Method for launching a structure into or through water

Abstract

LAUNCH STRUCTURES INTO THE WATER. The present invention relates to a structure such as a pipeline bundle that is pulled into or through shallow water, for example when launching the structure, by applying a tensile pulling force to the structure through a frame extending to the structure from a winch of a first vessel. The pulling force is at least partially reacted through a pennant line that extends from the first vessel to a second vessel, and which is suspended between the first and second vessels to anchor them to the seabed by friction. Vessels may also self-propel, to increase the pulling force. The pennant line includes a cluster weight, such as a bundle of chains, which can be easily repositioned for additional pulls, being suspended between vessels before being pulled to the seabed in a new location.

Description

1 / 17 METHOD FOR LAUNCHING A STRUCTURE INTO OR THROUGH WATER

[001] The present invention relates to pulling large products or structures from land into a body of water, which may be required after manufacturing a structure on land prior to its use or installation at sea.

[002] It is a routine in the field of marine engineering to assemble or construct structures on land before transferring them to sea. For example, towable platform jackets or pipeline packages for use in the subsea oil and gas industry are typically manufactured at a coastal yard or reel base. Once completed, the structure is dragged or towed across the coast and into the adjacent sea, usually by one or more tugboats stationed close to shore.

[003] To minimize stress (tension) on the structure during launching, it is desirable to manufacture the structure in a location where the seabed slopes only superficially from the shore. In this way, the structure can be dragged a considerable distance before it can float away from the seabed.

[004] Towing a structure within and along the sea involves connecting one end of the structure to at least one lead tug and pulling the structure by the traction force of the mooring post, generated by the tug's thrusters. When the structure is elongated, as exemplified by the pipeline bundle in US 4474507, one or more drag tugs may be used to support or guide an opposite end of the structure.

[005] Once the structure is fully in deep water, and is kept away from the seabed by buoyancy, the mooring pull can move the structure relatively easily. Before that, however, the mooring pull may overcome the resistance to Petition 870260034031, dated 04 / 13 / 2026, page 15 / 63 2 / 17 movement of the structure due to its interaction with the underlying land and / or seabed, particularly frictional forces.

[006] It will be evident that a tugboat used to pull a structure out to sea will be in shallow water when the mooring pull must be at its maximum, that is, when the structure is still at or near the shore. This presents a problem because tugboats cannot operate more efficiently in shallow water, for example less than 10m in depth. In such shallow water, the mooring pull available to pull a structure is reduced because the tugboat's thrusters disturb the seabed and therefore cannot transmit full force.

[007] To increase trawling pulling capacity, two or more tugboats can be combined in series, or in parallel as shown in KR 20140065046. When used in shallow water, multiple tugboats will still suffer from energy loss, but the aggregation of their available mooring pulling compensates for this loss. However, this solution suffers from the disadvantage of much higher expense, both in operating costs and valuable capital assets.

[008] The alternative of using a more powerful tugboat also adds costs and is not a solution, because in general, more powerful tugboats require deeper water to operate efficiently.

[009] In view of these challenges, the conventional solution to the problem of pulling a structure in shallow water is to anchor a tugboat or barge with drag anchors, and then pull the structure using a winch on board the tugboat or barge. A disadvantage of this solution is that anchoring is time-consuming: the anchors must be installed and removed each time the structure is advanced into the sea in a step-by-step manner. Another approach for very large structures is to anchor a tugboat or barge with poles. Petition 870260034031, dated 04 / 13 / 2026, p. 16 / 63 3 / 17 fixed, but the poles are even more time-consuming and expensive to install and remove.

[0010] A variant of the anchoring approach, known in the art as 'walking on anchors', is described in KR 20130066014. This involves pulling the structure using a winch and pulling on multiple mooring lines, while retrieving and moving their associated anchors in sequence. However, this technique is also time-consuming and complex to execute.

[0011] GB 1434357 discloses a method for constructing a gas pipeline on the floor of a body of water, which subjects a section of the pipeline to a tensile force while being transported to its destination, for connection with a length of existing pipeline.

[0012] JR 2005 / 121077 details a method for laying pipe bodies by towing the pipe bodies out of the sea, using a tugboat that uses a GPS system to determine its position.

[0013] GB 2574893 describes a method and apparatus for applying a buoyant thrust to an elongated underwater structure. A floating unit is provided that can float with water to affect the buoyant thrust provided, enabling mid-water towing of the elongated underwater structure.

[0014] Time is a precious commodity in the field of marine engineering. As noted above, vessels are valuable capital assets, which have high operating costs proportionate to the time taken to complete the launching operation. Furthermore, the time available to launch a structure may be limited to a narrow window of calm weather. If that window is missed, a larger project dependent on that structure may be significantly delayed, potentially at enormous cost.

[0015] Against this precedent, the invention can be expressed Petition 870260034031, dated 04 / 13 / 2026, page 17 / 63 4 / 17 as a method of pulling a structure into or through water, the method comprising: applying a tensile pulling force to the structure through framing extending to the structure from a first vessel, for example, using a winch on board the first vessel acting on the framing; and reacting that pulling force through a pennant line extending from the first vessel to a second vessel, and which by friction engages the seabed between the first and second vessels. In the context of this technical field and the invention described below, it will be evidenced that a pennant line is exemplified by a cable and / or a chain extending between and suspending from the first and second vessels.

[0016] The invention is suitable for use when pulling the structure along a coastline and within the water. In this case, the first vessel may be a tugboat close to the coast, and the second vessel may be a tugboat further offshore. More generally, the first vessel may be located in shallower water than the second vessel and may therefore, or otherwise, be unable to generate as much thrust or traction on the frame post as the second vessel.

[0017] Preferably, at least one weight of a pennant line group is anchored to the seabed. The, or each weight of the group may, for example, comprise one or more chains that are coupled to, or are in series with, the pennant line.

[0018] A central portion of the pennant line may be laid on the seabed, while the respective ends of the pennant line may be suspended from the first and second vessels between the surface and the seabed, for example in a catenary configuration.

[0019] The pulling force can also be reacted to, propelling the Petition 870260034031, dated 04 / 13 / 2026, p. 18 / 63 5 / 17 first and / or second vessel out of the structure. For example, by pushing the second vessel out of the structure, tension can be transmitted in the pennant line, movement of the pennant line towards the structure can be prevented, and the pennant line can still be moved out of the structure. As a contingency measure, movement of the pennant line towards the structure can be prevented, and the pennant line can still be moved out of the structure. As a contingency measure, movement in the pennant line towards the structure can also be prevented by engaging the seabed with a pennant line anchor.

[0020] The method of the invention may further comprise: relaxing the pulling force applied to the structure through the frame; suspending the pennant line to reduce or interrupt engagement by friction with the seabed; moving the first and second vessels and the pennant line out of the structure; lowering the pennant line to increase or resume anchoring by friction with the seabed; and reapplying the pulling force to the structure through the frame.

[0021] Part or substantially all of the pennant line may be suspended clear of the seabed. At least a portion of the pennant line may be suspended over the second vessel. The second vessel may be moved toward the first vessel for the purpose of suspending the pennant line.

[0022] Conveniently, the pennant line can be left attached to the first and second vessels while being raised, moved, and lowered. Similarly, the frame can be kept attached to the structure and the first vessel while moving the first vessel away from the structure. To accomplish this, the frame can be detached from the first vessel while moving the first vessel away from the structure. The frame Petition 870260034031, dated 04 / 13 / 2026, page 19 / 63 6 / 17 can float in the water between the first vessel and the structure.

[0023] The inventive concept also encompasses a corresponding pulling arrangement for pulling a structure into or through the water. This arrangement comprises: first and second towing vessels arranged in series, one with the other or with the structure; a frame extending onto the structure of the first vessel; and a pennant line extending from the first vessel to the second vessel, and which by friction anchors to the seabed between the first and second vessels.

[0024] The frame, which may be positively buoyant, appropriately extends to the structure of a winch on the first vessel. The pennant line may be coupled to the winch of the second vessel.

[0025] The pennant line may comprise at least one group weight, and may comprise at least one contingency anchor, which is arranged to bury itself in the seabed if the pennant line moves longitudinally toward the structure. Conversely, such an anchor may be arranged to disengage from the seabed if the pennant line moves longitudinally away from the structure.

[0026] The invention addresses the problem that, in shallow water, tugboats are limited in the pulling force they can provide by propulsion only due to the limited space under the keel. Thus, in order to reduce the thrust that tugboats have to produce to launch loads or structures, especially in shallow water, a group weight such as a chain can be introduced in line between nearshore and offshore tugboats used for launching.

[0027] The weight of a group of chains acts as a resistance to movement, causing tugboats to react against it. This reduces the Petition 870260034031, dated 04 / 13 / 2026, p. 20 / 63 7 / 17 required confidence of both tugboats, while allowing a greater traction force to be exerted by a winch on the edge of the tugboat close to the shore to launch the structure.

[0028] During a shallow water launching operation, tugboats have to be stationed away from the shore or shoreline in the launching area. Consequently, a considerable length of metal boom wire is required, which increases the launching loads. To reduce these launching loads, a pennant must be placed with a flotation rope between the towboat near the shore and the structure, to reduce the force on the boom when the frame does not touch the seabed.

[0029] By way of example, a chain weight may be in series with, coupled to, or incorporated within, a ship-to-ship pennant extending from a first tug close to shore to a second tug further offshore. An anchor may be added as a contingency against slippage.

[0030] As an example of tugboat assembly, the nearshore tugboat can be assembled as close to shore as possible, within the available water depth. A winch from the nearshore tugboat can be connected to the structure to be launched by the floating frame extending from the shore. The offshore tugboat can then be connected by a pennant between ships to the nearshore tugboat cable, followed by a weight from a group of chains as described above, which is laid on the seabed.

[0031] During a launching operation, both tugboats together provide available propulsion force to increase launching capacity. The tugboat closest to shore places the structure into the sea using its winch, entering the floating frame and reacting against the unloading chain weight. The tugboat Petition 870260034031, dated 04 / 13 / 2026, p. 21 / 63 8 / 17 away from the coast recovers and re-establishes the discharge chain weight, periodically or continuously, as may be required to continue the launching operation.

[0032] Thus, the invention increases traction capacity in shallow water without a proportional increase in the number or individual strength of tugboats, and without introducing multiple anchors or poles. The invention is more efficient than the use of fixed anchors and poles because the weight of a group can be transferred quickly if required by multiple traction stages during the launching operation. Apart from being faster than using anchors or poles, the resistance provided by a group weight such as a chain is easily controllable, for example, by putting down more weight in the form of additional or longer or heavier chains to achieve the additional resistance.

[0033] Embodiments of the invention implement a method for towing an item in shallow water, the method comprising: connecting a first tugboat comprising a winch for lowering the item; and deploying a pennant line between the first tugboat and the second tugboat by the second tugboat, wherein the pennant line is at least partially laid on the seabed and provides sufficient weight and friction for the first tugboat to tie the item down. The pennant line may, for example, secure the position in a catenary configuration between the first tugboat and the second tugboat.

[0034] The method may include the following steps: raising the pennant line by the second tug; advancing the first tug while paying for the tow line; and lowering the pennant line to continue towing by the first tug.

[0035] The pennant line may comprise at least segments of chains and / or weights of a group. The pennant line Petition 870260034031, dated April 13, 2026, p. 22 / 63 9 / 17 may also comprise a contingency anchor, to restrain the line in the event that the chain slips from the seabed to the shore.

[0036] In short, the invention enables a product or structure, such as a pipeline bundle, to be pulled into or through shallow water, for example when launching the structure, applying a tensile force to the structure through the frame, which extends to the structure from a winch on a first vessel. The tensile force is, at least partially, reacted through a pennant line extending from the first vessel to a second vessel, and which is suspended between the first and second vessels to anchor to the seabed by friction. One or both vessels may also self-propel in order to contribute their momentum to the tensile force.

[0037] The pennant line may include a group weight, such as a bundle of chains. The pennant line may be easily repositioned for additional pulls by suspending it from the seabed, for example, by being hoisted onto a second vessel before being lowered to the seabed again at a new location. Conveniently, the pennant line may be suspended between vessels while remaining attached to the vessels.

[0038] In order for the invention to be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which:

[0039] Figure 1 is a schematic side view of a traction arrangement of the invention, comprising nearshore and offshore tugboats, stationed in shallow waters close to the coast, and connected in series by ship-to-ship pennant laid partially on the seabed;

[0040] Figure 2 is an enlarged view, corresponding to Detail Petition 870260034031, dated April 13, 2026, p. 23 / 63 10 / 17 II of Figure 1;

[0041] Figure 3 is an additional enlarged view of the tugboats, and an inter-vessel tugboat shown in Figure 2;

[0042] Figure 4 is a plan view of a portion of the ship-to-ship pennant, shown in Figures 1 to 3, including a group weight and an optional contingency anchor; and

[0043] Figures 5a to 5f are a sequence of schematic side views, which show a traction arrangement of the invention during a launching operation, when pulling a structure from land along the coast into the sea.

[0044] With reference first to Figures 1 to 3 of the drawings, a tug arrangement 10 of the invention comprises a tug close to shore 12 and a tug far from shore 14. The tugs 12, 14 float on the surface 16 of the sea in shallow water above a seabed with smooth shelves 18. The tugs 12, 14 are in mutual alignment along a common head, which is substantially perpendicular to the shore 20.

[0045] The nearshore tugboat12 is as close to shore20 as the water depth can safely allow. The tugboats 12, 14 are spaced several hundred meters apart, for example, 700 m apart. Thus, due to the downward slope of the seabed 18 further offshore 20, the farshore tugboat 14 is in slightly deeper water than the nearshore tugboat 12. Consequently, the thrusters of the nearshore tugboat12 can apply somewhat less thrust than those of the farshore tugboat 14 during a launching operation.

[0046] As seen best in Figure 3, the frame 22 extends to shore 20, from a tugboat winch near shore12. The frame 22 is coupled to a structure or product such as a beam. Petition 870260034031, dated 04 / 13 / 2026, p. 24 / 63 11 / 17 of the gas pipeline, not shown in Figures 1 to 3, which is to be pulled across the coast 20 and into the sea. Preferably, as shown, the frame 22 is positively buoyant to light flotation of the seabed 18, consequently reducing friction along the maximum of its considerable length.

[0047] Tugboats 12, 14 are connected in series by a ship-to-ship pennant 24, which extends from the bow of the nearshore tugboat 12 to the stern of the offshore tugboat 14. Here, the pennant 24 is a cable and / or chain that extends between, and suspends from, the nearshore tugboat 12 and the offshore tugboat 14. According to the invention, the negatively buoyant pennant 24 is left partially on the seabed 18. In this example, a substantial central portion 24A of the pennant 24 lies on the seabed 18, representing approximately half the total length of the pennant 24. End portions 24B, 24C of the pennant 24 suspend as catenaries between the respective tugboats 12, 14 and the central portion 24A on the seabed 18.

[0048] A shore end portion 24B of pennant 24 coupled to the shore tug 12 is shown here under greater tension, and consequently a shallower inclination, than the shore end portion 24C of pennant 24 coupled to the shore tug 14. The increased tension in the shore end portion 24B of pennant 24 is in reaction to the tensile force exerted on the frame 22 by the winch of the shore tug 12.

[0049] It will be evident that applying this tension to the final portion near the shore 24B requires resistance to the longitudinal movement of the central portion 24A of the pennant 24 relative to the seabed 18. To this end, the central portion 24A comprises an elongated weight of a group 26, which encloses the seabed 18 by virtue of its mass and friction. The weight of a group 26 is in series with, or incorporated into, the Petition 870260034031, dated 04 / 13 / 2026, p. 25 / 63 12 / 17 pennant 24. Most or all of the remainder of pennant 24 is also negatively buoyant, and in this way contributes to additional mass and friction when in contact with the seabed 18.

[0050] Figure 4 shows the central portion 24A of pennant 24, comprising an example of a group weight 26. In this example, a group weight 26 comprises six lengths of 35 m of six-inch (152.4 mm) chains bundled together in parallel, jutes weighing approximately one hundred tons.

[0051] The remainder of pennant 24, or at least the remainder of the central portion 24A, comprises a single six-inch (152.4 mm) chain 28. For example, a chain length 28 of 150 m of six inches (152.4 mm), weighing approximately seventy tons, leads to a tugboat's locker / chain from the shore 14.

[0052] A delta-shaped anchor 30, weighing approximately five tons, is added to the pennant 24 as a contingency against sliding along the seabed 18. The anchor 30 is incorporated within the pennant 24, at one end of the weight of a group 26. The anchor 30 is oriented to have a directional effect, in particular to engage with and bury itself in the seabed 18, if pulled towards the tugboat from close to shore12, i.e. to the left as shown in Figure 4.

[0053] Figures 5a to 5f show schematically how the pulling arrangement of the invention can be used during a launching operation, when pulling a structure 32 from the land along the coast 20 and into the sea.

[0054] In Figure 5a, the nearshore tug12 is positioned as close as possible to shore 20, ready for the launching operation to begin. For this purpose, the frame 22 extends between a stern winch of the nearshore tug12 Petition 870260034031, dated April 13, 2026, p. 26 / 63 13 / 17 and structure 32. According to the invention, the tugboats 12, 14 are connected in series by the ship-to-ship pennant 24, comprising the weight of a group 26, which is disposed on the seabed 18. The pennant 24 extends from the bow of the tugboat near the coast 12 to a winch on the stern of the tugboat far from the coast 14, and suspends like a catenary between the tugboats 12, 14 and the seabed 18.

[0055] Figure 5b shows the start of the launch operation. Responding to the anchoring by friction with the seabed 18 of the pennant 24 including the weight of a group 26, the tugboat's winch near the shore12 applies tension to the frame 22 to pull the structure 32 across the shore 20 into the sea.

[0056] The tugboat close to shore12 can also, through its properties, propel itself away from the shore 20 in reaction to the propulsive force that its winch exerts on the frame 22. Although the contribution of this impulse is limited by the depth of the water beneath the tugboat close to shore12, the supplementary reaction force conferred by the tension in the pennant 24, between the tugboat close to shore12 and the weight of a group 26, enables the winch of the tugboat close to shore12 to apply additional tension to the frame 22.

[0057] Thus, the tension in the frame 22 that applies pulling force to the structure 22 is determined by the aggregate tension in the pennant 24 and the self-propulsion of the tugboat near shore12. Consequently, the supplementary reaction force attributed to the tension in the pennant 24 reduces the thrust required from the tugboat's thrusters near shore12 to apply a given thrust force to the structure 32 through the frame 22.

[0058] The frictional resistance to the movement of pennant 24 relative to the seabed 18, largely due to the mass of pennant 24 including the weight of a group 26, can be implemented by Petition 870260034031, dated 04 / 13 / 2026, page 27 / 63 14 / 17 engagement of anchor 30 shown in Figure 4 with the seabed 18. Specifically, if the pennant 24 begins to slide along the seabed 18 towards the shore 20, the anchor 30 will tend to bury itself in the seabed 18 to stop this sliding. This prevents the movement of the pennant 24, and consequently of the tugboat near the shore12, relative to the seabed 18 as a result of the tension applied to the frame 22.

[0059] The tugboat far from the coast 14 can also apply thrust through its propellers to propel itself away from the coast 20, consequently applying tension to the pennant 24 in a direction away from the coast 20. This tension can still resist the slippage of the pennant 24, and consequently of the tugboat near the coast 12, relative to the seabed 18 towards the coast 20 in response to the tension applied to the frame 22.

[0060] The tension applied to the pennant 24 by any of such impulses from the tugboat far from the coast 14, needs only to be sufficient for the pennant 24 including the weight of a group 26 to maintain the station, that is, to remain substantially stationary in relation to the seabed 18, despite the tension applied to the frame 22 by the tugboat's winch near the coast12.

[0061] In this example, when structure 32 began to enter the sea as shown in Figure 5b, the winch of the tugboat near shore12 had pulled the frame 22 to the point where tugboats 12, 14 must be repositioned to their respective stations still from shore 20, for a second pull to continue or complete the launching operation. Figure 5c shows that the launching operation is paused for this purpose, while the weight of a group 26 is temporarily suspended from the seabed 18 by the winch of the tugboat far from shore 14.

[0062] It will be evident that, by virtue of its operation and orientation Petition 870260034031, dated April 13, 2026, p. 28 / 63 15 / 17 directional, the anchor will not withstand the weight of a group 26 and the pennant 24 being suspended from the seabed 18, by the winch of the offshore tug 14. Conversely, if anchored to the seabed 18, the anchor 30 will be removed from the seabed 18 when the winch of the offshore tug 14 pulls the pennant 24,

[0063] When being suspended and moved, the weight of a group may be suspended as part of the pennant 24 held in tension between the tugs 12, 14, as shown, or may be pulled aboard the offshore tug 14, before being deployed back to the seabed 18. Considering the weight of a group 28 of one or more chains makes the weight of a group 26 easy to lift in shallow water, and for the offshore tug 14 to handle.Furthermore, to facilitate lifting the weight of a group 26, the tugboat further offshore 14 can temporarily move toward the shore 20, to close the distance to the tugboat closer to the shore12 as shown in Figure 5c.

[0064] Figure 5d shows the tugboat near shore12 repositioned while still on the shore 20 and the structure 32 after freeing the frame 22, to accommodate the increasing distance between itself and the structure 32. Advantageously, the positively buoyant frame 22 floats on the surface 16, as shown to avoid frictional resistance from the seabed 18.

[0065] The weight of a group 26 is then lowered back to the seabed 18, still from the shore 20 as shown in Figure 5s. The resistance to movement of the weight of a group 26 relative to the seabed 18 is then available to react against the tension in the frame 22 during a second pull, as shown in Figure 5f. Again, one or both tugboats 12, 14 can apply self-propulsive force, directing their propellers towards the shore 20 during a second pull. Petition 870260034031, dated 04 / 13 / 2026, page 29 / 63 16 / 17

[0066] In this example, structure 32 is fully in the water at the end of the second pull as shown in Figure 5f. Structure 32 is then kept clear on the seabed 18 by its buoyancy, and therefore it is relatively easy to move it away from shore 20 without further recourse to the invention, potentially using only one of the tugboats 12, 14. However, the pulling arrangement 10 of the invention can still be used to pull structure 32 away from shore 20 if desired.

[0067] Many other variations are possible within the inventive concept. For example, the offshore tug 14 can, in principle, apply sufficient thrust to drag the pennant 24, including the weight of a group 26 along the seabed 18 out of the shore 20, while the winch of the nearshore tug 12 continues to apply tension to the frame 22. In this way, the thrust of the offshore tug 14 can contribute to adding the reaction force opposite to the tension in the frame 22, thus enabling a further increase in the thrust force, which can be applied to the structure 32 by the winch of the nearshore tug 12.

[0068] Consequently, the launching operation does not necessarily have to be paused to allow the tugboats 12, 14 to be repositioned before an additional pull. Instead, it should be possible for the tugboats 12, 14 to move continuously out of the shore 20 in unison in order to continue pulling the structure 32 into the water. When doing so, the tugboats 12, 14 will balance the tension on the frame 22 against its aggregate impulses, reacting against the resistance to movement of the pennant 24 including the weight of a group 26.

[0069] Even if the launching operation is paused to allow the positions of tugboats 12, 14 to be re-established, the weight of a group 26 does not need to be completely lifted, of course. Petition 870260034031, dated 04 / 13 / 2026, page 30 / 63 17 / 17 from the seabed 18. The weight of a group 26 only needs to be suspended to the extent that the tugboat away from the coast 14 can overcome the resistance of the weight of a group 26 to be dragged along the seabed 18 away from the coast 20.

[0070] In a broad sense, the invention can be used not only to tow a cargo from land into the water, but also through a body of water. Thus, the invention may involve at least one first tug and at least one second tug in series with the first tug, the first or each tug being disposed between the cargo and the second or each tug.

[0071] There may be at least one additional tug in series with the first and second tugs, with an additional pennant line on the seabed between the additional tug and the second tug. Petition 870260034031, dated April 13, 2026, p. 31 / 63

Claims

1 / 3 CLAIMS 1. Method for launching a structure (32) into or through water, characterized in that it comprises: applying a tensile force to the structure (32) through the frame (22) extending to the structure (32) from a first vessel (12); and reacting the force to launch through a pennant line (24) extending from the first vessel (12) to a second vessel (14) and which by friction engages the seabed (18) between the first and second vessels (12, 14).

2. Method according to claim 1, characterized in that it comprises anchoring by friction the seabed (18) with at least one weight of a group (26) of the pennant line (24).

3. Method according to claim 2, characterized in that one or each weight of a group (26) comprises two or more chains coupled or in series with the pennant line (24).

4. Method according to any one of claims 1 to 3, characterized in that it also comprises reacting force to pull by propulsion the first and / or second vessels (12, 14) out of the structure (32).

5. Method according to claim 4, characterized in that it comprises applying tension to the pennant line (24) moving the second vessel (14) away from the structure (32).

6. Method according to claim 5, characterized in that it comprises resisting the movement of the pennant line (24) in the direction of the structure (32) by moving the second vessel (14) away from the structure (32).

7. Method according to claim 6, characterized in that it comprises moving to move the pennant line Petition 870260034031, dated 13 / 04 / 2026, page 32 / 63 2 / 3 (24) away from the structure (32) actuating to move the second vessel (14) away from the structure (32).

8. Method according to any one of claims 1 to 7, characterized in that it comprises resisting the movement of the pennant line (24) in the direction of the structure (32) by anchoring to the seabed (18) with an anchor (30) of the pennant line (24).

9. Method according to any one of claims 1 to 8, characterized in that it comprises operating a winch on board the first vessel (12) in order to apply the force to pull the structure (32).

10. Method according to any one of claims 1 to 9, characterized in that it further comprises: relaxing the tension force applied to the structure (32) through the frame (22); suspending the pennant line (24) to reduce or interrupt the friction anchoring on the seabed (18); moving the first and second vessels (12, 14) and the pennant line (24) away from the structure (32); lowering the pennant line (24) to increase or resume the friction anchoring with the seabed (18); and reapplying the force to pull the structure (32) through the frame (22).

11. Method according to claim 10, characterized in that it comprises substantially suspending the entire pennant line (24) from the seabed (18).

12. Method according to claim 10 or 11, characterized in that it comprises collecting at least a portion of the pennant line (24) for the second vessel (14).

13. Method according to claim 12, characterized Petition 870260034031, dated 04 / 13 / 2026, page 33 / 63 3 / 3 by the fact that it comprises moving the second vessel (14) towards the first vessel (12) by retrieving the pennant line (24).

14. Method according to any one of claims 10 to 13, characterized in that it comprises holding the pennant line (24) attached to the first and second vessels (12, 14) while suspending, moving and lowering the pennant line (24).

15. Method according to any one of claims 10 to 14, characterized in that it comprises freeing the frame (22) from the first vessel (12) while moving the first vessel (12) away from the structure (32).

16. Method according to any one of claims 10 to 15, characterized in that it comprises keeping the frame (22) coupled to the structure (32) and to the first vessel (12) while moving the first vessel (12) away from the structure (32).

17. Method according to any one of claims 1 to 16, characterized in that it comprises floating the frame (22) on the water between the first vessel (12) and the structure (32).

18. Method according to any one of claims 1 to 17, characterized in that it comprises suspending the respective ends of the pennant line (24) of the vessels (12, 14) in a catenary configuration.

19. Method according to any one of claims 1 to 18, characterized in that the first vessel (12) is located in shallower water than the second vessel (14).

20. Method according to any one of claims 1 to 19, characterized in that it is used when pulling the structure (32) across a shore (20) and into the water, wherein the first vessel (12) is a tug close to shore, and the second vessel (14) is a tug away from shore. Petition 870260034031, dated 13 / 04 / 2026, p. 34 / 63

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