EP4247701A1

EP4247701A1 - Floating unit assembly

Info

Publication number: EP4247701A1
Application number: EP21814782.5A
Authority: EP
Inventors: Niklas NORMAN
Original assignee: Semar AS
Current assignee: Semar AS
Priority date: 2020-07-14
Filing date: 2021-11-19
Publication date: 2023-09-27
Also published as: KR20230107268A; NO20200826A1; WO2022013145A1; NO20230565A1; WO2022106619A1; NO347179B1; WO2022012769A1

Abstract

The present disclosure relates to a floating unit assembly (10) arranged in a body of water (12) with a seafloor (14). The floating unit assembly (10) comprises: - a plurality of floating units (16, 18, 20, 22, 24), - a plurality of buoys (26, 28, 30, 32, 34), each buoy (26, 28, 30, 32, 34) being connected to the seafloor (14) via one or more taut lines (48), and - a plurality of connection lines (38, 40, 42, 44, 46) by which at least one floating unit (16, 18, 20, 22, 24) is connected to a plurality of buoys (26, 28, 30, 32, 34) and at least one buoy (26, 28, 30, 32, 34) is connected to a plurality of floating units (16, 18, 20, 22, 24). Each connection line (38, 40, 42, 44, 46) connects a buoy connection point (52) of a buoy (26, 28, 30, 32, 34) to a floating unit connection point (54) of a floating unit (16, 18, 20, 22, 24) and each connection line (38, 40, 42, 44, 46) is associated with a nominal horizontal distance (d_nom) and a maximum horizontal distance (d_max), wherein: i. the nominal horizontal distance (d_nom) is the horizontal distance between the buoy connection point (52) and the floating unit connection point (54) in a condition when no environmental loads are imparted on the floating unit assembly (10), and ii. the maximum horizontal distance (d_max) is the largest horizontal distance that can be obtained between the buoy connection point (52) and the floating unit connection point (54) whilst being connected by the connection line (38, 40, 42, 44, 46). According to the present disclosure, for at least a first connection line (38, 40, 42, 44, 46) of the connection lines (38, 40, 42, 44, 46), the ratio between the maximum horizontal distance (d_max) and the nominal horizontal distance (d_nom) is less than 110%, preferably less than 105%, more preferred less than 102%.

Description

FLOATING UNIT ASSEMBLY

TECHNICAL FIELD

The present invention relates to a floating unit assembly arranged in a body of water with a seafloor.

BACKGROUND OF THE INVENTION

A floating unit assembly, e.g. a system that comprises a plurality of floating units, may be maintained in a desired position range by means of a mooring system.

For instance, CN111071400A discloses a system that contains a plurality of anchor bases, each one of which being connected to several floating units by means of mooring lines. For large water depths, CN111071400A also proposes the use of buoys in the system.

However, the mooring system disclosed in CN111071400A mainly offers an individual flexibility for each floating unit in the system which results in an expensive and complex mooring system.

SUMMARY OF THE INVENTION

In view of the above, an object of the present invention is to provide a floating unit system that can provide appropriate mooring system characteristics in a cost-efficient manner.

The above object is obtained by a first aspect of the present invention in accordance with claim 1.

As such, a first aspect of the present disclosure relates to a floating unit assembly arranged in a body of water with a seafloor. The floating unit assembly comprises:

- a plurality of floating units,

- a plurality of buoys, each buoy being connected to the seafloor via one or more taut lines,

- a plurality of connection lines by which at least one floating unit is connected to a plurality of buoys and at least one buoy is connected to a plurality of floating units, - wherein each connection line connects a buoy connection point of a buoy to a floating unit connection point of a floating unit and each connection line is associated with a nominal horizontal distance and a maximum horizontal distance, wherein: i. the nominal horizontal distance is the horizontal distance between the buoy connection point and the floating unit connection point in a condition when no environmental loads are imparted on the floating unit assembly, and ii. the maximum horizontal distance is the largest horizontal distance that can be obtained between the buoy connection point and the floating unit connection point whilst being connected by the connection line.

According to the present invention, for at least a first connection line of the connection lines, the ratio between the maximum horizontal distance and the nominal horizontal distance is less than 110%, preferably less than 105%, more preferred less than 102%.

As such, the floating unit assembly according to the first aspect of the present invention comprises at least a first connection line that only to a limited extent provides station keeping flexibility to the floating unit assembly, thereby implying that a large portion of the station keeping flexibility of the floating unit assembly may be attributed to the flexibility of the buoys and taut lines rather than the connection lines.

This in turns implies an appropriate restoring load sharing capability in-between floating units connected to the same buoy which in turn may result in appropriately low costs for the floating unit assembly. To this end, though purely by way of example, the inventors of the present invention have realized that each floating unit connected to the same buoy need not necessarily receive a restoring force in the same direction at the same time from the buoy. As an example, for an environmental condition with environmental loads in a certain direction, a floating unit on the leeward side of a buoy may be imparted a restoring force component from the buoy whereas a floating unit on the windward side of the same buoy need not necessarily be imparted a restoring force component from the same buoy. This implies an efficient use of the buoy in terms of station keeping.

As used herein, the term “horizontal distance” refers to the Euclidean horizontal distance between two points. As such, for a first point pi with coordinates (xi ,yi ,zi) and second point P2 with coordinates (X2,y2,z2), the horizontal distance d between the points pi and P2 can be determined by the following equation: d = (%i - x₂)² + (y_x - y₂)²

Any distance related to the present disclosure may be determined in a plurality of different ways. Purely by way of example, distances may be determined by establishing the coordinates of a certain point in certain conditions using mooring system software, such as MIMOSA®, OrcaFlex® or Flexcom®, and thereafter determining distances by, for instance, using the above equation.

Moreover, as used herein, the expression “when no environmental loads are imparted on the floating unit assembly" relates to a weather condition that corresponds to a flat water surface with no wind and no water currents acting on the floating unit assembly.

Optionally, the buoy, to which the first connection line is connected, is connected to the seafloor via one or more taut lines in such a manner that:

- the buoy connection point assumes a nominal buoy position in a condition when no environmental loads are imparted on the floating unit assembly, and

- the buoy connection point assumes a maximum buoy position when the floating unit assembly is in a condition in which the maximum horizontal distance is reached between the buoy connection point and the floating unit connection point for the first connection line, wherein a horizontal distance between the nominal buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference between the maximum horizontal distance and the nominal horizontal distance.

As such, as seen in a direction from the sea floor to the floating unit connected to the first connection line, a major part of the flexibility, viz the movement on the floating unit as compared to a nominal position of the floating unit, may be attributed to the movement of the buoy rather than to the characteristics of the first connection line.

Optionally, at least the first connection line of the connection lines is associated with an intermediate horizontal distance being the average of the nominal horizontal distance and the maximum horizontal distance, wherein the buoy, to which the first connection line is connected, is connected to the seafloor via one or more taut lines in such a manner that:

- the buoy connection point assumes an intermediate buoy position when the floating unit assembly is in a condition in which the intermediate horizontal distance is reached between the buoy connection point and the floating unit connection point for the first connection line, wherein a horizontal distance between the intermediate buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference between the maximum horizontal distance and the intermediate horizontal distance.

The above features imply that when the floating unit has been offset from its nominal position and thereafter is offset further, a major part of the flexibility may be attributed to the movement of the buoy rather than to the characteristics of the first connection line. This in turns implies that in a storm condition for instance, in which elements of the floating unit assembly will be positioned in static offset positions as compared to nominal positions, a major part of the dynamic flexibility may be attributed to the movement of the buoy rather than to the characteristics of the first connection line. As such, the first connection lines to be used in the floating unit assembly may be selected independently of the line’s flexibility properties throughout the line’s operational life. This may result in that the costs of the first connection lines may be kept relatively low.

A second aspect of the present disclosure relates to a floating unit assembly arranged in a body of water with a seafloor, the floating unit assembly comprising:

- a plurality of floating units,

- a plurality of connection lines by which at least one floating unit is connected to a plurality of buoys and at least one buoy is connected to a plurality of floating units,

- wherein each connection line connects a buoy connection point of a buoy to a floating unit connection point of a floating unit and each connection line is associated with a nominal horizontal distance and a maximum horizontal distance, wherein: i. the nominal horizontal distance is the horizontal distance between the buoy connection point and the floating unit connection point in a condition when no environmental loads are imparted on the floating unit assembly, and ii. the maximum horizontal distance is the largest horizontal distance that can be obtained between the buoy connection point and the floating unit connection point whilst being connected by the connection line, wherein the buoy, to which the first connection line is connected, is connected to the seafloor via one or more taut lines in such a manner that:

- the buoy connection point assumes a nominal buoy position in a condition when no environmental loads are imparted on the floating unit assembly,

- the buoy connection point assumes a maximum buoy position when the floating unit assembly is in a condition in which the maximum horizontal distance is reached between the buoy connection point and the floating unit connection point for the first connection line.

According to the second aspect of the present invention, a horizontal distance between the nominal buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference between the maximum horizontal distance and the nominal horizontal distance.

Again, the floating unit assembly according to the second aspect of the present disclosure implies that a major part of the flexibility may be attributed to the movement of the buoy rather than to the characteristics of the first connection line.

It should be noted that the term “wherein the buoy, to which the first connection line is connected” of the second aspect of the present disclosure could for example encompass “wherein a buoy, to which a first connection line is connected”.

Optionally, the first connection line is associated with an intermediate horizontal distance being the average of the nominal horizontal distance and the maximum horizontal distance, wherein the buoy, to which the first connection line is connected, is connected to the seafloor via one or more taut lines in such a manner that:

Again, the floating unit assembly according to the above implies that a major part of the dynamic flexibility may be attributed to the movement of the buoy rather than to the characteristics of the first connection line.

Optionally, each one of the connection lines comprises at least one of the following: synthetic fibres, a metal wire or a fibre-metal composite.

Optionally, the body of water is associated with a water depth being the vertical distance from the seafloor to a still water surface of the body of water, preferably the water depth is less than 100 meters, preferably less than 50 meters.

Optionally, the buoy connection point of each one of the plurality of buoys is adapted to be located at a vertical nominal distance above the seafloor when no environmental loads are imparted on the floating unit assembly, wherein for at least one, preferably for each one, of the plurality of buoys, the nominal distance is at least 30%, preferably at least 50%, more preferred at least 70%, of the water depth.

Optionally, the water depth is less than 300 meters and the buoy connection point of each one of the plurality of buoys is adapted to be located at a vertical nominal distance above the seafloor when no environmental loads are imparted on the floating unit assembly, wherein for at least one, preferably for each one, of the plurality of buoys, the nominal distance is at least 30%, preferably at least 50%, more preferred at least 70%, of the water depth.

Optionally, the water depth is greater than 1000 meters and the buoy connection point of each one of the plurality of buoys is adapted to be located at a vertical nominal distance above the seafloor when no environmental loads are imparted on the floating unit assembly, wherein for at least one, preferably for each one, of the plurality of buoys, the nominal distance is at least 50%, preferably at least 70%, more preferred at least 90%, of the water depth.

A location of the buoy connection point within any one of the above ranges implies that pendulum motion of the buoy connection points may be able to provide sufficiently large station-keeping flexibility to the floating unit assembly. Such location of the buoy connection points also implies a significant horizontal component of the connecting lines which in turn implies low line-tension at the floating unit connection points and possibly also lower up-lift- force at the anchors.

A location within any one of the above ranges implies that relatively large part of the above-mentioned flexibility may be achieved in a simple and cost-efficient manner.

Optionally, at least one, preferably each one, of the plurality of buoys is adapted to intersect a still water surface of the body of water when no environmental loads are imparted on the floating unit assembly.

Optionally, at least one, preferably each one, of the plurality of buoys has a cylindrical shape with a buoy base and a buoy height, wherein a buoy diameter corresponds to the diameter of a largest circle that can be inscribed within the circumference of the buoy base, a ratio between the buoy height and the buoy diameter being at least two, preferably at least three.

Optionally, at least one, preferably each one, of the plurality of buoys is connected to at least two to six, preferably three to six, more preferred three, floating units.

Optionally, at least one, preferably more than one, of the plurality of buoys is connected to exactly three floating units.

An embodiment in which at least one, preferably more than one, of the plurality of buoys is connected to exactly three floating units implies that the buoy or each one of the buoys connected to exactly three floating units may be imparted at least approximately the same loads from the three floating units for an environmental load of a certain magnitude, irrespective of the heading of such an environmental load. This in turn implies that the load imparted from a single floating unit on the buoy in an environmental condition, including the heading of the environmental loads associated with the environmental condition, in which the single floating unit will impart the largest load on the buoy can be approximately the same as the total load imparted by the three buoys for any heading of the environmental loads. This in turn implies a simplified design of the floating unit assembly.

Optionally, the buoy being connected to at least two to six, preferably three to six, more preferred three, floating units, is connected to each floating unit such that for each connection line connecting the buoy to a floating unit, the ratio between the maximum horizontal distance and the nominal horizontal distance is less than 110%, preferably less than 105%, more preferred less than 102%.

The effect implied by the above ratio limits has been presented hereinabove and is not repeated here for the sake of brevity.

Optionally, the buoy being connected to at least two to six, preferably three to six, more preferred three, floating units, is connected to the seafloor via one or more taut lines in such a manner that, for each floating unit and its associated connection line connected to the buoy:

- the buoy connection point assumes a nominal buoy position in a condition when no environmental loads are imparted on the floating unit assembly;

- the buoy connection point assumes a maximum buoy position when the floating unit assembly is in a condition in which the maximum horizontal distance is reached between the buoy connection point and the floating unit connection point for the connection line, and

- a horizontal distance between the nominal buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference between the maximum horizontal distance and the nominal horizontal distance.

Optionally, the buoy being connected to at least two to six, preferably three to six, more preferred three, floating units, is connected to the seafloor via one or more taut lines in such a manner that, for each for each floating unit and its associated connection line connected to the buoy:

- the buoy connection point assumes an intermediate buoy position when the floating unit assembly is in a condition in which the intermediate horizontal distance is reached between the buoy connection point and the floating unit connection point for the connection line, and

- a horizontal distance between the intermediate buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference between the maximum horizontal distance and the intermediate horizontal distance.

Again, the effect implied by the above ratio limits has been presented hereinabove and is not repeated here for the sake of brevity.

Optionally, one connection line connecting one of the two to six, preferably three to six, more preferred three, floating units to the same buoy has a largest nominal horizontal distance of the connection lines connecting the floating units to the same buoy and wherein one connection line connecting one of the two to six, preferably three to six, more preferred three, floating units to the same buoy has a smallest nominal horizontal distance of the connection lines connecting the floating units to the same buoy. The ratio between the largest nominal horizontal distance and the smallest nominal horizontal distance is less than 1.1, preferably less than 1.05.

As such, the lines connecting floating unit to the same buoy may be of approximately the same length.

Optionally, the connection lines connected to at least one, preferably each one, of the plurality of buoys, as seen in a plan view of the floating unit assembly, extend equiangularly from the buoy when no environmental loads are imparted on the floating unit assembly.

Optionally, the floating unit assembly comprises at least a pattern portion being such that a plan view of the portion forms a hexagonal pattern having straight lines and corners, wherein three floating units and three buoys are connected to each other by connection lines, forming the straight lines, and are located in the corners of the hexagonal pattern such that a floating unit and a buoy are always located in two adjacent corners of the hexagonal pattern.

Optionally, at least one pattern portion with the hexagonal pattern comprises an additional buoy located within the lines forming the hexagonal pattern, as seen in a plan view of the pattern portion, the additional buoy being connected to each one of the three floating units defining the hexagonal pattern by means of a connection line.

The additional buoy introduced hereinabove implies an increased redundancy to the floating unit assembly.

Optionally, one connection line connecting one of the three floating units to the additional buoy has a largest nominal horizontal distance of the connection lines connecting the three floating units to the additional buoy and wherein one connection line connecting one of the three floating units to the additional buoy has a smallest nominal horizontal distance of the connection lines connecting the three floating units to the additional buoy, the ratio between the largest nominal horizontal distance and the smallest nominal horizontal distance being less than 1.1, preferably less than 1.05.

As such, the lines connecting floating unit to the additional buoy may be of approximately the same length.

Optionally, the pattern portion is such that a plan view of the portion forms an equilateral hexagonal pattern.

Optionally, a floating unit assembly comprises a plurality of pattern portions according to the above.

Optionally, each floating unit is associated with a floating unit displacement, wherein at least one, preferably each one, of the plurality of buoys has a buoyancy, when the buoy is fully submerged, is within the range of 1 - 10 % of the floating unit displacement.

Optionally, at least one, preferably each one, of the connection lines imparts a restoring force on the floating unit to which the connection line is connected when no environmental loads are imparted on the floating unit assembly. The restoring force has a horizontal component being at least 75%, preferably at least 85%, more preferred at least 95 % of the restoring force.

Optionally, one of the floating units has a largest floating unit displacement of the floating units forming part of the floating unit assembly and another one of the floating units has a smallest floating unit displacement of the floating units forming part of the floating unit assembly. The ratio between the largest floating unit displacement and the smallest floating unit displacement may be less than 1.1 , preferably less than 1.05. As such, the floating units forming part of the floating unit assembly may be substantially similar.

Optionally, at least one, preferably each one, of the floating units comprises a wind turbine.

Optionally, for at least one buoy connected to a plurality of floating units, each connection line connecting the buoy to one of the floating units is connected to an individual buoy connection point of the buoy. Each individual buoy connection point is located at a nonzero distance in a vertical direction from each one of the other individual buoy connection points associated with the buoy when no environmental loads are imparted on the floating unit assembly. By virtue of the fact that the individual buoy connection points are separated in the vertical direction, the risk for obtaining large dynamic loads, for instance due to snapping, may be reduced.

Optionally, an adjacent buoy connection points distance in the vertical direction between two adjacent individual buoy connection points is in the range of 0.3 - 15 meters, preferably in the range of 1 - 5 meters when no environmental loads are imparted on the floating unit assembly.

Optionally, an adjacent buoy connection points distance in the vertical direction between two adjacent individual buoy connection points is in the range of 0.005%-0.05% of the water depth when no environmental loads are imparted on the floating unit assembly.

Optionally, the buoy is associated with a largest adjacent buoy connection points distance between two adjacent individual buoy connection points in the vertical direction and the buoy is associated with a smallest adjacent buoy connection points distance between two adjacent individual buoy connection points in the vertical direction. The ratio between the largest adjacent buoy connection points distance and the smallest adjacent buoy connection points distance is less than 1.1 , preferably less than 1.05 when no environmental loads are imparted on the floating unit assembly. As such, adjacent buoy connection points distances for one buoy may be approximately the same.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

In the drawings:

Fig. 1 is a schematic plan view of a portion of floating unit assembly according to an embodiment of the present invention;

Figs. 2a - 2c illustrate schematic side views of a portion of an embodiment of a floating unit assembly;

Figs. 3a - 3b illustrate schematic side views of a portion of another embodiment of a floating unit assembly;

Fig. 4 illustrates a portion of a floating unit assembly according to an embodiment of the present invention;

Fig. 5 illustrates the Fig. 4 portion of a floating unit assembly when imparted on by environmental loads from a first direction;

Fig. 6 illustrates the Fig. 4 portion of a floating unit assembly when imparted on by environmental loads from a second direction;

Fig. 7 is a schematic plan view of a portion of floating unit assembly according to another embodiment of the present invention, and

Fig. 8 illustrates a schematic perspective view of a portion of another embodiment of a floating unit assembly. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 is a schematic plan view of a portion of floating unit assembly 10 according to an embodiment of the present invention. It should be noted that the Fig. 1 embodiment comprises components (i.e. outside the dotted line in Fig. 1) in addition to the components illustrated in Fig. 1. Moreover, Figs. 2a - 2c illustrate a side view of a portion of the Fig. 1 embodiment of the floating unit assembly 10 in different conditions.

As may be gleaned from Fig. 1 , the floating unit assembly 10 is arranged in a body of water 12 with a seafloor 14 (see Figs. 2a - 2c). The floating unit assembly 10 comprises a plurality of floating units 16, 18, 20, 22, 24. Purely by way of example, each one of the floating units 16, 18, 20, 22, 24 may comprise a wind turbine (not shown in Fig. 1). However, it is also envisaged that one or more of the floating unit assemblies 16, 18, 20, 22, 24 may - instead of or in addition to - a wind turbine accommodate other equipment such as equipment for extracting energy from the environment - such as solar, wave or current energy - and/or equipment for drilling into the seafloor.

Moreover, though purely by way of example, one of the floating units 16, 18, 20, 22, 24 may have a largest floating unit displacement of the floating units 16, 18, 20, 22, 24 forming part of the floating unit assembly 10 and another one of the floating units 16, 18, 20, 22, 24 may have a smallest floating unit displacement of the floating units 16, 18, 20, 22, 24 forming part of the floating unit assembly 10. As a non-limiting example, the ratio between the largest floating unit displacement and the smallest floating unit displacement may be less than 1.1 , preferably less than 1.05. As such, as a non-limiting example, the floating units 16, 18, 20, 22, 24 forming part of the floating unit assembly 10 may be substantially similar.

Furthermore, as illustrated in Fig. 1, the floating unit assembly 10 comprises a plurality of buoys 26, 28, 30, 32, 34. Each buoy 26, 28, 30, 32, 34 is connected to the seafloor via one or more taut lines 48 (see Figs. 2a - 2c). Fig. 2a illustrates an embodiment comprising a single taut line 48 connecting a seafloor connection point 50 to a buoy 26. However, it is also envisaged that other embodiments may comprise a plurality of taut lines (not shown) connecting a buoy 26 to the seafloor 14. Purely by way of example, the seafloor connection point 50 may be implemented as an anchor (not shown). Purely by way of example, and as indicated in Fig. 2a for instance, at least one, preferably each one, of the plurality of buoys 26 has a cylindrical shape with a buoy base and a buoy height H. A buoy diameter D corresponds to the diameter of a largest circle that can be inscribed within the circumference of the buoy base. Purely by way of example, the buoy base may have a circular shape but is it also envisaged that the buoy base may have other shapes such as a square or rectangular shape. Moreover, a ratio between the buoy height and the buoy diameter may for instance be at least two, preferably at least three.

A such, at least one, preferably each one, of the plurality of buoys may be implemented as a so-called SPAR buoy, i.e. a relatively high and thin buoy. An advantage associated with a SPAR buoy is that it will generally be imparted relatively low environmental loads, e.g. wave loads, in particular relatively low horizontal loads.

Purely by way of example, each floating unit 16, 18, 20, 22, 24 may be associated with a floating unit displacement. Furthermore, at least one, preferably each one, of the plurality of buoys 26, 28, 30, 32, 34 has a buoyancy, when the buoy is fully submerged, that is within the range of 1 - 10 % of the floating unit displacement. The term “floating unit displacement” relates to the displacement of, viz the weight of the water that is displaced by, the floating unit when no environmental loads are imparted on the floating unit assembly 10. Purely by way of example, the buoyancy of a buoy when fully submerged may be determined by determining the total volume of the buoy and multiplying that volume with the density of the water in the body of water 12. As may be realized from the above, the ratio between the buoyancy of a buoy and the floating unit displacement may be determined using the total volume of the buoy and the volume of the fluid displaced by the floating unit when no environmental loads are imparted on the floating unit assembly 10.

Moreover, as indicated in Fig. 2a, the body of water 12 is associated with a water depth WD which is the vertical distance from the seafloor 14 to a still water surface 36 of the body of water 12. Purely by way of example, the water depth WD may be less than 100 meters, preferably less than 50 meters.

As a non-limiting example, the of buoys 26, 28, 30, 32, 34 may be arranged such that the vertical distance between the top of each buoy and the still water surface 36 is at least 20 meters in order to ensure that vessels, e.g. supply vessels, may travel above the buoys 26, 28, 30, 32, 34.

Moreover, again with reference to Fig. 2a, the buoy connection point 52 of each one of the plurality of buoys 26 may be adapted to be located at a vertical nominal distance VND above the seafloor 14 when no environmental loads are imparted on the floating unit assembly 10. Moreover, as exemplified in Fig. 2a, for at least one, preferably for each one, of the plurality of buoys 26, the nominal distance is at least 30%, preferably at least 50%, more preferred at least 70%, of the water depth WD.

As another non-limiting example, the water depth may be less than 300 meters and the buoy connection point 52 of each one of the plurality of buoys 26, 28, 30, 32, 34 is adapted to be located at a vertical nominal distance above the seafloor 14 when no environmental loads are imparted on the floating unit assembly 10. Furthermore, though purely by way of example, for at least one, preferably for each one, of the plurality of buoys 26, 28, 30, 32, 34, the nominal distance is at least 30%, preferably at least 50%, more preferred at least 70%, of the water depth.

As a further non-limiting example, the water depth may be greater than 1000 meters and the buoy connection point 52 of each one of the plurality of buoys 26, 28, 30, 32, 34 is adapted to be located at a vertical nominal distance above the seafloor 14 when no environmental loads are imparted on the floating unit assembly 10. Furthermore, though purely by way of example, for at least one, preferably for each one, of the plurality of buoys 26, 28, 30, 32, 34, the nominal distance is at least 50%, preferably at least 70%, more preferred at least 90%, of the water depth.

With reference to Figs. 1 and 2a - 2c, the floating unit assembly 10 comprises a plurality of connection lines 38, 40, 42, 44, 46 by which at least one floating unit 16 is connected to a plurality of buoys 26, 30, 34 and at least one buoy 30 is connected to a plurality of floating units 16, 20, 22. Purely by way of example, each one of the connection lines 38, 40, 42, 44, 46 comprises at least one of the following: fibres, a metal wire or a fibre-metal composite. It is also envisaged that at least one, or each one, of the connection lines 38, 40, 42, 44, 46 may comprise a plurality of line segments (not shown) forming the line. As a non-limiting example, at least one, preferably each one, of the plurality of buoys 26, 28, 30, 32, 34 is connected to at least two to six, preferably three to six, more preferred three, floating units 16, 18, 20, 22, 24. In the Fig. 1 embodiment, the connection lines 38, 40, 42, 44, 46 connected to at least one, preferably each one, of the plurality of buoys 26, 28, 30, 32, 34, as seen in a plan view of the floating unit assembly, extend equiangularly from the buoy 26, 28, 30, 32, 34 when no environmental loads are imparted on the floating unit assembly.

As a non-limiting example, and as exemplified in Fig. 1 , the floating unit assembly 10 may comprise at least a pattern portion being such that a plan view of the portion forms a hexagonal pattern having straight lines and corners, wherein three floating units 16, 18, 20 and three buoys 26, 30, 32 are connected to each other by connection lines, forming the straight lines, and are located in the corners of the hexagonal pattern such that a floating unit and a buoy are always located in two adjacent corners of the hexagonal pattern. Purely by way of example, and as indicated in Fig. 1, the pattern portion may be such that a plan view of the portion forms an equilateral hexagonal pattern. Preferably, and as also indicated in Fig. 1 , a floating unit assembly 10 may comprise a plurality of pattern portions, e.g. hexagonal pattern portions.

Purely by way of example, in a situation when for instance three floating units are connected to the same buoy, such as a configuration illustrated in Fig. 1, two out of the three floating units connected to the same buoy may load the same buoy with their simultaneous maximum force, imparting a resultant force at the shared buoy equal to the maximum force at the buoy from only one floating unit, meaning the shared buoy need not be bigger or more expensive compared to a buoy accommodating only one floating unit.

Moreover, with reference to Figs. 2a - 2b, the floating unit assembly 10 is such that each connection line 38 connects a buoy connection point 52 of a buoy 26 to a floating unit connection point 54 of a floating unit 16 and each connection line is associated with a nominal horizontal distance d_nOm and a maximum horizontal distance d_max.

With reference to Fig. 2a, the nominal horizontal distance d_nOm is the horizontal distance between the buoy connection point 52 and the floating unit connection point 54 in a condition when no environmental loads are imparted on the floating unit assembly 10. Purely by way of example, and as may be gleaned in Fig. 2a, the connection line 38 may have a catenary shape when no environmental loads are imparted on the floating unit assembly 10. In Fig. 2a, such a catenary shape has been exaggerated in order to elucidate the difference between the Fig. 2a and Fig. 2b conditions. As has been indicated above, the nominal horizontal distance d_nOm may for instance be determined using mooring system software such as as MIMOSA®, OrcaFlex® or Flexcom®.

Further, as indicated in Fig. 2a, at least one, preferably each one, of the connection lines 38 imparts a restoring force R on the floating unit to which the connection line is connected when no environmental loads are imparted on the floating unit assembly 10. The restoring force R has a horizontal component Rhor being at least 75%, preferably at least 85%, more preferred at least 95 % of the restoring force. As such, the ratio between the horizontal component Rhor and the total restoring force R may be at least 75%, preferably at least 85%, more preferred at least 95 %.

Moreover, as illustrated in Fig. 2b, the maximum horizontal distance d_max is the largest horizontal distance that can be obtained between the buoy connection point 52 and the floating unit connection point 54 whilst being connected by the connection line. In Fig. 2b, the connection line 38 has been illustrated as a substantially straight line connecting the buoy connection point 52 and the floating unit connection point 54 when the maximum horizontal distance d_max therebetween is obtained. However, it is of course possible that the connection line 38 will assume a catenary shape - although less pronounced as compared to the Fig. 2a condition - also when the maximum horizontal distance dmax is obtained.

Purely by way of example, the maximum horizontal distance dmax is the maximum distance that can be obtained between the buoy connection point 52 and the floating unit connection point 54 until a breaking load or breaking stress has been obtained in the connection line 38. As a non-limiting example, the maximum horizontal distance dmax may for instance be determined using mooring system software such as as MIMOSA®, OrcaFlex® or Flexcom®. To this end, with reference to Fig. 2b, for instance using a mooring system software, the floating unit 16 may be imparted a movement away from the seafloor connection point 50 until the load or stress in the connection line 38 has reached a predetermined breaking load or stress. When such a predetermined braking load or stress is identified, the maximum horizontal distance dmax may be determined. Of course, the above procedure can also be carried out for each of the of the floating units 16, 18, 20, 22, 24 at the same time.

According to the present invention, for at least a first connection line 38 of the connection lines, the ratio between the maximum horizontal distance d_max and the nominal horizontal distance d_nOm is less than 110%, preferably less than 105%, more preferred less than 102%.

The above ratio can be achieved in a plurality of different ways. Purely by way of example, and as indicated in Fig. 2a and Fig. 2b, the ratio can be achieved by implementing the connection line 38 so as to assume a catenary shape when no environmental loads are imparted on the floating unit assembly 10 (see Fig. 2a) and so as to assume a shape with a less pronounced catenary shape when the maximum horizontal distance d_max is obtained between the buoy connection point 52 and the floating unit connection point 54.

As another non-limiting example, the above-mentioned ratio can be obtained by an elastic connection line 38 that may be substantially straight even when no environmental loads are imparted on the floating unit assembly 10 and which is allowed to be extended, e.g. elastically extended, in order to arrive at the maximum horizontal distance dmax.

Of course, it is also envisaged that a combination of the above-mentioned alternatives, viz the catenary shape and the extension, e.g. elastic extension, of the connection line 38 may be implemented in embodiments of the floating unit assembly 10.

According to embodiments of the floating unit assembly 10, as exemplified in Fig. 2a and Fig. 2b, the buoy 26, to which the first connection line 38 is connected, is connected to the seafloor 14 via one or more taut lines 48 in such a manner that the buoy connection point 52 assumes a nominal buoy position in a condition when no environmental loads are imparted on the floating unit assembly. Again, such a condition is illustrated in Fig. 2a.

Moreover, the buoy 26, to which the first connection line 38 is connected, is connected to the seafloor 14 via one or more taut lines 48 in such a manner that the buoy connection point assumes a maximum buoy position when the floating unit assembly 10 is in a condition in which the maximum horizontal distance dmax is reached between the buoy connection point 52 and the floating unit connection point 54 for the first connection line 38.

Moreover, a horizontal distance L_max between the nominal buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference A_max between the maximum horizontal distance d_max and the nominal horizontal distance d_nOm.

Moreover, with reference to Fig. 2c, in embodiments of the floating unit assembly 10, at least the first connection line 38 of the connection lines is associated with an intermediate horizontal distance dmter being the average of the nominal horizontal distance and the maximum horizontal distance. Furthermore, in the Fig. 2c embodiment, the buoy 26, to which the first connection line 38 is connected, is connected to the seafloor 14 via one or more taut lines 48 in such a manner that the buoy connection point 52 assumes an intermediate buoy position when the floating unit assembly is in a condition in which the intermediate horizontal distance dmter is reached between the buoy connection point and the floating unit connection point for the first connection line.

Moreover, as indicated in Fig. 2c, a horizontal distance Lmter between the intermediate buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference Amter between the maximum horizontal distance d_max and the intermediate horizontal distance djnter-

The above features imply that when the floating unit has been offset from its nominal position and thereafter is offset further, a major part of the flexibility may be attributed to the movement of the buoy rather than to the characteristics of the first connection line. This in turns implies that in a storm condition for instance in which elements of the floating unit assembly will be positioned in static offset positions as compared to nominal positions, a major part of the dynamic flexibility may be attributed to the movement of the buoy rather than to the characteristics of the first connection line.

It should be noted that in embodiments of the floating unit assembly 10 the first connection lines need not necessarily have the above-mentioned ratio between the maximum horizontal distance dmax and the nominal horizontal distance d_nOm. Instead, the desired distribution of the station keeping flexibility of the floating unit assembly 10 may be achieved by the fact that the flexibility derivable from the taut lines and the buoys is greater than the flexibility derivable from the connection lines even when a not negligible flexibility can be attributed to the connection lines.

As such, with reference to Figs. 2a - 2b, in embodiments of the floating unit assembly 10, the nominal horizontal distance d_nOm is the horizontal distance between the buoy connection point 52 and the floating unit connection point 54 in a condition when no environmental loads are imparted on the floating unit assembly. Moreover, as has been presented hereinabove with reference to Fig. 2b, the maximum horizontal distance d_max is the largest horizontal distance that can be obtained between the buoy connection point 52 and the floating unit connection point 54 whilst being connected by the connection line.

Moreover, with reference to Fig. 2a and Fig. 2b, the buoy 26, to which the first connection line is connected 38, is connected to the seafloor 14 via one or more taut lines 48 in such a manner that the buoy connection point 52 assumes a nominal buoy position in a condition when no environmental loads are imparted on the floating unit assembly 10. Again, such a condition is illustrated in Fig. 2a. Moreover, with reference to Fig. 2b, the buoy 26 is connected to the seafloor 14 via one or more taut lines 48 in such a manner that the buoy connection point 52 assumes a maximum buoy position when the floating unit assembly 10 is in a condition in which the maximum horizontal distance d_max is reached between the buoy connection point 52 and the floating unit connection point 54 for the first connection line 38.

Embodiments of the floating unit assembly 10 may be such that a horizontal distance L_max between the nominal buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference A_max between the maximum horizontal distance dmax and the nominal horizontal distance d_nOm.

Moreover, again with reference to Fig. 2b and Fig. 2c, the first connection line 38 may be associated with an intermediate horizontal distance dmter being the average of the nominal horizontal distance d_nOm and the maximum horizontal distance dmax. Moreover, the buoy 26, to which the first connection line 38 is connected, is connected to the seafloor 14 via one or more taut lines 48 in such a manner that the buoy connection point 52 assumes an intermediate buoy position (see Fig. 2c) when the floating unit assembly 10 is in a condition in which the intermediate horizontal distance dmter is reached between the buoy connection point 52 and the floating unit connection point 54 for the first connection line 38. A horizontal distance Lmter between the intermediate buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference between the maximum horizontal distance dmax and the intermediate horizontal distance d_nOm.

Fig. 3a illustrates a portion of another embodiment of a floating unit assembly 10. The portion of the Fig. 3a embodiment has many features in common with the embodiments discussed hereinabove with reference to Figs. 2a - 2c and such features are not elaborated on herein for the sake of brevity. However, a difference between e.g. the Fig. 2a and Fig. 3a embodiments is that in the Fig. 3a embodiment, at least one, preferably each one, of the plurality of buoys 26 is adapted to intersect the still water surface 36 of the body of water 12 when no environmental loads are imparted on the floating unit assembly 10.

An advantage with the fact that at least one of the buoys 26 intersects the still water surface 36 of the body of water 12 is that in normal conditions of the floating unit assembly 10, e.g. in benign environmental conditions, an uplifting force imparted on the seafloor connection point 50, e.g. an anchor, by the buoy 26 may be relatively low since only a portion of the buoy 26 is submerged. This in turn implies that the costs for the seafloor connection points 50, e.g. anchors, may be kept appropriately low.

As will be presented hereinbelow with reference to Fig. 3b, an increased submersion of the buoy 26 may occur when the floating unit 16 has been offset from its nominal position, e.g. when the floating unit assembly 10 is subjected to large environmental loads. Such an increased submersion may result in an increased uplift on the seafloor connection point 50 but such an increased uplift will only occur for a limited period of time during the life of the floating unit assembly 10.

Furthermore, Fig. 3a schematically illustrates that the floating unit 16 may comprise a wind turbine 60. Moreover, in the Fig. 3a embodiment, the buoy connection point 52 is located beneath the buoy 26. To this end, Fig. 3a illustrates an embodiment in which the buoy connection point 52 is connected to the one or more taut lines 48 such that a bottom portion 48’ of the one or more taut lines 48 connects the seafloor connection point 50 to the buoy connection point 52 and a top portion 48” of the of the one or more taut lines 48 connects the buoy connection point 52 to the buoy 26. It should be noted that the above- mentioned implementation that the buoy connection point 52 is located beneath the buoy 26 may be used for any embodiment of the floating unit assembly 10, e.g. the embodiment that have been discussed above with reference to Figs. 2a - 2c.

Furthermore, it should be noted that in other embodiments of the floating unit assembly 10, the buoy connection point 52 may assume other positions relative a buoy 26. Purely by way of example, in embodiments of the floating unit assembly 10 a buoy connection point 52 may be located in an upper region, e.g. the top 20%, of a buoy 26.

Fig. 3b illustrates the Fig. 3a portion of the floating unit assembly embodiment wherein the floating unit 16 has been offset from the position that it assumes when no environmental loads are imparted on the floating unit assembly 10. As may be gleaned in Fig. 3b, when the floating unit is offset, the buoy 26 may be further, possibly even fully, submerged, resulting in an increased buoyancy of the buoy 26. Such an increased buoyancy implies that the buoy 26 imparts a more rapid increase of the restoring force on the floating unit 16, as compared to a condition in which the buoy is fully submerged also in a nominal condition, thus implying that the horizontal stiffness from the one or more taut lines 48 and the buoy 26 may increase more rapidly when the floating unit 16 is displaced from its initial position.

Fig. 4 illustrates a portion of a floating unit assembly 10 according to an embodiment of the present invention. Purely by way of example, the portion illustrated in Fig. 4 may form part of any one of the embodiments presented hereinabove with reference to Fig. 1 - Fig. 3b.

As has been intimated hereinabove, at least one, preferably each one, of the plurality of buoys 26, 28, 30, 32, 34 may be connected to at least two to six, preferably three to six, more preferred three, floating units 16, 18, 20, 22, 24. The portion of a floating unit assembly 10 illustrated in Fig. 4 comprises a buoy 30 that is connected to exactly three floating units 16, 20, 22. Purely by way of example, and as indicated in Fig. 4, the connection lines 42, 44, 46 connected to the Fig. 4 buoy 30, as seen in a plan view of the floating unit assembly 10, extend equiangularly from the buoy 30 when no environmental loads are imparted on the floating unit assembly 10.

Moreover, though purely by way of example, the Fig. 4 buoy 30 may be connected to each floating unit 16, 20, 22 such that for each connection line 40, 42, 44 connecting the buoy 26 to a floating unit 16, 20, 22, the ratio between the maximum horizontal distance dmax (see e.g. Fig. 2b) and the nominal horizontal distance d_nOm (see e.g. Fig. 2a) is less than 110%, preferably less than 105%, more preferred less than 102%.

Moreover, though purely by way of example, instead of or in addition to the above relation between the maximum horizontal distance d_max and the nominal horizontal distance d_nOm, the Fig. 4 buoy 30 may be connected to the seafloor 14 (see e.g. Fig. 2a) via one or more taut lines 48 (see e.g. Fig. 2a) in such a manner that, for each floating unit 16, 20, 22 and its associated connection line 42, 44, 46 connected to the buoy 30:

- the buoy connection point 52 (see Fig. 2a) assumes a nominal buoy position in a condition when no environmental loads are imparted on the floating unit assembly 10;

- the buoy connection point 52 assumes a maximum buoy position when the floating unit assembly 10 is in a condition in which the maximum horizontal distance dmax is reached between the buoy connection point 52 and the floating unit connection point 54 for the connection line 42, 44, 46, and

- a horizontal distance L_max between the nominal buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference Amax between the maximum horizontal distance dmax and the nominal horizontal distance d_nOm.

Moreover, though purely by way of example, instead of or in addition to the above relation between the maximum horizontal distance dmax and the nominal horizontal distance d_nOm, and/or the relation between the horizontal distance L_max between the nominal buoy position and the maximum buoy position and the difference Amax, the buoy 30 connected to the three floating units 16, 20, 22 in Fig. 4 may be connected to the seafloor 14 via one or more taut lines 48 in such a manner that, for each for each floating unit 16, 20, 22 and its associated connection line 42, 44, 46 connected to the buoy 30: - the buoy connection point 52 (reference again being made to Fig. 2a for instance) assumes an intermediate buoy position when the floating unit assembly 10 is in a condition in which the intermediate horizontal distance dmter (see Fig. 2c) is reached between the buoy connection point 52 and the floating unit connection point 54 for the connection line 40, 42, 44, and

- a horizontal distance Lmter between the intermediate buoy position and the maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference Amter between the maximum horizontal distance d_max and the intermediate horizontal distance dmter.

Moreover, again with reference to Fig. 4, one connection line 42, 44, 46 connecting one of the three floating units 16, 20, 22 to the same buoy 30 has a largest nominal horizontal distance d_nOm,max of the connection lines 42, 44, 46 connecting the floating units 16 20, 22 to the same buoy 30. In Fig. 4, the largest nominal horizontal distance d_nOm,max is exemplified as being attributable to line 42 but the largest nominal horizontal distance dnom.max may of course be attributable to any one of the other lines 44, 46 instead.

Moreover, one connection line 42, 44, 46 connecting one of the three floating units 16, 20, 22 to the same buoy 30 has a smallest nominal horizontal distance d_nOm,min of the connection lines connecting the floating units 16, 18, 20, 22, 24 to the same buoy 30. In Fig. 4, the smallest nominal horizontal distance d_nOm,min is exemplified as being attributable to line 44 but the smallest nominal horizontal distance d_nOm,min may of course be attributable to any one of the other lines 42, 46 instead.

In embodiments of the floating unit assembly 10, the ratio dnom,max/dnom,min between the largest nominal horizontal distance d_nOm,maxand the smallest nominal horizontal distance dnom,min may be less than 1.1 , preferably less than 1.05.

It should be noted that the features that have been presented with reference to Fig. 4 are equally applicable to embodiments of the floating unit assembly 10 in which at least one, preferably each one, of the plurality of buoys 26, 28, 30, 32, 34 is connected to fewer or more than three buoys. For instance, the above features are equally applicable to embodiments in which at least one, preferably each one, of the plurality of buoys 26, 28, 30, 32, 34 is connected to at least two to six, preferably three to six, floating units (not shown in Fig. 4). However, advantages associated with the Fig. 4 embodiment, in which a buoy 30 is connected to exactly three floating units 16, 20, 22, will be presented hereinbelow with reference to Fig. 5 and Fig. 6.

Fig. 5 illustrates the Fig. 4 embodiment of the floating unit assembly 10 in a first environmental condition. The environmental loads associated with the first environmental condition are illustrated by arrows at the bottom of Fig. 5, which arrows are directed upwards in Fig. 5, indicating that the environmental loads are directed upwards in Fig. 5. Such environmental loads will cause the floating units 16, 20, 22 to be displaced upwards in Fig. 5, as a consequence of which the buoy 30 will also be displaced upwards. In Fig. 5, the nominal position of elements of the floating unit assembly 10 is illustrated by dashed lines and the displaced position of elements of the floating unit assembly 10 is illustrated by solid lines.

In the displaced condition illustrated in Fig. 5, the lines 44, 46 will be slackened, thus imparting a low, almost negligible, load on the buoy 30. As such, in the Fig. 5 condition, the load imparted on the buoy 30 will emanate from the upper buoy 16 in Fig. 5 and the upper buoy 16 may impart a resulting load F_res on the buoy 30.

Fig. 6 illustrates the Fig. 4 embodiment of the floating unit assembly 10 in a second environmental condition. The environmental loads associated with the second environmental condition are illustrated by arrows at the top of Fig. 6, which arrows are directed downwards in Fig. 6, indicating that the environmental loads are directed downwards in Fig. 6. Such environmental loads will cause the floating units 16, 20, 22 to be displaced downwards in Fig. 6, as a consequence of which the buoy 30 will also be displaced downwards. As for Fig. 5, in Fig. 6, the nominal position of elements of the floating unit assembly 10 is illustrated by dashed lines and the displaced position of elements of the floating unit assembly 10 is illustrated by solid lines.

In the displaced condition illustrated in Fig. 6, the line 42 will be slackened, thus imparting a low, almost negligible, load on the buoy 30. As such, in the Fig. 6 condition, the loads imparted on the buoy 30 will emanate from the lower buoys 20, 22. However, as may be gleaned from Fig. 6, the loads from the buoys 20, 22 will have components in a transversal direction (viz sideways) in Fig. 6 as well as in a longitudinal direction (viz from bottom to top) in Fig. 6. Moreover, as may be realized from Fig. 6, the transversally extending components of the loads from the buoys will cancel out each other, or at least substantially cancel out each other, as a consequence of which the resulting load from the buoys 20, 22 emanates from the vertical load components only. The vertical load components will sum up to a resulting load F_res on the buoy 30 which is substantially the same as the resulting load F_res from the Fig. 5 condition, assuming that the magnitude of the environmental loads is the same in the Fig. 5 and Fig. 6 environmental conditions.

Thus, irrespective of the heading of the environmental loads imparted on the Fig. 4 embodiment of the floating unit assembly 10, the load imparted on the buoy 30 may be substantially the same. This in turn implies that the buoys and the associated one or more taut lines (not shown in Figs. 4 - 6) may have a standardised design that in turn may result in that that the buoys and/or taught lines may be produced in a straightforward manner at reasonable costs.

For the Fig. 4 embodiment, it is beneficial if the ratio between the largest floating unit displacement and the smallest floating unit displacement may be less than 1.1 , preferably less than 1.05, as has been presented hereinabove. However, the load sharing and load cancelling features of the Fig. 4 embodiment may still be present, even if there are differences, e.g. differences in displacement, amongst the floating units connected to the same buoy.

As has been presented hereinabove with reference to Fig. 1 , the floating unit assembly 10 may comprise at least a pattern portion being such that a plan view of the portion forms a hexagonal pattern having straight lines and corners. Moreover, three floating units 16, 18, 20, 22, 24 and three buoys 26, 28, 30, 32, 34 are connected to each other by connection lines 38, 40, 42, 44, 46, forming the straight lines, and may be located in the corners of the hexagonal pattern such that a floating unit 16, 18, 20, 22, 24 and a buoy 26, 28, 30, 32, 34 are always located in two adjacent corners of the hexagonal pattern.

Moreover, Fig. 1 illustrates an embodiment of a floating unit assembly 10 with such a hexagonal pattern wherein the area delimited by a hexagonal is free from floating units and buoys. However, Fig. 7 illustrates a portion of another embodiment of the floating unit assembly 10 in which at least one pattern portion with the hexagonal pattern comprises an additional buoy 50 located within the lines forming the hexagonal pattern, as seen in a plan view of the pattern portion. The additional buoy 50 is connected to each one of the three floating units 16, 18, 20 defining the hexagonal pattern by means of a connection line 54, 56, 58.

Moreover, one connection line 54, 56, 58 connecting one of the three floating units 16, 18, 20 to the additional buoy may have a largest nominal horizontal distance d_nOm,maxOf the connection lines connecting the three floating units 16, 18, 20 to the additional buoy 52. Moreover, one connection line 54, 56, 58 connecting one of the three floating units 16, 18, 20 to the additional buoy 52 may have a smallest nominal horizontal distance d_nOm,min of the connection lines 54, 56, 58 connecting the three floating units 16, 18, 20 to the additional buoy 52.

The ratio dnom.max/ dnom.min between the largest nominal horizontal distance dnom,max and the smallest nominal horizontal distance d_nOm,min may be less than 1.1 , preferably less than 1.05.

Moreover, as for the Fig. 1 embodiment, the pattern portion of the Fig. 7 embodiment may be such that a plan view of the portion forms an equilateral hexagonal pattern.

In the embodiments presented hereinbelow, one or more of the plurality of connection lines may be connected to a common buoy connection point of a buoy. However, Fig. 8 illustrates a portion of an embodiment of a floating unit assembly 10 in which each line associated with a buoy 26 has an individual buoy connection point. In Fig. 8, the portion is illustrated in a perspective view in order to illustrate the differences in vertical positions as well as the horizontal extensions of the lines 42, 44, 46. Although Fig. 8 only illustrates a single buoy 28, the embodiments and implementations presented hereinbelow may be applied to a plurality of buoys, or even each buoy, of a floating unit assembly 10, wherein each one of the buoys is connected to a plurality of floating units by means of connection lines.

Fig. 8 illustrates a portion of floating unit assembly 10, which portion comprises a buoy 26 that is connected a seafloor connection point 50 by means of a single taut line 48. However, in other embodiments of the floating unit assembly 10, a plurality of taut lines (not shown) may be used for connecting the buoy 26 to the seafloor.

Moreover, in the Fig. 8 embodiment, each one of three connection lines 42, 44, 46 connects an individual floating unit (not shown in Fig. 8) to the buoy 26. However, it is of course contemplated that other embodiments of the floating unit assembly 10 may comprise fewer or more connection lines than three, each one of which connecting an individual floating unit to the buoy 26.

Furthermore, as indicated in Fig. 8, for at least one buoy, such as the buoy 26 illustrated in Fig. 8, connected to a plurality of floating units, each connection line 42, 44, 46 connecting the buoy 26 to one of the floating units is connected to an individual buoy connection point 62, 64, 66 of the buoy 26. As such, in the Fig. 8 example, a first connection line 42 is connected to a first individual buoy connection point 62 of the buoy 26, a second connection line 44 is connected to a second individual buoy connection point 64 of the buoy 26 and a third connection line 46 is connected to a third individual buoy connection point 66 of the buoy 26.

In the example illustrated in Fig. 8, each one of the connection points 62, 64, 66 is located on the single taut line 48 such that each connection line 42, 44, 46 is connected to the single taut line 48. However, it should be noted that in other embodiments of the floating unit assembly 10, each connection point 62, 64, 66 may be located on an individual taut line (not shown) connecting the buoy 26 to the seafloor. As another non-limiting example, one or more of the connection points 62, 64, 66 may be located on the buoy 26 as such, as a consequence of which each connection line 42, 44, 46 may be directly connected to the buoy 26.

Moreover, as indicated in Fig. 8, each individual buoy connection point 62, 64, 66 is located at a non-zero distance in a vertical direction V from each one of the other individual buoy connection points associated with the buoy 26 when no environmental loads are imparted on the floating unit assembly 10.

As indicated in Fig. 8, though purely by way of example, the first individual buoy connection point 62 and the second individual buoy connection point 64 are adjacent each other and there is a first adjacent buoy connection points distance Di between the connection points 62, 64. In a similar vein, though purely by way of example, the second individual buoy connection point 64 and the third individual buoy connection point 66 are adjacent each other and there is a second adjacent buoy connection points distance D2 between the connection points 64, 66. For the sake of completeness, it should be noted that the first individual buoy connection point 62 and the third individual buoy connection point 66 are not adjacent each other since the second individual buoy connection point 64 is located therebetween. Again, the above distances relate to a condition in which no environmental loads are imparted on the floating unit assembly 10.

Purely by way of example, an adjacent buoy connection points distance Di , D2 in the vertical direction V between two adjacent individual buoy connection points may be in the range of 0.3 - 15 meters, preferably in the range of 1 - 5 meters.

As another non-limiting example, an adjacent buoy connection points distance Di , D2 in the vertical direction between two adjacent individual buoy connection points may be in the range of 0.005%-0.05% of the water depth WD.

Moreover, the buoy 26 may be associated with a largest adjacent buoy connection points distance Di between two adjacent individual buoy connection points 62, 64 in the vertical direction V and the buoy 26 may be associated with a smallest adjacent buoy connection points distance D2 between two adjacent individual buoy connection points 64, 66 in the vertical direction V. As a non-limiting example, the ratio D1/D2 between the largest adjacent buoy connection points distance Di and the smallest adjacent buoy connection points distance D2 may be less than 1.1, preferably less than 1.05.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

1. A floating unit assembly (10) arranged in a body of water (12) with a seafloor (14), said floating unit assembly (10) comprising:

- a plurality of floating units (16, 18, 20, 22, 24),

- a plurality of buoys (26, 28, 30, 32, 34), each buoy (26, 28, 30, 32, 34) being connected to said seafloor (14) via one or more taut lines (48),

- a plurality of connection lines (38, 40, 42, 44, 46) by which at least one floating unit (16, 18, 20, 22, 24) is connected to a plurality of buoys (26, 28, 30, 32, 34) and at least one buoy (26, 28, 30, 32, 34) is connected to a plurality of floating units (16, 18, 20, 22, 24),

- wherein each connection line (38, 40, 42, 44, 46) connects a buoy connection point (52) of a buoy (26, 28, 30, 32, 34) to a floating unit connection point (54) of a floating unit (16, 18, 20, 22, 24) and each connection line (38, 40, 42, 44, 46) is associated with a nominal horizontal distance (d_nOm) and a maximum horizontal distance (d_max), wherein: i. said nominal horizontal distance (d_nOm) is the horizontal distance between said buoy connection point (52) and said floating unit connection point (54) in a condition when no environmental loads are imparted on said floating unit assembly (10), and ii. said maximum horizontal distance (d_max) is the largest horizontal distance that can be obtained between said buoy connection point (52) and said floating unit connection point (54) whilst being connected by said connection line (38, 40, 42, 44, 46), c h a ra cte r i z e d i n t h a t : for at least a first connection line (38, 40, 42, 44, 46) of said connection lines (38, 40, 42, 44, 46), the ratio between said maximum horizontal distance (dmax) and said nominal horizontal distance (d_nOm) is less than 110%, preferably less than 105%, more preferred less than 102%.

2. The floating unit assembly (10) according to claim 1 , wherein said buoy (26, 28, 30, 32, 34), to which said first connection line (38, 40, 42, 44, 46) is connected, is connected to said seafloor (14) via one or more taut lines (48) in such a manner that:

- said buoy connection point (52) assumes a nominal buoy position in a condition when no environmental loads are imparted on said floating unit assembly (10), and - said buoy connection point (52) assumes a maximum buoy position when said floating unit assembly (10) is in a condition in which said maximum horizontal distance (d_max) is reached between said buoy connection point (52) and said floating unit connection point (54) for said first connection line (38, 40, 42, 44, 46), wherein a horizontal distance (L_max) between said nominal buoy position and said maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference (A_max) between said maximum horizontal distance (d_max) and said nominal horizontal distance (d_nOm). The floating unit assembly (10) according to claim 2, wherein at least said first connection line (38, 40, 42, 44, 46) of said connection lines (38, 40, 42, 44, 46) is associated with an intermediate horizontal distance (dmter) being the average of said nominal horizontal distance (d_nOm) and said maximum horizontal distance (dmax), wherein said buoy (26, 28, 30, 32, 34), to which said first connection line (38, 40, 42, 44, 46) is connected, is connected to said seafloor (14) via one or more taut lines (48) in such a manner that:

- said buoy connection point (52) assumes an intermediate buoy position when said floating unit assembly (10) is in a condition in which said intermediate horizontal distance (dmter) is reached between said buoy connection point (52) and said floating unit connection point (54) for said first connection line (38, 40, 42, 44, 46), wherein a horizontal distance (Lmter) between said intermediate buoy position and said maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference (Amter) between said maximum horizontal distance (dmax) and said intermediate horizontal distance (d inter). A floating unit assembly (10) arranged in a body of water (12) with a seafloor (14), said floating unit assembly (10) comprising:

- a plurality of floating units (16, 18, 20, 22, 24),

- wherein each connection line (38, 40, 42, 44, 46) connects a buoy connection point (52) of a buoy (26, 28, 30, 32, 34) to a floating unit connection point (54) of a floating unit (16, 18, 20, 22, 24) and each connection line (38, 40, 42, 44, 46) is associated with a nominal horizontal distance (d_nOm) and a maximum horizontal distance (d_max), wherein: i. said nominal horizontal distance (d_nOm) is the horizontal distance between said buoy connection point (52) and said floating unit connection point (54) in a condition when no environmental loads are imparted on said floating unit assembly (10), and ii. said maximum horizontal distance (d_max) is the largest horizontal distance that can be obtained between said buoy connection point (52) and said floating unit connection point (54) whilst being connected by said connection line (38, 40, 42, 44, 46), wherein said buoy (26, 28, 30, 32, 34), to which said first connection line (38, 40, 42, 44, 46) is connected, is connected to said seafloor (14) via one or more taut lines (48) in such a manner that:

- said buoy connection point (52) assumes a nominal buoy position in a condition when no environmental loads are imparted on said floating unit assembly (10),

- said buoy connection point (52) assumes a maximum buoy position when said floating unit assembly (10) is in a condition in which said maximum horizontal distance (dmax) is reached between said buoy connection point (52) and said floating unit connection point (54) for said first connection line (38, 40, 42, 44, 46), ch a ra cte ri ze d i n th at a horizontal distance (L_max) between said nominal buoy position and said maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference (A_max) between said maximum horizontal distance (dmax) and said nominal horizontal distance (d nom)- A floating unit assembly (10) according to claim 4, wherein said first connection line (38, 40, 42, 44, 46) is associated with an intermediate horizontal distance (dmter) being the average of said nominal horizontal distance (d_nOm) and said maximum horizontal distance (d max), wherein said buoy (26, 28, 30, 32, 34), to which said first connection line (38, 40, 42, 44, 46) is connected, is connected to said seafloor (14) via one or more taut lines (48) in such a manner that:

- said buoy connection point (52) assumes an intermediate buoy position when said floating unit assembly (10) is in a condition in which said intermediate horizontal distance is reached between said buoy connection point (52) and said floating unit connection point (54) for said first connection line (38, 40, 42, 44, 46), wherein a horizontal distance between said intermediate buoy position and said maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference (Amter) between said maximum horizontal distance (d_max) and said intermediate horizontal distance (d inter). The floating unit assembly (10) according to any of the preceding claims, wherein each one of said connection lines (38, 40, 42, 44, 46) comprises at least one of the following: fibres, a metal wire or a fibre-metal composite. The floating unit assembly (10) according to any of the preceding claims, wherein said body of water (12) is associated with a water depth being the vertical distance from said seafloor (14) to a still water surface of said body of water (12), preferably said water depth is less than 100 meters, preferably less than 50 meters. The floating unit assembly (10) according to claim 7, wherein the buoy connection point (52) of each one of said plurality of buoys (26, 28, 30, 32, 34) is adapted to be located at a vertical nominal distance above said seafloor (14) when no environmental loads are imparted on said floating unit assembly (10), wherein for at least one, preferably for each one, of said plurality of buoys (26, 28, 30, 32, 34), said nominal distance is at least 30%, preferably at least 50%, more preferred at least 70%, of said water depth. The floating unit assembly (10) according to claim 7 or claim 8, wherein said water depth is less than 300 meters and the buoy connection point (52) of each one of said plurality of buoys (26, 28, 30, 32, 34) is adapted to be located at a vertical nominal distance above said seafloor (14) when no environmental loads are imparted on said floating unit assembly (10), wherein for at least one, preferably for each one, of said plurality of buoys (26, 28, 30, 32, 34), said nominal distance is at least 30%, preferably at least 50%, more preferred at least 70%, of said water depth. The floating unit assembly (10) according to claim 7 or claim 8, wherein said water depth is greater than 1000 meters and the buoy connection point (52) of each one of said plurality of buoys (26, 28, 30, 32, 34) is adapted to be located at a vertical nominal distance above said seafloor (14) when no environmental loads are imparted on said floating unit assembly (10), wherein for at least one, preferably for each one, of said plurality of buoys (26, 28, 30, 32, 34), said nominal distance is at least 50%, preferably at least 70%, more preferred at least 90%, of said water depth. The floating unit assembly (10) according to any of the preceding claims, wherein at least one, preferably each one, of said plurality of buoys (26, 28, 30, 32, 34) is adapted to intersect a still water surface of said body of water (12) when no environmental loads are imparted on said floating unit assembly (10). The floating unit assembly (10) according to any of the preceding claims, wherein at least one, preferably each one, of said plurality of buoys (26, 28, 30, 32, 34) has a cylindrical shape with a buoy base and a buoy height, wherein a buoy diameter corresponds to the diameter of a largest circle that can be inscribed within the circumference of said buoy base, a ratio between said buoy height and said buoy diameter being at least two, preferably at least three. The floating unit assembly (10) according to any of the preceding claims, wherein at least one, preferably each one, of said plurality of buoys (26, 28, 30, 32, 34) is connected to at least two to six, preferably three to six, more preferred three, floating units (16, 18, 20, 22, 24). The floating unit assembly (10) according to any of the preceding claims, wherein at least one, preferably more than one, of said plurality of buoys (26, 28, 30, 32, 34) is connected to exactly three floating units (16, 18, 20, 22, 24). The floating unit assembly (10) according to claim 13 or 14, wherein said buoy (26, 28, 30, 32, 34) being connected to at least two to six, preferably three to six, more preferred three, floating units (16, 18, 20, 22, 24), is connected to each floating unit (16, 20, 22) such that for each connection line (40, 42, 44) connecting said buoy (26) to a floating unit (16, 20, 22), the ratio between said maximum horizontal distance (d_max) and said nominal horizontal distance (d_nOm) is less than 110%, preferably less than 105%, more preferred less than 102%. The floating unit assembly (10) according to any one of claims 13 to 15, wherein said buoy (26, 28, 30, 32, 34) being connected to at least two to six, preferably three to six, more preferred three, floating units (16, 18, 20, 22, 24), is connected to said seafloor (14) via one or more taut lines (48) in such a manner that, for each floating unit (16, 20, 22) and its associated connection line (38, 40, 42, 44, 46) connected to said buoy (26, 28, 30, 32, 34):

- said buoy connection point (52) assumes a nominal buoy position in a condition when no environmental loads are imparted on said floating unit assembly (10);

- said buoy connection point (52) assumes a maximum buoy position when said floating unit assembly (10) is in a condition in which said maximum horizontal distance (d_max) is reached between said buoy connection point (52) and said floating unit connection point (54) for said connection line (38, 40, 42, 44, 46), and

- a horizontal distance (L_max) between said nominal buoy position and said maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference (Amax) between said maximum horizontal distance (dmax) and said nominal horizontal distance (d nom)- The floating unit assembly (10) according to claim 16, wherein said buoy (26, 28, 30, 32, 34) being connected to at least two to six, preferably three to six, more preferred three, floating units (16, 18, 20, 22, 24), is connected to said seafloor (14) via one or more taut lines (48) in such a manner that, for each for each floating unit (16, 20, 22) and its associated connection line (38, 40, 42, 44, 46) connected to said buoy (26, 28, 30, 32, 34): - said buoy connection point (52) assumes an intermediate buoy position when said floating unit assembly (10) is in a condition in which said intermediate horizontal distance (dmter) is reached between said buoy connection point (52) and said floating unit connection point (54) for said connection line (40, 42, 44), and

- a horizontal distance (Lmter) between said intermediate buoy position and said maximum buoy position is greater than, preferably at least two times greater than, more preferred at least five times greater than, the difference (Amter) between said maximum horizontal distance (d_max) and said intermediate horizontal distance (djnter).

18. The floating unit assembly (10) according to any one of claims 13 to 17, wherein one connection line (38, 40, 42, 44, 46) connecting one of said two to six, preferably three to six, more preferred three, floating units (16, 18, 20, 22, 24) to the same buoy (30) has a largest nominal horizontal distance (d nom,max ) of the connection lines connecting said floating units (16, 18, 20, 22, 24) to the same buoy (30) and wherein one connection line (38, 40, 42, 44, 46) connecting one of said two to six, preferably three to six, more preferred three, floating units (16, 18, 20, 22, 24) to the same buoy (30) has a smallest nominal horizontal distance (dnom.min ) of the connection lines connecting said floating units (16, 18, 20, 22, 24) to the same buoy (30), the ratio (d_nOm,max/ d_nOm,min) between the largest nominal horizontal distance (d_nOm,max) and the smallest nominal horizontal distance (d_nOm,min) being less than 1.1 , preferably less than 1.05.

19. The floating unit assembly (10) according to any of the preceding claims, wherein the connection lines (38, 40, 42, 44, 46) connected to at least one, preferably each one, of said plurality of buoys (26, 28, 30, 32, 34), as seen in a plan view of said floating unit assembly (10), extend equiangularly from said buoy (26, 28, 30, 32, 34) when no environmental loads are imparted on said floating unit assembly (10).

20. The floating unit assembly (10) according to any of the preceding claims, wherein said floating unit assembly (10) comprises at least a pattern portion being such that a plan view of said portion forms a hexagonal pattern having straight lines and corners, wherein three floating units (16, 18, 20, 22, 24) and three buoys (26, 28, 30, 32, 34) are connected to each other by connection lines (38, 40, 42, 44, 46), forming said straight lines, and are located in the corners of said hexagonal pattern such that a floating unit (16, 18, 20, 22, 24) and a buoy (26, 28, 30, 32, 34) are always located in two adjacent corners of said hexagonal pattern.

21. The floating unit assembly (10) according to claim 20, wherein at least one pattern portion with said hexagonal pattern comprises an additional buoy (52) located within said lines forming said hexagonal pattern, as seen in a plan view of said pattern portion, said additional buoy (52) being connected to each one of said three floating units (16, 18, 20) defining said hexagonal pattern by means of a connection line (52, 54, 56).

22. The floating unit assembly (10) according to claim 21 , wherein one connection line (54, 56, 58) connecting one of said three floating units (16, 18, 20) to said additional buoy (52) has a largest nominal horizontal distance (d nom,max ) of the connection lines connecting said three floating units (16, 18, 20) to said additional buoy (52) and wherein one connection line (54, 56, 58) connecting one of said three floating units (16, 18, 20) to said additional buoy (52) has a smallest nominal horizontal distance (d_nOm,min) of the connection lines (54, 56, 58) connecting said three floating units (16, 18, 20) to said additional buoy (52), the ratio (d_nOm,max/ dnom,min ) between the largest nominal horizontal distance (d nom,max ) and the smallest nominal horizontal distance (d_nOm,min) being less than 1.1 , preferably less than 1.05.

23. The floating unit assembly (10) according to any one of claims 20 to 22, wherein said pattern portion is such that a plan view of said portion forms an equilateral hexagonal pattern.

24. The floating unit assembly (10) comprising a plurality of pattern portions according to any one of claims 20 to 23.

25. The floating unit assembly (10) according to any of the preceding claims, wherein each floating unit (16, 18, 20, 22, 24) is associated with a floating unit displacement, wherein at least one, preferably each one, of said plurality of buoys (26, 28, 30, 32, 34) has a buoyancy, when said buoy is fully submerged, being within the range of 1 - 10 % of said floating unit displacement. The floating unit assembly (10) according to any of the preceding claims, wherein, at least one, preferably each one, of said connection lines (38, 40, 42, 44, 46) imparts a restoring force on the floating unit to which said connection line (38, 40, 42, 44, 46) is connected when no environmental loads are imparted on said floating unit assembly (10), said restoring force having a horizontal component being at least 75%, preferably at least 85%, more preferred at least 95 % of said restoring force. The floating unit assembly (10) according to any of the preceding claims, wherein one of said floating units (16, 18, 20, 22, 24) has a largest floating unit displacement of said floating units (16, 18, 20, 22, 24) forming part of said floating unit assembly (10) and wherein another one of said floating units (16, 18, 20, 22, 24) has a smallest floating unit displacement of said floating units (16, 18, 20, 22, 24) forming part of said floating unit assembly (10), the ratio between said largest floating unit displacement and said smallest floating unit displacement being less than 1.1 , preferably less than 1.05. The floating unit assembly (10) according to any of the preceding claims, wherein at least one, preferably each one, of said floating units (16, 18, 20, 22, 24) comprises a wind turbine. The floating unit assembly (10) according to any of the preceding claims, wherein for at least one buoy (26) connected to a plurality of floating units (16, 20, 22), each connection line (42, 44, 46) connecting said buoy (26) to one of said floating units (16, 20, 22) is connected to an individual buoy connection point (62, 64, 66) of said buoy (26), wherein each dividual buoy connection point (62, 64, 66) is located at a non-zero distance in a vertical direction (V) from each one of the other individual buoy connection points (62, 64, 66) associated with said buoy (26) when no environmental loads are imparted on said floating unit assembly (10). The floating unit assembly (10) according to claim 29, wherein an adjacent buoy connection points distance (Di , D2) in said vertical direction (V) between two adjacent individual buoy connection points (62, 64, 66) is in the range of 0.3 - 15 meters, preferably in the range of 1 - 5 meters when no environmental loads are imparted on said floating unit assembly (10). The floating unit assembly (10) according to any one of claims 29 and 30, when dependent on claim 7, wherein an adjacent buoy connection points distance (Di , D2) in said vertical direction (V) between two adjacent individual buoy connection points (62, 64, 66) is in the range of 0.005%-0.05% of said water depth when no environmental loads are imparted on said floating unit assembly (10). The floating unit assembly (10) according to any one of claims 29 -31 , wherein said buoy (26) is associated with a largest adjacent buoy connection points distance (Di) between two adjacent individual buoy connection points (62, 64) in said vertical direction (V) and wherein said buoy is associated with a smallest adjacent buoy connection points distance (D2) between two adjacent individual buoy connection points (64, 66) in said vertical direction (V), the ratio (D1/D2) between the largest adjacent buoy connection points distance (Di) and the smallest adjacent buoy connection points distance (D2) being less than 1.1 , preferably less than 1 .05, when no environmental loads are imparted on said floating unit assembly (10).