US20070240624A1 - Mooring System - Google Patents
Mooring System Download PDFInfo
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- US20070240624A1 US20070240624A1 US10/572,438 US57243804A US2007240624A1 US 20070240624 A1 US20070240624 A1 US 20070240624A1 US 57243804 A US57243804 A US 57243804A US 2007240624 A1 US2007240624 A1 US 2007240624A1
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- Prior art keywords
- mooring system
- line
- anchor
- harness
- removably attached
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
- B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
Abstract
A mooring system for a floating aquatic structure includes a harness, a primary weight, and a first anchor. The harness has first and second ends. The first end is pivotally attached to the structure. The primary weight is removably attached to a connecting line and suspended from the second end of the harness. The anchor is removably attached to the primary weight to resist movement of the structure in a first direction.
Description
- The present invention relates to a system for the mooring and retrieval of floating aquatic installations and structures.
- Known mooring systems for floating structures comprise a number of anchors, weights and associated tether lines which are attached to the installation or structure. The anchors can take different forms, but each is intended to hold its associated tether line on the bed of the body of water upon which the structure is floating. Additional weights can be added to the anchor lines in order to counter the forces on the structure (e.g. wind, waves or tidal currents) and maintain the position of the structure on the water. Additional mooring and restraint lines can also be incorporated depending on the conditions which the structure is expected to encounter.
- One problem with such known mooring systems is that they present problems when the structure has to be retrieved from the water. With the number of tether and restraint lines attached to the structure, it is necessary for these all to be disconnected before the structure can be removed from the water. This normally requires human intervention, with an operator having to climb onto the structure in order to detach the various lines before the structure can be retrieved. In particularly heavy seas or bad weather, this cannot sometimes be done for safety reasons. The retrieval of the structure can therefore be delayed, for days at a time in some instances. Such delay can have serious time and cost implications, with maintenance or installation schedules being affected because of the delays.
- A further disadvantage of the known systems is that they are normally intended to moor only one structure per system. If a number of structures are to be installed at the same location, separate anchor points, weights and tether lines are needed for each structure. As a result, the structures need to be a certain distance from one another to avoid fouling the various lines. Having to space the structures from one another in this manner is not an effective use of space. It is often desired to place a number of structures in as small a space on the water as possible, normally for economic, aesthetic or environmental reasons.
- Another disadvantage is that known mooring systems do not make efficient use of the available water depth. The excursion required to cope with extreme waves and currents require large ranges of motion before the mooring lines become taut. If mooring lines become taut loads rise extremely fast—a process known as line snatching. This problem becomes serious if the structure is to be moored in shallow water and large waves and/or strong currents. Also, known systems do not make efficient use of the suspended weight of the mooring lines or components. Suspended weight costs money and may itself impart loads on the structure that may be large or undesirable.
- Yet another disadvantage is that known mooring systems do not provide for ready, protected connection of the structure to one or more utility supplies such as power, fluid or water. Typically such connection must be made on or near the water surface, independently of mooring line connections.
- In addition, a lot of known mooring systems are limited in that they are only intended to encounter loading from a single direction (e.g. a marine structure which is only intended to encounter waves from one direction). Such systems can lack stability if they encounter forces from an unexpected direction. Such forces can lead to rotational or yaw movements of the structure which can cause damage to both the structure and the components of the mooring system.
- It is an aim of the present invention to obviate or mitigate one or more of the disadvantages of these known mooring systems.
- According to a first aspect of the present invention, there is provided a mooring system for a floating aquatic structure, the system comprising:
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- a harness having first and second ends, the first end being adapted to be pivotally attached to the structure;
- at least one primary weight removably attached to a connecting line, and suspended on the connecting line from the second end of the harness; and
- at least one first anchor removably attached to said primary weight by at least one first anchor line, wherein the first anchor is adapted to resist movement of the structure in a first direction.
- Preferably, the mooring system further comprises at least one second anchor removably attached to the connecting line by at least one second anchor line, wherein the second anchor is adapted to resist movement of the structure in a second direction substantially opposite to the first direction.
- Preferably, the mooring system further comprises a support line having one end adapted to be removably attached to the structure and its other end removably attached to the second anchor line, the support line adapted to restrict yaw motion of the structure.
- Preferably, the mooring system further comprises one or more secondary weights attached to one or more of the first and second anchor lines.
- In one preferred embodiment the system comprises at least two first anchors removably attached to said primary weight by respective first anchor lines, wherein each first anchor is adapted to resist movement of the structure in the first direction.
- Preferably, the at least one primary weight comprises a frame member and one or more chain links suspended from said frame member. The frame member includes at least two first mechanical attachment means adapted to removably attach the connecting line and at least one first anchor line thereto. Most preferably, the first mechanical attachment means are universal joints having detachable pin members.
- In a further preferred embodiment, the mooring system comprises:
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- first and second primary weights attached to first and second connecting lines, respectively, and suspended on the connecting lines from the second end of the harness; and
- a pair of first anchors having respective first anchor lines, one of the first anchors removably attached to the first primary weight by one first anchor line and the other first anchor being removably attached to the second primary weight by the other first anchor line, wherein the first anchors are adapted to resist movement of the structure in a first direction.
- Preferably, the system further comprises a third primary weight attached to a third connecting line and suspended on the third connecting line from the second end of the harness; and
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- at least one second anchor removably attached to the third connecting line by at least one respective second anchor line, wherein the second anchor is adapted to resist movement of the structure in a second direction substantially opposite to the first direction.
- Preferably, the system further comprises a support line having one end adapted to be removably attached to the structure and its other end removably attached to the second anchor line, the support line adapted to restrict yaw motion of the structure.
- In a still further preferred embodiment, the system further comprises a pair of second anchors each having respective second anchor lines, one of the second anchors being removably attached to the first primary weight by one second anchor line and the other second anchor being removably attached to the second primary weight by the other second anchor line, wherein the second anchors are adapted to resist movement of the structure in a second direction substantially opposite to the first direction.
- Preferably, the system further comprises first and second support lines, each support line having one end adapted to be removably attached to the structure and its other end removably attached to one of the second anchor lines, the support lines adapted to restrict yaw motion of the structure.
- Preferably, the harness comprises first and second arm members and a shaft member, wherein the arm members have first and second ends and the shaft member is connected between the respective first ends of the arm members to form the first end of the harness, and wherein the shaft member has an axis of rotation about which the harness pivots. The harness is adapted to apply roll restraint to the structure.
- Preferably, said shaft member and at least one of said arm members are hollow, the harness further comprising at least one conduit that is at least partially located in the hollow arm member and the shaft member. Preferably, the harness further comprises connecting means for connecting one or more utility supplies to the harness.
- Preferably, said connecting means comprises a junction box having one or more connectors therein, the junction box being in communication with the at least one conduit, and the conduit carrying utility supply through the harness to the structure.
- Preferably, the harness further comprises retrieval means to facilitate retrieval of the harness from a body of water.
- Preferably, the retrieval means comprises one or more slots provided on the harness. Most preferably, the retrieval means further comprises one or more roller members provided on the harness.
- Preferably, the harness further comprises a second mechanical attachment means for removably attaching the connecting line thereto. Most preferably, the second mechanical fixing means is a universal joint having a detachable pin therethrough.
- Preferably, the at least one connecting line includes a linking plate member, and wherein the at least one second anchor line is removably connected to the connecting line by the linking plate member.
- Preferably, the linking plate member includes:
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- retrieval means adapted to allow the mooring system to be retrieved from the water; and
- stabilising means adapted to hold the plate member in substantially the same plane during retrieval. Most preferably, the linking plate member further includes locking means adapted to secure the plate member to a marine vessel.
- Preferably, the floating aquatic structure is a wave energy converter.
- According to a second aspect of the present invention, there is provided weight for a mooring system, the weight comprising a frame member and at least two chain links suspended from said frame member.
- Preferably, the weight comprises a plurality of chain links suspended from the frame member.
- Preferably, the frame member includes at least two mechanical attachment means adapted to removably attaching components of a mooring system thereto. Most preferably, the mechanical attachment means are universal joints having detachable pin members.
- According to a third aspect of the present invention there is provided a recovery apparatus for a marine vessel, the apparatus comprising:
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- a rotatable drum;
- a recovery line having a first end adapted to be removably attached to a portion of an object to be recovered and a second end adapted to be removably attached to the rotatable drum;
- a retention means comprising a base member and a retaining member attached to the base member by a spherical bearing, the retaining member being adapted to have a portion of the recovered object removably attached thereto; and
- a guide means adapted to guide the recovery line over the retaining member during winding and unwinding of the line.
- Preferably, said guide means is a ramp having an inclined surface lying in a ramp surface plane, and wherein the retention means is housed on the ramp.
- Preferably, the base member is adapted to permit longitudinal movement of the retention means relative to the ramp.
- Preferably, the ramp further comprises a guide track in which the base member is located. Preferably, the guide track has first and second portions, wherein the first portion lies at a greater angle relative to the horizontal than the second portion.
- In a preferred embodiment, the first guide track portion lies at an angle relative to the ramp surface plane and the second guide track portion is substantially parallel to the ramp surface plane.
- Preferably, the guide track includes locking means adapted to lock the retention means in one or more positions on the guide track.
- Preferably, the recovery apparatus further comprises a tensioning roller member adjacent a first end of the guide means for tensioning the recovery line.
- Preferably, a second end of the guide means terminates adjacent the stern of the marine vessel, and the apparatus further comprises a recovery roller member adjacent the stern of the vessel, the recovery roller member adapted to assist in the recovery of an object onto the guide means.
- Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
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FIG. 1 (a) shows a perspective view of a first embodiment of a mooring system used in conjunction with a wave energy converter; -
FIG. 1 (b) shows a schematic plan view of the mooring system ofFIG. 1 (a); -
FIG. 2 shows the mooring system ofFIG. 1 when applied to an array of wave energy converters; - FIGS. 3(a) and 3(b) are side and end elevations, respectively, detailing a yoke component of the mooring system of
FIG. 1 ; - FIGS. 4(a) and 4(b) are side elevations showing the mooring system of
FIG. 1 in operation; - FIGS. 5(a) and 5(b) are plan views showing the mooring system of
FIG. 1 in operation; -
FIG. 6 is an end elevation of the yoke of FIGS. 3(a) and 3(b) in operation; -
FIG. 7 is an end detail view of the upper part of the yoke of FIGS. 3(a) and (b); - FIGS. 8(a) and 8(b) are end and side detail views, respectively, of the lower part of the yoke of FIGS. 3(a) and 3(b);
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FIG. 9 is an end elevation of a tether weight component of a mooring system; - FIGS. 10(a) and 10(b) show the tether weight of
FIG. 9 in operation with the mooring system ofFIG. 1 ; - FIGS. 11(a)-(c) show detail views of the tether weight of
FIG. 9 in operation; - FIGS. 11(d) and 11(e) show detail views of a prior art tether weight in operation;
-
FIG. 11 (f) shows a graph detailing the comparative loads put on the tether line by the tether weight ofFIG. 9 and the prior art tether weight of FIGS. 11(d) and 11(e); - FIGS. 12(a) and 12(b) show detail views of a recovery apparatus for retrieving the yoke component of a mooring system;
- FIGS. 13(a)-(c) show end, side and plan views of an attachment mechanism of the retrieval apparatus;
- FIGS. 14(a) and 14(b) schematically show the various components of the recovery apparatus shown in FIGS. 12(a) and 12(b);
- FIGS. 15(a)-(d) show the retrieval apparatus in operation; and
- FIGS. 16(a)-(h) show the steps for retrieving the yoke component of the mooring system of
FIG. 1 from the water; - FIGS. 17(a) and 17(b) show alternative steps for retrieving the yoke component of the mooring system of
FIG. 1 ; -
FIG. 18 shows a schematic view of a second embodiment of a mooring system; -
FIG. 19 shows a detail view of a link plate used in the mooring system shown inFIG. 18 ; - FIGS. 20(a) and 20(b) show schematic views of the mooring system of
FIG. 18 being retrieved to a vessel; -
FIG. 21 shows a schematic view of a third embodiment of a mooring system; and -
FIG. 22 shows a schematic view of a fourth embodiment of a mooring system. - A first embodiment of a mooring system for a floating aquatic structure in accordance with the present invention is shown in FIGS. 1(a) and 1(b). The mooring system is intended for use with any structure, marine vessel or installation which requires securing in water at a particular location. However, in the illustrated embodiment, the mooring system is securing a wave energy converter (WEC), which is itself the subject of International Patent Application No PCT/GB99/03204 to the same Applicant. The WEC will therefore not be described further here.
- As seen in
FIG. 1 (a), theWEC 1 floats on the surface of the water and is provided with a pivoting harness oryoke 2 at itsfront end 3—that is, the end facing in the direction of the anticipated wave action or current. Attached to theyoke 2 below is a connecting ortether weight line 11 to which is secured a primary ortether weight 10. First orfront anchor lines 16 are attached to thetether weight arrangement 10 and have first or front anchors 15 of a known type at the ends of thefront anchor lines 16 remote from thetether weight arrangement 10. Although, the embodiment shown in FIGS. 1(a) and 1(b) is provided with threefront anchors 15 and front anchor lines 16, the system need only utilise one front anchor and front anchor line. Additional front anchors and front anchor lines can be added depending on the operational requirements of the system. Optional secondary or clump weights may also be provided on thefront anchor lines 16 to provide additional friction if desired. - Also connected to the
yoke 2 is a second orrear anchor line 13 and its associated second orrear anchor 18, again of a known type. A support oryaw line 14 is also connected between theWEC 1 and therear anchor line 13 to help stabilise theWEC 1, as will be described below. Again, it should be understood that the rear anchor and yaw lines are optional components which may be used in certain applications.FIG. 1 (b) shows a schematic plan view of theWEC 1 and front and rear anchor lines 16,13 when under the action of waves coming from the direction shown byarrow 4. - One of the advantages of the mooring system shown in FIGS. 1(a) and 1(b) is that it is particularly suitable for securing aquatic structures in an array. As shown in
FIG. 2 , a number of WECs or other structures can be held by shared anchor points on the sea bed and can also share electrical connections and such like. Where an array ofWECs 1 is to be moored at the same location, they can be arranged in rows, as shown inFIG. 2 . EachWEC 1 has substantially the same mooring system as that described with reference to FIGS. 1(a) and 1(b). However, where the mooring system differs in an array is that the front anchors 15 are shared byadjacent WECs 1. Thus, thefront anchor lines 16 ofadjacent WECs 1 share the samefront anchor 15. Where there is more than one row of WECs/structures, the front anchors 15 of each row also act as the rear anchors of the adjacent row. As shown inFIG. 2 , therear anchor line 13 of theWEC 1 is connected between thetether line 11 of theWEC 1 and thefront anchor 15 of the WEC in the next row. In addition to sharing anchors, the adjacent WECs also can also share a variety of utilities via one or more umbilicalutility supply lines 27, which in the illustrated embodiment are electrical cables. As will be explained further below, theumbilical lines 27 are adapted so that they may continue to supply utilities around the array, even if one WEC is temporarily removed for some reason. - Furthermore, as the umbilical lines are connected “mid-water” (i.e. they lie under the surface of the water but not on the floor of the body of water), only a
main supply cable 80 to the array need be on the floor. This avoids the need to have a variety of cables or umbilical lines lying on the floor in addition to the lines of the mooring system. - In the particular embodiment shown in
FIG. 2 , electrical switchgear is provided in eachWEC 1 in order to act as circuit breakers. Thus, if there is a fault in one of theelectrical cables 27 connected between twoWECs 1 in the array, the circuit breakers in the associated WECs trip in order to isolate the faulty cable. Thus, the array can continue to operate whilst the faulty cable is replaced. - FIGS. 3(a) and 3(b) show the
yoke 2 of the mooring system in more detail. Theyoke 2 is designed to pivot relative to theWEC 1 in a substantially vertical plane (when viewed in FIGS. 3(a) and 3(b)) through a large angle range 5, both above and below thesurface 9 of the water. This allows theyoke 2 to pivot about thefront end 3 of theWEC 1 so that the lower end of theyoke 2 can be recovered to thesurface 9 without removing any attachments, as will be explained below. Theyoke 2 is also adapted to pivot in order to allow theWEC 1 to move on its moorings without theyoke 2 and theWEC 1 coming into contact. - Referring now to
FIG. 3 (b), it can be seen that theyoke 2 comprises a pair ofarm members 7 which are connected together at their lower ends. The first or upper ends of thearm members 7 are also connected to respective ends of ahollow shaft member 8, such that theyoke 2 is substantially triangular in shape. Theyoke 2 may also be provided with one ormore crossbrace members 6 which allow theyoke 2 to spread the mooring loads. The crossbrace member(s) 6 strengthen theyoke 2 whilst still allowing it to pivot about thefront 3 of theWEC 1. - FIGS. 4(a) and 4(b) show how the mooring system provides restorative forces to the
WEC 1 when it is subjected to wave action. As described above, the lower end of theyoke 2 is connected to thetether weight 10 by thetether line 11. Therear anchor line 13 andrear anchor 18 are connected to the tether line, preferably by alink plate 12, although they may be attached by any other suitable means. Thetether weight 10 is linked to the front anchors 15 using the front anchor lines 16. At rest, the system is arranged such that thetether weight 10 is suspended just off thesea bed 17. Therear anchor line 13 is connected to therear anchor 18 at the rear of theWEC 1 and mooring system to provide restraint should theWEC 1 and system move forwards. -
FIG. 4 (a) shows how the system generates a restoring force RH for rearward displacement of theWEC 1 under wave action from the direction illustrated byarrow 4. During the rearward displacement, theyoke 2 andtether line 11 adopt an angle φ to the vertical which generates a restoring force RH back to the rest position due to the effect of thetether weight 10. The system remains linear in behaviour for angles φ up to approximately 30 degrees (approximately half water depth). After this, the restoring force RH becomes more non-linear with displacement but ‘snatching’ is avoided for angles less than approximately 60 degrees (approximately 85% of water depth) As will be understood by those skilled in the art, snatching occurs when a slack mooring line is suddenly subjected to a high load. An example of snatching occurs when the tether weight is lying on the seabed and the slack tether line is subjected to a high load by movement of the structure. As the line goes taught, the tether weight will be lifted from the seabed, the inertial and possible suction forces on the weight as it lifts from the sediment on the bed can also increase the load on the tether line. These sudden loads on the line are known as snatch loads. -
FIG. 4 (b) shows how the system generates a restoring force RH for forward displacements towards thedirection 4 of the waves. Therear anchor 18 andrear anchor line 13 act on the bottom of theyoke 2 to generate an angle on the yoke. This leads to a restoring force RH as shown. - The mooring system allows the
WEC 1 to yaw about the vertical axis in response to changes in the incident wave direction, as shown in FIGS. 5(a) and 5(b). The available range of motion is limited by theyaw line 14 acting in conjunction with therear anchor line 13. The lengths of theselines direction 4 of incoming waves for a coastal location.FIG. 5 (a) shows a typical limiting angle for waves coming from the starboard direction shown byarrow 19.FIG. 5 (b) shows a typical limiting angle for waves coming from the port direction shown byarrow 20. If more yaw angle is required the mooring system can be provided with a swivel to allow it to rotate fully, and electrical/other interconnection would be through slip rings or similar means. - A further function of the mooring system is to provide greater rotational stability about a particular axis. For the WEC illustrated, the mooring system is used to provide additional roll stability. The
yoke 2,tether line 11 andtether weight 10 combine to give the WEC additional roll stability about its longitudinal axis, as shown inFIG. 6 . With thetether weight 10 attached to its lower end, theyoke 2 behaves in the same manner as the keel of a yacht, producing a counteracting force to counter the roll action of the WEC. -
FIG. 7 shows a detail view of the upper part of theyoke 2. The twoarm members 7 of theyoke 2 are connected to respective ends of ahollow shaft 8. Theshaft 8 provides a structural link between thearm members 7, which ensures that theyoke 2 is a rigid, structurally efficient frame able to withstand large mooring loads while remaining relatively lightweight. Theshaft 8 is located in a housing at thefront end 3 of theWEC 1 andbearings 21 are provided between theshaft 8 and the housing. Thesebearings 21 allowlow friction rotation 22 of the yoke about the rotational axis 23 of theshaft 8.Conduits 24 are also provided which are located within either one or both of thearm members 7 and theshaft 8. Theconduits 24 allow electrical and communications wiring, and/or hydraulic or other lines to run between the upper and lower ends of theyoke 2. Theconduits 24 exit theshaft 8 at one ormore exit apertures 25 with theflexible end portions 26 of theconduits 24 connecting to theWEC 1. Theflexible end portions 26 are designed to allow theyoke 2 to pivot freely about the rotational axis 23 of theshaft 8 while minimising strain on the internal wires or other lines. This allows all internal/external connections to theyoke 2 andmachine 1 to be made at the lower end of theyoke 2. As a result, the connection/disconnection of theWEC 1 from the mooring system can be done without needing human intervention on theWEC 1 whilst in the water. The arrangement also protects the wiring and other connections from the water. - FIGS. 8(a) and 8(b) show details views of the lower end of the
yoke 2. The lower ends of thearm members 7 meet to form the corner or apex of the substantiallytriangular yoke 2. All of the mechanical, electrical and/or other connections to the machine are housed at this lower end of theyoke 2. These connections typically comprise flexible umbilicalutility supply lines 27 which usually contain electrical, communication, hydraulic or other lines interconnecting adjacent WECs in an array such as that shown inFIG. 2 , or connecting the WEC to main supply lines on the sea bed. In the embodiment shown, theumbilical lines 27 betweenadjacent WECs 1 are made “mid-water”. In other words, theumbilical lines 27 lie below the surface of the water, but are not in contact with the sea bed. Theseumbilical lines 27 are connected via sealedconnectors 28 to a connecting means in the form of ajunction box 29 mounted on theyoke 2. Thejunction box 29 is linked to theconduits 24 to provide a path for the various lines to the upper part of theyoke 2 and then subsequently into theWEC 1, as shown inFIG. 7 . If twoumbilical lines 27 are used, theconnectors 28 are designed to be a male/female mating pair so that they can be connected together in order to maintain continuity for an array of WECs if thisparticular WEC 1 andyoke 2 are off-site for any reason. - The lower part of the
yoke 2 also includes the main mechanical attachment to thetether line 11. In the illustrated embodiment, this is provided by a universal joint 30 to allow free motion about two perpendicular rotational axes and to minimise wear of the connection in service. This connection is made using asingle pin 31 to allow straightforward and rapid attachment and removal of the tether line. In addition, back-up lines (not shown) may be provided to maintain integrity of the mooring system in the event of failure of any of the components. - The lower part of the
yoke 2 is also provided with a retrieval means to allow easier retrieval of theyoke 2 onto the rear of an installation/removal vessel, as will be described further below. This retrieval means comprises profiledslots 32 or may alternatively comprise a ball and socket joint (not shown) or any similar connection. In addition, to facilitate simple, safe recovery of theyoke 2 onto the vessel, skids orrollers 33 are also provided. These allow the system to be easily and safely pulled up over stern of the vessel and guide the end of theyoke 2 into a latching means. Further guides, rollers, or latches may also be added to aid the safe and rapid recovery of theyoke 2. - A
tether weight 10 which is used in the mooring system is shown inFIG. 9 . Thetether weight 10 comprises aframe member 34 for attachment to thetether line 11 and thefront anchor lines 16 and any other ancillary or back-up lines (not shown). The attachment of the various lines is again made usinguniversal joints 30 to allow full and free motion and minimise wear of the connection. Loops or lengths ofchain links 35 are suspended from theframe 34 to provide the weight required to generate the mooring reaction forces, as will be described below. - The operation of the
tether weight 10 is shown inFIGS. 10 and 11 (a)-(c). The mooring system is arranged such that when it is not experiencing any displacement forces from the water, thetether weight 10 is positioned as close as possible to, or partially resting on, thesea bed 17. In large waves, the vertical motion or pitch of theWEC 1 may be great, as shown in FIGS. 10(a) and 10(b). When thefront 3 of theWEC 1 is on top of a wave crest, as shown inFIG. 10 (a), thetether weight 10 will be lifted away from thesea bed 17. Conversely, when the front of the machine is in a wave trough, as shown inFIG. 10 (b), thetether weight 10 will fall onto thesea bed 17 unless sufficient clearance is provided. - With known tether weights, it is undesirable for the weight to touch the sea bed. However, the clearance required from the sea bed would seriously compromise the linear range of motion if the tether weight is not allowed to touch down on the sea bed. The
tether weight 10 shown inFIG. 9 allows a progressive pick-up from the sea bed, as shown in FIGS. 11(a)-(c). The chain links 35 are progressively picked up by theframe 34, ensuring a smooth increase in the mass of thetether weight 10 as it rises from thesea bed 17. - The problem with known solid tether weights touching down on the sea bed is illustrated in FIGS. 11(d)-(f). When a
solid tether weight 36 hits the sea bed, thetether line 11 goes slack. When the next wave crest comes along, thetether line 11 tightens again as thetether weight 36 is lifted back off the sea bed, and the resultant accelerations involved are very high, putting large snatch loads on theline 11. As thesolid tether weight 36 is lifted from the sea bed, it can also be subjected to a suction effect by the mud and sediment on the sea bed, which worsens the aforementioned snatch load on thetether line 11. Thus, with knownsolid weights 36 an extreme snatch load on thetether line 11 will be encountered as the tether weight is lifted from the sea bed under the wave action. -
FIG. 11 (f) shows how the load in the tether line would vary with time for both types of tether weight during the passage of a large wave. The time represented bypoint 38, the tether weights are resting fully on the sea bed. At the time represented bypoint 39, the tether line tightens as the weights start to be lifted back off the sea bed. Thelarge snatching load 40 with the solid tether weight is caused by the rapid vertical acceleration of the moored structure during the wave action and the suction effect of the sea bed sediment on the tether weight. This snatching load is many times larger than the normal loads intended for the tether line to encounter in service, and can lead to damage and, in extreme cases, failure of the tether line. In using a tether weight as shown inFIG. 9 , the weight rises from the sea bed more progressively, and a muchsmaller snatch load 41 is placed on the tether line, as shown in the graph ofFIG. 11 (f). - One of the advantages of the mooring system as described above is that the moored machine or structure can be disconnected whilst out of the water. In this way, there is no need for an operator to either be in the water or on the structure during the connection or disconnection.
- This is facilitated thanks to the yoke, as it houses the connections to the utility umbilical lines and the tether weight and anchors. As will be explained below, the yoke remains attached to the machine/structure when the umbilical line(s) and connecting line to the tether weight are disconnected, thus allowing the remainder of the mooring system to remain in the water when the structure and yoke are retrieved.
- In order to permit the connection and disconnection of the mooring system out of the water, a recovery or retrieval apparatus is required for retrieving the yoke from the water. An example of such an apparatus is shown in FIGS. 12(a) and 14(b). The
retrieval apparatus 45 is installed on thedeck 46 of a support vessel and is arranged to hold the end of theyoke 2, as shown inFIG. 12 (b), during connection or disconnection of the remainder of the mooring system. The structure and yoke can then be towed to a suitable location for the maintenance work, or else they can be lifted onto a barge or the like for maintenance or transportation. - The retrieval apparatus is provided with a
ramp 47 onto which the lower end of theyoke 2 is recovered, as has been previously described with reference toFIGS. 12 and 13 . Theramp 47 has an inclined surface which lies in a ramp surface plane. The rear end of the ramp is inclined at an angle to the ramp surface plane in order to help with the recovery of the yoke. Furthermore, either the rear of the vessel itself or theramp 47 is provided with a recovery roller or drum 44 to ensure the smooth recovery or deployment of the various lines and umbilicals attached to theyoke 2. A tensioningroller 48 is also provided at the top end of theramp 47 to ensure that therecovery line 42 is pulled onto its drum (not shown) at the proper angle and tension.Guide plates 49 are located on either side of theramp 47 to guide theyoke 2 onto a retention means 50 of theapparatus 45. - As seen best in FIGS. 13(a)-(c), the retention means 50 comprises a retaining member or block 51 which has a pair of
coaxial bars 52 on either side thereof. Theblock 51 is mounted on aspherical bearing 53 which ensures that theblock 51 can move in all three axes (i.e. move in any roll, pitch or yaw motion). Thebearing 53 and block 51 are mounted on a base member comprising apedestal 54 mounted on acarriage 55, as shown in FIGS. 14(a) and 16(b). - The
carriage 55 has a number of rollers 57 which are housed within a set of guide tracks 56 so that the whole retention means may move longitudinally relative to theramp 47. As can be seen in FIGS. 14(a) and 16(b), the guide tracks 56 have first and second, or lower and upper,portions lower portion 58 is at a steeper angle to the ramp surface plane in order that theattachment block 51 lies generally in the ramp surface plane when theyoke 2 is pulled onto theramp 47. Theupper portion 58 of theguide track 56 is substantially parallel to the ramp surface plane. - FIGS. 15(a)-(d) show the steps of the
yoke 2 being retrieved. InFIG. 15 (a), theyoke 2 has been pulled up onto theramp 47 as therecovery line 42 is wound onto its drum (not shown). With thecarriage 55 in position in thelower portion 58 of theguide track 56, the lower end of theyoke 2 and theattachment block 51 come into contact. Thecoaxial bars 52 of theblock 51 locate in the previously describedslots 32 of theyoke 2. With the lower end of theyoke 2 now attached to and supported by theattachment block 51 andcarriage 55, thecarriage 55 moves up theguide track 56 as the windingrecovery line 42 continues to pull theyoke 2 up theramp 47. This stage is shown inFIG. 15 (b), as thecarriage 55 moves from thelower portion 58 to theupper portion 59 of theguide track 56. - In each of FIGS. 15(a)-(d), it can also be seen that the connecting
line 11 of theprimary weight 10 is still connected to theyoke 2 and running up over thestern roller 44. Theretrieval apparatus 45 may also be provided with acatch 60 on theramp 47 in order to secure the connectingline 11 once it is disconnected from theyoke 2, as shown in FIGS. 15(c) and 17(d). In this instance, the connectingline 11 is provided with asleeve 61 located at a point on theline 11 such that when thecarriage 55 andyoke 2 reach the uppermost point of theguide track 56, the sleeve has been pulled up past thecatch 60. Therecovery line 42 can then be slackened a little so that thesleeve 61 hangs on thecatch 60, as shown inFIG. 15 (d). By doing this, the load of the connectingline 11 andprimary weight 10 are then removed from the mechanical attachment joint 30 of theyoke 2. Theattachment pin 31 and connectingline 11 may then be easily and safely removed from theyoke 2. - In addition, locking pins 63 may be located in
holes 62 in the sides of theguide track 56 in order to lock thecarriage 55 in position. Once this has been done, therecovery line 42 can also be disconnected from theyoke 2, and the WEC or other structure will then be held or towed directly through theblock 51 andbearing 53. Any umbilical utility lines may also be disconnected from theyoke 2 at this point. Finally, theyaw line 14 can be disconnected from the WEC or structure using either a surface buoy or boat hook, as described below with reference toFIG. 16 , or by some other remotely operated means. Theyoke 2 andWEC 1 are now fully separated from the remainder of the mooring system. Theyoke 2 and WEC are now ready for towing, as shown inFIG. 12 (b). In order to reconnect theyoke 2 and the remainder of the mooring system, the steps described above are simply undertaken in reverse. - FIGS. 16(a)-(h) illustrate one method of recovering the
yoke 2 andWEC 1 to a support vessel 100. As seen inFIG. 16 (a), theWEC 1 is held by the mooring system as previously described. To aid recovery without having to have operators entering the water, arecovery line 42 is permanently attached to the lower end of theyoke 2 when theyoke 2 andWEC 1 are moored. The end of therecovery line 42 remote from theyoke 2 is held by abuoy 102. The recovery line may be provided with one ormore clump weights 104 and/orbuoyancy aids 106, as required. During this initial stage, the support vessel 100 arrives at thebuoy 102. The remote end of therecovery line 42 is retrieved from thebuoy 102 and is attached to its winding drum (not shown) on the vessel 100. -
FIG. 16 (b) shows the next stage of the recovery procedure. Once therecovery line 42 has been attached to the drum, thebuoy 102 is retrieved and placed on the deck of the vessel 100. As therecovery line 42 is wound in, theclump weight 104 is lifted from the sea bed and rises towards the vessel 100. If fitted, the buoyancy aids 106 will also rise to the surface as therecovery line 42 is wound in. Once therecovery line 42 has been wound in enough to take up any slack in theline 42, it will then begin to raise the lower end of theyoke 2 towards the vessel 100. As theline 42 raises the lower end of theyoke 2, theyoke 2 will pivot about the axis of rotation 23 of theshaft 8, as shown inFIG. 16 (c). With the pivoting of theyoke 2, theyoke 2 will raise thetether line 11 and associatedtether weight 10. As seen inFIG. 16 (d), therecovery line 42 will continue to be wound in until such time as theyoke 2 is recovered to the deck of the vessel 100, which is the state previously described with reference to FIGS. 12(b) and 15(c). - As illustrated in
FIG. 15 (d), thetether line 11 can be disconnected from theyoke 2 along with any other lines or umbilicals once the yoke is attached to theattachment mechanism 50. To prevent thetether line 11 sinking to the sea bed once it has been disconnected, it is attached to thebuoy 102 and the buoy is replaced in the water, which is the state shown inFIG. 16 (e). - At the same time as the vessel 100 is undertaking the steps shown in FIGS. 16(a)-(e), a
second vessel 110 is used to detach the rear anchor andyaw lines WEC 1. This is shown in FIGS. 16(f) and 16(g), which illustrate schematic end views of the mooring system andWEC 1. A second recovery orchaser line 112 is attached by a first end to theWEC 1 and by a second end to theyaw line 14. Thesecond vessel 110 recovers the first end from theWEC 1 and winds in thechaser line 112, as shown inFIG. 16 (f). As thechaser line 112 is wound onto thesecond vessel 110, the rear anchor andyaw lines second vessel 110, as illustrated inFIG. 16 (g). Once on thesecond vessel 110, the rear anchor andyaw lines further buoy 114, as shown inFIG. 16 (h). - FIGS. 17(a) and 17(b) show an alternative arrangement, in which the
recovery line 42 is clipped to theyoke 2. By clipping therecovery line 42 to theyoke 2, there is no need for therecovery line 42 to be provided with clump weights or buoyancy aids. It can simply be unclipped fromyoke 2 and recovered in the same way as described with reference toFIG. 16 . -
FIG. 18 shows a second embodiment of a mooring system in accordance with the present invention. The mooring system inFIG. 18 shares a number of components with the mooring system previously described, and these features will be assigned the same reference numerals, but with a 2—prefix. Further description of certain components is not considered necessary given their description above. - As with the previously described embodiment, this second embodiment of a mooring system is shown in
FIG. 18 mooring aWEC 201. The mooring system has a pivoting harness oryoke 202 at thefront end 203—that is, the end facing in the direction of the anticipated wave action or current—of theWEC 201. Where the second embodiment differs from the previous embodiment is that attached to theyoke 202 below are first and second connecting or tether weight lines 211A,211B, rather than a single connecting line. Connecting together the first and second connecting lines 211A,211B is alink plate 212, which will be described in more detail below. The primary ortether weight 210 is hung from the second connecting line 211B. As before, first orfront anchor lines 216 are attached to thetether weight arrangement 210 and have first or front anchors (not shown) of a known type at the ends of thefront anchor lines 216 remote from thetether weight arrangement 210. - A
recovery line 242 incorporating a suitable float is also connected to thelink plate 212 to facilitate recovery of theWEC 201. Also connected to thelink plate 212 is a second orrear anchor line 213 and its associated second or rear anchor (not shown), again of a known type. A support oryaw line 214 is also connected between theWEC 201 and therear anchor line 213 to help stabilise theWEC 201. - The link plate arrangement of the second embodiment is shown in detail in
FIG. 19 . As can be seen, thelink plate 212 has a generally triangular shape and has four connection points for connecting together the first and second connecting lines 211A,211B,rear anchor line 213 andrecovery line 242.Rear anchor line 213 is connected to thelink plate 212 via aconnection fork 150. Stabiliser bars 152 are also provided either side of thelink plate 212 to ensure it remains stable when removed from the water. - The
link plate 212 makes the connections between all the main lines in the mooring system. Thanks to the generally triangular shape of theplate 212 and the stabiliser bars 152, theplate 212 can be easily retrieved over the stern or stern roller of an installation/removal vessel. As well as the stabiliser bars 152, each side of thelink plate 212 is also provided with achannel 154. By providing theplate 212 with substantiallyidentical channels 154 on either side, theplate 212 can be locked in KARM forks or similar. - The
link plate 212 and rear anchorline connection fork 150 give a clean load of wires back over a stern roller. The first connecting line 211A is provided with a hang-off pad-eye 158 to allow tow loads to be taken off theconnection pin 156. Theconnection pin 156 is extracted remotely using a wire or hydraulic ram to avoid having personnel operating near the mooring system as thepin 156 is removed. - FIGS. 20(a) and 20(b) show schematically how the second embodiment of the mooring system is retrieved onto the deck of a support vessel. As with the previously described embodiment, the
recovery line 242 is first retrieved, preferably via a float, and is wound onto a drum or the like on the vessel. In winding in therecovery line 242 thelink plate 212 andother lines 211A,211B,213 are also pulled towards the vessel as well. As thelink plate 212 reaches the vessel, as seen inFIG. 20 (a), it slides onto the deck of the vessel. To assist the retrieval, the vessel may have arecovery roller 244 at the stern. - Once on the deck of the vessel, as shown in
FIG. 20 (b), the generally triangular shape of thelink plate 212 andstabiliser bars 152 provided thereon allow thelink plate 212 to slide across the deck with relatively little friction and no twisting, thus ensuring that thevarious lines 211A,211B,213 do not become entangled with one another. The deck of the vessel is provided withKARM forks 160 or a similar locking arrangement to hold thelink plate 212 on the deck so that thelines 211A,211B,213 can be detached. As shown best inFIG. 19 , thelink plate 212 haschannels 154 either side thereof which receive theKARM forks 160. Additionally, guiderollers 162 can also be provided on the deck to ensure that thelink plate 212 passes over theKARM forks 160 when being retrieved. -
FIG. 21 shows a third embodiment of a mooring system in accordance with the present invention. This third embodiment shares a number of components with the previously described first and second embodiments and as before is shown mooring aWEC 301. The mooring system has a pivoting harness oryoke 302 at thefront end 303—that is, the end facing in the direction of the anticipated wave action or current—of theWEC 301. Where this third embodiment differs from the previous embodiments is that attached to the second end of theyoke 302 are first, second and third connecting or tether weight lines 311A,311B,311C. At the end of each connecting line 311A,311B,311C is attached a respective primary or tether weight 310A,310B,310C. Attached to the first and second tether weights 310A,310B are first orfront anchor lines 316 which have first or front anchors 315 at the remote ends thereof. Attached to the third tether weight 310C is the second orrear anchor line 313 and its associated second orrear anchor 318, again of a known type. A support oryaw line 314 is also connected between theWEC 301 and therear anchor line 313 to help stabilise theWEC 301. - A fourth embodiment of the mooring system of the present invention is shown in
FIG. 22 . As before, this fourth embodiment shares a number of components with the previously described embodiments and as before is shown mooring aWEC 401. The mooring system has a pivoting harness oryoke 402 at thefront end 403—that is, the end facing in the direction of the anticipated wave action or current—of theWEC 401. The fourth embodiment differs from the previous embodiments in that attached to the second end of theyoke 402 are first and second connecting or tether weight lines 411A,411B. At the end of each connecting line 411A,411B is attached a respective primary or tether weight 410A,410B. Attached to the first and second tether weights 410A,410B are first orfront anchor lines 416 which have first or front anchors 415 at the remote ends thereof. Also attached to each tether weight 410A,410B are respective second or rear anchor lines 413A,413B and their associated second or rear anchors 418. Support or yaw lines 414A,414B are also connected between theWEC 401 and the rear anchor lines 413A,413B for stabilising theWEC 401. - The present invention allows a large array of machines to be installed on the same site. This helps reduce costs as the WECs or other structures can share anchor points. In particular, it is desirable for WECs to be spaced closely. Thus, a mooring system such as that of the present invention which has a small spread between anchor points is advantageous. In addition, the mooring system of the present invention provides a large dynamic range of motion which is sufficient to cope with extreme waves while minimising extreme loads on the system and anchors.
- The mooring system can also provide restraint to other forms of motion such as yaw. This allows the system to respond to the incident waves while avoiding complete rotation about the mooring axis which would require expensive and potentially unreliable assemblies for electrical (or other) interconnection.
- The mooring system also combines a number of reaction means on the seabed to address different wave- or current-induced loads. Wave loading is characterised most of the time by small, steady and unsteady drift loads due to wave action on the machine/installation. However, in very large and extreme seas very large loads occasionally may be experienced. Small lightweight solid secondary or clump weights provide sufficient reaction for small normal loads accounting for the vast majority of operating conditions and are cheap and easy to deploy in large numbers. The reaction provided by these small weights can be effectively augmented for extreme conditions by the use of conventional embedment anchors, conventional or suction piles, larger clump weights, or by the interlinking of smaller clump weights. Alternatively a weighted suction pile provides both means of reaction where the sea bed is of a suitable composition—the mass of the pile provides adequate reaction for small waves and under the action of extreme loads the suction of the pile in the seabed provides large resistance to short-term large loads.
- A further benefit of the present invention comes from the use of a pivoting harness/yoke assembly or linking plate member to provide a means of mechanical connection and disconnection of the structure to/from the mooring system. This allows the structure to be connected or disconnected in rough seas without having to have personnel board the structure itself. The pivoting yoke mechanism or linking plate can be recovered to the deck of an installation/recovery vessel by retrieval of the recovery line remote from the machine and the various connections can then be attended to from the comparative safety of the vessel. Such a provision is vital to allow intervention activities to be carried out safely in large seas, thereby reducing the weather dependence of these operations and the associated cost and risk. The yoke assembly also provides restraint to the WEC or structure in combination with the suspended tether weight(s). As illustrated in
FIG. 6 , and in particular for a WEC, the harness and tether weight provide additional roll restraint to the moored structure. This is beneficial as it reduces the requirement for ballast on or in the structure to provide roll stability. The reduction in the ballast required can reduce the size, mass and volume of the structure, directly reducing the cost thereof. - Furthermore, the provision on the yoke of the electrical or other (e.g. hydraulic or pneumatic) utility interconnections alongside the mechanical attachment means ensures that these can be connected or disconnected at the same time as the mechanical attachment without personnel having to board the WEC or other marine/offshore installation. This means that adjacent machines may be connected in an array ‘mid-water’. That is to say that a the umbilical lines connect adjacent machines via the lower ends of the yokes without contact with the seabed. This greatly eases the tasks of installing, inspecting and repairing the electrical or other interconnection, reducing cost and increasing reliability.
- A benefit is also provided in connecting the rear anchor line to the lower end bottom of the yoke or the linking plate member. In this way, connection or disconnection of the rear anchor line can be done at the same time as the connection or disconnection of the main connecting line(s). For the WEC machine of the illustrated embodiments, the rear anchor line acts as a surge restraint to prevent the system surging forward under the action of small waves from an offshore direction, or tidal currents when waves are small. Sufficient slack in the complete system is provided to allow the lower end of the yoke or linking plate to be recovered to the deck of a support vessel without moving or recovering any of the anchor/reaction points.
- The use of heavy suspended tether weights hanging from the end of the yoke and linked to the main mooring lines is also advantageous, as this is what provides the means of restraint to the system. The combination of the yoke, tether line(s) and tether weight(s) behaves like a pendulum to provide location restraint to the system being moored. The tether weights are effectively fixed in location by the main mooring lines. The system provides a ‘soft’ or low-rate spring restraint which stops ‘snatching’ of the mooring lines under extreme motions.
- The new arrangement of tether weight used in the present invention also has advantages of known arrangements. The tether weight of the present invention can descend to, rest on and rise from the sea bed with progressive loss and recovery of suspended weight. This is done thanks to the suspended and interlinked chain segments. The new tether weight can rest close to (or even partially on) the seabed, maximising the length of the tether assembly and, as a result, its range of motion for a given range of tether/yoke angle to the vertical. This allows the mooring system of the present invention to be used in siting WECs or other installations in shallower water depths near the shore/coastline and in energetic wave regimes.
- The provision of the retrieval apparatus on the back of the support vessel ensures that the lower end of the yoke or linking plate can be recovered onto the back of the support vessel without direct human intervention. This allows the mechanical connections between the yoke or linking plate and the remainder of the mooring system and also the umbilical utility lines to be attached or detached in safety from the deck of the support vessel. Thus, personnel do not need to board the WEC or other structure/installation in heavy seas or similarly adverse conditions.
- Although the tether weights of the illustrated embodiments are shown suspended off the sea bed in the rest position, they may alternatively be partially resting on the sea bed in the rest position. It should also be understood that additional clump weights or any other form of anchorage such as suction anchors or piles may be used in addition to or instead of the conventional anchors described above. As regards the recovery procedure illustrated in
FIG. 16 , the rear anchor and yaw lines may be disconnected prior to the disconnection of the tether line. In this way, the same vessel could do both tasks and there would be no need for a second vessel. Finally, the recovery lines used in the recovery procedure can be attached to the WEC or structure by release means which are remotely controlled. The lines can therefore be remotely released from the WEC and then recovered to the vessel without intervention required on the machine. These and other modifications and improvements may be made without departing from the scope of the invention.
Claims (40)
1. A mooring system for a floating aquatic structure, the system comprising: a harness having first and second ends, the first end being adapted to be pivotally attached to the structure;
at least one primary weight removably attached to a connecting line, and suspended on the connecting line from the second end of the harness; and
at least one first anchor removably attached to said primary weight by at least one first anchor line, wherein the first anchor is adapted to resist movement of the structure in a first direction.
2. The mooring system of claim 1 , further comprising at least one second anchor removably attached to the connecting line by at least one second anchor line, wherein the second anchor is adapted to resist movement of the structure in a second direction substantially opposite to the first direction.
3. The mooring system of claim 2 , further comprising a support line having one end adapted to be removably attached to the structure and its other end removably attached to the second anchor line, the support line adapted to restrict yaw motion of the structure.
4. The mooring system of claim 2 , further comprising one or more secondary weights attached to one or more of the first and second anchor lines.
5. The mooring system of claim 2 , wherein the system comprises at least two first anchors removably attached to said primary weight by respective first anchor lines, wherein each first anchor is adapted to resist movement of the structure in the first direction.
6. The mooring system of claim 1 , wherein the at least one primary weight comprises a frame member and one or more chain links suspended from said frame member.
7. The mooring system of claim 6 , wherein the frame member includes at least two first mechanical attachment means adapted to removably attach the connecting line and at least one first anchor line thereto.
8. The mooring system of claim 7 , wherein the first mechanical attachment means are universal joints having detachable pin members.
9. The mooring system of claim 1 , further comprising: first and second primary weights attached to first and second connecting lines, respectively, and suspended on the connecting lines from the second end of the harness; and a pair of first anchors having respective first anchor lines, one of the first anchors removably attached to the first primary weight by one first anchor line and the other first anchor being removably attached to the second primary weight by the other first anchor line, wherein the first anchors are adapted to resist movement of the structure in a first direction.
10. The mooring system of claim 9 , wherein the system further comprises a third primary weight attached to a third connecting line and suspended on the third connecting line from the second end of the harness; and at least one second anchor removably attached to the third connecting line by at least one respective second anchor line, wherein the second anchor is adapted to resist movement of the structure in a second direction substantially opposite to the first direction.
11. The mooring system of claim 10 , further comprising a support line having one end adapted to be removably attached to the structure and its other end removably attached to the second anchor line, the support line adapted to restrict yaw motion of the structure.
12. The mooring system of claim 9 , wherein the system further comprises a pair of second anchors
each having respective second anchor lines, one of the second anchors being removably attached to the first primary weight by one second anchor line and the other second anchor being removably attached to the second primary weight by the other second anchor line, wherein the second anchors are adapted to resist movement of the structure in a second direction substantially opposite to the first direction.
13. The mooring system of claim 12 , further comprising first and second support lines, each support line having one end adapted to be removably attached to the structure and its other end removably attached to one of the second anchor lines, the support lines adapted to restrict yaw motion of the structure.
14. The mooring system of claim 1 , wherein the harness comprises first and second arm members and a shaft member, wherein the arm members have first and second ends and the shaft member is connected between the respective first ends of the arm members to form the first end of the harness, and wherein the shaft member has an axis of rotation about which the harness pivots.
15. The mooring system of claim 14 , wherein the harness is adapted to apply roll restraint to the structure.
16. The mooring system of claim 14 , wherein said shaft member and at least one of said arm members are hollow, the harness further comprising at least one conduit that is at least partially located in the hollow arm member and the shaft member.
17. The mooring system of claim 16 wherein the harness further comprises connecting means for connecting one or more utility supplies to the harness.
18. The mooring system of claim 17 , wherein said connecting means comprises a junction box having one or more connectors therein, the junction box being in communication with the at least one conduit, and the conduit carrying utility supply through the harness to the structure.
19. The mooring system of claim 1 , wherein the harness further comprises retrieval means to facilitate retrieval of the harness from a body of water.
20. The mooring system of claim 19 , wherein the retrieval means comprises one or more slots provided on the harness.
21. The mooring system of claim 20 , wherein the retrieval means further comprises one or more roller members provided on the harness.
22. The mooring system of claim 1 , wherein the harness further comprises a second mechanical attachment means for removably attaching the connecting line thereto.
23. The mooring system of claim 22 , wherein the second mechanical fixing means is a universal joint having a detachable pin therethrough.
24. The mooring system of claim 2 , wherein the at least one connecting line includes a linking plate member, and wherein the at least one second anchor line is removably connected to the connecting line by the linking plate member.
25. The mooring system of claim 24 , wherein the linking plate member includes: retrieval means adapted to allow the mooring system to be retrieved from the water; and stabilising means adapted to hold the plate member in substantially the same plane during retrieval.
26. The mooring system of claim 25 , wherein the linking plate member further includes locking means adapted to secure the plate member to a marine vessel.
27. The mooring system of claim 1 , wherein the floating aquatic structure is a wave energy converter.
28. A weight for a mooring system, the weight comprising a frame member and at least two chain links suspended from said frame member.
29. The weight of claim 28 , wherein the weight comprises a plurality of chain links suspended from the frame member.
30. The weight of claim 28 , wherein the frame member includes at least two mechanical attachment means adapted for removably attaching components of a mooring system thereto.
31. The weight of claim 30 , wherein the mechanical attachment means are universal joints having detachable pin members.
32. A recovery apparatus for a marine vessel, the apparatus comprising: a rotatable drum;
a recovery line having a first end adapted to be removably attached to a portion of an object to be recovered and a second end adapted to be removably attached to the rotatable drum;
a retention means comprising a base member and a retaining member attached to the base member by a spherical bearing, the retaining member being adapted to have a portion of the recovered object removably attached thereto; and
a guide means adapted to guide the recovery line over the retaining member during winding and unwinding of the line.
33. The recovery apparatus of claim 32 , wherein said guide means is a ramp having an inclined surface lying in a ramp surface plane, and wherein the retention means is housed on the ramp.
34. The recovery apparatus of claim 33 , wherein the base member is adapted to permit longitudinal movement of the retention means relative to the ramp.
35. The recovery apparatus of claim 34 , wherein the ramp further comprises a guide track in which the base member is located.
36. The recovery apparatus of claim 35 , wherein the guide track has first and second portions, wherein the first portion lies at a greater angle relative to the horizontal than the second portion.
37. The recovery apparatus of claim 36 , wherein the first guide track portion lies at an angle relative to the ramp surface plane and the second guide track portion is substantially parallel to the ramp surface plane.
38. The recovery apparatus of claim 35 , wherein the guide track includes locking means adapted to lock the retention means in one or more positions on the guide track.
39. The recovery apparatus of claim 32 , further comprising a tensioning roller member adjacent a first end of the guide means for tensioning the recovery line.
40. The recovery apparatus of claim 32 , wherein a second end of the guide means terminates adjacent the stem of the marine vessel, and the apparatus further comprises a recovery roller member adjacent the stern of the vessel, the recovery roller member adapted to assist in the recovery of an object onto the guide means.
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CN107148381A (en) * | 2014-10-27 | 2017-09-08 | 原理动力有限公司 | For the connection system for the array cable of marine energy device that can be disconnected |
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AU2019253870B2 (en) * | 2014-10-27 | 2021-07-01 | Principle Power, Inc. | Connection System For Array Cables Of Disconnectable Offshore Energy Devices |
US10858075B2 (en) | 2014-10-27 | 2020-12-08 | Principle Power, Inc. | Floating electrical connection system for offshore energy devices |
CN110040212A (en) * | 2014-10-27 | 2019-07-23 | 原理动力有限公司 | The float connector system of marine energy converter devices and the method for installing the system |
US10421524B2 (en) * | 2014-10-27 | 2019-09-24 | Principle Power, Inc. | Connection system for array cables of disconnectable offshore energy devices |
US20160114863A1 (en) * | 2014-10-27 | 2016-04-28 | Principle Power, Inc. | Connection system for array cables of disconnectable offshore energy devices |
US10174744B2 (en) | 2015-06-19 | 2019-01-08 | Principle Power, Inc. | Semi-submersible floating wind turbine platform structure with water entrapment plates |
US10514019B2 (en) | 2016-07-26 | 2019-12-24 | Gaynor Dayson | Floating piezoelectric assembly for generating energy from waves |
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WO2022216032A1 (en) * | 2021-04-08 | 2022-10-13 | 삼성중공업 주식회사 | Floating offshore structure having one-side spread mooring system applied thereto |
CN114572348A (en) * | 2022-04-01 | 2022-06-03 | 广州睿海海洋科技有限公司 | Three-point connector and mooring system with same |
Also Published As
Publication number | Publication date |
---|---|
NZ546579A (en) | 2009-01-31 |
WO2005025978A2 (en) | 2005-03-24 |
ATE434557T1 (en) | 2009-07-15 |
CN1882472A (en) | 2006-12-20 |
EP2110307A3 (en) | 2011-09-07 |
GB0321768D0 (en) | 2003-10-15 |
IS8419A (en) | 2006-04-18 |
BRPI0414530A (en) | 2006-11-07 |
CA2539373A1 (en) | 2005-03-24 |
AU2004272356A1 (en) | 2005-03-24 |
EP2110307B1 (en) | 2013-12-25 |
EP2110307A2 (en) | 2009-10-21 |
NO20061707L (en) | 2006-06-16 |
AU2004272356B2 (en) | 2010-09-30 |
EP1670675A2 (en) | 2006-06-21 |
JP2007505784A (en) | 2007-03-15 |
EP1670675B1 (en) | 2009-06-24 |
DE602004021709D1 (en) | 2009-08-06 |
WO2005025978A3 (en) | 2006-03-02 |
ZA200603040B (en) | 2007-09-26 |
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