A method for seafastening a wind turbine component

Abstract

The invention provides a method for seafastening a wind turbine component, the method comprising - providing a seafastening flange (301) on a deck of a marine surface vessel, - positioning a component flange (1401) of a wind turbine component adjacent to the seafastening flange (301), so that a plurality of through holes (302) in the seafastening flange are positioned so as to be aligned with a plurality of through holes (1402) in the component flange, - positioning a bolt supporting device (303) so as to be supported by a device supporting arrangement (304) which is fixed in relation to the seafastening flange, so that one or more downwardly facing contact surfaces (305) of the bolt supporting device are left exposed, and so that a plurality of bolt receiving positions on the bolt supporting device are located below the seafastening flange, - positioning a plurality of bolts (306) on the bolt receiving positions on the bolt supporting device (303), - operating one or more actuators (307) so as to come into contact with respective ones of the contact surfaces (305) of the supported bolt supporting device (303), and so as to lift the bolt supporting device away from the support of the device supporting arrangement (304) so as for the bolts (306) supported by the bolt supporting device to penetrate respective ones of the through holes (302, 1402) in the seafastening flange (301) and in the component flange (1401).

Description

[0001] A METHOD FOR SEAFASTENING A WIND TURBINE COMPONENT

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method for seafastening a wind turbine component, a seafastening assembly for seafastening of a wind turbine component, and a marine surface vessel comprising a seafastening assembly.

[0004] BACKGROUND

[0005] A horizontal axis wind turbine is known to have an electric generator in a nacelle on top of a tower, where a rotor, with one or more blades, with a substantially horizontal axis, is mounted to the nacelle and arranged to drive the generator.

[0006] Due to large blade sizes of modern wind turbines, challenges are created for the installation and service of the wind turbines.

[0007] For example, for installing offshore wind turbines, the towers thereof, or sections of the towers thereof, may be transported on marine vessels to the installation site. For this transportation, the towers, or tower sections, may be fastened to a deck of the vessel in vertical positions. Thereby, seafastening flanges may be provided on the deck, and tower flanges of the towers, or tower sections, may be moved by a crane and positioned on the seafastening flanges. Thereby, a plurality of through holes in each seafastening flange are positioned so as to be aligned with a plurality of through holes in the respective tower flange. Thereafter, bolts are positioned so as to penetrate the aligned through holes so that the tower flange can be secured to the seafastening flange.

[0008] A problem with this kind of seafastening procedure is that the bolt positioning step is labour intensive and time consuming. Each bolt may have a mass of 20 kg or more. The handling of heavy bolts is strenuous for persons involved in the handling. While the bolts are positioned the crane has to remain engaged with the tower or tower section. This creates a relatively long time for the use of the crane which is inefficient and costly. This is a problem occurring regardless of the mass of the bolts, e.g. even if the mass is below 20 kg. SUMMARY OF THE INVENTION

[0009] An object of the present invention is to make seafastening procedures of wind turbine components faster.

[0010] This object of the invention is reached with a method according to claim 1. Thus, the invention provides a method for seafastening a wind turbine component, the method comprising providing a seafastening flange on a deck of a marine surface vessel, positioning a component flange of a wind turbine component, adjacent to the seafastening flange, so that a plurality of through holes in the seafastening flange are positioned so as to be aligned with a plurality of through holes in the component flange, positioning a bolt supporting device so as to be supported by a device supporting arrangement which is fixed in relation to the seafastening flange, so that one or more downwardly facing contact surfaces of the bolt supporting device are left exposed, and so that a plurality of bolt receiving positions on the bolt supporting device are located below the seafastening flange, positioning a plurality of bolts on the bolt receiving positions on the bolt supporting device, e.g. while the bolt supporting device is supported by the device supporting arrangement, operating one or more actuators so as to come into contact with respective ones of the contact surfaces of the supported bolt supporting device, and so as to lift the bolt supporting device away from the support of the device supporting arrangement so as for the bolts supported by the bolt supporting device to penetrate respective ones of the through holes in the seafastening flange and in the component flange.

[0011] The wind turbine component could be a wind turbine tower, or a section of a wind turbine tower. Thereby, the component flange could be a tower flange, e.g. intended for a final installation of the tower to a foundation. Thereby, the method could comprise positioning the tower flange of the wind turbine tower, or of the section of a wind turbine tower, adjacent to the seafastening flange. In other embodiments, the wind turbine component could be a nacelle. Thereby, the component flange could be a nacelle flange, e.g. intended for a final installation of the nacelle of the top of a tower. Thereby, the method could comprise positioning the nacelle flange adjacent to the seafastening flange.

[0012] When the bolts are positioned on the bolt supporting device, preferably they extend vertically. By lifting the bolt supporting device away from the device supporting arrangement so as for the bolts supported by the bolt supporting device to penetrate the through holes in the seafastening flange and in the component flange, a plurality of bolts may be simultaneously positioned in the flanges. Thereby, the bolt positioning step of the wind turbine component seafastening procedure becomes considerably less labour intensive and time consuming.

[0013] The seafastening flange may be fixed to a seafastening structure. The seafastening flange may be oriented horizontally.

[0014] The actuators may be provided in any suitable form. For example, they may be powered manually, electrically, hydraulically and / or pneumatically. In some embodiments, the actuators may be provided as lifting jacks, e.g. such as jacks used to lift a wheel of a car from the ground. Preferably, where a plurality of actuators are used, the operations of the actuators to lift the bolt supporting device is coordinated, e.g. by signals between actuator operators, or by a control system, so that during the lifting the actuators have the substantially the same degrees of actuation or extension.

[0015] Preferably, operating the one or more actuators comprises positioning the one or more actuators in respective of one or more actuation preparation positions. Thereby, the actuators may be loose items which can be moved between different positions at separate bolt positioning procedures.

[0016] Preferably, the one or more actuation preparation positions are below bolt supporting device. Thereby, the bolt supporting device may be lifted by extension of the actuators.

[0017] The actuators may be retracted to move out of through holes or cut-outs in the device supporting arrangement. This allows inspection or service of the actuators or the device supporting arrangement. The actuators may be movable, e.g. by a person. In some embodiments, the method comprises, after the step of operating, e.g. by actuating, the one or more actuators, removing at least one of the one or more actuators from the preparation position. As suggested, thereby the actuators can be moved to different positions at a separate bolt positioning procedure.

[0018] Thus, the actuators could be in a moveable device to be moved around inside the wind turbine component seafastening structure. Once the bolts are secured to the flanges, the bolt supporting device can be lowered to again be supported by the device supporting arrangement. If no parts of the actuators are connected or fixed to the device supporting arrangement or to the seafastening structure, the actuators can be moved away from the device supporting arrangement. Then, the actuators may be moved to lift a bolt supporting device with bolts at another place. This assures re-use of the actuators, and easy handling of the bolts. The other place may be within the same seafastening structure. Preferably, each actuator has a mass below 20 kg. Thereby, manual handling of the actuators are made possible.

[0019] For example, the device supporting arrangement may be a first device supporting arrangement. Thereby, the step of positioning the bolt supporting device may comprise positioning the bolt supporting device below a first portion of the seafastening flange. Thereby, the method may further comprise positioning the bolt supporting device, or a further bolt supporting device, below a second portion of the seafastening flange so as to be supported by the first device supporting arrangement, or by a second device supporting arrangement, which is fixed in relation to the seafastening flange, so that one or more downwardly facing contact surfaces of the bolt supporting device positioned below the second portion of the seafastening flange are left exposed. The second portion of the seafastening flange may be different from the first portion of the seafastening flange. The method may further comprise positioning a plurality of bolts on the bolt supporting device positioned below the second portion of the seafastening flange, and operating, e.g. by actuating, one or more actuators so as to come into contact with respective ones of the contact surfaces of the supported bolt supporting device positioned below the second portion of the seafastening flange, and so as to the lift the bolt supporting device so as for the bolts supported by the bolt supporting device to penetrate respective ones of the through holes in the second portion of the seafastening flange. Thereby, at least one of the one or more actuators, that are actuated so as to come into contact with the contact surfaces of the bolt supporting device positioned below the second portion of the seafastening flange, may be the removed actuator. More specifically, at least one of the one or more actuators, that are actuated so as to come into contact with the contact surfaces of the bolt supporting device positioned below the second portion of the seafastening flange, may be an actuator that was removed from the preparation position below bolt supporting device positioned below the first portion of the seafastening flange.

[0020] Preferably, operating the one or more actuators comprises actuating the one or more actuators, e.g. when in the actuation preparation positions, for coming into said contact with respective ones of the contact surfaces of the supported bolt supporting device. Thereby, the contacts may be made in a controlled manner. However, in some embodiments, the one or more actuators come into contact with respective ones of the contact surfaces of the supported bolt supporting device when placed in the respective actuation preparation positions.

[0021] Preferably, operating the one or more actuators comprises actuating the one or more actuators, e.g. when in the actuation preparation positions, for said lift of the bolt supporting device away from the device supporting arrangement.

[0022] Where the seafastening flange is fixed to a seafastening structure, the method may further comprise, before the step of positioning the bolt supporting device below the seafastening flange, mounting the device supporting arrangement to the seafastening structure or to the seafastening flange. Thereby, the method may comprise, after the step of operating, e.g. by actuating, the one or more actuators, demounting the device supporting arrangement from the flange supporting structure or from the seafastening flange.

[0023] A movable device supporting arrangement may allow flexibility in the installation of the device supporting arrangement. For example, the method may comprise determining individual lengths of the bolts positioned on the bolt supporting device, determining, in dependence on the determined individual lengths of the bolts, a vertical position of the device supporting arrangement, wherein the device supporting arrangement is mounted to the seafastening structure or to the seafastening flange so as to assume the determined vertical position. Thereby, the method may be adapted to different lengths of bolts. Advantageously, the method comprises, after the step of operating, e.g. by actuating, the one or more actuators, removing the bolts from the seafastening flange, removing the wind turbine component from the seafastening flange, and reusing the bolts for seafastening a further wind turbine component.

[0024] Removing the bolts from the seafastening flange may comprise supporting the bolts by a bolt supporting device, operating one or more actuators in contact with the bolt supporting device so as to lower the bolt supporting device so as for the supported bolts to evacuate respective ones of the through holes in the seafastening flange and in the component flange. Thereby, the bolt supporting device with the supported bolts could be moved into a support by a device supporting arrangement which is fixed in relation to the seafastening flange.

[0025] When the bolts have been removed from the seafastening flange, they could stay sypported by the bolt supporting device, e.g. while the vessel travels back to port, until another wind turbine component is to be secured to the seafastening flange.

[0026] The object is also reached with seafastening assembly for seafastening of a wind turbine component, comprising a seafastening structure, a seafastening flange which is fixed to the seafastening structure, the seafastening flange presenting a plurality of through holes positioned so as to be, when a component flange of a wind turbine component is positioned adjacent to the seafastening flange, aligned with a plurality of through holes in the component flange, and a bolt supporting device adapted to support a plurality of bolts below the seafastening flange,

[0027] - wherein the seafastening assembly further comprises a device supporting arrangement adapted to be fixed to the seafastening structure or to the seafastening flange,

[0028] - wherein the device supporting arrangement is adapted to support the bolt supporting device while leaving one or more downwardly facing contact surfaces of the bolt supporting device exposed,

[0029] - wherein the seafastening assembly further comprises one or more actuators which are adapted to come into contact with respective ones of the contact surfaces and to lift the bolt supporting device away from the support of the device supporting arrangement so as for a plurality of bolts supported by the bolt supporting device to penetrate respective ones of the through holes in the seafastening flange.

[0030] The seafastening flange may be circular. In some embodiments, the seafastening flange is formed by a plurality of part-circular flange portions.

[0031] In some embodiments, the seafastening flange is fixed to the seafastening structure so as to protrude radially inwards from the seafasting structure. Thereby the bolt supporting device may be positioned inside the seafastening structure. However, in other embodiments, the seafastening flange is fixed to the seafastening structure so as to protrude radially outwards from the seafasting structure. Thereby the bolt supporting device may be positioned outside of the seafastening structure.

[0032] In some embodiments, where the seafastening flange is fixed to the seafastening structure so as to protrude radially inwards from the seafasting structure, there is a further seafasting flange which is fixed to the seafastening structure so as to protrude radially outwards from the seafasting structure. These flanges may form a T-flange on the seafastening structure. Thereby, a wind turbine component with a T-flange may be seafastened. Thereby, a further bolt supporting device may be provided, and adapted to support a plurality of bolts below the outwardly protruding seafastening flange. Thereby, the seafastening assembly may comprise a further device supporting arrangement adapted to be fixed to the seafastening structure or to the seafastening flange, and adapted to support the further bolt supporting device while leaving one or more downwardly facing further contact surfaces of the further bolt supporting device exposed. Thereby, one or more further actuators may be adapted to come into contact with respective ones of the further contact surfaces and to lift the further bolt supporting device away from the support of the further device supporting arrangement so as for a plurality of bolts supported by the further bolt supporting device to penetrate respective ones of the through holes in the outwardly protruding seafastening flange.

[0033] The bolt supporting device may be elongated and part-circular. The bolt supporting device may form a shelf for the bolts. In some embodiments, the device supporting arrangement is part-circular and extend along a portion of the circumference of the seafastening flange. In other embodiments, the device supporting arrangement extends all around the seafastening structure.

[0034] Preferably, the one or more actuators are adapted to be positioned so that upon actuation of the one or more actuators the one or more actuators come into contact with respective ones of the contact surfaces of the bolt supporting device when the bolt supporting device is supported by the device supporting arrangement.

[0035] In some embodiments, the one or more contact surfaces of the bolt supporting device are left exposed by respective through holes in the device supporting arrangement. Alternatively, the device supporting arrangement may have cut-outs for exposing the contact surfaces of the bolt supporting device. In some embodiments, the device supporting arrangement may comprise a plurality of device supporting elements which are provided at a distance from each other, so as to allow exposure of the contact surfaces of the bolt supporting device between them.

[0036] Preferably, the one or more actuators are adapted to be, when lifting the bolt supporting device, supported by one or more actuator supporting elements without being fixed to the one or more actuator supporting elements. Thereby, the one or more actuators may be adapted to be, when positioned so as to come into contact with respective ones of the contact surfaces of the bolt supporting device, supported by the one or more actuator supporting elements without being fixed to the one or more actuator supporting elements.

[0037] Preferably, the device supporting arrangement is adapted to be removably mounted to the seafastening structure or to the seafastening flange. Thereby, the device supporting arrangement may be removed after use, e.g. to be used at another portion of the seafastening flange, or at another seafastening flange. In other embodiments, the device supporting arrangement is permanently fixed to the seafastening structure or to the seafastening flange, e.g. by welded, bolting, riveting, or similar.

[0038] The device supporting arrangement may be secured with magnets to the seafastening structure or the seafastening flange, e.g. to an inside thereof. In some embodiments, the magnetic connection is adapted to be released in case a force is applied to the device supporting arrangement by one or more of the actuators, e.g. as a result of the actuator being incorrectly operated. Thereby damage to the device supporting arrangement, the seafastening structure, or the seafastening flange may be avoided.

[0039] Preferably, the bolts comprise respective heads adapted for engagement of a bolt turning tool, wherein the bolt supporting device presents, for the support of the bolts, formations with a shape that is complementary to the shape of the heads of the bolts, so that the bolts can be engaged by the formations to prevent turning of the bolts when the bolts are supported by the bolt supporting device. Thereby, the bolts do not have to be held to avoid turning of them while the nuts are screwed onto the bolts. The bolt supporting device formations may form bolt receiving positions on the bolt supporting device.

[0040] Preferably, the seafastening assembly comprises a guiding arrangement adapted to guide the bolt supporting device when the bolt supporting device is lifted away from the device supporting arrangement.

[0041] The object is also reached with a marine surface vessel comprising a seafastening assembly according to any embodiment of the invention.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Below examples of the invention will be described in detail with reference to the drawings, in which:

[0044] - fig. 1 is a front view of an offshore wind turbine,

[0045] - fig. 2 is a side view of a marine vessel onto which wind turbine towers are loaded for transportation to an offshore wind turbine installation site,

[0046] - fig. 3 is a view from above of a seafastening assembly according to an embodiment of the invention,

[0047] - fig. 4 and fig. 6 are cross-sectional views with the cross-section oriented as indicated with the arrows IV-IV in fig. 3,

[0048] - fig. 5 is a flow diagram depicting steps in an embodiment of a method according to the invention,

[0049] - fig. 7 and fig. 8 are cross-sectional views similar to the ones in fig. 4 and fig. 6, of a seafastening assembly according to another embodiment of the invention, - fig. 9 is a view from above of a part of a seafastening assembly according to a further embodiment of the invention,

[0050] - fig. 10 and fig. 12 are cross-sectional views with the cross-section oriented as indicated with the arrows X-X in fig. 9, and

[0051] - fig. 11 and fig. 13 are cross-sectional views with the cross-section oriented as indicated with the arrows XI-XI in fig. 9.

[0052] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0053] Fig. 1 shows a horizontal axis wind turbine 1. In this example, the wind turbine is an offshore wind turbine.

[0054] The wind turbine is supported by a monopile foundation 17. However, could be a jacket foundation or a floating foundation. The foundation 17 is arranged in a body of water, such as a sea or a lake.

[0055] The wind turbine 1 comprises a tower 14 supporting a nacelle 15. A rotor 16 is mounted to the nacelle. The tower is supported by the foundation 17. The nacelle 15 can be turned, or yawed, in relation to the tower 14, around a vertical axis.

[0056] Fig. 2 shows a marine vessel 2 used to transport wind turbine parts to an offshore wind turbine installation site. The vessel could be a jack-up ship 2. For the transportation towers 14 of the wind turbines are secured to a deck 21 of the vessel in upright, vertical positions. As noted above, the invention may be used for seafastening of wind turbine components other than towers, such as nacelles. The wind turbine components, in this example the towers, are lifted one by one onto the vessel with lifting means 4. The lifting means 4 may be a crane. The lifting means may be provided on the marine vessel. The support of the wind turbine component by the lifting means 4 may be done by means of a holding device, such as a yoke, of the lifting means. The holding device may be suspended in one or more wires from a crane boom 404. The vertical position of the wind turbine component may be adjusted by feeding the wire in or out, as depicted by the double arrow WF. The position of the wind turbine component may be also adjusted by adjusting the angle BA of the crane boom. The crane boom may be arranged to rotate around a vertical axis. Such a rotation may be referred to as a slewing action SA of the crane. Reference is made also to fig. 3. For fastening the wind turbine components to the vessel, the deck of the vessel is provided with seafastening assemblies 3. Fig. 3 shows a seafastening assembly from above. The seafastening assembly comprises a circular seafastening flange 301. The seafastening flange 301 presents a plurality of through holes 302 distributed along the flange 301. The through holes 302 are positioned so as to be, when a component flange 1401 of a wind turbine component 14 is positioned adjacent to the seafastening flange, aligned with a plurality of through holes in the component flange.

[0057] As understood from fig. 4, the seafastening flange 301 is fixed to a seafastening structure 308. The seafastening assembly further comprises a device supporting arrangement 304 adapted to be removably mounted to the seafastening structure 308.

[0058] A bolt supporting device 303 is adapted to support a plurality of bolts 306 below the seafastening flange 301. The bolt supporting device 303 could be provided as a bent shelf extending along a part of the seafastening flange 301. The device supporting arrangement 304 is adapted to support the bolt supporting device 303. Thereby, a plurality of downwardly facing contact surfaces 305 of the bolt supporting device are left exposed. This exposure is provided by through holes in the device supporting arrangement 304.

[0059] The seafastening assembly further comprises one or more actuators 307. In this example, the actuators are in the form of lifting jacks.

[0060] With reference to fig. 5, a method according to an embodiment of the invention will be described.

[0061] The method comprises mounting SI the device supporting arrangement 304 to the seafastening structure. For example, the device supporting arrangement 304 may be mounted to the seafastening structure 308 by means of magnets.

[0062] The method further comprises positioning S2 the bolt supporting device 303 so as to be supported by the device supporting arrangement 304. Thereby, a plurality of bolt receiving positions 3034 on the bolt supporting device are located below the seafastening flange 301. The method further comprises positioning S3 a plurality of bolts 306 on the bolt receiving positions 3034 on the bolt supporting device 303. The bolt receiving positions are aligned with the through holes 302 in the seafastening flange 301.

[0063] It should be noted that the method may comprise determining individual lengths of the bolts 306 to be positioned on the bolt supporting device 303. In dependence on the determined individual lengths of the bolts, a vertical position of the device supporting arrangement 304 is determined. Thereupon, the device supporting arrangement is mounted to the seafastening structure 308 so as to assume the determined vertical position.

[0064] The method further comprises positioning S4 a plurality of actuators in respective of a plurality of actuation preparation positions. The actuation preparation positions are below respective of the downwardly facing contact surfaces 305 of the bolt supporting device 303. The actuators 307 are supported by an actuator supporting element 309 without being fixed to the actuator supporting element.

[0065] The method further comprises positioning S5 a wind turbine component 14 on the seafastening flange 301. Thereby, a component flange 1401 of the wind turbine component 14 is in contact with the seafastening flange 301. Further, a plurality of through holes 1402 in the component flange are positioned so as to be aligned with the through holes 302 in the seafastening flange.

[0066] As understood from fig. 6, the actuators 307 are actuated S6 so as to come into contact with respective ones of the contact surfaces 305 of the supported bolt supporting device 303. Thereby, the actuators extend through respective of the through holes 310 in the device supporting arrangement 304. The actuators 307 are further actuated S7 so as to lift the bolt supporting device away from the support of the device supporting arrangement 304. Thereby, the bolts 306 supported by the bolt supporting device penetrate respective ones of the through holes 302, 1402 in the seafastening flange 301 and in the component flange 1401.

[0067] In some embodiments, a guiding arrangement (not shown) could be adapted to guide the bolt supporting device 303 when the bolt supporting device is lifted away from the device supporting arrangement 304. Nuts are screwed onto the bolts to secure S8 the bolts to the flanges. In this example, the bolts 306 comprise respective heads adapted for engagement of a bolt turning tool. The bolt supporting device 303 presents at the bolt receiving positions, for the support of the bolts, formations 3034 with a shape, e.g. hexagonal, that is complementary to the shape of the heads of the bolts. Thereby, the bolts can be engaged by the formations to prevent turning of the bolts when the bolts are supported by the bolt supporting device, and nuts are screwed onto the bolts.

[0068] When the flanges have been secured to each other by means of the bolts, the actuators are retracted S9. Further, the actuators are removed S10 from the preparation position. The actuators may then be used somewhere else, e.g. for positioning further bolts in the flanges.

[0069] When the wind turbine components have been secured to the seafastening assemblies, the wind turbine components can be transported to the installation by means of the vessel. Once the vessel has arrived at the installation site, for each wind turbine component, the bolts 306 are removed from the seafastening flange 301, and the wind turbine component is removed, e.g. by means of the crane, from the seafastening flange, and onto an offshore foundation.

[0070] Reference is made to fig. 7 and fig. 8 showing an embodiment of the invention which is similar to the embodiment described with reference to fig. 3 - fig. 6, but with the following substantial differences. The device supporting arrangement 304 is adapted to be fixed to the seafastening flange 301, e.g. by magnets. The bolt supporting device 303 comprises a bolt supporting part 3031. A plurality of arms 3032 extend vertically upwards from the bolt supporting part 3031. The arms 3032 extend through through holes 3041 in the device supporting arrangement 304. Widened parts 3033 are provided on the arms 3032, above the device supporting arrangement 304. The widened parts 3033 rest against the device supporting arrangement 304. The arms 3032 may be formed by threaded pins, and the widened parts may be formed by nuts threaded onto the pins. Thereby, the bolt supporting device 303 is supported by the device supporting arrangement 304.

[0071] As understood from frig. 7 and from fig. 8, the actuators 307 are actuated so as to come into contact with respective ones of the contact surfaces 305 of the supported bolt supporting device 303. Further, the actuators 307 are actuated so as to lift the bolt supporting device away from the support of the device supporting arrangement 304. Thereby, the widened parts 3033 are lifted away from the device supporting arrangement 304. In addition, the bolts 306 supported by the bolt supporting device penetrate respective ones of the through holes 302, 1402 in the seafastening flange 301 and in the component flange 1401.

[0072] Reference is made to fig. 9 - fig. 13 showing an embodiment of the invention which is similar to the embodiment described with reference to fig. 3 - fig. 6, but with the following substantial differences. As understood from fig. 9 and fig. 10, the device supporting arrangement 304 is provided in the form of a plurality of, in this example four, brackets 304 fastened to the seafastening structure 308. The bolt supporting device 303 rests on the brackets 304. As understood from fig. 11, the actuators 307 are provided in the form of combinations of vertical teethed poles 3071 and motors 3072 which are arranged to drive respective cog wheels (not shown) which are engaged with a respective of the teethed poles 3071. The teethed poles 3071 extend upwards from feet 3073 resting on the actuator supporting element 309. The motors 3072 may be in any suitable form, e.g. electric, hydraulic, or pneumatic.

[0073] As understood from fig. 10 - fig. 13, the actuators 307 are actuated so as to come into contact with respective ones of contact surfaces 305 of the supported bolt supporting device 303. The contact surfaces 305 are located between the brackets 304. Further, the actuators 307 are actuated so as to lift the bolt supporting device 303 away from the support of the brackets 304. Thereby, the bolts 306 supported by the bolt supporting device penetrate respective ones of the through holes in the seafastening flange 301 and in the component flange.

[0074] As will be understood by those skilled in the present field of art, numerous changes and modifications may be made to the above described and other embodiments of the present invention, without departing from its scope as defined in the appending claims.

Claims

CLAIMS1. A method for seafastening a wind turbine component, the method comprising providing a seafastening flange (301) on a deck of a marine surface vessel, positioning a component flange (1401) of a wind turbine component adjacent to the seafastening flange (301), so that a plurality of through holes (302) in the seafastening flange are positioned so as to be aligned with a plurality of through holes (1402) in the component flange, positioning a bolt supporting device (303) so as to be supported by a device supporting arrangement (304) which is fixed in relation to the seafastening flange, so that one or more downwardly facing contact surfaces (305) of the bolt supporting device are left exposed, and so that a plurality of bolt receiving positions on the bolt supporting device are located below the seafastening flange, positioning a plurality of bolts (306) on the bolt receiving positions on the bolt supporting device (303), operating one or more actuators (307) so as to come into contact with respective ones of the contact surfaces (305) of the supported bolt supporting device (303), and so as to lift the bolt supporting device away from the support of the device supporting arrangement (304) so as for the bolts (306) supported by the bolt supporting device to penetrate respective ones of the through holes (302, 1402) in the seafastening flange (301) and in the component flange (1401).

2. A method according to claim 1, wherein operating the one or more actuators (307) comprises positioning the one or more actuators in respective of one or more actuation preparation positions.

3. A method according to claim 2, wherein the one or more actuation preparation positions are below bolt supporting device (303).

4. A method according to any one of claims 2-3, comprising, after the step of operating the one or more actuators (307), removing at least one of the one or more actuators from the preparation position.

5. A method according to any one of the preceding claims, wherein operating the one or more actuators (307) comprises actuating the one or more actuators (307) for coming into said contact with respective ones of the contact surfaces (305) of the supported bolt supporting device (303).

6. A method according to any one of the preceding claims, wherein operating the one or more actuators (307) comprises actuating the one or more actuators (307) for said lift of the bolt supporting device away from the device supporting arrangement (304).

7. A method according to any one of the preceding claims, wherein the seafastening flange (301) is fixed to a seafastening structure (308), the method further comprising, before the step of positioning the bolt supporting device (303), mounting the device supporting arrangement (304) to the seafastening structure or to the seafastening flange.

8. A method according to claim 7, comprising determining individual lengths of the bolts (306) positioned on the bolt supporting device (303), and determining, in dependence on the determined individual lengths of the bolts, a vertical position of the device supporting arrangement (304), wherein the device supporting arrangement is mounted to the seafastening structure (308) or to the seafastening flange (301) so as to assume the determined vertical position.

9. A method according to any one of the preceding claims, comprising, after the step of operating the one or more actuators (307), removing the bolts (306) from the seafastening flange (301), removing the wind turbine component from the seafastening flange, and reusing the bolts for seafastening a further wind turbine component.

10. A seafastening assembly (3) for seafastening of a wind turbine component, comprising a seafastening structure (308), a seafastening flange (301) which is fixed to the seafastening structure (308), the seafastening flange presenting a plurality of through holes positioned so as to be, when a component flange (1401) of a wind turbine component is positionedadjacent to the seafastening flange, aligned with a plurality of through holes in the component flange, and a bolt supporting device (303) adapted to support a plurality of bolts (306) below the seafastening flange (301), characterised in that- the seafastening assembly further comprises a device supporting arrangement (304) adapted to be fixed to the seafastening structure (308) or to the seafastening flange (301),- wherein the device supporting arrangement (304) is adapted to support the bolt supporting device (303) while leaving one or more downwardly facing contact surfaces of the bolt supporting device exposed,- wherein the seafastening assembly further comprises one or more actuators (307) which are adapted to come into contact with respective ones of the contact surfaces and to lift the bolt supporting device (303) away from the support of the device supporting arrangement (304) so as for a plurality of bolts (306) supported by the bolt supporting device to penetrate respective ones of the through holes in the seafastening flange (301).

11. A seafastening assembly according to claim 10, wherein the one or more actuators (307) are adapted to be, when lifting the bolt supporting device (303), supported by one or more actuator supporting elements (309) without being fixed to the one or more actuator supporting elements.

12. A seafastening assembly according to any one of claims 10-11, wherein the device supporting arrangement (304) is adapted to be removably mounted to the seafastening structure (308) or to the seafastening flange (301).

13. A seafastening assembly according to any one of claims 10-12, wherein the bolts (306) comprise respective heads adapted for engagement of a bolt turning tool, wherein the bolt supporting device (303) presents, for the support of the bolts, formations with a shape that is complementary to the shape of the heads of the bolts, so that the bolts can be engaged by the formations to prevent turning of the bolts when the bolts are supported by the bolt supporting device.

14. A seafastening assembly according to any one of claims 10-13, comprising a guiding arrangement adapted to guide the bolt supporting device (303) when the bolt supporting device is lifted away from the device supporting arrangement (304).

15. A marine surface vessel comprising a seafastening assembly according to any one of claims 10-14.

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