CN116443192A - Hull structure of semi-submersible wind power platform - Google Patents

Abstract

The invention relates to a hull structure of a semi-submersible wind power platform, comprising: first, second and third floating stability columns extending substantially in a vertical direction; elongated submerged first, second and third pontoon structures extending in a substantially horizontal direction; wherein the hull structure has a generally triangular shape in a horizontal plane, the first, second and third pontoon structures forming sides of a triangle; wherein the pontoon structure extends between lower portions of the columns and is connected to the columns; and the third pontoon structure is disposed such that an upper surface of the third pontoon structure is positioned lower than upper surfaces of both the first and second pontoon structures in a horizontal direction. The invention also relates to a method of loading a set of hull structures of the above-mentioned type onto a semi-submersible transport vessel, and to a marine vessel carrying a set of hull structures of the above-mentioned type.

Description

Hull structure of semi-submersible wind power platform

Technical Field

The invention relates to a ship structure of a semi-submersible wind power platform. The invention also relates to a loading method for loading the above-mentioned set of hull structures onto a semi-submersible transport vessel, and to a vessel for transporting the above-mentioned set of hull structures.

Background

There is an increasing interest in offshore wind power (i.e. wind power plants/fans located offshore for the production of electrical energy). Such fans may have a fixed underwater base or, in the case of water depths exceeding 50-60 meters, may employ a floating platform moored to the sea floor.

The floating wind power platform can adopt a semi-submersible type, and the wind turbines are arranged on a semi-submersible type ship body structure. Such hull structures are typically comprised of a number of buoyancy stability columns or other connection structures connected by semi-submersible floats. The fan is typically mounted on one of the uprights. Such as a semi-submersible platform disclosed in WO 2021/219787.

Such platforms belong to large building structures. For example, for a 10 megawatt fan platform, each column may be up to 30 meters and the column spacing may be up to 60-80 meters. The total weight of the platform structure may be in excess of 3000 tons. The height of the wind tower may be 150 meters above sea level, while the blade length of the wind turbine may exceed 100 meters.

One of the challenges facing the offshore wind farm is the manufacture, transportation and installation of semi-submersible wind platforms. The towing operation of a platform on which wind towers and blades are mounted is very complex and challenging, and therefore it is desirable to shorten the towing distance of the complete platform, while the wind towers and blades are mounted in close proximity to the final working sea area, while the shelter sea area is relatively close to the final working sea area. If the hull structure is built at a factory remote from the shelter, transportation of that hull structure would be a particular challenge, and there would not be a suitable factory near the shelter to build such large hull structures. In this case, the hull structure needs to be transported over a long distance.

Another challenge with semi-submersible wind platforms is: the structural design of the device ensures enough strength and stability so that the device can work for many years under the severe sea conditions of the working sea area.

Yet another challenge remains: the construction, transportation, installation, and operation of such platforms or hull structures must be cost effective to attract and increase industry interest in offshore wind power.

Disclosure of Invention

One of the objects of the present invention is to provide a hull structure for a semi-submersible wind power platform with optimized performance in terms of maritime loading and transportation, which provides better transportation economy without affecting the strength and stability of the structure itself. It is another object of the present invention to provide a method of loading a set of such hull structures on a semi-submersible transport vessel.

The hull structure refers to a hull structure of a semi-submersible wind power platform, and comprises the following components: first, second, third floating stability columns running substantially vertically; first, second, third floats running substantially horizontally; the hull structure has a triangular shape in the horizontal direction, and the first, second and third floats form three sides of this triangle.

The first floating body is arranged between the first upright post and the second upright post and is connected with the lower ends of the two upright posts. Similarly, the second floating body is arranged between the second upright post and the third upright post and is connected with the lower ends of the two upright posts. The third floating body is arranged between the first upright post and the third upright post and is connected with the lower ends of the two upright posts.

Each of the first, second and third floating bodies has an upper end face directed upward. The third floating body is slightly lower in height than the first and second floating bodies. Thereby the upper end surface of the third floating body is lower than the upper end surfaces of the first and second floating bodies.

In short, the hull structure of the present invention forms a generally triangular shape in a horizontal plane, wherein the three floats form three sides of the triangle and are connected to the three columns at the three corner ends. The blower may be arranged on one of the columns or on an additional column or support structure provided on the hull. The triangular structure is relatively simple and provides a stable and robust platform.

In a special design of the invention, the third floating body is lower in height than the first and second floating bodies, i.e. the thickness of the third floating body in the vertical direction is smaller than the corresponding thickness of the first and second floating bodies. The position of the upper end face of the third floating body is lower than that of the upper end faces of the first floating body and the second floating body. Typically, the lower end surfaces of the three floating bodies are positioned on the same horizontal plane as the lower end surfaces of the three upright posts, so that the overall structure has a flush bottom surface (which can be stably erected on the ground during construction). Because the third floating body is lower in height than the first and second floating bodies, the upper end surface of the third floating body can be positioned on a horizontal plane lower than the upper end surfaces of the first and second floating bodies.

This particular arrangement provides the possibility of efficiently loading a group of hull structures of the type described above onto the carrier by "inserting" the second hull structure (i.e. the triangular corner end where the second column is located) partly between the first and second buoy structures, with the second hull between the first and second buoy structures of the adjacent first hull structure and above the third buoy structure of the first hull structure. When stowed in this way, the second hull structure occupies a slightly inclined position in the horizontal plane, being supported by the first hull structure and the deck section (the third buoy structure and a specific support surface, e.g. the first hull structure, supports the second hull structure, the third buoy structure of the second hull structure and possibly also its first and third columns are located on and supported by the deck). A row of several triangular hull structures may be efficiently stowed in such a way that at least the second, third, fourth etc. hull structures will occupy a slightly tilted position and that the first hull structure in the row may not be tilted with respect to the horizontal. The structure of the storage device and the process of achieving storage are described in more detail below.

One of the main advantages of the above design hull structure is that more platforms can be loaded onto the same transport vessel, e.g. for transporting the wind turbines from the construction site to the shelter where the wind turbines are installed, which reduces the transport costs.

Conventional triangular hull structures cannot be loaded onto a transport vessel in an efficient manner. In the previous studies of transportation methods, it was always simple to load one hull structure side by side with another on a ship, which loading was not very efficient. The three connection structures or pontoons of the conventional triangular hull structure are too tall to be efficiently loaded of the type described above.

Another approach is to transport the hull structure in a state of only partial assembly to increase loading efficiency, for example by having one buoy structure form a single part which has not yet been connected to the columns at each end. However, this requires complex assembly work after transportation, which may not be feasible, or at least may be complex and expensive.

As will be described further below, the hull structures disclosed herein will enable one ship to transport about four to five hull structures, if they are designed in a conventional manner and placed side-by-side on a ship, the ship can be loaded with two similarly sized hull structures. Since the transportation costs of large hull structures are very high, significant cost benefits can be obtained by letting the transportation vessel load more hull structures.

The platform and hull structures are semi-submersible, which means that the platform/hull structures may be partially below the water surface during operation. The entire pontoon structure and a portion of the columns are typically located below the water surface. The anchoring/positioning of the platform/hull structure on the sea floor may take different forms, for example: catenary mooring, tension leg mooring, or tension tendon mooring.

The third pontoon structure may have a different width and length than the first and second pontoon structures.

In one embodiment of the invention, each of the first, second and third pontoon structures has a downwardly facing lower surface, and wherein the lower surfaces of the first, second and third pontoon structures are substantially aligned in a horizontal plane.

In one embodiment of the invention, the lower surfaces of the first, second and third pontoon structures are substantially aligned with the bottom surfaces in the first, second and third buoyancy stabilizing columns. As mentioned above, the bottom surface of the entire hull structure will be substantially flush.

In one embodiment of the invention, the first and second pontoon structures each have a downwardly facing bottom surface, wherein the top surface of the third pontoon structure is substantially aligned with, or at a lower level than, the top surfaces of the first and second pontoon structures.

Such a platform can be loaded in the same efficient manner as described above, and the loading operation can be simplified, because according to the present embodiment, the platform does not have to be loaded in an inclined posture.

In one embodiment of the invention, the bottom surfaces of the first and second pontoon structures are substantially aligned with the bottom surface of the second buoyant stability column. Thus, when loading the platforms, the second column of the first platform may be placed on and supported by the third buoy structure of the second platform. When the third pontoon structure is not available, for example when the platform is at the end of a row of such platforms, a separate support structure may be provided under the second column in order to hold such platform in a horizontal position.

In one embodiment of the invention, the bottom surfaces of the first and second pontoon structures are substantially aligned with a (first) portion of the bottom surface of the second pontoon structure, while another (second) portion of the bottom surface of the second pontoon structure is positioned at a lower position. Typically, this lower (second) portion is substantially aligned with the bottom surface of the third pontoon and the bottom surfaces of the first and third columns. And by arranging a first portion of the underside of the first platform above the third pontoon of the second platform, the first platform can be stowed adjacent to the second platform, while a second lower portion of the bottom surface of the second column contacts the deck, providing overall support towards the platform, thereby maintaining the platform in a horizontal position.

In one embodiment of the invention, the bottom surface of the third pontoon structure is substantially flush with the bottom surfaces of the first and third floating stability columns.

In one embodiment of the invention, the bottom surface of the third pontoon structure is substantially aligned with a portion of the bottom surfaces of the first and third pontoon structure, and another portion of the bottom surfaces of the first and third pontoon structure is positioned at a higher position.

In one embodiment of the invention, the height of the third pontoon structure is less than 75%, preferably less than 50%, of the height of at least one of the first and second pontoon structures. In one example, the height of each of the first and second pontoon structures is about 7m, and the height of the third pontoon structure is about 3m, thus less than 50% of the height of the first and second pontoon structures. In a further example, the height of the third buoy structure is 2-4m.

In one embodiment of the invention the third pontoon has a height which is at least 1 meter, preferably as low as 2 meters or even 3 meters, lower than the height of at least one of the first and second pontoons.

In one embodiment of the invention, the first, second and third pontoon structures have substantially equal lengths. The entire hull structure thus forms an equilateral triangle.

In one embodiment of the invention, the hull structure exhibits: i) Forming a first included angle in a horizontal plane between a central longitudinal axis of the first pontoon structure and a central longitudinal axis of the second pontoon structure; ii) a second angle is formed by a) a first virtual line passing between the center point of the first stabilizing column and the center point of the second stabilizing column, and b) a second virtual line passing between the center point of the second stabilizing column and the center point of the third stabilizing column. Wherein the second included angle is greater than the first included angle.

This means that the first and second pontoon structures do not extend along nor parallel to the respective virtual line between the second column and the centre point of the first or third column, but extend in a direction offset from the virtual line between the centre points of the columns. The second angle being greater than the first angle further means that the first and second pontoon structures extend offset in direction such that a straight pontoon structure may extend from an outer portion of the second column to an inner portion of the first or third column. Where "outboard" and "inboard" are with respect to a center point of the hull structure in a horizontal plane and do not refer to a pontoon structure extending from an inboard portion of the second column to an outboard portion of the first or third column.

The "center point" refers to the center point of the bottom of each upright.

The advantage of arranging the hull structure so as to present a first angle and a second angle as described above is that the loading efficiency is further improved. The hull structure can be more compact. The first and second angles and their relationship actually provide this effect, as will be further explained and illustrated below.

In one embodiment of the invention, at least one of the first and second pontoon structures has a width along a major portion of its length that is less than the width of the lower portion of the second stabilizing column. That is, the overall width of the first and second pontoon structures at the connection to the second column is less than the width of the second column. The second pillar has a varying width in the vertical direction, for example a cone. The width of the lower portion of the second stability column refers to the width in a direction perpendicular to the longitudinal axis of the respective pontoon structure. The width of the lower portion of the second stabilizing column may be the diameter of the second column if the lower portion has a circular cross section, or the distance between two opposite sides if the cross section is generally polygonal. Typically, the first and second pontoon structures also have a width that is less than the width of the first and third columns.

The first and second pontoon structures are narrower than the second column, and are particularly useful in connection with the first and second included angles on the arrangement. The angles are arranged by providing the first or second buoy structure such that its outer side, i.e. the side of the buoy structure facing away from the hull structure, is located at a first distance from the outer side of the second column, whereas the inner side of the buoy structure (relative to its outer side) is located at a second distance from the inner side of the second column, wherein the first distance is smaller than the second distance. The other end of the pontoon structure is then suitably connected to the first or third column such that the second angle becomes greater than the first angle. The other end of the pontoon structure may be centered on the first or third column or located closer to the inner side of the first or third column in order to increase the difference between the first and second angles.

In one embodiment of the invention, each of the first and second pontoon structures has an outer side facing away from the hull structure, wherein the outer side of at least one of the first and second pontoon structures is substantially aligned with the outer side of the second stabilizing column. The outside of the pontoon structure may thus be substantially tangential to the curved side surface portion of the second column (e.g. in the case of a circular cross-section) or substantially aligned with the planar surface portion of the second column (e.g. in the case of a polygonal cross-section).

This embodiment may be combined with aligning the other end of the pontoon structure with (or near) the inner side of the first or third column. This can increase the difference between the first and second angles and improve the loading efficiency.

In one embodiment of the invention, each of the first and second pontoon structures has an outer side facing away from the hull structure and an inner side facing inwardly towards the hull structure, wherein at least one of the first and second pontoon structures is arranged such that its outer side is closer to the outer side of the second stabilizing column than its inner side is to the inner side of the second stabilizing column.

The pontoon structure arranged in this way is thus not centered on the second column, but is arranged closer to its outer side. The outside of the pontoon structure may be substantially aligned with the outside of the second stabilizing column to increase the difference between the first angle and the second angle. However, if there is a distance between the outside of the pontoon structure and the outside of the column, the attachment of the pontoon structure to the column is typically simplified, i.e. the outside of the pontoon structure is not perfectly aligned with the outside of the column. Another reason for the incomplete alignment of the outside of the pontoon structure with the outside of the second column is that it may be more desirable to maintain some distance between the first and second pontoons of adjacent hull structures loaded onto the carrier.

In one embodiment of the invention, at least the outer part of the lower side of the third buoy structure is inclined with respect to the horizontal plane, the inclination being arranged such that the outer part of the lower side of the third buoy structure is at a higher level than the inner part of the lower side of the third buoy structure, wherein the inner part is closer to the second stability column than the outer part.

The inclined surface provided on the underside of the third buoy structure helps to provide support for the hull structure when loaded onto the vessel in a slightly inclined attitude. The inclination of the support surface should correspond to the inclined attitude of the stowed hull structure. The precise measurement of such inclination depends on the precise measurement of the hull structure and generally on the size and type of the hull structure. In most cases tilt angles in the interval 5-15 deg. are useful. An appropriate range of 8-10 is possible.

In one embodiment of the invention, at least a portion of the undersides of the first and third stabilizing columns are inclined with respect to the horizontal plane, such an arrangement of inclination corresponding to the inclination of the undersides of the third pontoon structures. The provision of inclined support surfaces allows the hull structure to be better supported if the first and third columns are also located on the deck of the carrier. Depending on the size of the hull structure and the width of the transport vessel, the first and third columns may be located outside the deck on both sides, respectively, when the hull structure is arranged on the vessel. In this case it may still be an advantage to provide the first and third uprights with inclined support surfaces, since the required additional support structure may be easier to build (since it may be easier to connect surfaces having the same inclination).

In one embodiment of the invention, the upper side of the third buoy structure is inclined with respect to the horizontal plane, wherein the inclination is arranged such that an outer part of the upper side of the third buoy structure is located at a lower vertical level than the inner side, while an inner part of the upper side of the third buoy structure is located closer to the second stability column than the outer part. This forms an inclined support surface on the upper side of the third buoy structure. It is advantageous that at least a first hull structure of a row of hull structures loaded onto the marine transport vessel is provided with such an inclined support surface, as this allows the first hull structure to be loaded horizontally onto the vessel while still providing an inclined support surface for the next hull structure in the row of loading. In this embodiment, the underside of the third pontoon structure of this hull may be horizontal.

As mentioned above, for the lower inclined support surface, the inclination of the upper support surface should also correspond to the inclined attitude of the loaded hull structure (i.e. "next" hull structure). Likewise, the inclination may be 5-15 °, or 8-10 °. The "next" hull structure and the other hull structures of the row will not be inclined relative to each other, so that in a group or row of hull structures it may not be necessary to provide an inclined support surface on the upper side of the third plurality of pontoon structures.

Alternatively, the first hull structure in the row may be arranged in an inclined position using special support members arranged on the deck of the vessel. In this case it is not necessary to provide the upper side of any one third buoy structure of a group or row of hull structures with an inclined support surface.

In one embodiment of the invention, the hull structure includes a support structure disposed at the second stability column between the first and second pontoon structures. The support structure may be used to both strengthen the hull structure as a whole and to provide a support surface for a second column of another hull structure carried thereon.

The support structure can preferably be provided with a support surface which is substantially the same height as the upper surface of the third buoy structure. Thus, the support surface will also be located below the upper surfaces of the first and second buoy structures. By i) combining such a support surface at the second column between the lower parts of the first and second buoy structure and ii) the upper surface of the third buoy structure, a good support can be provided for the further hull structure loaded thereon.

In one embodiment of the invention, the hull structure includes a controllable ballast system that can control the pitch for the hull structure floating in the water. The controllable ballast system is not only useful in the operational state of a semi-submersible wind power platform, as described further below, but it can also be used in operations where a set of hull structures are arranged in a row for loading onto a marine transport vessel.

The invention also relates to a method for loading a group of hull structures onto a semi-submersible carrier, a part of which can be submerged to a position below the water surface and then lifted to a position above the water surface, whereby cargo is loaded onto the ship. Wherein the set of hull structures comprises at least a first and a second hull structure of the type described above. As is also known, such vessels are transported with the hull structure above the water surface.

The method comprises the following steps: floating a set of hull structures on water; arranging a set of hull structures in a row above the vessel when the transport vessel is submerged to a lower position; the vessel is lifted to an upper position for loading a row of hull structures onto the vessel.

In one embodiment of the invention, the step of arranging the set of hull structures in a row comprises: the first and second hull structures are arranged adjacent to each other such that the second hull structure is above the third pontoon structure of the first hull structure and the second hull structure is above the third pontoon structure of the first hull structure. The second column of the second hull structure is positioned between the first and second pontoon structures of the first hull structure, wherein the second column of the second hull structure is closer to the second column of the first hull structure than to the first and third columns of the first hull structure.

One embodiment of the method comprises: at least one of the first and second hull structures is placed (e.g., ballasted) in an inclined position to allow the second hull structure to float above the third buoy structure of the first hull structure to a position adjacent the hull structure.

For example, the first hull structure may be positioned substantially horizontally and loaded to a somewhat deep draft, while the second hull structure may be set in an inclined position such that the third buoy structure is located a distance below the water surface and such that the second column bottom of the second hull structure is lifted close to the water surface. This tilt attitude can be achieved by using a controllable ballast system provided on the hull structure. After the second hull structure is towed to a position close to the first hull structure, the two hull structures may be secured to each other. A third hull structure adjacent to the second hull structure in the row may be positioned in a similar inclined position, towed in place and secured to the second hull structure. A similar procedure can be used for e.g. the fourth and fifth hull structures, thereby forming a row of five hull structures.

In one embodiment, as described above, the first hull structure in the row is provided with a support structure at the second stability column arranged between the first and second buoy structures, the method comprising: and aligning the second upright post of the second hull structure on the support structure of the first hull structure. As mentioned above, the support structure may comprise a support surface at the same level as the upper surface of the third buoy structure. Preferably all hull structures of the set of hull structures are provided with such a support structure. The method may thus comprise: positioning a second column of a second hull structure on the support surface of the first hull structure, and: the first and second pontoon structures of the second hull structure are positioned on an upper surface of the third pontoon structure of the first hull structure. The second hull structure may then be supported by the support surface and a third pontoon structure of an adjacent first hull structure. The second hull structure may also be supported by its own third buoy structure located on the deck of the vessel when the hull structure is loaded onto the vessel.

In one embodiment of the invention, the first hull structure in the row is supported on an inclined support surface provided on the upper surface of the third buoy structure. Whereby the first hull structure can be arranged horizontally on the vessel while still providing a suitably inclined support surface. Additional support members may be provided for providing good support for the next hull structure in the row.

In one embodiment of the invention the second hull structure in the row is provided with an inclined support surface on the underside of the third pontoon structure (and possibly also the underside of the first and third columns), as described above. The second hull structure may then be positioned on the vessel in a slightly inclined position with the suitably inclined support surface facing the deck of the vessel. The first and second pontoon structures of the second hull structure may be positioned on and supported by a third pontoon structure of an adjacent first hull structure. Further, the second upright of the second hull structure may be positioned on and supported by the support surface of the first hull structure proximate to the second upright of the first hull structure.

In one embodiment of the invention, the step of arranging the hull structures in a row comprises: the first hull structure and the second hull structure are arranged adjacent to each other with the first and second pontoon structures of the second hull structure above the third pontoon structure, wherein the second column of the second hull structure is positioned between the first and second pontoon structures of the first hull structure, wherein the second column of the second hull structure is positioned closer to the second column of the first hull structure than to the first and third columns of the first hull structure.

The invention also relates to a transport vessel capable of carrying a row of hull structures comprising at least a first and a second hull structure of the kind described above.

In one embodiment of the invention, the set of hull structures is arranged in a row, wherein the first hull structure and the second hull structure are adjacent to each other, the second hull structure is located above the third pontoon structure of the first hull structure, and the second column of the second hull structure is located between the first and second pontoon structures of the first hull structure, wherein the second column of the second hull structure is located closer to the second column of the first hull structure than to the first and third columns of the first hull structure.

In one embodiment of the invention, the second upright of the second hull structure is positioned on and supported by a support surface of the first hull structure.

When loaded onto the vessel, at least a third hull structure of the row of hull structures is supported by the support surface of the adjacent hull structure and the third buoy structure surface, while being supported by its own third buoy structure located on the deck of the transport vessel.

Drawings

The following description of the invention refers to the accompanying drawings, in which:

fig. 1 shows a perspective view of a first embodiment of a hull structure according to the present disclosure.

Fig. 2A and 2B show a top view (fig. 2A) and a longitudinal section (fig. 2B) of a second embodiment of a hull structure according to the present disclosure.

Fig. 3A and 3B show a top view (fig. 3A) and a longitudinal cross-section (fig. 3B) of a third embodiment of a hull structure according to the present disclosure.

Fig. 4 shows a perspective view of the hull structure of fig. 3A and 3B, wherein a support structure for a fan tower is provided.

Fig. 5 shows in schematic side view the first group of hull structures being loaded in rows onto the deck of a marine vessel.

Fig. 6A and 6B show in schematic side view the second set of hull structures in rows to be loaded on the deck of a marine vessel (fig. 6B), wherein the first hull structure on the right has a special design (fig. 6A)).

Fig. 7A and 7B show first and second perspective views (fig. 7A and 7B) of a set of hull structures configured in rows for loading onto the deck of a marine vessel.

Fig. 8A to 8F show in steps how the hull structure group according to fig. 7A and 7B is loaded onto the deck of a marine transport vessel.

Fig. 9A to 9D show a comparison of loading efficiencies between groups of hull structures having different hull structure designs.

FIG. 10 illustrates a semi-submersible wind power platform including a hull structure in accordance with the present disclosure.

Fig. 11 shows a perspective view of another embodiment of a hull structure according to the present disclosure.

Fig. 12 shows a side view of another embodiment of a hull structure according to the present disclosure.

Fig. 13 shows a set of hull structures loaded in rows according to fig. 12.

Fig. 14 shows a side view of the embodiment according to fig. 11.

Fig. 15 shows a set of hull structures according to fig. 14, which are loaded in a row.

Fig. 16 shows a perspective view of yet another embodiment of a hull structure according to the present disclosure.

Detailed Description

Fig. 1 shows a first embodiment of a hull structure 10 for a semi-submersible wind power platform 100. The hull structure 10 comprises first, second and third buoyancy stabilizing columns 1, 2, 3 extending in a substantially vertical direction and elongated first, second and third submerged buoy structures 11, 12, 13 extending in a substantially horizontal direction. The hull structure 10 has a substantially triangular shape in the horizontal plane, the first, second and third buoy structures 11, 12, 13 forming the sides of the triangle. In this example, the first, second and third pontoon structures 11, 12, 13 have substantially equal lengths, forming a generally equilateral triangular hull structure, with columns disposed at each corner end.

As an example of the illustrative dimensions, the height of the uprights 1, 2, 3 can have a diameter of about 13m and about 30-35 m. Each pontoon structure 11, 12, 13 may have a length of about 50-70m and a width of about 6-10m. The height of the first and second buoy structures 11, 12 may be about 6-9m.

The first pontoon structure 11 extends between and is connected to the first and second columns 1, 2, and the first pontoon structure 11 is connected to the lower portions 1c, 2c of the first and second columns 1, 2, respectively. A second pontoon structure 12 extends between and is connected to the second and third columns 2, 3, and the second pontoon structure 12 is connected to lower portions 2c, 3c of the second and third columns 2, 3, respectively. A third pontoon structure 13 extends between and is connected to the first and third columns 1, 3, and the third pontoon structure 13 is connected to the lower portions 1c, 3c of the first and third columns 1, 3, respectively. In this case, the lower portions 1c, 2c, 3c of the uprights 1, 2, 3 are the lowest portions of these uprights. In this case all three buoy structures 11, 12, 13 are floating buoy structures.

The first, second and third buoy structures 11, 12, 13 each have a lower surface 11b, 12b, 13b. These lower surfaces 11b, 12b, 13b are substantially aligned with each other in the horizontal plane and also with the lower surfaces 1b, 2b, 3b of the first, second and third buoyancy stabilizing columns 1, 2, 3.

Furthermore, the width in both the first and second buoy structures 11, 12 is smaller than the width of the lower part 2c of the second stability column 2. As shown in fig. 1, all buoy structures 11, 12, 13 are straight and of constant width. In other embodiments, the first and second buoy structures 11, 12 may have other designs.

As shown in fig. 1, the third buoy structure 13 has a height that is smaller than the heights of the first and second buoy structures 11, 12. Since the pontoon structures in fig. 1 are arranged on the same horizontal plane, the upper surface 13a of the third pontoon structure 13 is horizontally lower than the upper surfaces 11a, 12a of the first and second pontoon structures 11, 12. As described below. The main purpose of the specific structure and arrangement of the third buoy structure 13 is that it allows the hull structure to be more space-efficient to load on the marine transport vessel, thereby allowing the vessel to carry a greater number of hull structures.

In the example, the third buoy structure 13 has a height of about 3m, whereas the first and second buoy structures 11, 12 have a height of about 7m. The height of the third buoy structure 13 is thus less than 50% of the height of the first and second buoy structures 11, 12.

The hull structure 10 is also provided with a controllable ballast system (not shown in the figures) which can control the inclination of the hull when the hull structure 10 is floating in water.

The embodiment of the hull structure shown in fig. 2A, 2B to 10 is mainly constructed in a similar manner to the hull structure 10 shown in fig. 1, and therefore the same reference numerals are used for similar components throughout the drawings.

Fig. 2A and 2B show a top view (fig. 2A) and a longitudinal cross-section (fig. 2B) of a second embodiment of a hull structure 20 for a semi-submersible wind power platform 100.

As shown in fig. 2A, the hull structure 20 presents a first angle α in the horizontal plane between the central longitudinal axis 11c of the first pontoon structure 11 and the central longitudinal axis 12c of the second pontoon structure 12 (i.e., the angle of the longitudinal axes in the first and second pontoon structures). The hull structure 20 further forms a second angle beta in the horizontal plane, namely an angle formed by a) a first virtual line 21 between the centre point of the first stabilizing column 1 and the centre point of the second stabilizing column 2 and b) a second virtual line between the centre point of the second stabilizing column 2 and the centre point of the third stabilizing column 3. As further shown in fig. 2A, the second included angle β is greater than the first included angle α. This further increases the space efficiency of the loading of the hull structure, as will be further described below.

As shown in fig. 2B, the lower surface 13B of the third buoy structure 13 is inclined with respect to the horizontal plane to form an inclined surface 130. The inclination has an angle y with respect to the horizontal plane such that the outer side of the lower surface 13b of the third buoy structure 13 is located at a higher vertical level than the inner side of the lower surface 13b of the third buoy structure 13, wherein the inner side is closer to the second stability column 2 than the outer side. When the hull structure 20 is loaded onto the deck of the transport vessel in a slightly tilted attitude (angle γ), the tilted surface 130 forms a support surface for the hull structure 20, as will be described further below. Furthermore, a portion of the undersides 1b, 3b of the first and third stabilizing columns 1, 3 are inclined at an angle γ with respect to the horizontal plane to correspond to the inclined surface 130.

The hull structure 20 is also provided with a support structure 5, the support structure 5 being arranged at the second stability column 2 between the first and second buoy structures 11, 12. The support structure 5 connects the first and second buoy structures 11, 12 and the entire hull structure 20. The support structure 5 comprises a support surface 6, which support surface 6 extends between the first and second buoy structures 11, 12, the height of which corresponds to the height of the upper surface 13a of the third buoy structure 13. The support surface 6 serves to support adjacent hull structures when a group of hull structures is loaded onto the carrier, as will be described further below.

The hull structure 20 is also provided with cross braces 7, the cross braces 7 extending between the columns 1, 2, 3 and being connected in a substantially similar manner to the pontoon structures 11, 12, 13, but the cross braces being arranged between the upper parts of the columns 1, 2, 3. When the hull structure is to be loaded and transported, no cross brace between the first and third columns 1, 3 is installed, as it would prevent a compact loading. The end portions of the cross brace may be preloaded onto the first and third uprights and the remainder may be installed after shipping. The assembled wale is generally not too complex after transport.

Another difference between the hull structures of fig. 1 and 2A and 2B is that the second column 2 of the hull structure 20 of fig. 2A and 2B is slightly larger (in diameter) than the first and third columns 1, 3. The purpose of this is to provide better support conditions for the fan tower arranged on the second column 2. Another object is to make it possible to adjust the longitudinal centre of buoyancy (LCF) of the hull structure, because a larger diameter of the second column means a larger cross-sectional area, which in turn means that the second column will exhibit a larger water plane area than the other columns when the hull structure/platform is run together with the pontoon structure below the water surface and the columns extending through the water surface. The location of the LCF is dependent on the water plane area of the columns, and adjusting the LCF can reduce the movement of the hull structure/platform during open sea operations.

Fig. 3A and 3B show a top view (fig. 3A) and a longitudinal section (fig. 3B) of a third embodiment of a hull structure 30. The hull structure 30 of fig. 3A and 3B is generally similar to the hull structure 20 of fig. 2A and 2B. The main difference is that the first and second buoy structures 11, 12 of the hull structure 30 are arranged with a reduced first angle α, thereby increasing the difference between the second angle β and the first angle α. The first angle a can be further reduced by using a second pillar of larger diameter.

As shown in fig. 3A, both the first and second buoy structures 11, 12 have outer surfaces 11d, 12d facing away from the hull structure 30. In the embodiment of fig. 3A and 3B, the first and second buoy structures 11, 12 are arranged such that the outer surfaces 11d, 12d in the first and second buoy structures 11, 12 are substantially aligned with the outer surface 2d of the second stability column 2. Furthermore, the inner surfaces of the first and second buoy structures 11, 12 are substantially aligned with the inner surfaces of the first and third stability columns 1, 3, respectively.

This further increases the difference between the second angle beta and the first angle alpha, thereby further improving the ability of the hull structure 30 to be loaded onto the marine transport vessel in a space-saving manner.

Fig. 4 shows a perspective view of the hull structure 30 of fig. 3A and 3B, on which an interface/support 101 for a fan tower arranged on top of the second stabilizing column 2 is provided.

Fig. 5 shows a first set of hull structures 20, 30, in this example five hull structures, in a schematic side view, which are loaded in rows onto the deck 65 of the marine vessel. The hull structure in fig. 5 may be of the type shown in fig. 2A and 2B or fig. 3A and 3B. All five hull structures are in an inclined position, the inclination angle y corresponding to the inclination surface 130 on the lower surface 13b of the third buoy structure 13. The rightmost hull structure is supported below its second upright 2 by supports 66 arranged on the vessel deck 65. The remaining hull structures are loaded and supported in the same manner, i.e. the second column 2 is supported by the support surface 6 of the adjacent hull structure, the inclined support surface 130 being flush with the deck 65 and supported by the deck 65. The first and second buoy structures 11, 12 of all other hull structures are located on and supported by the third buoy structure 13 of the adjacent hull structure.

Fig. 6A and 6B show in schematic side view a second set of hull structures 20, 30, 40, in this example five hull structures, loaded in rows onto the deck 65 of a marine transport vessel (fig. 6B), wherein the first hull structure 40 on the right has a special design (fig. 6A). The remaining four hull structures 20, 30 may be of the type shown in fig. 2A and 2B or fig. 3A and 3B.

As shown in fig. 6A, the special hull structure 40 is not provided with a bevel 130 on the lower surface 13b of the third buoy structure 13. Instead, the lower surface 13b is flat. However, the upper surface 13a of the third buoy structure 13 of the hull structure 40 is inclined with respect to the horizontal plane, thereby forming an upper inclined surface 140. The inclination is arranged such that the outer portion of the upper surface 13a is located at a lower vertical level than the inner portion of 13a, which is closer to the second stability post 2 than the outer portion.

This means that a particular hull structure 40 may and should be placed horizontally on the deck 65 and into an end structure ("first" structure) in the hull structure row as shown in fig. 6B. The first hull structure 40 is thereby arranged in a very stable position on the deck 65 and no additional deck supports 66 are required to arrange the hull structure in an inclined position. The next (second) hull structure 20, 30 adjacent to the first hull structure 40 occupies an inclined position and is supported by the upper inclined surface 140 of the first hull structure 40 and by its own lower inclined surface 130, as shown in fig. 5. An additional support 67 may be arranged below the second upright 2 of the second hull structure 20, 30. The remaining three hull structures 20, 30 are stowed in the same manner as in fig. 5.

Fig. 7A and 7B show a first and a second perspective view of a set of hull structures loaded in rows onto the deck 65 of a semi-submersible vessel 60 (fig. 7A and 7B), which vessel is designed to lower parts of the hull below the water surface to a lower position and also to be lifted to a higher position for loading cargo at the water surface above the vessel onto the vessel.

The row of hull structures in fig. 7A and 7B comprises a first hull structure 40 of the type shown in fig. 6A and four further hull structures 30a-30d, each of the type shown in fig. 4 (with the middle portion of the cross brace 7 between the first and third uprights 1, 3 removed). The hull structure of fig. 7A and 7B is stowed on the deck 65 in a substantially similar manner as the hull structure in fig. 6B.

Fig. 8A to 8F show how the hull structure sets according to fig. 7A and 7B are loaded onto the deck 65 of the marine transport vessel 60 in a stepwise manner.

The method for loading a set of hull structures 40, 30a-30d onto a semi-submersible transport vessel 60 generally includes the steps of:

-a set of hull structures 40, 30a-30D floating in water (fig. 8A-8D);

-arranging the sets of hull structures 40, 30a-30d in a row above the vessel 60 when the vessel is in its lower position (fig. 8E); and

Lifting the vessel 60 to its upper position for loading the entire row of hull structures 40, 30a-30d onto the vessel 60 (fig. 8F).

As shown in fig. 8B, wherein the hull structure sets include at least a first hull structure 40 and a second hull structure 30a, the step of arranging the hull structure sets in a row includes: the first 40 and second 30a hull structures are arranged adjacent to each other such that the second hull structure 30a is located above the third pontoon structure 13 of the first hull structure 40 and the second column 2 of the second hull structure 30a is located between the first and second pontoon structures 11, 12 of the first hull structure 40. Wherein the second column 2 of the second hull structure 30a is closer to the second column 2 of the first hull structure 40 than to the first and third columns 1, 3 of the first hull structure 40.

As shown in fig. 8A, the method may further include: at least one of the first and second hull structures is stowed in an inclined position (in this case the second hull structure 30a, see fig. 8A) and the first hull structure 40 is ballasted to a slightly larger draft to allow the second hull structure 30a to float above the third buoy structure 13 of the first hull structure 40 into a position adjacent the first hull structure 40 (as shown in fig. 8B). The controllable ballast system is used to set the second hull structure 30a in a tilted attitude.

As shown in fig. 8B-8E and fig. 6B, 7A and 7B, the method may further include: the second upright 2 of the second hull structure 30a is positioned onto the support structure 5, 6, 67 of the first hull structure 40.

The remaining hull structures 30b, 30c, 30d are arranged in a row in substantially the same manner as described above for the first and second hull structures 40, 30 a. For example, the third hull structure 30b in the row is arranged in a tilted posture and is moved/towed to a position of the adjacent second hull structure 30a that has been positioned in the respective tilted posture. Since the second and third hull structures 30a, 30b are not inclined relative to each other, no additional support 67 is required. As described above, the third hull structure 30b is supported by the third buoy structure 13 and the support surface 6 of the second hull structure 30a (supported after lifting of the vessel 60). The third hull structure 30b is also supported by its own third buoy structure located on the deck 65. The process of arranging the fourth and fifth hull structures 30c, 30d in a row is similar.

The hull structures 40, 30a-30d are preferably secured to each other prior to lifting the vessel 60. Wood members or the like may be placed between the hull structures to prevent wear.

Figures 9A-9D show a comparison of loading efficiencies between groups of hull structures having different hull structure designs a-D. Fig. 9A-9C show hull structural designs a-C in which the first included angle α is equal to the second included angle β (see fig. 2A and 3A for an example of β > α).

The difference between the a-C designs is the location of the first and second pontoon structures: in design a, they are located inside the column (fig. 9A); in design B, they are located outside the column (fig. 9B); in the C design, they are located in the center of the columns (fig. 9A), similar to the hull structure 10 shown in fig. 1.

The hull structure β > α of the D design is similar to the hull structure 30 shown in fig. 3A and 3B.

The a-D designs all have the same column diameter and pontoon width.

As shown in fig. 9A-9D, the number of hull structures loadable on a deck of a given length of the vessel 60 is 3 for the a design, 4 for the B and C designs, and 5 for the D design. It is apparent that arranging the hull structure such that β > α further improves the loading efficiency of such triangular hull structures, i.e. collapsible triangular hull structures with lower third pontoons.

The thin lines in fig. 9A-9C represent the fourth and fifth hull structures in fig. 9A and the fifth hull structure in fig. 9B and 9C to show the respective lengths of the five complete structures of different designs. These figures illustrate that the vessel 60 cannot be loaded with more hull structures.

Fig. 10 shows a semi-submersible wind power platform 100 comprising a hull structure 30 according to fig. 4. Platform 100 is provided with a fan tower 102, which fan tower 102 is in turn provided with three blades 103 (as well as a generator, etc., not shown).

Fig. 11-16 show an embodiment of a hull structure 50, 51 similar to that described above, but wherein each of the first and second pontoon structures 11, 12 has a downwardly facing lower surface 11b, 12b, and wherein the upper surface 13a of the third pontoon 13 is substantially aligned with or located lower than the lower surfaces 11b, 12b of the first and second pontoon structures 11, 12.

In the hull structure 50 shown in fig. 12 and 13, the lower surfaces 11b, 12b of the first and second pontoons 11, 12 are substantially aligned with the entire downwardly facing lower surface 2b of the second buoyancy stabilizing column 2.

In the hull structure 51 shown in fig. 11, 14 and 15, the lower surfaces 11b, 12b of the first and second pontoons 11, 12 are substantially aligned with only a portion 2b of the downward lower surface of the second buoyancy stabilizing column. Another portion 2e of the downwardly facing lower surface of the second stabilizing upright 2 is located at a lower level. As best shown in fig. 14, the (second) portion 2e located at the lower level is substantially aligned with the lower surface 13b of the third pontoon 13 and the lower surfaces of the first and third columns 1, 3.

Fig. 13 shows a group of hull structures according to fig. 12 being loaded in a row, while fig. 15 shows a group of hull structures according to fig. 11 and 14 being loaded in a row.

When there is no third pontoon support, for example when the platform is at the end of a row of similar platforms or during assembly, a separate support structure 52 may be provided below the second column, see fig. 13, in order to maintain the hull structure according to fig. 12 in a substantially horizontal position.

The hull structure shown in fig. 11 and 14 can be positioned substantially horizontally without any separate support structure 52, since the lower surface of the third pontoon 3, the lower surfaces of the first and third columns 1, 3 and the lower (second) portion 2e of the second column are aligned with each other, see fig. 11, 14 and 15.

The hull structures shown in fig. 11-16 may be horizontally oriented with a small step or incline between the lower surface 11b of the first pontoon 11 and the lower surface 12b of the second pontoon 12 to allow a stop between the first and second pontoons and the upper surface 13a of the hull structure adjacent the lower side.

The hull structures shown in fig. 11-16 may be positioned at a small inclination (e.g. 1-2 degrees) to allow a stop to be formed between the first and second pontoon lower surfaces 11b, 12b and the adjacent hull structure pontoon upper surface 13a, the third pontoon lower surface 13b also being wedge-shaped with a height change for the stop.

In the embodiment of fig. 11-16, pontoons 11, 12, 13 are connected to the lower parts of the columns 1, 2, 3, i.e. these pontoons are typically below the water surface when the wind power platform is in operation.

In the hull structure shown in fig. 16, the undersides of the first and third columns 1, 3 have portions 1e, 3e located at a lower level and another portion (denoted as 1b and 3b in fig. 16) located at a higher level. In this example, the lower portions 1e, 3e are aligned with the lower surface 13b of the third pontoon 13, and the upper portions 1b, 3b are aligned with the lower surfaces 11b, 12b of the first and second pontoons 11, 12. The upper parts 1b, 3b provide an operating point for lifting and moving the platform on land, for example using a self-propelled modular transport vehicle. Any hull structure disclosed herein may be provided with such an upper/lifting point.

The invention is not limited to the embodiments described above, but may be modified in various ways within the scope of the claims. For example, the cross-section of the columns and pontoon structures may be different from the examples, such as polygonal columns, circular or polygonal pontoon structures.

Reference numerals

1: first floating stability column

2: second buoyancy stability column

3: third floating stability column

1a, 2a, 3a: the upper surface of the upright post

1b, 2b, 3b: lower surface of the upright post

1c, 2c, 3c: the lower part of the upright post

2d: the outside of the second upright post

1e:1b lower position

2e:2b lower position

3e:3b lower position

5: supporting structure

6: bearing surface on the support structure 5

7: cross support

10. 20, 30, 40, 50, 51: ship body structure

11: long-strip-shaped submergible first buoy structure

12: strip-shaped submergible second buoy structure

13: long-strip-shaped submergible third pontoon structure

11a, 12a, 13a: upper surface of floating bridge structure

11b, 12b, 13b: lower surface of floating bridge structure

11c, 12c: the central longitudinal axis of the first and second pontoon structures

11d, 12d: the outside of the first and second pontoon structures

Alpha: a first angle in a horizontal plane between the central longitudinal axes of the first and second pontoon structures

21: a first imaginary line between the center points of the first and second stability columns

22: a second imaginary line between the center points of the second and third stability columns

Beta: a second included angle between the first and second imaginary lines in a horizontal plane

52: supporting structure

60: marine transport ship

65: deck of marine transport ship

66: additional first support member

67: additional second support member

100: semi-submersible wind power platform

101: fan tower support

102: fan tower

103: fan blade

130: lower inclined surface of third pontoon structure

140: upper inclined surface of third pontoon structure

Gamma: inclination angle

Claims (32)

1. A hull structure (10, 20, 30, 40, 50, 51) for a semi-submersible wind power platform (100), wherein the hull structure (10) comprises:

first, second and third buoyancy stabilizing columns (1, 2, 3) extending in a substantially vertical direction; and

elongated first, second and third submerged buoy structures (11, 12, 13) extending in a substantially horizontal direction;

wherein the hull structure (10, 20, 30, 40) has a substantially triangular shape in a horizontal plane, the first, second and third buoy structures (11, 12, 13) forming sides of a triangle;

wherein the first pontoon structure (11) extends between and connects the first and second columns (1, 2), and wherein the first pontoon structure (11) is connected to the lower portions (1 c, 2 c) of the first and second columns (1, 2);

wherein a second pontoon structure (12) extends between and connects the second and third columns (2, 3), and wherein the second pontoon structure (12) is connected to lower portions (2 c, 3 c) of the second and third columns (2, 3);

Wherein a third pontoon structure (13) extends between the first and third columns (1, 3) and is connected at a lower portion (1 c, 3 c) thereof;

wherein each of the first, second and third pontoon structures (11, 12, 13) has an upwardly facing upper surface (11 a, 12a, 13 a);

wherein the third pontoon structure (13) has a height smaller than the heights in the first and second pontoon structures (11, 12);

wherein the third buoy structure (13) is arranged such that its upper surface (13 a) is lower than the upper surfaces (11 a, 12 a) in the first and second buoy structures (11, 12).

2. The hull structure (10, 20, 30, 40) of claim 1, wherein the first, second and third pontoon structures (11, 12, 13) each have a downward lower surface (11 b, 12b, 13 b), and wherein the lower surfaces of the first, second and third pontoon structures are substantially aligned with each other in a horizontal plane.

3. The hull structure (10, 20, 30, 40) according to claim 2, wherein the lower surfaces (11 b, 12b, 13 b) of the first, second and third pontoon structures (11, 12, 13) are substantially aligned with the downward lower surfaces (1 b, 2b, 3 b) of the first, second and third buoyancy stabilizing columns (1, 2, 3).

4. The hull structure (50, 51) according to claim 1, wherein the first and second buoy structures (11, 12) each have a downward lower surface (11 b, 12 b), and wherein the upper surface (13 a) of the third buoy structure is substantially aligned with or at a lower level than the lower surfaces (11 b, 12 b) of the first and second buoy structures (11, 12).

5. The hull structure (50, 51) according to claim 4, wherein the lower surfaces (11 b, 12 b) of the first and second pontoon structures (11, 12) are substantially aligned with the downwardly facing lower surface (2 b) of the second buoyancy column (2).

6. The hull structure (50, 51) according to claim 4, wherein the lower surfaces (11 b, 12 b) of the first and second pontoons (11, 12) are substantially aligned with a portion of the lower surface (2 b) of the second stability column (2) facing downwards, the other portion of the lower surface (2 b) of the second stability column (2) being located at a lower position.

7. A hull structure (50, 51) according to any of claims 4-6, wherein the lower surface (13 b) of the third buoy structure is substantially aligned with the downwardly facing lower surfaces (1 b, 3 b) of the first and third buoyancy stabilizing columns (1, 3).

8. A hull structure (50, 51) according to any of claims 4-6, wherein the lower surface (13 b) of the third buoy structure is substantially aligned with a portion (1 e, 3 e) of the downwardly facing lower surfaces of the first and third buoyancy columns (1, 3). The other part of the lower surface (1 b, 3 b) of the first and third buoyancy stabilizing columns (1, 3) facing downwards is located at a higher position.

9. A hull structure (10, 20, 30, 40, 50, 51) according to any of the preceding claims, wherein the height of the third buoy structure (13) is 75%, preferably less than 50%, smaller than the height of at least one of the first and second buoy structures (11, 12).

10. A hull structure (10, 20, 30, 40, 50, 51) according to any of the preceding claims, wherein the height of the third buoy structure (13) is at least 1 meter, preferably as low as 2 meters and even as low as 3 meters lower than the height of at least one of the first and second buoy structures (11, 12).

11. A hull structure (10, 20, 30, 40, 50, 51) according to any preceding claim, wherein the first, second and third buoy structures (11, 12, 13) have substantially equal lengths.

12. The hull structure (20, 30, 40) according to any of the preceding claims, wherein the hull structure exhibits:

i) The central longitudinal axis (11 c) of the first pontoon structure (11) and the central longitudinal axis (12 c) of the second pontoon structure (12) form a first angle (alpha) in a horizontal plane; and

ii) a second angle (beta) formed by a) a first virtual line (21) between the centre point of the first stabilizing column (1) and the centre point of the second stabilizing column (2) and b) a second virtual line (22) between the centre point of the second stabilizing column (2) and the centre point of the third stabilizing column (3),

Wherein the second angle (β) is larger than the first angle (α).

13. A hull structure (10, 20, 30, 40, 50, 51) according to any preceding claim, wherein the first and second pontoon structures (11, 12) have a length of at least a major part thereof smaller than the width of the lower portion (2 c) of the second stabilizing column (2).

14. The hull structure (30, 40) according to any of the preceding claims, wherein each of the first and second buoy structures (11, 12) has an outer side (11 d, 12 d) facing away from the hull structure (30), wherein the outer side (11 d, 12 d) of at least one of the first and second buoy structures (11, 12) is substantially flush with the outer side (2 d) of the second stability column (2).

15. Hull structure (20, 30) according to any of the preceding claims, wherein at least the outer part of the lower surface (13 b) of the third buoy structure (13) is inclined with respect to the horizontal plane so as to form an inclined surface (130) which locates the outer part of the lower surface (13 b) of the third buoy structure (13) at a higher position than the inner part of the lower surface (13 b), wherein the inner part is closer to the second stability column (2) than the outer part.

16. Hull structure (20, 30) according to claim 15, wherein at least a part of the lower surfaces (1 b, 3 b) of the first and third stabilizing columns (1, 3) are inclined with respect to the horizontal plane, wherein this inclination arrangement corresponds to the inclination of the lower surface (13 b) of the third buoy structure (13).

17. The hull structure (40) according to any of the preceding claims, characterized in that: the upper side (13 a) of the third pontoon structure (13) is inclined with respect to a horizontal plane to form an upper inclined surface (140) which is arranged obliquely such that the outer part of the upper side (13 a) of the third pontoon structure (13) is located at a lower vertical height than the inner part of the upper side (13 a) of the third pontoon structure (13), wherein the inner part is closer to the second stability column (2) than the outer part.

18. The hull structure (20, 30, 40) according to any of the preceding claims, wherein the hull structure is provided with a support structure (5) on the second stability column (2) between the first and second buoy structure (11, 12).

19. Hull structure (20, 30, 40) according to any of the preceding claims, wherein the support structure (5) is provided with a support surface (6) of substantially the same vertical height as the upper surface (13 a) of the third buoy structure (13).

20. Hull structure (10, 20, 30, 40, 50, 51) according to any of the preceding claims, wherein the hull structure is provided with a controllable ballast system which, when floating in water, can control the inclination of the hull structure.

21. Method of loading a set of hull structures (30 a-30d, 40, 50, 51) onto a semi-submersible transport vessel (60), a part of the semi-submersible transport vessel (60) being submersible below the water surface to a lower position, and also being liftable to a higher position for loading cargo at the water surface above the vessel onto the vessel, wherein the set of hull structures comprises at least a first hull structure (40, 30 a) and a second hull structure (30 a, 30 b), the arrangement being according to any of the preceding claims, the method comprising:

A set of hull structures (30 a-30d, 40) floating in water;

-arranging a set of hull structures (30 a-30d, 40) in a row above the vessel (60) when the transport vessel is submerged to a lower position; and

the vessel (60) is lifted to its upper position for loading a row of hull structures (30 a-30d, 40) onto the vessel (60).

22. The method of claim 21, arranging the set of hull structures (30 a-30d, 40) in a row, comprising:

the first and second hull structures (40, 30a, 30 b) are arranged adjacent to each other such that the second hull structure (30 a, 30 b) is located above the third pontoon structure of the first hull structure (40, 30 a) and the second column of the second hull structure (30 a, 30 b) is located between the first and second pontoon structures of the first hull structure (40, 30 a), wherein the second column of the second hull structure (30 a, 30 b) is located closer to the second column of the first hull structure (40, 30 a) than to the first and third columns of the first hull structure (40, 30 a).

23. The method of claim 22, the method comprising:

at least one of the first and second hull structures (40, 30a, 30 b) is arranged in a tilted attitude to allow the second hull structure (30 a, 30 b) to float above the third pontoon structure of the first hull structure (40, 30 a) into a position adjacent the first hull structure.

24. The method according to claim 22 or 23, wherein the first hull structure (30 a) is arranged according to claim 19, the method comprising:

positioning a second column of a second hull structure (30 b) on the support surface (6) of the first hull structure (30 a), and/or

The first and second pontoon structures of the second hull structure (30 b) are positioned on an upper surface (13 a) of the third pontoon structure (13) of the first hull structure (30 a).

25. A method according to any one of claims 21-24, wherein the first hull structure (40) is arranged according to claim 17.

26. A method according to any one of claims 21-25, wherein the second hull structure (30, 30 b) is arranged according to claim 15 or 16.

27. The method of claim 21, arranging the set of hull structures (50, 51) in a row, comprising:

the first and second hull structures are arranged adjacent to each other with the first and second pontoon structures (11, 12) of the second hull structure being located above the third pontoon structure (13) of the first hull structure, the second column (2) of the second hull structure being located between the first and second pontoon structures (11, 12) of the first hull structure, wherein the second column (2) of the second hull structure is closer to the second column (2) of the first hull structure than to the first and third columns (1, 3) of the first hull structure.

28. Vessel (60) carrying a set of hull structures (30 a-30d, 40, 50, 51), wherein the set of hull structures comprises at least a first and a second hull structure (40, 30a, 30b, 50, 51) arranged according to any of claims 1-20.

29. The vessel (60) of claim 28, wherein the set of hull structures (30 a-30d, 40, 50, 51) are arranged in a row, wherein the first hull structure and the second hull structure are adjacent to each other, wherein the second hull structure is located above a third pontoon structure of the first hull structure, and a second column of the second hull structure is located between the first and second pontoons of the first hull structure, wherein the second column of the second hull structure is closer to the second column of the first hull structure than to the first and third columns of the first hull structure.

30. Vessel (60) according to claim 28 or 29, wherein the first hull structure (30 a) is arranged according to claim 19, wherein the second upright of the second hull structure (30 b) is located on the support surface (6) of the first hull structure (30 a), and the first and second pontoons of the second hull structure (30 b) are located on the upper surface (13 a) of the third pontoon (13) of the first hull structure (30 a).

31. Transport vessel (60) according to any of claims 28-30, wherein the first carried hull structure (40) is arranged according to claim 17.

32. Transport vessel (60) according to any of claims 28-31, wherein the second hull structure (30 a, 30 b) carried is arranged according to claim 18 or 19.