CLAIM OF PRIORITY

[001] This patent application claims the benefit of priority to U S.

Provisional Application Serial No. 62/685,515, filed June 15, 2018, which is incorporated by reference herein in its entirety.

TECHNOLOGICAL FIELD

[002] The present disclosure relates to novel and advantageous cranes and crane systems. Particularly, the present disclosure relates to novel and advantageous cranes and crane systems having improved versatility and maneuverability. More particularly, the present disclosure relates to a crane skidding system having rails on which cranes may be maneuvered to desired positions and orientations

BACKGROUND

[003] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[004] Lifting devices such as cranes are used for hoisting and moving loads for various applications, both on and offshore. One common type of crane is a rotational crane, having a boom rotatable on a pedestal or bearing. Rotational cranes may provide a relatively wide range of motion, in comparison to other types of crane, by virtue of their rotatability. Rotational cranes may include post and slew bearing cranes. On marine vessels, rotational cranes are frequently used for transporting loads on, to, or from a deck of the vessel. However, rotational cranes may be relatively expensive, requiring relatively complex rotational and other mechanisms. Moreover, some rotational cranes, such as post cranes, may have a relatively low lifting capacity. Additionally, some rotational cranes, such as slew bearing cranes, may have relatively large components that require a large amount of deck space on the vessel. Another common type of crane used in both on and offshore operations is a shear leg crane, which may have a pivotable or fixed boom. In general, shear leg cranes may provide relatively high load carrying capacities, in comparison with other similarly-sized cranes of different types. However, shear leg cranes may have a relatively limited range of motion, as compared with, for example, rotational cranes.

SUMMARY

[005] The following presents a simplified summary of one or more embodiments of the present disclosure in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments, nor delineate the scope of any or all embodiments.

[006] The present disclosure, in one or more embodiments, relates to a crane skidding system or maneuvering a shear leg crane having an A-frame. The crane skidding system may include a rail and a pair of skidding feet configured to engage and selectively move along the rail. Each skidding foot may be coupled to a leg of the A-frame. In some embodiments, the crane skidding system may have a pair of longitudinal rails, and may further have a lateral rail. In other embodiments, the system may have a pair of lateral rails, and may further have a longitudinal rail. The crane skidding system may allow the crane to be reoriented from a first position to a second position. The second position may be arranged at an angle of rotation from the first position. In some embodiments, the skidding system may be arranged on a marine vessel, and the first position may provide for lifting operations at a stern or bow end of the vessel, while the second position may provide for lifting operations at a port or starboard side of the vessel . In some embodiments, each skidding foot may have a turntable. In some embodiments, the skidding system may have at least one tractor configured to engage with a skidding foot while sliding along the rail. Each tractor may include a hydraulic cylinder. Additionally, the first and second legs of the A-frame may be pivotable coupled to one another at an apex.

[007] The present disclosure, in one or more embodiments, additionally relates to a method of reorienting a shear leg crane from a first position to a second position, the shear leg crane having an A-frame arranged on a first and second skidding feet. The method may include moving the first skidding foot along a first rail to reorient a first leg of the frame, and moving the second skidding foot along a second rail to reorient a second leg of the A-frame. In some embodiments, the second rail may be arranged perpendicular or parallel to the first rail. In other embodiments, the second rail and the first rail may comprise the same rail. The second position may be arranged at an angle of rotation from the first position. For each of the first and second skidding feet, moving the skidding foot along the rail may include coupling at least one skidding tractor to the skidding foot, and actuating the skidding tractor(s) to push or pull the skidding foot along the rail. Additionally, each skidding tractor may have a hydraulic cylinder and a pair of tractor shoes. In some embodiments, actuating a skidding tractor to push or pull the skidding foot may include coupling a first tractor shoe to the rail, while leaving a second tractor shoe decoupled from the rail. Actuating the tractor shoe may additionally include actuating the hydraulic cylinder to extend the second tractor shoe away from the first tractor shoe, coupling the second tractor shoe to the rail and decoupling the first tractor shoe from the rail, and retracting the hydraulic cylinder to retract the first tractor shoe toward the second tractor shoe.

[008] The present disclosure, in one or more embodiments, additionally relates to a marine vessel having a rail and a crane with an A-frame. The A-frame may have a first leg and a second leg, and a skidding foot coupled to each of the first and second legs. The skidding feet may be configured to engage the rail. In some embodiments, the vessel may have a pair of parallel rails. In some embodiments, the vessel may have a pair of perpendicular rails. In some embodiments, the crane may be a first crane, and the vessel may have a second crane with an A-frame having a first leg and second leg, and a skidding foot coupled to each of the first and second legs and configured to engage the rail.

[009] While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the various embodiments of the present disclosure are capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

[010] While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the various embodiments of the present di sclosure, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying Figures, in which:

[011] FIG. 1 is a perspective view of a marine vessel having two cranes and a crane skidding system of the present disclosure, according to one or more embodiments, wherein the cranes are generally oriented toward a port side of the vessel.

[012] FIG. 2 is an overhead view of the marine vessel of FIG. 1, according to one or more embodiments, wherein the cranes are oriented in a different direction.

[013] FIG. 3 is a side view of the marine vessel of FIG. 1, according to one or more embodiments, wherein the cranes are oriented in a different direction.

[014] FIG. 4 is a perspective view of a skidding foot arranged on a rail with three sub-rails, according to one or more embodiments.

[015] FIG. 5 is a perspective view of a rail engaging portion of a skidding foot arranged on a rail with three sub-rails, according to one or more embodiments.

[016] FIG. 6 is a bottom perspective view of a rail engaging portion of a skidding foot arranged on a rail with three sub-rails, according to one or more embodiments.

[017] FIG. 7 is a top view of a skidding foot arranged on a rail with three sub-rails, according to one or more embodiments.

[018] FIG. 8 is a side view of a crane skidding foot, according to one or more embodiments.

[019] FIG. 9 is a perspective view of a crane skidding foot arranged on a rail with two sub -rails, according to one or more embodiments.

[020] FIG. 10 is a perspective view of a rail engaging portion of a skidding foot arranged on a rail with two sub-rails, according to one or more embodiments.

[021] FIG. 11 is a bottom perspective view of a skidding foot arranged on a rail with two sub-rails, according to one or more embodiments.

[022] FIG. 12 is a bottom view of a rail engaging portion of a skidding foot arranged on a rail with two sub-rails, according to one or more embodiments.

[023] FIG. 13 is a side view of a skidding foot, according to one or more embodiments.

[024] FIG. 14A is a top view of skidding tractor, according to one or more embodiments.

[025] FIG. 14B is a perspective view of a skidding tractor, according to one or more embodiments. [026] FIG. 14C is a side view of a skidding tractor, according to one or more embodiments.

[027] FIG. 14D is an end view of a skidding tractor, according to one or more embodiments.

[028] FIG. 15 is a side view of a skidding tractor, according to one or more embodiments.

[029] FIG. 16 is a perspective cross-sectional view of a skidding tractor, according to one or more embodiments.

[030] FIG. 17 is a perspective view of a skidding tractor, according to one or more embodiments.

[031] FIG. 18 is a perspective view of a tractor shoe of a skidding tractor, according to one or more embodiments.

[032] FIG. 19 is a cross-sectional view of a skidding tractor, according to one or more embodiments.

[033] FIG. 20 is a perspective view of a skidding tractor arranged on a sub-rail, according to one or more embodiments.

[034] FIG. 21 is a perspective view of a skidding tractor arranged on a sub-rail, according to one or more embodiments.

[035] FIG. 22 is a perspective view of a skidding tractor having first and second tractor shoes, with pins extended on the second tractor shoe, according to one or more embodiments.

[036] FIG. 23 is a perspective view of the skidding tractor of FIG. 22, with hydraulic cylinders extended to push the first tractor shoe, according to one or more embodiments.

[037] FIG. 24 is a perspective view of the skidding tractor of FIG. 23, with pins extended on the first tractor shoe, according to one or more embodiments.

[038] FIG. 25 is a perspective view of the skidding tractor of FIG. 24, with pins retracted on the second tractor shoe, according to one or more embodiments.

[039] FIG. 26 is a perspective view of the skidding tractor of FIG. 25, with hydraulic cylinders prepared to retract, according to one or more embodiments.

[040] FIG. 27 is a perspective view of the skidding tractor of FIG. 26, with hydraulic cylinders retracted to pull the second tractor shoe, according to one or more embodiments. [041] FIG. 28 is a perspective view of the skidding tractor of FIG. 27, with pins extended on the second tractor shoe, according to one or more embodiments.

[042] FIG. 29 is a perspective view of the skidding tractor of FIG. 28, with pins retracted on the first tractor shoe, according to one or more embodiments.

[043] FIG. 30 is a flow diagram of a method of reorienting a crane of the present disclosure, according to one or more embodiments.

[044] FIG. 31 is a perspective view of a marine vessel having two cranes and a crane skidding system of the present disclosure, according to one or more embodiments, wherein the cranes are arranged in a first position.

[045] FIG. 32 is another perspective view of the marine vessel of FIG. 31, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[046] FIG. 33 is another perspective view of the marine vessel of FIG. 32, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[047] FIG. 34 is another perspective view of the marine vessel of FIG. 33, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[048] FIG. 35 is another perspective view of the marine vessel of FIG. 34, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[049] FIG. 36 is another perspective view of the marine vessel of FIG. 35, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[050] FIG. 37 is another perspective view of the marine vessel of FIG. 36, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[051] FIG. 38 is another perspective view of the marine vessel of FIG. 37, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[052] FIG. 39 is another perspective view of the marine vessel of FIG. 38, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments. [053] FIG. 40 is another perspective view of the marine vessel of FIG. 39, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[054] FIG. 41 is another perspective view of the marine vessel of FIG. 40, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[055] FIG. 42 is another perspective view of the marine vessel of FIG. 41, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[056] FIG. 43 is another perspective view of the marine vessel of FIG. 42, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[057] FIG. 44 is another perspective view of the marine vessel of FIG. 43, wherein the two cranes are arranged in a second position, according to one or more embodiments.

[058] FIG. 45 is an overhead view of a marine vessel having two cranes and a crane skidding system of the present disclosure, according to one or more embodiments, wherein the cranes are arranged in a first position.

[059] FIG. 46 is another overhead view of the marine vessel of FIG. 45, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[060] FIG. 47 is another overhead view of the marine vessel of FIG. 46, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[061] FIG. 48 is another overhead view of the marine vessel of FIG. 47, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[062] FIG. 49 is another overhead view of the marine vessel of FIG. 48, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[063] FIG. 50 is another overhead view of the marine vessel of FIG. 49, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments. [064] FIG. 51 is another overhead view of the marine vessel of FIG. 50, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[065] FIG. 52 is another overhead view of the marine vessel of FIG. 51, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[066] FIG. 53 is another overhead view of the marine vessel of FIG. 52, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[067] FIG. 54 is another overhead view of the marine vessel of FIG. 53, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[068] FIG. 55 is another overhead view of the marine vessel of FIG. 54, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[069] FIG. 56 is another overhead view of the marine vessel of FIG. 55, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[070] FIG. 57 is another overhead view of the marine vessel of FIG. 56, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[071] FIG. 58 is another overhead view of the marine vessel of FIG. 57, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[072] FIG. 59 is another overhead view of the marine vessel of FIG. 58, wherein the two cranes are arranged in a second position, according to one or more embodiments.

[073] FIG. 60 is a side view of a marine vessel having two cranes and a crane skidding system of the present disclosure, according to one or more embodiments, wherein the cranes are arranged in a first position.

[074] FIG. 61 is another side view of the marine vessel of FIG. 60, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments. [075] FIG. 62 is another side view of the marine vessel of FIG. 61, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[076] FIG. 63 is another side view of the marine vessel of FIG. 62, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[077] FIG. 64 is another side view of the marine vessel of FIG. 63, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[078] FIG. 65 is another side view of the marine vessel of FIG. 64, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[079] FIG. 66 is another side view of the marine vessel of FIG. 65, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[080] FIG. 67 is another side view of the marine vessel of FIG. 66, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[081] FIG. 68 is another side view of the marine vessel of FIG. 67, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[082] FIG. 69 is another side view of the marine vessel of FIG. 68, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[083] FIG. 70 is another side view of the marine vessel of FIG. 69, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[084] FIG. 71 is another side view of the marine vessel of FIG. 70, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments.

[085] FIG. 72 is another side view of the marine vessel of FIG. 71, with the skidding feet of each crane having skidded incrementally along their respective rails, according to one or more embodiments. [086] FIG. 73 is another side view of the marine vessel of FIG. 72, wherein the two cranes are arranged in a second position, according to one or more embodiments.

DETAILED DESCRIPTION

[087] The present disclosure relates to skidding systems for orienting one or more relatively high capacity cranes. In some embodiments, a crane of the present disclosure may be arranged on one or more rails. In particular, a crane may have one or more skidding feet configured to engage with and skid along the one or more rails. In some embodiments, the rails may be arranged on, or may be part of, an offshore vessel. Rails may include one or more longitudinal rails and one or more lateral rails. The crane may be a shear leg crane in some embodiments, having a support frame, which may be or include an A-frame structure. In some embodiments, each leg of the A-frame may have, or may be arranged on, a skidding foot for skidding on the rail(s). The skidding feet may be selectively moved along the rail(s) to reach a desired position or orientation, and may be secured to the rails to maintain the desired position or orientation.

[088] Turning now to FIGS. 1 -3, two cranes 102 of the present disclosure are shown arranged on a vessel 100. In some embodiments, each of the two cranes 102 may be a shear leg crane. However, in other embodiments, other crane types may be provided. Each crane 102 may be configured for lifting or hoisting operations. In some embodiments, the cranes 102 may be configured and arranged to operate in tandem to lift a load 130. Each of the cranes 102 may be configured to maneuver about a deck 104 or platform of the vessel 100, or about another surface, using a crane skidding system. The crane skidding system may include a pair of longitudinal rails 106 and a pair of lateral rails 108 extending between the longitudinal rails. The rails 106, 108 may be configured to support the cranes 102 and hoisting loads, and may further be configured to allow for reorientation of the cranes. Each crane 102 may have one or more skidding feet 122 configured to engage with the rails 106, 108.

[089] The vessel 100 may generally be configured for offshore lifting operations. In some embodiments, the vessel 100 may be particularly configured for offshore drilling operations, for example. While the cranes 102 are shown in FIGS 1-3 arranged on an offshore vessel 100, cranes and skidding systems of the present disclosure are not limited to offshore operations. In some embodiments, a crane skidding system of the present disclosure may be provided as part of an onshore operation.

[090] As shown in FIGS. 1-3, in some embodiments, a crane skidding system of the present disclosure may include one or more rails 106, 108. Where the skidding system is arranged on, or as part of a vessel 100, the rails 106, 108 may be arranged on a platform or deck 104 of the vessel, as shown in FIGS. 1-3. The rails 106, 108 may be arranged directly on the deck 104 or platform, or may be raised above the deck or platform by a plurality of support members 112, so as to allow a skidding foot 122 to wrap around, or partially around, the rails. The rails 106, 108 may be configured to support one or more cranes 102 arranged thereon. Additionally, the rails 106, 108 may be configured to support loads due to hoisting operations of the one or more cranes 102. In some embodiments, the one or more rails 106, 108 may be modular.

[091] The rails 106, 108 may be arranged on the deck 104 surface, such that cranes 102 may be moved along the deck surface. In other embodiments, however, rails 106, 108 may be arranged on different surfaces. In some embodiments, each rail 106, 108 may be arranged on, and generally supported by a plurality of support members 112. In some embodiments, the rails 106, 108 may be arranged beneath, or partially beneath, the deck 104 surface, such that the rails may not interfere with deck space or deck operations. Still further, in some embodiments, a covering or partial covering may be arranged over or around the recessed rails, leaving exposed only an upper surface of the rails or another suitable portion of the rails as needed to allow movement of the cranes 102. This may help to further reduce interference with deck operations or deck space.

[092] The rails 106, 108 may have any suitable design and structure. In some embodiments, each rail 106, 108 may include two, three, or more parallel sub-rails. For example, FIGS. 4-7 show one embodiment of a rail 400 having three parallel sub- rails 402. The sub-rails 402 may be configured to together support a skidding foot 404 of a crane, such that the skidding foot may engage all three sub-rails as it slides along the rail 400. In some embodiments, the sub -rails 402 may be evenly spaced across the width of the rail 400. That is, where there are three sub-rails 402, the rail 400 may have two outer sub-rails and a centrally arranged sub-rail centered between the two outer sub-rails. In other embodiments, the sub-rails may have any other suitable spacing. [093] In some embodiments, each sub-rail 402 may be constructed of two rail brackets 406. Each rail bracket 406 may have a top portion 410 and a side portion 408. The side portion 408 of each rail bracket 406 may extend generally upward from the deck of the vessel, or from another suitable surface on which the rail 400 is generally arranged. For each rail bracket 406, the top portion 410 may extend inward from the side portion 408 toward an opposing top portion of an opposing rail bracket. The top portion 410 may extend from the side portion 408 at an angle of between approximately 60 degrees and approximately 120 degrees in some embodiments, or an angle of between approximately 80 degrees and approximately 100 degrees. The top portions 410 of opposing rail brackets 406 may form a rail surface configured to engage with a skidding foot of a crane. Each pair of rail brackets 406 may be arranged such that a gap 412 is positioned between the opposing top portions 410. The gap 412 may be configured to receive a rail engaging portion of a skidding foot. The rail engaging portion may extend through the gap 412 and between the side portions 408 of the opposing rail brackets 406, as described more fully below.

[094] FIGS. 9-12 illustrate another embodiment of a rail 500, wherein the rail has two parallel sub-rails 502 configured to engage and support a skidding foot 504. Each of the two parallel sub-rails 502 may have a pair of opposing rail brackets 506. Each rail bracket 506 may in turn have a side portion 508 and a top portion 510, wherein the opposing top portions of a rail bracket form a rail surface and a gap 512 for engaging with the skidding foot 504. In other embodiments, a rail may have any other suitable number of sub-rails.

[095] Each rail, whether composed of a single component or of a plurality of sub- rails, may have a width of between approximately 4 meters and approximately 14 meters, or between approximately 6 meters and approximately 12 meters, or between approximately 8 meters and approximately 10 meters. In some embodiments, each rail may have a width spanning approximately 9 meters.

[096] In other embodiments, rails of the present disclosure may have configurations other than those described above with respect to FIGS. 4-11. For example, each rail may have a base or foot, a head providing a rail surface, and a web extending between the foot and the head. The foot may be arranged on the deck surface, on another suitable surface, or recessed below the deck surface as described above. In some embodiments, the foot may be a widest component of a rail. The head may provide a rail surface on which the one or more cranes may skid or move. The head and/or rail surface may be configured to engage with the skidding feet of the crane(s). The web may have a relatively narrow width and may extend between the foot and head of the rail. It is to be appreciated that in some embodiments, a rail may have a generally I- beani shape.

[097] With reference back to FIGS. 1-3, in some embodiments, the crane skidding system may include one or more, and in some embodiments a pair of, longitudinal rails 106. The longitudinal rails 106 may be arranged parallel with a longest dimension of the deck 104 or of the vessel 100. In some embodiments, a longitudinal rail 106 may be arranged along each of two parallel edges of the deck 104. In other embodiments, a longitudinal rail 106 may be centrally arranged along the deck 104 surface, or may be longitudinally arranged at a different location on the deck. In some embodiments, the longitudinal rails 106 may extend the full length, or nearly the full length, of the deck 104 so as to allow maneuverability of cranes 102 along the length of the deck surface.

[098] Additionally or alternatively, the crane skidding system may include one or more, and in some embodiments a pair of, lateral rails 108. The lateral rails 108 may be arranged orthogonal to the longitudinal rails 106. As shown in FIGS. 1-3, in some embodiments, one or more lateral rails 108 may be arranged between each of two longitudinal rails 106. The lateral rails 108 may be arranged at suitable locations along the deck 104. For example, a pair of lateral rails 108 may be arranged generally nearer a stem end of the vessel 100 than a bow end. In other embodiments, one or more lateral rails 108 may additionally or alternatively be arranged nearer a bow end of the vessel 100. In still other embodiments, lateral rails 108 may be laterally arranged at different locations along the deck 104.

[099] In some embodiments, the lateral 108 and longitudinal 106 rails may intersect, such that junctions are formed between intersecting sub-rails. For example, FIG. 9 shows one embodiment of a first rail 500a, which may be a lateral rail, intersecting a second rail 500b, which is perpendicular to the first rail and may be a longitudinal rail. It is to be appreciated that only one sub-rail 502 of the second rail 500b is shown in FIG. 9. At each intersection, each sub-rail 502 of the first rail 500a may form a junction 505 with each sub-rail of the second rail 500b. At each junction 505, each rail bracket 506 of a sub -rail 502 may couple to each rail bracket of the perpendicular sub-rails. The rail brackets 506 may couple together at approximately 90-degree angles or other suitable angles or radii of curvature to form the junctions 505 between the perpendicular sub -rails 502. The junctions 505 may be configured such that a skidding foot 504 moving along a rail 500 may change direction and move to a perpendicular rail via the junctions. For example, on a first side of a sub-rail 502 of the second rail 500b, a rail bracket 506a of the first rail 500a may couple to a rail bracket 506c of the second rail at approximately a 90-degree angle. On an opposing side of the sub-rail 502 of the second rail 500b, the rail bracket 506a may couple to another rail bracket 506d of the second rail at approximately a 90-degree angle. The rail bracket 506a may thus have a gap between the connections to the two rail brackets 506c, 506d of the second rail 500b. A second rail bracket 506b of the first rail 500a may couple to each of the first and second rail brackets 506c, 506d of the second rail 500b via angles of approximately 90 degrees as well. In this way a skidding foot 504, or a portion thereof, moving through the junction 505 may be able to move from the junction in any of four directions (i.e. in either direction along either the first or second rails). As additionally shown in FIGS. 9-12, some junctions 505 may be configured for three directions of travel (i.e. in either direction along the first rail 500a or in one direction along the second rail 500b), such as where the second rail 500b ends at its connection to the first rail 500a and does not continue beyond the first rail. Other junctions 505 may be configured for only two directions of travel, such as where neither rail 500a, 500b continues beyond the connection therebetween.

[0100] With reference back to FIGS. 1-3, in other embodiments, the rails 106, 108 may intersect and/or couple together using other suitable means or configurations. In still other embodiments, the rails 106, 108 may overlap one another. For example, longitudinal rails 106 may overlap lateral rails 108 where the rails otherwise meet perpendicularly, or lateral rails may overlap longitudinal rails, for example. In this way, a skidding foot 122 on the overlapping rail may be permitted to pass beyond the position of the overlapped rail without being limited thereby.

[0101] In some embodiments, the rails 106, 108 may be generally fixed to, or over, the deck 104. The rails 106, 108 may be configured to be permanently attached to the deck 104. As described above, rails may be recessed below or within the deck 104 surface or another surface. However, in some embodiments, one or more lateral 108, longitudinal 106, or other rails may be configured to be temporary or removable. In this way, a temporary rail may be arranged in a location along the deck 104 as needed to allow a temporary change in orientation of a crane, for example. [0102] In some embodiments, each crane 102 may be a shear leg crane having a boom 128. However, in other embodiments, one or more other types of cranes may be arranged on a crane skidding system of the present disclosure. In some embodiments, each crane 102 may have a support structure, which may be or include an A-frame 1 14 having two legs extending arranged on the crane skidding system. A first leg 116, which may be a front leg, of the A-frame 114 may extend upward from a location on the vessel 100 generally near or proximate an area of operation of the crane 102. A second leg 118, which may be a rear leg, of the A-frame 114 may extend upward from a location on the vessel 100 generally distal from the area of operation of the crane 102 The front 116 and rear 118 legs of the A-frame 1 14 may couple together at an apex 120 of the A-frame. In some embodiments, the front 116 and rear 1 18 legs may be coupled with a pivotable connection at the apex 120.

[0103] Each leg 116, 118 of the A-frame 114 may be constructed of one or more beams or structures. In some embodiments, each leg 116, 118 may be or include a monolithic beam structure. Additionally or alternatively, each leg 116, 118 may be or include a lattice structure. In some embodiments, one or more legs 116, 118 may narrow or taper as the leg extends from the deck 104 toward the apex 120 of the A- frame 114. Each leg 116, 1 18, and the beams it comprises, may have a round, square, rectangular, I-beam, L-beam, or any other suitable cross-sectional shape.

[0104] Each leg 116, 118 of the A-frame 114 may be arranged on, or may be coupled to, a skidding foot 122. Each skidding foot 122 may be arranged on a rail 106, 108. The skidding feet 122 may be configured to be secured to the rails 106, 108, so as to hold the A-frame 118 in a fixed position during lifting operations. Additionally, the skidding feet 122 may be configured to selectively engage the rails 106, 108 by sliding or skidding along the rails so as to reorient or reposition the crane 102. The skidding feet 122 may be configured to engage with the rails 106, 108 using, for example, one or more rollers, a low-friction sliding engagement, a walking mechanism, or other suitable sliding or skidding mechanisms.

[0105] FIGS. 4-8 show one embodiments of a skidding foot 404 configured for a rail 400 having three sub-rails 402. Additionally, FIGS. 9-13 show another embodiment of a skidding foot 504 configured for a rail 500 having three sub-rails 502. As shown for example in FIGS. 9-13, each skidding foot 500 may generally have a crane coupling portion 513 and a rail engaging portion 509. The crane coupling portion 513 may be configured to couple the skidding foot 504 to an end of a crane leg, such that the crane leg may be supported by the skidding foot. The crane coupling portion 513 may have one or more ears 511 or pairs of ears configured to receive a pin or bolt for coupling to the crane legs. In other embodiments, the crane coupling portion 513 may have clamps, bolts, screws, pins, and/or other suitable coupling or securing mechanisms. The rail engaging portion 509 may be configured for engaging with a rail 500, so as to secure the skidding foot 504 (and the crane) to the rail, and to selectively move the skidding foot (and the crane) along the rail. The rail engaging portion 509 may have one or more rail guides 516 for engaging with the rail. Each rail guide 516 may be configured to slidingly engage with a rail, or a portion thereof such as a sub -rail. For example, where the rail 500 has two sub -rails 502, the skidding foot 504 may have at least two rail guides 516, such that at least one rail guide may be arranged in or on each of the two sub-rails. As shown for example in FIG. 10, in some embodiments, the skidding foot 504 may have two rail guides 516 for each sub -rail 502, for a total of four rail guides where there are two sub-rails. In other embodiments, the skidding foot 504 may have any other suitable number of rail guides for each rail or sub-rail.

[0106] As may be seen for example in FIG. 11, the rail guides 516 may be configured to extend through the gap 512 between the rail brackets 506, and extend both above and below the gap. In particular, and as shown in FIG. 13, each rail guide 516 may have an above rail portion 518, a below rail portion 520, and a post portion 522 extending therebetween. The above rail portion 518 may extend from, or may generally be arranged within the rail engaging portion 509 of the skidding foot 504. The above rail portion 518 may generally be configured to slide along or above a rail surface of the rail 500. The above rail portion 518 may have any suitable shape, and may be sized with a width or diameter larger than the width of the gap 512 between the rail brackets 506. The below rail portion 520 may be shaped and/or sized similar to the above rail portion 518, with a width or diameter larger than that of the gap 512. The below rail portion 520 may be configured to slide along between opposing side portions 508 of a pair of rail brackets 506. In some embodiments, the below rail portion 520 may slide against or otherwise may engage an inner surface of the side portions 508 of the rail brackets 506. The above rail portion 518 and below rail portion 520 may be coupled together via the post portion 522. That is, in some embodiments, the post portion 522 may be configured with the above rail portion 518 at one end and the below rail portion 520 at an opposing end. The post portion 522 may have a width or diameter configured to allow the post portion to extend through the gap 512 between the rail brackets 506. In some embodiments, the rail guide 516 may have one or more bushings 524 configured to reduce friction as the rail guide slides along the rail 500. For example, a bushing 524 may be arranged on each side of the above rail portion 518 and the below rail portion 520. The bushings 524 may be constructed using aluminum, bronze, and/or any other suitable and relatively low friction metals or other materials.

[0107] In some embodiments, the rail guides 516 may couple to, or engage with, the skidding foot 504 via a turntable 514. In some embodiments, the turntable 514 may include a circular track formed by an inner track 526 and an outer track 528 defining a gap therebetween. As shown in FIG. 10, for example, the post portion 522 of each rail guide 516 may extend through the gap defined between the inner track and the outer track, and the above rail portion 518 may be arranged between inner sidewalls of the inner track and the outer track. In this way, the turntable 514 may be configured to slide in a circular motion across or around the rail guides 516. The crane coupling portion 513 of the skidding foot 504 may be configured on the turntable 514 such that it may rotate with the turntable. In other embodiments, however, skidding feet 500 may have other rotation or turning means or mechanisms, configured to allow the crane to generally rotate about its connection to the rails.

[0108] The skidding feet 504 may generally have any suitable shape and size configured to engage a rail 500, including sub-rails 506, and configured to withstand loading from the crane. In some embodiments, as shown for example in FIGS. 9-13, the skidding feet 504 may have a generally round shape consistent with the shape of the turntable 514. However, in other embodiments, the skidding feet 504 may have a shape different from that of the turntabl e 514, and the turntable may be, for example, beneath or embedded within a differently shaped skidding foot.

[0109] With reference back to FIGS. 1-3, each crane 102 may have a hoisting or lifting system, which may include one or more winch assemblies and one or more lines extending therefrom. For example, a winch assembly 124 may be arranged on or near the rear leg 1 18 of a crane’s A-frame 114. A line may extend from the winch assembly 124 along the rear leg 118, and over the apex 120 of the A-frame 114. In some embodiments, the line may extend over or across one or more standoffs 126 extending from, or near, the apex 120 of the A-frame 114. The standoffis) 126 may generally be configured to hold or maintain the line away from one or more pivot points of the A-frame 114 and/or the boom 128. The line may be coupled to a boom 128 to control motion of the boom in one or more directions. Alternatively, the line may extend from the boom 128 for coupling to and hoisting a load 130. In some embodiments, a winch assembly 132 may be arranged on or near the front leg 116 of a crane’s A-frame 114. A line may extend from the winch assembly 132 along the front leg 116, and to or across a boom 128 for controlling the boom or for hoisting a load 130. Each of the lines may extend across or through one or more sheave assemblies.

[0110] In some embodiments, the boom 128 may be a utility boom extending from the A-frame 114. For example, the utility boom 128 may extend from the front leg 116 of the A-frame 114 near the apex 120 of the A-frame 114. In some embodiments, the boom 128 may be pivotably coupled to the A-frame 114, such that it may be pivoted about a generally horizontal axis, for example. However, in other embodiments, the boom 128 may be fixed with respect to rotation about a generally horizontal axis. Additionally, the boom 128 may be pivotable about a generally vertical axis in some embodiments, such that it may rotate to extend laterally from the A-frame 114. Where two cranes 102 are arranged adjacent to one another, it is to be appreciated that the two utility booms 128 may be configured to rotate about respective vertical axes toward one another, such that the two utility booms may together form a spreader beam between the two cranes.

[0111] In other embodiments, one or more cranes 102 of the present disclosure may have different booms having any suitable configuration. For example, in some embodiments a crane 102 of the present disclosure may have a boom extending from at or near the front leg’s 116 connection to the skidding foot 122. The boom may be configured to luff up and down in a forward luffing operation, pivoting about a generally horizontal axis and in a generally vertical plane. In some embodiments, a boom may be configured for reverse luffing (i.e. performing lifting operations generally behind the crane) in addition to forward luffing, as described in U.S. Provisional Application No. 62/656,235, entitled Reverse Luffing and Utility Boom Cranes, and filed April 1 1, 2018, the content of which is incorporated by reference herein in its entirety. For example, a crane skidding system of the present disclosure may be used to slide or skid a front leg 116 of an A-frame 114 forward to transition the crane from a forward luffing operation to a reverse luffing operation, as described in U.S. Provisional Application No. 62/656,235, previously incorporated herein by reference.

[0112] In some embodiments, a crane skidding system of the present disclosure may include one or more tractors for causing a skidding foot to move along a rail. In particular, one or more tractors may be arranged on, over, or mounted to, a rail, and may be configured to push or pull a skidding foot along the rail. FIGS. 14-21 show an example of a tractor 600, according to one or more embodiments. Each tractor 600 may have one or more actuators or cylinders, such as one or more hydraulic cylinders 602, arranged between a pair of tractor shoes 604. Each tractor shoe 604 may generally have a pair of actuatable pins 606 and a rail guide 608 arranged on a mounting bracket 610.

[0113] Each hydraulic cylinder 602 may have a rod 612 coupled to a piston 614 and arranged within a barrel 616, the rod configured to extend out of the barrel. The rod 612 may be coupled to a first tractor shoe 604, and the barrel 616 may be coupled to a second tractor shoe. As the rod 612 extends out of the barrel 616, a distance between the two tractor shoes 604 may increase. Likewise, as the rod 612 withdraws into the barrel 616, the tractor shoes 604 may be drawn closer together. The hydraulic cylinder 602 may have a stroke length of between approximately 8 inches and approximately 36 inches, or between approximately 16 inches and approximately 24 inches. In some embodiments, as shown in FIGS. 14-21, the tractor 600 may have two hydraulic cylinders 602 arranged in parallel between the two tractor shoes 604. However, in other embodiments, one, three, four, or any other suitable number of hydraulic cylinders 602 may be used. Moreover, it is to be appreciated that electrically actuated cylinders or other telescoping mechanisms may be used in place of the one or more hydraulic cylinders 602.

[0114] Each tractor shoe 604 may be configured to slidingly engage a rail, and further may be configured to couple to or engage a skidding foot or a portion thereof. As indicated above, each tractor shoe 604 may have a mounting bracket 610, which may include one or more steel or other material plates, for example. As the tractor shoe 604 slides along a rail, the mounting bracket 610 may slide along a tail surface of the rail. In some embodiments, one or more lugs 618 or flanges may be arranged on, or may generally extend from, the mounting bracket 610 For example, one or more lugs 618 may be used to couple the tractor shoe 604 to the one or more cylinders 602.

Additionally, one or more lugs 618 may be used to couple the tractor shoe 604 to a skidding foot or a portion thereof. In other embodiments, however, the tractor shoe 604 may additional or alternative mechanisms for coupling to a skidding foot or a portion thereof

[0115] Each tractor shoe 604 may have a rail guide 608 extending therefrom and configured to slidingly engage a rail or a sub-rail. As shown in FIG. 17, a sub-rail 630 may have a pair of rail brackets 632, which may be similar to those described above. As additionally shown in FIG. 17, the rail guide 608 may have a post portion 620 extending from the mounting bracket 610 and configured to extend through a gap 634 between opposing rail brackets. The rail guide 608 may additionally have a below rail portion 622 extending from the post portion 620 and configured to be arranged between opposing side portions of rail brackets. As shown in FIGS. 18 and 19, the rail guide 608 may have a bushing 624 configured for reducing friction between the rail guide and the rail or sub-rail.

[0116] In some embodiments, each tractor shoe 604 may have one or more actuatable pins 606, such as shot pins, for holding a position on the rail or sub-rail. The one or more pins 606 may be configured to selectively engage with holes arranged along a rail surface, or other surface, or the rail or sub -rail. As shown for example in FIGS. 17 and 18, a rail or sub-rail 630 may have one or more holes 636, grooves, or openings arranged along a rail surface. The pins 606 may be sized and configured to selectively extend into the holes 636. When the pins 606 of a tractor shoe 604 are extended into the rail holes 636, that tractor shoe may be generally held in position on the rail or sub-rail. Likewise, when the pins 606 are withdrawn from the holes 636, the tractor shoe 604 may be generally free to slide along the rail or sub-rail. The pins 606 may be actuatable via an electric, hydraulic, or other suitable actuating mechanism.

[0117] In use, a crane skidding system of the present disclosure may provide for repositioning and/or reorientation of one or more cranes. For example, in some embodiments, a crane with two skidding feet may be arranged on a same rail. By skidding both feet down the rail, the crane may be repositioned for lifting operations at a different location on or alongside the vessel, or other surface, for example. In another embodiment, a crane with two skidding feet may be arranged with one skidding foot on one rail, and a second skidding foot on a parallel rail. The two skidding feet may be moved in a same direction down the two rails to reposition the crane for lifting operations at a different location. The two skidding feet may additionally be moved in opposing directions on the parallel rails to rotate or pivot the crane. In other embodiments, a crane with two skidding feet may be arranged with a first skidding foot on a first rail (such as a longitudinal rail), and a second skidding foot on an second, perpendicular rail (such as a lateral rail). By skidding a first foot toward an intersection point of the perpendicular rails (or toward a point defined by an intersection of the longitudinal axes of the perpendicular rails if the rails do not actually intersect), and moving a second foot away from this point, the crane may be pivoted or rotated to face a different direction. In general, a crane may be pivoted or rotated using a crane skidding system to face or operate in an appreciably different direction. For example, a crane may be pivoted or rotated using a crane skidding system up to an angle of approximately 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 degrees. In still other embodiments, a crane may be rotated up to, for example, 180, 270, or 360 degrees using a crane skidding system. In other embodiments, a crane may be pivoted or rotated to any other suitable angle of rotation. In this way, as a particular example, a crane of the present disclosure may be reoriented from performing lifting operations off a side of the vessel to performing lifting operations off a back end of the vessel.

[0118] In some embodiments, one or more skidding tractors may be used to move a skidding foot along a rail. As described above, each skidding foot of a crane may have one or more rail guides configured to engage the rail. Or where a rail has multiple sub -rails, a skidding foot may have one or more rail guides configured to engage each sub-rail. To move a skidding foot along a rail, one or more tractors may couple to the skidding foot to push or pull the skidding foot along the rail. In some embodiments, one or more tractors may couple directly to one or more rail guides of each skidding foot. In other embodiments, the tractors may couple to different components of the skidding feet.

[0119] The tractors may skid along the rail using the actuatable pins to selectively hold the tractor shoes in place along the rails and the hydraulic cylinder(s) to alternatively push and pull the tractor shoes along the rail. FIGS. 22-29 illustrate a method of skidding a tractor 600. As shown in FIG. 22, while the tractor 600 is arranged on a rail or sub-rail (not shown), the pins 606 of a first tractor shoe 604a may be withdrawn while the pins of a second tractor shoe 604b may be extended to engage holes arranged along a rail. In this way, the first tractor shoe 604a may be generally free to slide along the rail, while the second tractor shoe 604b may be held in a fixed position on the rail via the pins 606. As shown in FIG. 23, with the second tractor shoe 604b held in place, the hydraulic cylinders 602 may be actuated. With the pins 606 of the first tractor shoe 604a retracted, the cylinders 602 may cause the first tractor shoe to slide outward, away from the second tractor shoe 604b. As shown in FIG. 24, the pins 606 of the first tractor shoe 604a may then be extended into the holes of the rail to fix the first tractor shoe in place. Next, as shown in FIG. 25, with the hydraulic cylinders 602 still extended, the pins 606 of the second tractor shoe 604b may be withdrawn, such that the second tractor shoe may be slidable along the rail. As shown in FIGS. 26-27, the hydraulic cylinders 602 may be retracted, which may in turn cause the second tractor shoe 604b to be pulled toward the fixed first tractor shoe 604a. As shown in FIG. 28, with the cylinders 602 retracted, the pins 606 of the second tractor shoe 604b may be extended into the holes of the rail to fix the second tractor shoe in place. As shown in FIG. 29, the pins 606 of the first tractor shoe 604a may then be retracted to once again allow the first tractor shoe to be pushed outward from the second tractor shoe 604b. This process of using the pins and cylinders to push a leading tractor shoe and pull a trailing tractor shoe may be repeated until the tractor reaches a desired position along the rail. The tractor may be skidded in this manner by itself, so as to bring a tractor in proximity to a skidding foot for example, and may be moved in this manner while coupled to a skidding foot, so as to move the skidding foot along the rail to a desired location.

[0120] Turning now to FIG. 30, a method 200 of repositioning a crane using a skidding system of the present disclosure is shown. The method 200 may include the steps of, for each skidding foot of the crane: skidding at least one tractor to the skidding foot 202; coupling the tractor(s) to the skidding foot 204; skidding tractor(s) along the rail to a desired position 206; and decoupling the tractor(s) from the skidding foot 208. In other embodiments, the method 200 may include additional or alternative steps.

[0121] Skidding at least one tractor to the skidding foot 202 may include using the tractor shoe pins and the cylinders, as described above, to push a leading tractor shoe and pull a trailing tractor shoe along the rail or sub-rail. The tractor shoe may be skidded in this manner until it is adjacent to or beneath a skidding foot. In some embodiments, one tractor may be brought to a position on the rail alongside or adjacent each skidding foot. In other embodiments, two, three, four, or any other suitable number of tractors may be brought alongside or adjacent each skidding foot. For example, where the rail includes two sub -rails, one tractor may be arranged on each sub-rail to either push or pull the skidding foot. In some embodiments, two tractors may be arranged on each of the two sub-rails, such that two tractors may pull the skidding foot from one side of the skidding foot while two tractors simultaneously push the skidding foot from an opposing side. In some embodiments, tractors may be configured to be arranged beneath a skidding foot during pushing and/or pulling operations.

[0122] The tractors may be coupled to the skidding feet 204 using the lugs arranged on the tractor shoes. For example, lugs or flanges extending from the skidding foot near the rail or sub -rail may be configured to align or interlock with the lugs of the tractor, and a pin or bolt may be arranged through the aligned or interlocked lugs. In other embodiments, other suitable coupling mechanisms may be used to couple the one or more tractors to each skidding foot. In some embodiments, the tractors may couple directly to the rail guides of the skidding feet.

[0123] Skidding the tractors along the rail to a desired position 206 may include using the pins and cylinders of each tractor to push or pull each skidding foot along the rail to a desired position. In general, one or more tractors may operate to pull a skidding foot by coupling to the skidding foot on a leading side of the skidding foot, facing the direction of travel . The tractor(s) may couple a trailing tractor shoe to the skidding foot. After a leading tractor shoe extends outward via the cylinders, the cylinders may pull the trailing tractor shoe together with the skidding foot toward the leading tractor shoe. Additionally or alternatively, one or more tractors may operate to push a skidding foot by coupling to the skidding foot on a trailing side of the skidding foot, opposing the direction of travel. The tractor(s) may couple a leading tractor shoe to the skidding foot. The cylinders may operate to push the leading tractor shoe, together with the skidding foot, away from the trailing tractor shoe, and the cylinders may in turn pull the trailing tractor shoe toward the leading shoe and the skidding foot. Once the skidding foot reaches a desired position along the rail, the tractors may be decoupled from the skidding foot.

[0124] Decoupling the tractors from the skidding foot 208 may include removing a pin or bolt from the aligned or interlocking lugs in some embodiments, or otherwise disengaging the coupling mechanism used to couple the tractors to the skidding foot. In some embodiments, the skidding foot may have pins or other mechanisms for maintaining a fixed position along the rails once decoupled from the tractors. The tractors may then be skidded along the rail where desired, such as to move another crane along the rails. In other embodiments, however, the tractors may remain coupled to the skidding feet, and the pins of the tractor shoes may engage holes of the rails to help fix the skidding feet in place on the rails. In this way, it is to be appreciated that the tractors may remain coupled to the skidding feet during lifting operations in some embodiments.

[0125] It is to be appreciated that the method described above with respect to FIG. 30 may be performed for each skidding foot of a crane. For example, the method may be performed with respect to each leg of the A-frame. In some embodiments, the skidding feet of a crane may be moved simultaneously or substantially simultaneously, such that the A-frame moves as a unit along the rail(s). However, in other embodiments, the skidding feet may be moved consecutively. For example, a first leg of the A-frame may be positioned, after which a second leg of the A-frame may be positioned.

[0126] FIGS. 31-44 illustrate a perspective view of the reorientation of two cranes 302 using a skidding system of the present disclosure, according to one or more embodiments. FIGS. 45-59 illustrate the same reorientation from an overhead view. FIGS. 60-73 illustrate the same reorientation from a side view. As shown in FIGS. 31, 45, and 60, two cranes 302 may be arranged on a vessel 300 and may be configured to operate in tandem. A first crane 302a may have an A-frame 314a with a front leg 316a and a rear leg 318a. A second crane 302b may have an A-frame 314b with a front leg 316b and a rear leg 318b. A skidding system may have a pair of longitudinal rails 306 extending longitudinally along a deck 304 of the vessel 300, and a pair of lateral rails 308 extending between the longitudinal rails. Each of the two cranes 302 may be arranged with one leg on a longitudinal rail 306 and one leg on a lateral rail 308. In particular, the first crane 302a may have a front leg 316a on a first longitudinal rail 306a via a skidding foot 322, and a rear leg 318a on a first lateral rail 308a via a skidding foot. The second crane 302b may have a front leg 3 l6b on a second lateral rail 308b via a skidding foot 322, and a rear leg 318b on a second longitudinal rail 306b via a skidding foot. In other embodiments, the cranes 302 may be arranged differently on the skidding system rails.

[0127] Using the skidding foot 322 coupled thereto, the front leg 316a of the first crane 302a may be configured to selectively slide or skid along the first longitudinal rail 306a to any desired or suitable position. Similarly, using the skidding foot 322 coupled thereto, the rear leg 318a of the first crane 302a may be configured to selectively slide or skid along the first lateral rail 308a to any desired or suitable position. Moreover, the front leg 316b of the second crane 302b may be configured to selectively slide or skid along the second lateral rail 308b to any desired or suitable position, and the rear leg 318b of the second crane may be configured to slide or skid along the second longitudinal rail 306b to any desired or suitable position. In some embodiments, skidding tractors may be used to push and/or pull the skidding feet along the rails, as described above. By arranging the cranes 302 between different longitudinal 306 and lateral 308 rails, the cranes may have a relatively high degree of maneuverability and reorientation capability via the skidding system. For example, as shown in the progression of FIGS. 31-44, 45-59, and 60-72, the cranes 302 in this configuration may be oriented to perform lifting operations generally off an end (such as a back or stem end) of the vessel 300, and alternatively may be oriented to perform lifting operations generally off a side of the vessel (such as a port or starboard side).

[0128] As shown in FIGS. 31, 45, and 60, the cranes 302 may be oriented in a first position, which may allow for lifting operations to be performed generally off of or near a back end, stem, or port or starboard quarter of the vessel 300. It is to be appreciated that the position of the cranes 302 may depend, at least in part, on the position, orientation, and length of the rails 306, 308. For example, where one leg of a crane 302 is on a longitudinal rail 306 and another leg of the crane is on a lateral rail 308, the crane may be prevented from be squarely aligned with the stern of the vessel, if the longitudinal and lateral rails do not overlap, interest, or join. However, in other embodiments, lateral 308 and longitudinal 306 rails may overlap, intersect, or join, allowing skidding feet 322 on perpendicular rails to be aligned squarely with a side or end of the vessel. Moreover, in other embodiments, one or more cranes 302 may be positioned with skidding feet 322 on parallel rails, such that the crane may be aligned squarely with an end or side of the vessel 300.

[0129] As shown in the progression of FIGS. 31-44, 45-59, and 60-72, each of the two cranes 302 may be reoriented to allow for lifting operations to be performed generally off of or near a port side of the vessel 300. For the first crane 302a, this orientation may include, using skidding tractors, skidding the front leg 3 l6a along the first longitudinal rail 306a toward a point of intersection defined by the first longitudinal rail and the first lateral rail 308a, and skidding the rear leg 3 l8a along the first lateral rail away from the point of intersection. For the second crane 302b, this orientation may include, using skidding tractors, skidding the front leg 3 l6b along the second lateral rail 308b away from a point of intersection defined by the second lateral rail and the second longitudinal rail 306b, and skidding the rear leg 318b along the second longitudinal rail toward the point of intersection. It is to be appreciated that skidding tractors are not generally shown in FIGS. 31-72. However, in some embodiments, the skidding feet may be configured to skid without the use of skidding tractors. As shown in the progression of FIGS. 31-44, 45-59, and 60-72, the front 316 and rear 318 legs for each crane 312 may be skidded substantially simultaneously, such that the crane may move as a unit. Moreover, as additionally shown in the figures, the two cranes 302 may be reoriented substantially simultaneously. It is to be appreciated, that simultaneous or substantially simultaneous reorientation of the cranes 302 may allow the cranes to be reoriented while carrying a load 330. In this way, a load 330 may be picked up while the crane(s) 302 are in a first position, and may be transported to a different location by reorienting the crane(s) to a second position.

[0130] FIGS. 44, 59, and 72 illustrate the cranes 302 oriented in a second position, according to some embodiments, which may allow for lifting operations to be performed generally off of or near a port side of the vessel 300. In reorienting the cranes 302 from the first position to the second position, the first and second positions may be configured to position the cranes (and the operational areas of the cranes) in appreciably different directions. For example, in some embodiments, the second position may be arranged at an angle of at least 5 degrees, at least 10 degrees, at least 15 degrees, at least 20 degrees, at least 25 degrees, at least 30 degrees, at least 35 degrees, at least 40 degrees, or at least 45 degrees from the first position. In other embodiments, the second position may be arranged at an angle of at least 50, 60, 70, 80, or 90 degrees from the first position. In still other embodiments, the first and second positions may be arranged at a different angle from one another. It is further to be appreciated that in addition to the first and second positions described above, the cranes 302 shown in FIGS. 31-72 may each be oriented in any suitable position between the first and second positions. Moreover, the cranes 302 may be oriented in separate positions, for example, to perform lifting operations independent of one another at separate locations on or off of the vessel 300. In some embodiments, rails may intersect, overlap, or join, which may allow for a wider range of positions for a particular crane 302. Thus in some embodiments, one or more cranes 302 (and the operational areas thereof) may be pivoted or rotated up to 45 degrees, up to 90 degrees, up to 180 degrees, up to 270 degrees, or up to 360 degrees.

[0131] As described above with respect to FIG. 9, in some embodiments, a crane skidding system of the present disclosure may have intersecting rails. For example, one or more longitudinal rails or sub-rails may intersect at an approximately 90 degree angle with one or more lateral rails or sub-rails. A crane may be configured to move through an intersection to transition from one rail to an intersecting rail. In some embodiments, skidding tractors may be used to facilitate the transition. For example and with particular reference to FIG. 9, one or more skidding tractors arranged along the first rail 500a may pull or push a crane until each skidding foot of the crane is arranged at a junction 505. Once the skidding feet of the crane are at the junctions 505, the tractors on the first rail 500a may be decoupled from the crane, and one or more tractors on the second rail 500b may be coupled to the crane. The tractors arranged on the second rail 500b may pull or push the crane onto and along the second rail. In some embodiments, once the crane has moved from the first rail 500a to the second rail 500b, tractors arranged on the first rail may be moved onto the second rail, or other additional tractors may be arranged on the second rail, behind the crane so as to help move the crane along the second rail.

[0132] The cranes and crane skidding systems and methods described herein may provide for improved versatility of cranes and crane systems on offshore vessels and in other offshore and onshore operations. The skidding systems described herein may allow cranes to be moved or reoriented as desired on the rails. Moreover, in some embodiments, the skidding system may be configured to support movement of the cranes while carrying a load, such that the cranes may be moved or reoriented to transport a load to a desired location. In this way, crane skidding systems and methods of the present disclosure may allow for shear leg cranes or other crane types to have rotational and mobile versatility similar to that of a rotational crane, but with a relatively high lifting capacity associated with shear leg cranes. For example, a shear leg crane arranged on a crane skidding system of the present disclosure may have a lifting capacity of up to or more than approximately 4,000 tons in some embodiments.

[0133] Various embodiments of the present disclosure may be described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products. It is understood that each block of the flowchart illustrations and/or block diagrams, and/or combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer- executable program code portions. These computer-executable program code portions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a particular machine, such that the code portions, which execute via the processor of the computer or other programmable data processing apparatus, create mechanisms for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. Alternatively, computer program implemented steps or acts may be combined with operator or human implemented steps or acts in order to carry out an embodiment of the invention.

[0134] Additionally, although a flowchart or block diagram may illustrate a method as comprising sequential steps or a process as having a particular order of operations, many of the steps or operations in the flowchart(s) or block diagram(s) illustrated herein can be performed in parallel or concurrently, and the f!owchart(s) or block diagram(s) should be read in the context of the various embodiments of the present disclosure. In addition, the order of the method steps or process operations illustrated in a flowchart or block diagram may be rearranged for some embodiments. Similarly, a method or process illustrated in a flow chart or block diagram could have additional steps or operations not included therein or fewer steps or operations than those shown. Moreover, a method step may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.

[0135] As used herein, the terms“substantially” or“generally” refer to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is“substantially” or“generally” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking, the nearness of completion will be so as to have generally the same overall result as if absolute and total completion were obtained. The use of“substantially” or “generally” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, an element, combination, embodiment, or composition that is“substantially free of’ or“generally free of’ an element may still actually contain such element as long as there is generally no significant effect thereof. [0138] In the foregoing description various embodiments of the present disclosure have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The various embodiments were chosen and described to provide the best illustration of the principals of the disclosure and their practical application, and to enable one of ordinary skill in the art to utilize the various embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present disclosure as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.