The invention in a first aspect relates to an as sembly for transferring a medium to a vessel, which assembly comprises a support member to which the vessel is to be con nected by means of secondary mooring members, such as a hawser comprising one or more mooring lines or mooring ca bles.

As used herein, the indication 'medium' has a very broad meaning, such as to encompass, among others, substanc es (such as any of or a combination of solids, liquids and gasses) as well as signals (such as electrical and optical signals) and electricity, and any combinations thereof, without being limited to these examples.

It is an object of the present invention to pro vide an improved assembly of the above type.

To achieve such goal, the assembly in accordance with the present invention is characterized in that the sup port member comprises a reel mounted thereon for a rotation around a vertical rotation axis, which reel is intended for winding thereon or unwinding therefrom a medium line intend ed for transferring the medium to the vessel, wherein a swivel is provided for connecting the medium line with a me dium pathway on the support member.

In accordance with the present invention the pro vision of a rotatable reel allows to wind or unwind the me dium line. When a medium transfer connection between the support member and a vessel has to be established, the medi um line may be wound off from the reel in a desired amount or length, depending on a distance between the support mem ber and vessel (for example, as established by the secondary mooring members, such as a hawser). When there is no vessel present (or when a vessel moored to the support member does not require a connection with the support member through a medium line), the medium line can be wound onto the reel and as a result will be protected against external influences.

The reel may be one of a variety of different types, such as preferably a helical type reel (on which the medium line is arranged as a spiral extending in a horizon tal plane). Depending on the type of reel, additional mem bers may be provided to assure that a medium line is cor rectly wound onto (and off from) the reel. For example, when a drum type reel would be provided, a so-called spooling de vice may be provided.

Preferably the reel is motor driven, such as to effectively control the winding off or on of the medium line. If applied, the motor may be remote-controlled (for example using a portable remote-control device), such that the support member may be operated without the presence of personnel on the support member itself. It is noted that al so a motor could be used for actively rotating a main bear ing.

Further it is preferred that the support member is provided with guide members, such as guide rollers or a feeder funnel, for the medium line. As a result, a correct winding on or off of the medium line may be assured.

It is also possible that the assembly according to the present invention is provided with control means for controlling the manner in which the medium line is wound on or from the reel, wherein said control means may comprise any one or any combination of: means for applying tension to the medium line (the use of which allows to spool out the medium line while avoiding a compressive force in the medium line; a spring return system may keep tension on the medium line while pulling it out); guide means installed around the reel intended for keeping the medium line on the reel (which is an alternative solution allowing to use the reel as main driving force for spooling out the medium line by subjecting the medium line to a compressive force); a motor for driving the reel, which motor for its control receives input from means for measuring a torque of the reel and/or from means for measuring a tension in the medium line (such that the reel will automatically start to pay out the medium line when a tension (pull) in the medium line is sensed, thus avoiding compression in the medium line and keeping it neat ly on the reel, but also offering the possibility to stop a rotation of the reel when the medium line is obstructed, for example when being twisted); a motor for directly driving the medium line (especially for spooling out the medium line; such a motor, for example, could drive guide rollers for the medium line in a feeder funnel during winding off the medium line. Another motor then could be used for rotat ing the reel during winding on the medium line, thus in both situations avoiding a compression of the medium line).

In an advantageous embodiment the assembly is pro vided with an activatable medium line disconnect and/or de activation mechanism. There may occur situations in which the medium line connection between the support member and vessel should be terminated for safety reasons and/or where in the transfer of the medium through the medium line should be terminated. One of such situations could be a hawser failure.

In such an embodiment, the medium line disconnect and/or deactivation mechanism may be provided at an end of the medium line which is to be connected to the vessel, or may be provided at an end of the medium line which is con nected to the reel, such that at those places the medium line is disconnected and/or that at those places the medium line is shut off (for example using a valve or switch, de pending on the type of medium line and medium transferred therethrough) .

In such a case it is possible that the medium line disconnect and/or deactivation mechanism for its activation is connected to a control means receiving input from means for determining a failure of the secondary mooring members, such that a disconnect and/or deactivation (shut off) of the medium line occurs automatically without the interference of an operator. For example, the means for determining a failure of the secondary mooring members may comprise a break-away monitoring line which is intended to extend between the sup port member and the vessel, wherein preferably said break away monitoring line at one end is to be connected to a strong point on the vessel and at the opposite end is at tached to a switch on the support member. When the secondary mooring members (such as a hawser) experience a failure, the load on the break-away monitoring line may increase to a level at which the switch is operated, which leads to a shut off of the medium line. As an alternative the increase of the load in the break-away monitoring line may lead to break of the break-away monitoring line, which may be sensed and used as a trigger.

Such a break-away monitoring line also might be used for earthing purposes (a static voltage level between the support member and vessel may be different with the re sulting risk of sparks or other hazardous situations).

In a preferred embodiment of the assembly accord ing to the present invention, the medium line is a power ca ble, the medium is electrical power and the swivel comprises at least one slipring assembly. Thus, the assembly allows a vessel to receive electric power while moored (and freely weathervaning in case the support member defines a buoy of the type to be explained later), for example when moored near shore or offshore like a standby or operation support vessel. The assembly may be designed for different voltage levels, such as, for example, l.lkV, 3.3kV, 6.6kV or llkV. The power cable (used as a medium line) typically may have a cable diameter D in the range of 15 cm, with a typical cable bending radius up to 20D static. It is noted, however, that these numbers only are examples without limiting the scope to these ranges.

In addition to the at least one slipring assembly for the transmission of the electric power to the vessel, the support member (in case the support member defines a buoy of the type to be explained later) also may be provided with at least one additional slipring assembly (for example a low voltage slipring assembly) for the transmission of power (or even signals, a fluid and/or gas) needed by such a buoy. This generally will be separated from the main (medium or high voltage) slipring assembly.

Preferably, the slipring assembly is not oil filled.

The medium line also may be provided with means to transfer control signals, typically fibre optics, between the vessel, support member and possibly a station ashore.

The medium line may be provided with buoyancy by means of one or more of the following features: an inherent buoyancy, additional separate buoyancy devices attached to the medium line, a floating hose surrounding the medium line, or the medium line may be allowed to extend between the support member and vessel in a (partly or fully) catena ry manner (although the last option is not the most pre ferred one if the support member is a buoy, because it may cause the vessel and buoy to be pulled towards each other). Such an effect is avoided when the medium line has a buoyan cy.

Further it is possible that a, preferably float ing, medium line messenger line is provided, which with a first end is connected to the forward end of the medium line and which with its opposite end is (permanently) connected to the end of the secondary mooring members intended to be connected to the vessel. After the secondary mooring members (such as a hawser) have been connected to the vessel (which operation may be carried out in any known manner, for exam ple using a pick-up rope and pick-up buoy attached to a for ward end of a hawser), the medium line messenger line may be picked up manually by a person using a grab hook (for this the medium line messenger line may be provided with a corre sponding loop) and the medium line messenger line may be pulled towards the vessel while at the same time the reel is operated for paying out the medium line until the forward end of the medium line reaches the vessel and may be con nected there to appropriate members (for example plugged in to a socket when the medium line is a power cable). Hoisting or lifting means may be provided for assisting in lifting the medium line.

A similar operation may be used for the break-away monitoring line, if applied, which then also may be provided with a loop and which may be connected to a strong point on the vessel. Similarly, such a break-away monitoring line al so may comprise a permanent connection between its forward end and the end of the secondary mooring members to be con nected to the vessel.

Especially in the case that the medium line is a power cable, the invention offers the advantage that the power cable can be reeled in, such as to avoid that the pow er cable and its forward end (for example equipped with a connector) are in the sea water permanently, which could have a negative effect on the lifespan of the power cable, and such as to avoid the risk of (collision) damage.

Although the support member may be embodied in many different ways, for example as a tower (for example resting on the seabed), a vessel or a platform, in a pre ferred embodiment of the assembly, the support member is a buoy for mooring a vessel, wherein the buoy comprises a first buoy part which by means of primary mooring members, such as mooring lines or mooring cables, can be geostation ary moored, and a second buoy part that is mounted on the first buoy part for a rotation relative thereto around a vertically extending first rotation axis and that is adapted to be connected to the vessel by means of the secondary mooring members, wherein the first buoy part and second buoy part respectively are provided with cooperating swivel parts which can rotate relative to each other around said first rotation axis for defining a primary swivel intended for transferring the medium from the first buoy part to the sec ond buoy part through a medium pathway extending through the cooperating swivel parts, wherein the reel is mounted on the second buoy part for a rotation around a second rotation ax is which extends vertically, and which coincides with the first rotation axis and wherein the primary swivel between the first buoy part and second buoy part also acts as a sec- ondary swivel between the second buoy part and the reel, such that the primary swivel and secondary swivel share com mon cooperating swivel parts which together define the swiv el.

A buoy of such a type (also sometimes referred to as a turret buoy or turntable buoy) may be used to moor a vessel in a manner to allow the vessel to weathervane around the buoy (for example under influence of changing conditions such as a change of wind direction or a change of current). In all positions of the vessel the swivel ensures that a re liable transfer of the medium, for example from a terminal ashore or from another external source, through the buoy and towards the vessel is safeguarded, using a medium line which extends between the buoy and the vessel and which is con nected to the medium pathway. Such buoys for example are used for the transfer of oil or gas, but are not limited to such media and, as described herein as a preferred embodi ment, also may be used for the transfer of electric power and/or signals.

As stated, the reel is mounted on the second buoy part for a rotation (which is fully independent from the ro tation between the buoy parts) around a second rotation axis which coincides with the first rotation axis. This simpli fies the construction of the buoy.

Further, because in such an embodiment it is pos sible that the primary swivel also acts as a secondary swiv el, the primary swivel and secondary swivel are made up of common cooperating swivel parts. Thus, a single swivel is sufficient .

It is noted that the buoy may be provided with a surrounding soft fender ring (because regular contact be tween the buoy and vessel may not be excluded). Further, when the medium line is a power cable, its forward end (also referred to as connector end) generally will be provided with an easily operable cap with reliable water-tight seal ing and easy means of integrity checking.

In a second aspect, the invention relates to a vessel for use with an assembly according to the present in- vention, comprising an outrigger adapted to be positioned in a position in which it projects beyond the circumference of the vessel, which outrigger is provided with support means for engaging and supporting a leading end of the medium line, preferably a leading end of a power cable, wherein the support means preferably define at least two different, sub stantially horizontally extending pivot axes, in such a man ner that the medium line is free to pivot around said pivot axes.

The pivot axes (which may define orthogonal hori zontally extending pivot axes) allow a double pivoting hang- off of the medium line (for example power cable) to reduce bending of the medium line and to increase its fatigue life.

Additionally, it is conceivable that the support means further define a third pivot axis extending substan tially vertically. As a result, parts of the support member, such as quick release hooks to be mentioned below, may as sume a position in which they are easily accessible from the ship.

The vessel further may comprise means for pulling in a messenger line connected to said leading end of the me dium line, wherein said means preferably comprise a manual ly, electrically, or hydraulically driven winch and prefera bly guiding members, such as sheaves, for the messenger line.

The messenger line (also sometimes referred to as forerunner rope) can be picked up and pulled in such that the leading end of the medium line is brought into a posi tion in the vicinity of the support means in which it can be brought into engagement therewith. The messenger line can have an end which is connected to a hawser used to moor the vessel to a buoy or other structure, as will be described at a later stage.

In one embodiment, the support means further com prise quick release hooks intended for engaging connector hang-off wires attached to the leading end of the medium line. Such quick release may define part of an activatable medium line disconnect mechanism as described before. It is noted, that as used herein, the indication 'wire' also intends to refer to other similar members, such as a rope or a chain.

The vessel further may comprise a connecting medi um line, preferably a connecting power cable (also referred to as jumper cable), for connecting the medium line to a dedicated connecting point, preferably an electric socket, on the vessel. Such a connecting medium line may be loose or may be connected permanently to a ship's interface (for ex ample an electric socket).

Such a connecting medium line at its end to be connected to the medium line may be provided with a connect or safety wire (rope, chain), whereas the support means com prise a strong point to which the connector safety wire is to be connected. This allows to keep the connecting medium line connected to the vessel, for example when the medium line is disconnected during a quick release procedure.

Finally, it is possible that the support means comprise, or are defined by components of, a davit or a ship's crane. As a component of a davit also a sliding beam may be used. The support means may be installed anywhere on the vessel, such as on the deck, but also in the hull, for example behind a hatch.

A vessel as described above allows to safely con nect and disconnect a vertically mounted medium line (such as a power cable) to a vessel in offshore conditions.

Hereinafter the invention will be elucidated while referring to the drawings which show an embodiment of the invention in which the support member is a buoy.

Herein:

Figure 1 schematically shows a general arrangement of a vessel moored to a buoy;

Figure 2 schematically shows the buoy on a larger scale in a partly broken away side elevational view;

Figure 3 schematically shows the buoy on a larger scale in a partly broken away top plan view, and Figures 4-9 show consecutive steps during connect ing a power cable to a vessel.

In a first instance referring to figure 1, a buoy 1 is illustrated which by means of primary mooring members 2 (such as, for example, mooring chains) is moored in a geo stationary manner, for example to the sea bottom or to an other (stationary) feature. A vessel 3 is moored to the buoy by means of secondary mooring members 4 (such as, for exam ple, a hawser).

In figure 2, which shows the buoy 1 on a larger scale in a partly broken away side elevational view, one can see that the buoy 1 comprises a first buoy part 1' with a lower end to which the primary mooring members 2 are at tached, and a second buoy part 1" that by means of at least a main bearing 5 (which is mounted on an upper end of the first buoy part 1') is mounted on the first buoy part 1' for a rotation relative thereto around a vertically extending rotation axis 6.

The secondary mooring members (hereinafter re ferred to as hawser) 4 are attached to the second buoy part 1", such that a vessel 3 moored to the buoy 1 can freely weathervane around the buoy. Such a type of buoy with a geo stationary first buoy part and a rotatable second buoy part to which a vessel can be moored, also may be referred to as a turret buoy. It is noted that the second buoy part 1" may be provided with a surrounding soft fender ring 24.

Referring both to figures 2 and 3, a reel 7 is provided which by means of a reel bearing 8 is mounted on the second buoy part 1" for a rotation around the rotation axis 6. The reel 7 (which in the illustrated embodiment de fines a helical type reel with vertical rotation axis, but which in another embodiment also could define another type of reel, such as a drum type reel) is intended for winding on or winding off a power cable 9 which has to be connected to the vessel 3 for providing electric energy to the vessel.

A power cable 10 (which, in a manner not shown, is connected to an external power source) runs through the low- er buoy part 1 and is connected to the power cable 9 on the reel 7 by means of a slipring assembly 11 centred around the vertical rotation axis 6 (and comprising cooperating slipring parts). Although in the illustrated embodiment the slipring assembly 11 comprises two sliprings, specifically an upper slipring 11' (for example a medium or high voltage slipring connecting the power cables 9 and 10) and a lower slipring 11" (for example a low voltage slipring connecting an additional power cable with electric equipment on the up per buoy part 1"), a single slipring would be sufficient for the transmission of power between the power cables 9 and 10, because in the illustrated embodiment the rotation axis of the reel 7 coincides with the rotation axis 6 between the two buoy parts 1 and 1".

The sliprings preferably are not oil-filled.

Further it is noted that, although the present in vention is primarily intended to provide means for the transmission of electric power between a buoy and a vessel, a similar constructional layout of the buoy also is possible for the transmission of another medium (for example (opti cal) signals, a fluid or a gas), and in such cases the power cable would be replaced by an appropriate medium line for transferring the specific medium, whereas further the sliprings then would be replaced by swivels comprising coop erating swivel parts.

The second buoy part 1 is provided with a motor 12 (such as an electric motor) for rotationally driving the reel 7. The motor 12 may be remote-controlled, such that the reel 7 may be operated without the need for the presence of an operator on the buoy 1. The reel 7, when driven by the motor 12, will dispense a required length of the power cable 9 to establish a connection with the vessel 3, or may again reel in the power cable 9 when it is disconnected from the vessel, such that the reeled-in power cable is protected against external influences (for example is not exposed to sea water) and/or is protected against collision damage (e.g. due to a collision with a vessel). Once the required length of the power cable 9 has been dispensed and the power cable 9 is connected to the vessel (for example in the manner described below with re spect to figures 4-9), the motor 12 is stopped (additional activatable locking members or brakes for locking/holding the reel 7 against an undesired rotation may be provided). Then the reel 7 together with the second buoy part 1 can freely rotate around the first buoy part 1', allowing the vessel 3 to weathervane around the buoy 1 while maintaining the electric connection between the buoy 1 (or external pow er source) and the vessel 3.

Referring specifically to figure 1, a power cable messenger line 13 is illustrated. A forward end of this mes senger line 13 (the end closest to the vessel 3) is attached to the corresponding forward end of the hawser 4 and in that region may be provided with a loop (not illustrated in de tail). An opposite end of the messenger line 13 is attached to the leading end of the power cable 9. The length of the messenger line 13 is such that the power cable 9 can remain fully wound onto the reel 7 when the vessel 3 is moored to the buoy 1 by means of the hawser 4. After the mooring by means of the hawser 4 is completed, the loop of the messen ger line 13 can be picked up by an operator 14 using a grab hook 15 and the messenger line can be pulled onto the ves sel, thus also pulling the power cable 9 towards the vessel (while, at the same time, the reel 7 is rotated by the motor 12 for dispensing the required length of the power cable).

In figure 1 a situation is shown in which the power cable 9 already has been pulled substantially halfway towards the vessel 3. When the power cable 9 reaches the vessel 3, it may be connected with a socket 16 (or another appropriate member) at an appropriate location (for example some dis tance inboard on a main deck) on the vessel. A specific man ner in which this may be achieved, will be elucidated below with reference to figures 4-9.

Referring specifically to figure 3, part of a break-away monitoring line 17 is illustrated which, after the mooring is completed and the power cable 9 has been con- nected to the vessel, in one embodiment will extend between the buoy and the vessel (in figure 1 this monitoring line has been illustrated only partly). In the illustrated embod iment one end of this monitoring line 17 will be attached to a strong point 18 (see figure 1) on the vessel 3, whereas the opposite end is attached to a switch 19 (or another ac- tivatable member) on the second buoy part 1 (see figure 3). When, for example, there is a failure of the hawser 4, the monitoring line 17 will be tensioned and, as a result, the switch 19 will be operated. This (for example through con trol means 21 connected to the switch, see figure 3) may lead to an emergency disconnect of the power cable 9 from the socket 16, while the power transmission through the pow er cable 9 may be shut-off at the same time (or, more pre cisely, a little bit earlier, because an electrical shutdown takes some time). As an alternative, such a power shut-off also may occur in the power cable 10 on the first buoy part 1 or even at the external power source).

As an alternative, it also is conceivable that in the event of failure of the hawser 4 (or another unwanted situation) the monitoring line 17 breaks and that this is sensed by appropriate means for triggering an emergency dis connect and/or a power shut-off as described above.

As a result, such a break-away monitoring line 17 can trigger an activatable power cable disconnect mechanism (for example provided at or combined with the socket 16) and/or an activatable deactivation mechanism (such as the power shut-off) which adds to a safe operation of the buoy, specifically a safe transfer of electric power to the ves sel.

The monitoring line 17 in its region near to the end to be connected to the vessel may be connected to the hawser 4 in a manner similar to the messenger line 13 (and thus also optionally being provided with a pick-up loop), while allowing sufficient play to enable its proper func tioning.

The power cable 9 preferably is provided with buoyancy, such that it will float and will not assume a ca- tenary position in which it would tend to pull the vessel 3 towards the buoy 1. Such a buoyancy can be achieved in dif ferent ways, such as by means of one or more of the follow ing features: an inherent buoyancy, additional separate buoyancy devices 20 attached to the power cable (see figure 1), as long as these do not impede the winding of the power cable onto the reel 7, or a floating hose surrounding the power cable.

For controlling the manner in which the power ca ble 9 is wound off or on the reel 7, additional control means may be provided. On one hand these control means may comprise constructional features such as guide members for the power cable 9 (a feeder funnel 22 or guides 23 surround ing the reel 7) or means for applying tension to the power cable, but on the other hand also may comprise functional features, for example for controlling the operation of the motor 12 based upon an input received from means for measur ing a torque of the reel 7 and/or from means for measuring a tension in the power cable.

Next, the consecutive steps of an exemplary pro cess for connecting a power cable 9 to the vessel 3 are de scribed with reference to figures 4-9.

In figure 4, the power cable 9 has arrived in the vicinity of the vessel 3. On the deck 25 of the vessel a davit or ship's crane 26 is mounted which is provided with an outrigger 27 which can be (or is) positioned in a posi tion in which it projects beyond the circumference (or the hull) of the vessel. The outrigger is provided with support means 28 which are adapted for engaging and supporting a leading end of the power cable 9 (in a manner which will be described below). In the illustrated embodiment the support means 28 define a first, substantially horizontal, pivot ax is 29 and a second, substantially horizontal, pivot axis 30 (preferably extending orthogonally with respect to each oth er). It also is possible that a third pivot axis (not illus trated) is provided extending (substantially) vertically.

The pivot axes allow the support means 28 to assume differ- ent positions, for example positions in which parts thereof are accessible from the vessel.

The support means further comprise quick release hooks 31, a strong point 32 and a pull-in sheave 33, the function of which will appear below.

The leading end of the power cable 9 is provided with a pull-in head and sealing cap 34 and connector hang- off wires 35. The power cable messenger line 13 (also some times referred to as forerunner rope) is connected to the pull-in head and sealing cap 34. In a first step said mes senger line 13 is retrieved (for example as described previ ously with respect to figure 1) and (as illustrated in fig ure 5) is routed over the pull-in sheave 33 of the support means 28 towards a pull-in winch 36 (which, in the illus trated embodiment, is supported by the davit/crane 26, but which also may have a position elsewhere on the vessel 3).

As a result, the power cable 9 with its leading end (pull-in head and sealing cap 34) is lifted towards the support means 28.

As a next step (figure 6), the connector hang-off wires 35 are connected to the quick release hooks 31. After this, the messenger line 13 is disconnected from the power cable 9 and the pull-in head and sealing cap 34 is removed (figure 7).

Then a connecting power cable 37 (also sometimes referred to as jumper cable) having a connector 38 with con nector safety rope 39 at one end is installed on the leading end of the power cable 9 (which can be provided with a mat ing connector 40, see figure 7). The connector safety rope 39 is attached to the strong point 32 of the support means 28. Finally, an opposite end of the connecting power cable 37 is connected to an interface cabinet 41 (which functions as the socket 16 described previously), thus completing the connection of the power cable 9 with the vessel 3.

Disconnecting the power cable 9 from the vessel 3 under normal, controlled, circumstances is carried out in a reverse order. However, when an emergency disconnect of the power cable 9 has to be initiated (for example under circum- stances as described previously with respect to figure 3), the quick release hooks 31 are activated and will release the connector hang-off wires 35. As a result the power cable 9 will be dropped into the sea due to gravity forces while the connection between the connector 38 of the connecting power cable 37 and the mating connector 40 on the power ca ble 9 is disrupted (aided by the connector safety rope 39 attached to the strong point 32 which prevents the connector 38 and connecting power cable 37 from moving down along with the power cable 9). The power cable 9 then can be reeled on to the reel 7 on the buoy 1, and its mating connector 40 is to be dried and inspected. The pull-in head and sealing cap 34 and messenger line 13 are to be retrieved from the vessel 3 for re-installation on the leading end (mating connector 40) of the power cable 9.

The invention is not limited to the embodiments described above which may be varied widely within the scope of the invention as defined by the appending claims.