412 results about "Mooring line" patented technology

The invention discloses a dual-mode dynamic cooperative control method and system based on pulling of a mooring line. The method comprises the steps that displacement electric signals are collected through double potentiometers; a Z-axis PWM signal is generated based on the displacement electric signal through a PWM signal generator; an XY-axis PWM signal is generated through the included angle difference between an XY rocker on the unmanned aerial vehicle and the mooring line; the Z-axis PWM signal is divided into two paths, one path is transmitted to a capstan electronic speed controller, and the other path is transmitted to the unmanned aerial vehicle and is combined with the X-axis PWM signal and the Y-axis PWM signal to form a three-dimensional control signal; setting a remote control signal and a winch potentiometer signal as well as a three-dimensional control signal and a winch manual signal as a first linkage group and a second linkage group respectively; when the first linkage group is switched on and the second linkage group is switched off, the unmanned aerial vehicle enters a first control mode; and when the second linkage group is switched on and the first linkage group is switched off, the unmanned aerial vehicle enters a second control mode. The method is used for solving the technical problems of single control mode, insufficient man-machine collaboration, poor environmental interference adaptability and limited control precision existing in traditional mooring unmanned aerial vehicle control.

The invention provides a floating type annular wave-resistant offshore photovoltaic structure. The floating type annular wave-resistant offshore photovoltaic structure comprises arc-shaped wave-resistant structure units, spring connectors, photovoltaic buoyancy tanks, photovoltaic modules, buoyancy tank mooring cables, mooring cables and pile anchors. The plurality of arc-shaped anti-wave structure units are flexibly and annularly connected through the spring connectors to form a floating type annular anti-wave structure; photovoltaic buoyancy tanks are fully paved in the circular ring of the floating type annular wave-resistant structure in parallel, and a photovoltaic module is fixedly mounted on the surface of each photovoltaic buoyancy tank. The structure main body of the novel floating type annular wave-resistant offshore photovoltaic structure adopts arc-shaped wave-resistant structures made of a high-density polyethylene material, the arc-shaped wave-resistant structures are connected into an integral circular ring through spring connectors, photovoltaic modules in the ring are protected and moored, a plurality of macromolecule buoyancy tank mooring cables are adopted in the ring to be connected with photovoltaic buoyancy tanks, and the photovoltaic buoyancy tanks are connected into a whole. The whole structure has certain flexibility and has the advantages of being small in steel consumption, high in weather resistance, low in building cost, high in wind wave resistance, easy and convenient to construct, good in power generation economical efficiency and the like.

A gravity type variable-length seabed single-point mooring connecting device of a floating fan comprises a floating body with at least two pulley fairlead devices, a single-point anchor arranged on the seabed and connected with a rotatable device, and at least one weight located in water below the floating body. Wherein the heavy block is connected with the single-point anchor through a mooring rope passing through the pulley fair lead. The offshore mooring system is small in seabed coverage area, environment-friendly, high in mooring system efficiency, safer, more reliable, practical and feasible, has a wind indicator function, and can be used for offshore mooring positioning of the floating type wind power platform with the water depth ranging from 50 m to 300 m or even larger than 1500 m.

A floating power-generation group comprises a floating hub such as a spar buoy that is anchored to subsea foundations by anchor lines. Floating power producer units such as wind turbines are connected electrically and mechanically to the hub. The power producer units are each moored by mooring lines. At least one mooring line extends inwardly toward the hub to effect mechanical connection to the hub and at least one other mooring line extends outwardly toward a subsea foundation. The groups are combined as a set whose hubs are connected electrically to each other via subsea energy storage units. Anchor lines of different groups can share subsea foundations. The storage units comprise pumping machinery to expel water from an elongate storage volume and generating machinery to generate electricity from a flow of water entering the storage volume. The pumping machinery can be in deeper water than the generating machinery.

The invention discloses a wind-fishing mechanism combining floating type fans and an oyster discharge field and a simulation method, and belongs to the technical field of wind power engineering, the wind-fishing mechanism comprises four floating type fans, the floating type fans are distributed in a rectangular shape, anchoring lines are installed at the bottom ends of the floating type fans, and shared mooring lines are arranged between the adjacent floating type fans. According to the method, the four sets of floating type fans are distributed in a rectangular mode, the floating type fans are preliminarily fixed through one set of anchoring lines respectively, then the adjacent floating type fans are reinforced through the shared mooring lines, a rectangle is defined by the adjacent floating type fans, and then the oyster ranks are arranged between the interiors of the floating type fans; and finally, the connecting mechanism is used for connecting the oyster raft with the shared mooring line, so that when the device is used, the material cost, the installation cost and the like of a floating wind power plant mooring / anchoring system are remarkably reduced, and on the other hand, the middle area is used for developing the oyster raft breeding pasture, and the characteristics of intensive sea use and three-dimensional sea use are achieved.

The invention discloses a mooring device with a wave compensation function, which is formed by bilaterally symmetrically arranging a first mooring winch to an Nth mooring winch on a ship deck along a ship side part, all the mooring winches are the same in composition and parameter setting, and the other end of each mooring winch is connected with a fixing anchor through a mooring cable; when the mooring winch on the left side draws the cable, the mooring winch on the right side draws the cable, and vice versa. The mooring device has the function of automatically buffering the impact of waves on the ship body, the ship can automatically return to the initial position under the action of the mooring device after the wave impact is eliminated, passive wave compensation is achieved, the good energy-saving effect is achieved, the moored ship can be in an unattended state for a long time, all mooring winch interfaces are unified, and the mooring effect is good. And engineering installation and implementation are facilitated, and cost reduction is facilitated. The invention further provides a control system and a control method of the mooring device.

A jacket foundation sharing anchoring system for offshore wind and light same-field power generation comprises a plurality of jacket foundations used for supporting a wind driven generator, and the jacket foundations are distributed in an array mode. The jacket foundations are divided into a plurality of groups, the number of each group of jacket foundations is at least three, and the jacket foundations in the same group can define a photovoltaic mounting area for accommodating a floating photovoltaic platform; the guide pipe frame foundation comprises a suction barrel inserted into the seabed, the suction barrel is fixedly and detachably connected with a plurality of mooring cables used for being connected with the floating type photovoltaic platform, and the mooring cables extend into the photovoltaic installation area. According to the jacket foundation sharing anchoring system and anchoring method for offshore wind and light same-field power generation, the floating type photovoltaic platform and the wind driven generator can share the jacket foundation, sharing anchoring is achieved, and the stability of the wind driven generator and the stability of the floating type photovoltaic platform are both improved.

An apparatus for securing watercraft against tidal action, wind and weather has an elongate vertical shaft having a top end and a bottom end and a slide block slidably attached to the elongate vertical shaft. The slide block slides between the top end and the bottom end and has a pair of slots therein and an opening positioned between the slots. The slots and opening are configured to allow a mooring line to be secured to the slide block. A top mounting bracket and bottom mounting bracket are attached to the top end and bottom end, respectively, of the elongate vertical shaft. The top and bottom mounting brackets are configured for attachment to mooring structures. The top mounting bracket includes an integral mooring line hook. A compression spring is mounted on the elongate vertical shaft and seated upon the bottom mounting bracket and absorbs the impact of the slide block.

The present invention discloses an offshore floating wind power and photovoltaic centralized mooring system, comprising: a floating wind turbine, a floating wind turbine mooring system, a floating photovoltaic array, and a floating photovoltaic mooring system. The floating wind turbine mooring system includes a mooring cable with one end connected to the floating wind turbine, and the other end of the mooring cable is connected to an anchor point; the floating photovoltaic mooring system includes an upper mooring cable, a lower mooring cable, and a rigid rod. One end of the upper mooring cable is connected to the floating photovoltaic array, the other end of the upper mooring cable is connected to the rigid rod, one end of the lower mooring cable is connected to the rigid rod, and the other end of the lower mooring cable is connected to the anchor point. The present invention also discloses a design method for an offshore floating wind power and photovoltaic centralized mooring system. The present invention reduces the construction difficulty, improves the construction efficiency, enhances the side structure strength of the floating photovoltaic array, and increases the installed capacity of the floating offshore photovoltaic.

The invention relates to the technical field of floating type platform mooring systems, and discloses a self-adaptive mooring cable, a manufacturing method and a self-adaptive mooring method.The self-adaptive mooring cable sequentially comprises a center main bearing layer, a middle protection layer and an outer self-adaptive regulation and control layer from inside to outside. The central main supporting layer is composed of synthetic fiber cables with high tensile strength; the middle protective layer wraps the periphery of the main bearing layer, is formed by weaving fiber materials and is used for preventing external media from invading; the outer-layer self-adaptive regulation and control layer covers the periphery of the protective layer and is woven into a net-shaped structure by shape memory alloy wires; the shape memory alloy woven mesh is configured to be capable of dynamically adjusting the overall rigidity of the mooring cable through thermoelastic martensite phase transformation based on environment temperature changes, and creep deformation of the synthetic fiber cable is slowed down. Through the synergistic effect of the three-layer structure, the structural stability and performance consistency of the mooring cable in long-term use are guaranteed.

Two types of single shared anchor mooring systems and installation method for station-keeping of floating offshore wind turbines are disclosed. The first type has one anchor on the seabed, a plurality of mooring lines, three-dimensional fairlead devices, and pendent gravity units. Each of the mooring lines runs from a first end attached to the corresponding pendent gravity unit suspended in mid-water vertically upward through the corresponding three-dimensional fairlead device attached to the floater and extends downward to a second end attached to the anchor. The mooring line has a constant tension equal to the submerged weight of the pendent gravity unit. The second type has one anchor on the seabed, one pendent gravity unit suspended in mid-water above the anchor, a plurality of mooring fairleads and interconnected mooring lines. Each of the mooring lines runs upward from a first end connected to the anchor through the mooring fairlead attached to the floater and extends downward to a second end connected to the pendent gravity unit. The mooring systems are secured to the floater at quayside, towed-out with the floater, and installed by lowering the anchor and the pendent gravity units under gravity at the offshore site.

A method of transporting a first vessel having wind turbine components to an offshore installation vessel. The method includes (i) securing the first vessel to a second vessel using a first tow line attached to a front end (or bow) of the first vessel, and (ii) securing the first vessel to a third vessel using a second tow line attached to a back end (or stern) of the first vessel. The method further includes transporting the first vessel to the offshore installation vessel using the second vessel and the third vessel secured to the first vessel via the first and second tow lines, respectively. The method also includes securing the first vessel to the offshore installation vessel. The first vessel can include one or more fender walls. The first vessel can be secured to the offshore installation vessel using one or more mooring lines.

The invention provides a breakwater floating body, a breakwater floating body structure optimization method and device and a storage medium, and the breakwater floating body comprises a first floating body which is fixed through a mooring rope and floats in the ocean; the second floating body is connected with the first floating body, open holes are formed in the surface of the second floating body, and the second floating body is hollow, so that the second floating body is communicated with seawater; the multiple damping parts are evenly distributed on the periphery of the second floating body at equal intervals, and each damping part is connected with the surface of the second floating body through a connecting piece; the damping parts are hollow, and the upper surfaces and the lower surfaces of the damping parts are provided with open holes to restrain the heaving motion of seawater. The structural parameters of the floating body of the damping component are iteratively optimized through the structural optimization method of the breakwater floating body, so that the stability and the wave resistance effect of the whole breakwater floating body are improved, the problem that potential risks are possibly caused by insufficient stability of a traditional floating breakwater is solved, and the safety of ships, coast and offshore structures is greatly improved.

Offshore energy production facility The present disclosure relates to an offshore energy production facility (100) comprising a floating platform (110), an energy production system mounted on the platform and preferably comprising at least one wind turbine (120), a mooring line (130, 140) connected to the platform, and a system for generating and / or storing energy (G2, G1), for example electrical energy, from a mechanical tension experienced by the mooring line. This constitutes an improved offshore energy production facility. [Fig 1]

The invention discloses a tension-leg-like mooring system suitable for a shallow-water-depth floating structure. The tension-leg-like mooring system comprises an anchor foundation, a mooring cable, a limiting spring and a suspension weight. The anchor foundation is fixed to the seabed and used for resisting horizontal and vertical mooring force. Three stand columns are arranged on the periphery of the floating body, balance weight cabins are arranged in the stand columns, overhanging weights are arranged in the balance weight cabins in the vertical direction in a sliding mode, limiting springs are installed at the top ends and the bottom ends in the balance weight cabins, one end of a mooring rope is connected with the anchor foundation, and the other end of the mooring rope is connected with the overhanging weights. The phenomenon that the mooring tension is sharply increased due to wave frequency motion of the floating body is avoided, and the problem that the catenary mooring platform with the low pretension design deviates too large is solved.

A floating photovoltaic system (1) comprising a flotation unit (100) and a mooring system (30), wherein the flotation unit (100) comprises at least one sail (2) having at least one vertical or near vertical photovoltaic panel (20) mounted on a mast (3) and supported on a base (5), wherein the base (5) further comprises at least one buoyancy element (10); and wherein the mooring system (30) comprises a single point mooring buoy (32) connected to at least one buoyancy element (10) or the base (5) via mooring lines (33), and at least one mooring line (34) from the single point mooring buoy (32) tethered to at least one anchor point (36).

A method of preparing a mooring rope for use in a mooring system for a floating offshore structure. The method comprises laying the mooring rope between a buoy and a seabed anchor; and tensioning the mooring rope between a buoyancy force from the buoy and the seabed anchor, thereby elongating the mooring rope towards a worked length condition. In another aspect, there is provided a method of preparing a mooring system for a floating offshore structure. The mooring system has at least one mooring line between a buoy and a seabed anchor, and the mooring line comprises a mooring rope. The method comprises tensioning the at least one mooring line between a buoyancy force from the buoy and the seabed anchor, thereby elongating the mooring rope towards a worked length condition. Preferred embodiments include tensioning the at least one mooring rope or mooring line between a buoyancy force from the buoy and a tensioning device acting against the buoyancy force. The tensioning device may be a part of the mooring system.

The invention discloses a multi-energy complementary ocean floating type power generation system which comprises a floating type wind power platform, a wave energy power generation device, a floating type photovoltaic platform array and a mooring device, and the floating type wind power platform is used for supporting and installing a wind generating set; the wave energy power generation device is arranged on the periphery of the floating type wind power platform, so that a protection water area is formed between the wave energy power generation device and the floating type wind power platform; the floating type photovoltaic platform array is arranged in a protection water area; according to the mooring device, the anchoring foundation, the underwater buoys, the main mooring cable and the branch mooring cables are used for constructing a mooring cable net, the floating type wind power platform, the wave energy power generation device and the floating type photovoltaic platform array are moored in one mooring cable net in a centralized mode, and by sharing the anchoring foundation and the main mooring cable, the number of anchor points and the total using amount of mooring materials are greatly reduced; the mooring structure is simplified, the manufacturing and mounting cost is reduced, and meanwhile the energy output efficiency of the whole system is improved.

The utility model discloses a tension leg floating type wind power platform pile foundation connecting device, and relates to the technical field of tension leg floating type wind power platform mooring connection, the tension leg floating type wind power platform pile foundation connecting device comprises a bottom connecting mechanism and a steel cable protection mechanism, the bottom connecting mechanism comprises a welding back plate, and a tongue plate is arranged on the welding back plate; the upper end of the tongue plate is connected with a steel cable joint through a pin shaft, a steel cable is connected to the steel cable joint, and the two ends of the tongue plate are locked and fixed through locking mechanisms respectively. The steel cable protection mechanism is located on one side of the pile foundation, and the steel cable is placed on the steel cable protection mechanism after being connected and used for preventing the steel cable from being bent and damaged when the steel cable is pre-laid to the seabed. The device is simple in structure, reliable in performance, convenient to operate and capable of adapting to underwater rapid connection, only one ROV is needed for auxiliary operation in the whole operation process, the tie-back installation process of the mooring rope and the anchoring device of the tension leg wind power platform is simplified, and the mooring and installation cost of the tension leg wind power platform is reduced.

The invention discloses an integrated floating platform system for multi-source ocean energy cooperative power generation and photovoltaic hydrogen production. The integrated floating platform system comprises a mooring power generation system, a photovoltaic hydrogen production platform and a vortex-induced vibration piezoelectric power generation system. The mooring power generation system comprises a mooring cable with an elastic cable, and the elastic cable is connected with a piezoelectric power generation device in series. The mooring rope is connected with the wave energy power generation anchor; the piezoelectric power generation device comprises an elastic unit connected in series on the elastic cable; the wave energy power generation anchor comprises a shell, the shell comprises a main cavity, and the main cavity communicates with branch cavities; an elastic film covers the opening of the sub-chamber; the main chamber and the branch chambers are divided into a first air passage and a second air passage; an air turbine is arranged in the first air channel; the first air channel is connected with a communicating pipe; a check valve is arranged between the communicating pipe and the first air channel; the vortex-induced vibration piezoelectric power generation system comprises an air cylinder with a piston rod, the piston rod is connected with an oscillation floater, an air turbine is arranged in the air cylinder, a second piezoelectric plate is arranged outside the air cylinder, and a spoiler is arranged at the end of the second piezoelectric plate. According to the invention, integration of offshore power generation and hydrogen production is realized, and the energy utilization rate is improved.

The application discloses a sea floating type wind turbine generator foundation mooring system, which comprises an anchoring foundation, a mooring system, a floating body foundation and an upper wind turbine; the mooring system comprises a bottom section mooring chain, an intermediate mooring cable and an upper section mooring chain; the length of the intermediate mooring cable is greater than the straight line connecting distance between the bottom section mooring chain and the upper section mooring chain, and the tension adjustment of the intermediate mooring cable is realized through the buoyancy effect, so as to realize the effective connection between the anchoring foundation and the floating body foundation; the anchoring foundation is connected with the bottom section mooring chain of the mooring system; the bottom section mooring chain is connected with the intermediate mooring cable; the intermediate mooring cable is connected with the upper section mooring chain; the upper section mooring chain is connected with the floating body foundation; the upper wind turbine is installed on the upper foundation; the whole mooring system does not use high-cost equipment such as tensioners, and the relatively expensive tensioner product cost and the cost of large ship machine equipment used for using the tensioner are saved through the buoyancy.

The utility model discloses an offshore wind power multifunctional observation buoy which comprises a truss, an observation platform arranged at the top of the truss and a ballast block arranged at the bottom of the truss, the ballast block is used for lowering the gravity center of the buoy, and the truss is used for providing buoyancy. And the ballast block is fixed on a seabed through a mooring cable. The buoy is long and thin in overall structure, and compared with a traditional buoy, the height difference between the gravity center and the buoyancy center of the buoy is greatly increased, so that the stability of the structure can be greatly improved, a platform can be provided for various ocean observation devices, and high-quality observation of ocean wind resources and ocean hydrology is achieved; the buoy is composed of the slender trusses and the ballast blocks, namely, the whole structure of the buoy extends to the deep position of water, and the wave load borne by the structure can be greatly reduced.

The invention discloses a multi-point mooring cylindrical FPSO dynamic response and mooring cable configuration digital twinning method. The multi-point mooring cylindrical FPSO dynamic response and mooring cable configuration digital twinning method comprises the following steps that S1, one sea condition combination is taken for analysis; s2, numerical simulation calculation; s3, fitting the configuration of each root mooring line by using a third-order Fourier series; s4, establishing a motion response and database of the multi-point mooring floating type ocean platform; s5, completing the training of a short-term forecasting model and an inversion model; s6, calculating sea conditions which do not appear in the training set through numerical simulation; s7, verifying the accuracy of the model; s8, completing model training and verification corresponding to all combined sea conditions; s9, enabling the model to be matched with the actual situation; and S10, applying the model to an actual platform. According to the multi-point mooring cylindrical FPSO dynamic response and mooring cable configuration digital twinning method, in the using process, data can be continuously updated according to the actual situation, and the accuracy of the model is improved.

The utility model discloses a hook with openable connecting points, which relates to the technical field of hooks and comprises a hook body and a baffle, the hook body comprises a hook portion and a connecting rod which are integrally formed, and a fixing ring with a notch at the top is integrally formed at the end of the connecting rod. The fixing ring is detachably provided with a baffle ring with a notch in the bottom through a screw, a first hinge lever is riveted to the corner, close to the fixing ring, of the baffle, the first hinge lever penetrates through the connecting rod, the first hinge lever and the connecting rod are rotationally connected, and torsional springs arranged on the outer ring of the first hinge lever in a sleeving mode are arranged on the two sides of the connecting rod correspondingly. The hook solves the problems that a bottom connecting point of an existing hook needs to be connected with a tying rope and other components, the tying rope often needs to be sewn and installed in the connecting point, the connecting point of the hook and an external component is not convenient to open, and the hook and the tying rope and other components are not convenient to connect and replace; and the large hook tying rope cannot be replaced after being damaged and needs to be integrally scrapped.

The present invention relates to an arrangement for retrieving broken moorings comprising: at least three shackles; at least two slings; at least one mooring; at least one hook; at least one ROV needle rope; and a treble hook. The upper end of the mooring is connected to a working rope with a swivel link, and the lower end of the mooring is connected to the treble hook. In addition, the invention also describes a method for retrieving broken moorings, using said arrangement for retrieving moorings, comprising the following steps: positioning a treble hook close to a mooring to be retrieved; passing a sling around the mooring; connecting a sling to the hook; applying traction; and accommodating the mooring. In this way, the invention combines the flexibility and adaptability necessary to operate in different suspension conditions on the seabed, ensuring the efficient retrieval of the broken moorings, both in environments with high-suspension seabeds and in low-suspension seabeds.

An offshore wind farm includes at least four floating structures designed to receive a wind turbine, with each floating structure having at least three mooring lines, and each mooring line is attached to a mooring point arranged around said floating structure. The mooring lines facing inward from the offshore wind farm form the inner mooring lines of the offshore wind farm and the mooring lines facing outward from the offshore wind farm form the peripheral mooring lines of the offshore wind farm, wherein two adjacent floating structures have at least one of their peripheral mooring lines crossing each other, with at least one of these peripheral mooring lines comprising a buoyancy element.

A disconnectable mooring system for offshore semi-submersible floating structures. A disconnectable buoy has a number of mooring lines which include a buoy chain between the mooring chain and the buoy. The mooring chain and the buoy chain are connected via a three way mooring connector, with the third connection configured to pull the mooring connector to a mooring point on the structure. In a first configuration the buoy is disconnected and supports the mooring chains for recovery at shallow depths to be pulled in. In a second configuration, the mooring lines are pulled in via the mooring connectors thereby providing a spread mooring to the structure with the buoy chain left as a catenary between the buoy and mooring point.

The present invention relates to a mooring method for an offshore floating structure for forming an offshore floating structure mooring system including the offshore floating structure, an anchor body, and a mooring line. The anchor body includes an anchor concrete structure having: a mooring line pass-through passage for passing the mooring line through formed on the inside; and a compressed air chamber that is closed on the top and sides. The mooring line is supported in a middle portion by the anchor body while passing through the mooring line pass-through passage, and both ends of the mooring line are connected to the offshore floating structure. Accordingly, the coupling force between the anchor concrete structure and the mooring line can be increased, and underwater work related to installation and replacement of the mooring line becomes unnecessary.

The utility model discloses a mooring rope anode sacrifice block protection device which comprises a steel cable and a mooring rope anchorage device, one end of the mooring rope anchorage device is connected with the steel cable, the outer wall of the mooring rope anchorage device is connected with a lifting point, and the mooring rope anchorage device achieves underwater lifting through the lifting point. An anode sacrifice block is arranged at the end, away from the steel cable, of the mooring cable anchorage device, a protection block is clamped to the anode sacrifice block so that the anode sacrifice block can be fixed to one end of the mooring cable anchorage device, the end, provided with the anode sacrifice block, of the mooring cable anchorage device is connected with a pin shaft, and the end, away from the mooring cable anchorage device, of the pin shaft is connected to the seabed. According to the mooring cable anode sacrifice block protection device, the protection block is clamped on the anode sacrifice block, so that the anode sacrifice block is fixed at one end of the mooring cable anchorage device, and on the basis that the original mooring cable anchorage device and the anode sacrifice block are connected through bolts, the protection block is used for achieving the purpose of protecting, optimizing and upgrading the anode sacrifice block for the mooring cable; assembly is simple and convenient.

The present invention belongs to the field of offshore power generation technology and specifically discloses a universal joint connection device for connecting an offshore wind turbine platform to the seabed. By installing a cross universal joint connection structure at the bottom of the tension-type floating wind power platform body and using the cross universal joint connection structure as the swing center, when encountering strong winds or waves, the platform can swing in response to the wind and waves and float under the action of buoyancy. At the same time, by connecting the floating platform to the seabed, the force acting on the platform body can be transmitted to the seabed through the universal joint, avoiding the phenomenon of twisting when using mooring cables, improving the stability of the connection between the platform body and the seabed, providing effective support for the wind power generation equipment, and allowing the wind turbine to maintain stable operation against the wind.