known by a person of ordinary skill in the art, may be used.
Drive motor 402 of hoist system 400 is configured to drive attached transfer frame 500 and/or carriage assembly 650 (once cradle 600 is installed), transversely along the track system 300 via the rack and pinion connection to hoist rack 303 of track system 300. Drive motor 402 drives the pinion gear secured directly to the rack 303 back and forth horizontally along track system 300. In an exemplary embodiment, hoist system 400 can drive transfer frame 500 and/or carriage 650 along track system 300 approximately 25 feet.
Lifting motor 403 is configured to raise/lift and lower attached transfer frame 500 and/or carriage 650. Particularly, the lifting motor 403 drives the lifting block structure of hoist system 400 up and down, which lifting block is connected to the second end of hoist system 400 secured to transfer frame 500. In exemplary embodiments, hoist system 400 includes chain link structures 405 that wrap around/mesh with sprockets located within structural plates 404408 and are tied to lifting motor 403 to assist lifting motor 403 in raising and lowering the lifting block structure. See FIGS. 10C to 10G. Chain link structures 405 are configured to impart structural tension to the block. In exemplary embodiments, lifting motor 403 is pneumatically actuated such that it rotates chain link structure 405, thereby facilitating raising and lowering of lifting block structure, which then allows for raising and lowering of transfer frame 500 and/or carriage 650. Hoist system 400 may raise the transfer frame 500 and/or carriage 650 above its nominal transfer height on command. In exemplary embodiments, hoist system 400 lifting/lowering rates ranges from approximately 0.2 to 0.6 inches per second. Once hoist system 400 is fully lowered, hoist system 400 is in an extended position 400a. See FIG. 10D. Once hoist system 400 is fully raised, hoist system 400 is in a retracted position 400b. See FIG. 10A. In an exemplary embodiment, hoist system 400 may raise/lift and lower transfer frame 500 and/or carriage 650 approximately 9 feet.
As shown in FIG. 10C, drive motor 402 and lifting motor 403 may be positioned external to hoist system 400 i.e. facing outward from transfer system 100. Alternatively, drive motor 402 and lifting motor 403 may face inward towards transfer system 100. In embodiments, drive motor 402 and lifting motor 403 may be positioned together on one side of hoist system 400. See, e.g., FIG. 10C. In other embodiments, each of drive motor 402 and lifting motor 403 may be positioned on either side of hoist system 400. See, e.g., FIGS. 11A and 11B. FIGS. 11A and 11B show another embodiment of hoist system 450 where the connection to transfer frame 500 is a hook type connection. Alternatively, hoist system 450 may attached to transfer frame 500 via any other attachment means. Hoist systems 400450 may be rated for 1.2 times the weight of a thruster lower gearbox. In exemplary embodiments, two hoist systems 400 are used, one on each I-beam 301. See FIG. 12. However, more or less hoist systems 400450 may be used as needed.
FIG. 13 is an isometric view of a cradle 600. FIGS. 13A, 13B, 13C, and 13D are additional fragmentary enlarged views of parts of the cradle 600. FIG. 14 is an isometric view of cradle 600 resting in the transfer frame 500. Cradle 600 is a substantially square or rectangular shaped structure configured to be lowered and fit directly on/into a transfer frame 500, and further, to securely hold/enclose a thruster 700 in place during removal and insertion of thruster 700 from hull 101. However, cradle 600 may have any other shape to correspond to a shape of transfer frame 500 and/or securely hold/enclose a thruster 700. Cradle 600 has an open top face for easy removal and insertion of thruster 700 from cradle 600.
Cradle has a padeye-flange connection 601 at its corners to easily rest on and stay in place on end plates 500a of transfer frame 500 upon insertion onto transfer frame 500. In an exemplary embodiment, the padeye-flange connection 601 has a flat bottom surface 601b configured to rest on a flat top surface of end plates 500a of transfer frame 500. See FIGS. 9, 13A, and 14. Padeyes 601 also include apertures 601a to allow for easy raising and lowering of cradle 600 via rigging from a crane and/or other lifting/lowering device. Cradle 600 includes two opposing kort nozzle saddle plates 602 positioned internally within cradle 600 such that outer surface of thruster 700 kort nozzle (i.e. large circular diameter around the propeller) may rest on kort nozzle saddle plates 602. See FIGS. 13B and 13C. Kort nozzle saddle plates 602 have a substantially curved shape to correspond to circular shape of thruster propeller. Kort nozzle saddle plates 602 assist in keeping thruster 700 stable and prevent it from moving while raising and lowering cradle 600. Cradle 600 further includes a gear case saddle plate 603 positioned internally within cradle 600 between kort nozzle saddle plates 602 such that outer surface of thruster 700 gear box housing may rest on gear box saddle plate 603. See FIGS. 13 and 13D. Gear box saddle plate 603 has a substantially curved shape to correspond to circular shape of thruster gear box. Gear box saddle plate 603 supports and stabilizes gear case in back of thruster 700 during thruster operations. Cradle 600 is designed for a Safety Factor of +2.5. In various embodiments, cradle 600 may be fabricated from alloy steel or carbon fiber composite materials.
Once cradle 600 is fully lowered such that it securely rests on transfer frame 500, drive motor 402 drives carriage/carriage assembly 650 along track system 300 in direction, B, towards thruster well opening, O, to facilitate removal of thruster 700 from hull 101. See FIG. 14. Lowering the carriage 650 to extended position 400a prior to moving carriage 650 across track system 300 is critical because not doing so will cause carriage 650 to come into contact with hull 101 and damage carriage 650 and/or hull 101. In an exemplary embodiment, carriage 650 will be approximately 190 inches below the hull 101 while in the extended position 400a. FIG. 15 shows the carriage 650 positioned under thruster well opening, O, with hoist system 400 in an extended position 400a. Once directly under opening, O, lifting motor 403 drives carriage 650 vertically towards and into opening, O, such that hoist system 400 is in a retracted position 400b. See FIG. 16. In an exemplary embodiment, carriage 650 will be raised via hoist system 400 such that it is approximately 139 inches below the hull 101 to arrive at retracted position 400b. In other embodiments, carriage 650 will be raised via hoist system 400 such that it is approximately 153 inches below the hull 101 to arrive at retracted position 400b.
Hoist system 400 raises the carriage 650 through opening, O, into a thruster well under hull 101. Thruster well is an air filled habitat under hull 101 where thruster 700 is located and where divers can safely enter and remove/install connections to thruster 700 from within hull 101. Particularly, divers in the thruster well may manually disconnect thruster 700 from its lifting/steering pipe to facilitate removal of thruster 700. Thruster 700 is then lowered from thruster well opening, O, into the carriage 650. See FIG. 17. In embodiments, once thruster 700 is inserted into the carriage 650, hoist system 400 may perform precision alignment/micro-positioning to ensure stability of the thruster 700 within the carriage 650. Precision alignment may be performed via connections of hoist system 400 to topside/deck or via manual control levers 410 operated by divers. Particularly, hoist system 400 may lift and/or drive carriage 650 inside a transfer envelope (amount of travel (x, y)) to determine the optimal/correct position of the carriage 650/thruster 700 under the thruster well, and/or the best position to ensure safe removal of thruster 700 from under hull 101. In exemplary embodiments, transfer envelope includes a travel of three to four inches in the X and Y axis. See FIG. 17.
Lifting motor 403 then drives carriage 650 vertically down and away from opening, O, such that hoist system 400 is back to the extended position 400a. See FIG. 18. Drive motor 402 then drives carriage 650 horizontally along track system 300 in direction, C, towards (outboard) position at end of track system 300. See FIGS. 18 and 19. Once positioned at the end of the track system 300 located external to hull 101, carriage 650 is raised via hoist system 400 to retracted position 400b to facilitate removal of cradle 600 and enclosed thruster 700. Cradle 600 and enclosed thruster 700 may then be raised from carriage 650/system 100 in direction, D, via rigging from a crane or other lifting/lowering device. See FIG. 20. In an exemplary embodiment, the crane or any other lifting/lowering device lifts cradle 600 and/or enclosed thruster 700 via the padeyes 601 located at the corners of the cradle 600 described herein. See FIG. 13. Cradle 600 and enclosed thruster 700 may be lifted onto a waiting barge via a barge crane. The crane may be located on a ship deck or on a structure near the ship, e.g., a dock. Transfer system 100 may allow for the transfer of thrusters 700 that are approximately 25 to 80 tons. Thruster 700 may be a retractable demountable thruster. In a particular embodiment, thruster 700 is an azimuth or azimuthing thruster.
In embodiments of the present disclosure, a method for removing, and subsequently reinserting, a thruster 700 from a hull 101 is shown. The method includes installing the transfer system 100 described herein to the hull 101. The method further includes moving the carriage 650 described herein, including the transfer frame 500 and cradle 600, across the track system 300 in a first direction, B, towards a position directly under a thruster well opening, O, under the hull 101 via the hoist system 400 described herein. The method includes raising the carriage 650 towards the opening, O, via the hoist system 400, lowering the thruster 700 from inside the hull 101 (i.e., from the thruster well) through the opening, O, and into the carriage 650, lowering the carriage 650 and enclosed thruster 700 down and away from the opening, O, via the hoist system 400, moving the carriage 650 and enclosed thruster 700 payload across the track system 500 in an opposite direction, C, towards an end of the track system 500, and removing the cradle 600 and enclosed thruster 700 from the transfer system 500 and onto an upper surface, for e.g., a deck, for further repair and/or replacement.
Once repaired and/or replaced, the cradle 600 and repaired/new thruster 700 may be lowered via the crane or other lifting/lowering device, in direction A, onto the transfer frame 500. The method includes moving the cradle-transfer frame structure, i.e. carriage 650, and enclosed thruster 700 across the track system 300 in direction, B, towards the position directly under the opening, O, of the hull 101 via the hoist system 400, raising the carriage 650 and enclosed thruster 700 towards the opening, O, via the hoist system 400, and raising the thruster 700 from the carriage 650 towards and through the opening, O, and into a thruster well for insertion into and within hull 101. Particularly, thruster 700 may be raised up to align with the disconnected steering pipe, and divers may manually connect/bolt steering pipe and thruster 700 together such that thruster 700 is fully installed within hull 101.
While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the disclosures is not limited to them. Many variations, modifications, additions, and improvements are possible, including removing and replacing items other than thrusters. Further still, any steps described herein may be carried out in any desired order, and any desired steps added or deleted.
Patent Application
20160167744
