Field of the Invention The present invention relates to improvements to anchoring assemblies as used in connection with anchoring water-borne structures. More specifically, but not exclusively, the present invention relates to improvements to mooring lugs as used, for example, on mooring piles associated with sea-borne structures such as oil and/or gas rigs.

Background to the Invention

It is known to anchor various kinds of water-borne structures to the bed of the body of water that such structures are located in. For example sea-borne oil platforms, otherwise known as oil rigs, are typically located some way off shore and often in deep waters. Such sea-borne rigs must be anchored to the sea-bed to stop them drifting and to enable drilling for oil and gas and extraction of these fluids to be effected.

Various kinds of anchoring assemblies for anchoring water-borne structures are known. A known and commonly used assembly is schematically illustrated in Figs. 1A-1C. The known assembly consists of a cylindrically shaped pile 101 that is located in the bed 102 of a body of water 103 and a tether 104 that connects the water-borne structure to the pile. In the example of oil-rigs a number of such anchoring assemblies are typically used to secure a given platform to the seabed. Typically nine such anchoring assemblies may be used each tether radiating out from the platform in a different direction to the next. The known tether 104 in such assemblies consists of a chain that is affixed to pile 101 via a known padeye 105 (also known as a pile lug or more generally, a mooring lug) that is formed as part of the pile. Such a padeye basically consists of a protrusion in the form of a plate that extends from the body of the pile. The plate has a hole

P2063.spec passing through it, the main length of the hole being disposed in a direction that is perpendicular to the main length of the pile and tangential to the surface of the pile at the point where the plate is attached thereto. To provide optimum strength the padeye is normally cast as part of the body of the pile although in some cases the padeye may be simply welded onto the body of the pile. In such a known assembly the tether is connected to the padeye using a u-shaped shackle 106 that connects to a retaining pin 107 that passes through the orifice, that is the aforementioned hole, of the padeye. Shackle 106 is configured to pass through the final link of the tethering chain thereby securing the tether to the padeye.

Padeye 105 is further schematically illustrated in Figs. 2A-2D which illustrate the padeye as formed in a section of the wall of an anchoring pile. Fig. 2A schematically illustrates padeye 105 in perspective view. Figs. 2B-2C respectively illustrate padeye 105 in plan view, side elevational view and front elevational view. In figs. 2A and 2B it is seen that located behind the padeye, within the body of the pile, there is formed a strengthening cross-bar member 201 extending from one side of the wall of the pile to the other.

Although the known anchoring assembly schematically illustrated in Figs. 1A-1C and Figs. 2A-2D has been proven to work well in many environments there have been some problems. In recent years various failures in relation to water-borne anchoring assemblies have occurred with serious health and safety consequences for all onboard the associated rigs. The cause of the problem has pointed to weaknesses with the known shackle arrangement and thus there is a need to provide an improved anchoring assembly for use in securing a water- borne structure to the bed of a body of water that such a structure is located in.

Summary of the Invention

An object of the present invention is to provide an improved attachment means for use in anchoring a water-borne structure to the bed of a body of water using a tether and wherein a shackle is not required.

P2063.spec An object of the present invention is to replace the traditional use of a known padeye in water-borne anchoring assemblies with an attachment means that does not use a shackle to connect to a tether.

Another object of the present invention is to provide an improved padeye type member on a mooring pile that is directly connectable to a mooring chain.

A further object of the present invention is to provide a structural member, such as a driven pile or a suction pile or a part thereof, comprising an improved tether attachment means that does not require the use of a shackle.

Yet a further object of the present invention is to provide a structural member, such as a driven pile or a suction pile or a part thereof, comprising an improved padeye type member that is directly connectable to a mooring chain.

According to a first aspect of the present invention there is provided an attachment means forming part of an anchoring assembly as used in anchoring a water-borne structure to the bed of a body of water using a tether,

said attachment means characterised by comprising:

a first substantially planar member occupying a first plane and a second substantially planar member occupying a second plane, said substantially planar members disposed substantially opposite to one another and separated by a channel therebetween; and

a connecting member extending across said channel, said connecting member configured to attach a said tether thereto,

wherein:

P2063.spec -A- said substantially planar members are configured to prevent out of plane bending of an end of said tether.

Preferably the planes occupied by said first and second substantially planar members are substantially parallel to one another.

Preferably a said substantially planar member is in the form of a plate having an inner face and an outer face, said inner face being tapered relative to said outer face such that said channel progressively widens in a direction away from said anchoring assembly.

Preferably the angular separation forming said channel is approximately 40 degrees or less.

Preferably said angular separation is approximately 30 degrees.

Preferably said connecting member is elongate having a main length and comprises a groove configured to receive an end of a said tether.

Preferably said groove of said connecting member is specifically configured to precisely locate said end of said tether in order to prevent out of plane bending of said end of said tether.

Preferably said substantially planar members and said groove are configured to work in conjunction in order to prevent out of plane bending of an end of said tether.

Preferably said groove extends in a direction that is transverse to said main length.

Preferably said connecting member comprises a groove to locate an end of said tether thereto, said groove shaped to substantially enable a tether

P2063.spec attached thereto to take advantage of the angular separation between said tapered inner faces of said first and said second substantially planar members.

Preferably said respective first and second substantially planar members each comprise a receiving orifice configured to receive the respective ends of said connecting member.

Preferably said receiving orifice comprises a hole that passes from said inner face to said outer face.

Preferably said connecting member extends across said channel in a direction that is substantially perpendicular to a said plane occupied by one of said substantially planar members.

Preferably said connecting member comprises an elongate pin.

Preferably said pin is detachable.

Preferably said connecting member is substantially cylindrical in shape.

Preferably said attachment means is comprised of steel.

Preferably said anchoring assembly and said substantially planar members are made of cast steel.

Preferably said connecting member is made of forged steel.

According to a second aspect of the present invention there is provided an anchoring assembly for use in anchoring a water-borne structure to the bed of a body of water, said anchoring assembly comprising an attachment means as claimed in any preceding claim.

P2063.spec Preferably said anchoring assembly comprises a three-dimensional shape bound by a wall, said anchoring assembly being substantially hollow.

Preferably said wall is substantially cylindrical.

Preferably said anchoring assembly is made of steel.

Preferably said anchoring assembly is, other than said connecting member, made of cast steel.

Preferably said connecting member is made of forged steel.

Preferably said first and second substantially planar members are formed as an integral part of said assembly.

Preferably said first and second substantially planar members are welded to said anchoring assembly.

Preferably said anchoring assembly is substantially a hollow cylindrical member and said first and second substantially planar members are located on the outer surface thereof with a cross-member being located substantially directly behind on the inside of the anchoring assembly.

Preferably said anchoring assembly is a driven pile.

Alternatively said anchoring assembly is a suction pile.

In accordance with a third aspect of the present invention there is provided an attachment means for use on an anchoring assembly as used in anchoring a water-borne structure to the bed of a body of water using a tether,

P2063.spec said attachment means characterised by comprising a clevis arrangement for receiving an end of said tether.

In accordance with a fourth aspect of the present invention there is provided a method of anchoring a water-borne structure to the bed of a body of water using a tether,

said method characterised by:

(a) forming an anchoring strucure having an attachment means located thereon, said attachment means comprising:

a first substantially planar member occupying a first plane and a second substantially planar member occupying a second plane, said substantially planar members disposed substantially opposite to one another and separated by a channel therebetween; and

a connecting member extending across said channel, said connecting member configured to attach a said tether thereto;

(b) attaching a tether to said attachment means; and

(c) locating the anchoring structure as required.

In accordance with a fifth aspect of the present invention there is provided a section of an anchoring pile for use in anchoring a water-borne structure to the bed of a body of water using a tether, said section of said anchoring pile comprising an attachment means located thereon,

said section characterised in that said attachment means comprises:

a first substantially planar member occupying a first plane and a second substantially planar member occupying a second plane, said substantially planar

P2063.spec members disposed substantially opposite to one another and separated by a channel therebetween; and

a connecting member extending across said channel, said connecting member configured to attach a said tether thereto.

In accordance with a sixth aspect of the present invention there is provided an elongate retaining pin for use in anchoring a water-borne structure to the bed of a body of water in which said structure is located, said retaining pin characterised in that:

said pin comprises a splayed groove having a locating portion configured to locate an end of a tether thereto, said groove shaped to substantially prevent out of plane bending of said end of said tether.

Preferably said groove is located substantially mid way along the length of said retaining pin.

Preferably said pin is cylindrical.

Preferably said groove extends around a portion of the circumference of said pin in a direction that is substantially perpendicular to the length of said pin.

In accordance with a seventh aspect of the present invention there is provided an attachment means forming part of an anchoring assembly as used in anchoring a water-borne structure to the bed of a body of water using a tether,

said attachment means characterised by comprising:

a first substantially planar member occupying a first plane and a second substantially planar member occupying a second plane, said substantially planar

P2063.spec members disposed substantially opposite to one another and separated by a channel therebetween; and

a connecting member extending across said channel, said connecting member configured to attach a said tether thereto.

Brief Description of the Drawings

For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:

Figs. 3A-3C schematically illustrate, in respective perspective views, an improved anchoring assembly, as configured in accordance with the present invention, for anchoring a water-borne structure to the bed of a body of water;

Figs. 4A-4D further schematically illustrate, in respective cross sectional views, the anchoring assembly of Figs. 3A-3C;

Figs. 5A and 5B further schematically illustrate in respective perspective views the assembly of Figs. 3A-3C, but without the retaining pin and terminal chain link being shown;

Figs. 6A and 6B schematically illustrate in respective perspective views the retaining pin of Figs. 3A-3C; and

Figs. 7A-7C further schematically illustrate, in cross sectional views, the retaining pin of Figs. 3A-3C and Figs. 6A and 6B.

Detailed Description

There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific

P2063.spec details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

Figs. 3A-3C respectively schematically illustrate perspective views of an improved anchoring assembly as configured in accordance with a preferred embodiment of the present invention. The anchoring assembly is suitable for anchoring a water-borne structure to the bed of a body of water. Thus, for example, such a water-borne structure may constitute an oil platform or a ship or some other structure floating in the sea or another body of water. By the term "bed of a body of water" it is meant the bed of the sea, ocean, a lake, a river or any other body of water. Furthermore, the term "bed" is also to be construed herein (in particular in the claims) as including the structural edge portions of such body of water such as a sea wall or a dock or the shore at the interface between the body of water and dry land.

The improved anchoring assembly 301 , in the example shown, comprises an anchoring pile such as, for example, a suction pile or a driven pile as used in anchoring an oil platform to the sea bed. The wall 302 of the anchoring pile is, in the example shown, substantially cylindrical and configured to be set in the bed of the body of water in which the pile is to be located. In the example shown wall 302 is merely a portion or section of a given pile to be so used. An aspect of the present invention relates to the means of attaching such a pile to a tether and the attachment means is generally illustrated at 303. The attachment means 303 comprises a first substantially planar member in the form of a plate 304 and a second substantially planar member in the form of a plate 305. Substantially planar members 304 and 305 are disposed substantially opposite to one another with a gap between them and thus they effectively face each other. The gap that separates the substantially planar members 304 and 305 thus constitutes a channel 306 that is specially configured to accommodate an end of a tether that

P2063.spec is used to attach the anchoring assembly 301 to a desired water-borne structure. The means for attaching a tether is provided not only by opposing plate-like members 304 and 305 and channel 306, but also by a connecting member 307 extending across channel 306. Connecting member 307 is preferably in the form of a retaining pin that is configured to attach a given tether thereto. In this application a suitable tether may constitute a mooring chain, the final link of which is shown at 308 in Figs 3A-3C. The end link 308 of the mooring chain is configured to be positioned around retaining pin 307. Thus retaining pin 307, being detachable from its in-use position in connecting plates 304 and 305, enables the terminal link 308 of the mooring chain to be inserted in channel 306. The terminal link is thus then held in place by virtue of the fact that retaining pin 307 passes through the centre of link 308.

Figs 4A-4D further schematically illustrate, in respective cross-sectional views, the anchoring assembly of Figs 3A-3C. Fig 4A schematically illustrates a plan view of the anchoring assembly that is schematically illustrated in Figs 3A- 3C. Similarly Figs 5A and 5B further schematically illustrate, in respective perspective views, the assembly of Figs 3A-3C, but without the retaining pin on the terminal mooring chain link being shown. Fig 4B schematically illustrates a side elevation view of the anchoring assembly illustrated in Fig 3B. Fig 4C schematically illustrates a cross sectional view along the line B-B of Fig 4B; and Fig 4D schematically illustrates the anchoring assembly as viewed by looking along the line A-A of Fig 4A from left to right (front elevation view). In order to describe the preferred embodiment shown in Figs 3A-3C, Figs 4A-4D and Figs 5A-5B various aspects of the invention will now be described with reference to all of these drawings.

Attachment means 303 is preferably formed as part of a steel wall of a structural member constituting a pile as is illustrated. In the best mode contemplated the wall of the structural member is made of cast steel, as are substantially planar members 304, 305. Connecting member 307 is held in place in relation to substantially planar members 304 and 305 substantially by virtue of

P2063.spec the latter substantially planar members respectively comprising orifices 309, 310 that are formed substantially through the respective centres of these plates. In this way a detachable connecting member 307, in the form of a retaining pin, may be inserted in and removed from plates 304, 305 by insertion into and withdrawal out of orifices 309 and 310. The preferred connecting member is elongate having a main length and the retaining member may be held in place by virtue of a locking arrangement utilizing a locking orifice 311 located at an end and at the edge of connecting member 307.

Returning to the preferred structural member to whom the attachment means 303 is attached, the anchoring pile comprises wall 302 that substantially surrounds a hollow region 312, the wall of the pile being substantially cylindrical. Substantially immediately behind the substantially planar members 304, 305 is provided a cross-member 313 that extends across the diameter of the pile from one side of the wall to the diametrically other side. This provides added strength to the pile and also to the connection between the attachment means 303 and the wall 302 of the pile. In the preferred embodiment attachment means 303 and the pile section 302 together with the cross member 313 are cast as a single integral unit. Casting in this way provides optimum strength to the configuration shown, but those skilled in the art will realize that for certain applications welding of the attachment means 303 onto a pile wall 302 would suffice.

As already described above the connecting member 307 is detachable and in this preferred embodiment substantially planar members 304, 305 each respectively comprise a receiving orifice 309, 310 to receive the respective ends of the connecting member. Preferably the receiving orifice comprises a hole that passes from one face to the other of a given substantially planar member. This aspect is particularly well illustrated in Figs 5A and 5B. As illustrated in the figures the connecting member extends across channel 306 in a direction that is preferably perpendicular to a given plane occupied by one of the substantially planar members 304 and 305. In the preferred embodiment connecting member 307 is substantially cylindrical in shape and made of steel. In the best mode

P2063.spec contemplated connecting member 307 is, in contrast to the pile wall and substantially planar members 304, 305, made of forged steel.

Substantially planar members 304, 305 are, as described above, each in the form of a plate. These plates have an inner face and an outer face, the inner faces facing each other and the inner faces being tapered relative to each respective outer face such that the channel 306 there between progressively widens in a direction away from the wall of the pile. An important feature is that the channel widens in a direction away from the pile wall. In a preferred embodiment the angular separation between substantially planar members 304, 305, that is the total angle subtending the two substantially planar members, is approximately 40°. In the best mode contemplated the angular separation is approximately 30°. Such an angular separation is required so as to allow the final tethering chain link 308 to accommodate any misalignment as between the straight line direction extending between the centre of channel 306 and the corresponding centre of the tethering point of the tethering location that is located on the given water-borne structure to be tethered. To further facilitate any such misalignment connecting member 307 is, in the best mode contemplated, configured with a groove or recess that is configured to receive the end link 308 of a mooring chain. Thus in the best mode contemplated the groove extends in a direction that is transverse, and preferably perpendicular, to the main length of the connecting member.

Figs 6A and 6B schematically illustrate in respective perspective views the retaining pin 307 of Figs 3A-3C. Grove 601 is schematically illustrated as a recessed portion cut out of the central part of cylindrical connecting member 307. In the preferred embodiment the groove extends around the circumference of connecting member 307 by approximately a third of the circumference and is configured such that it receives and thereby locates terminal link 308 of a mooring chain. Figs 7A-7C further schematically illustrate, in cross sectional views, the retaining member of Figs 3A-3C and Figs 6A and 6B. Fig 7A schematically illustrates, in side elevation view, retaining member 307 such that

P2063.spec groove 601 , shown to the right of the drawing, is seen as an indented portion of the central region of the main body of the cylindrical member 307. Fig 7B schematically illustrates, in side elevation view, retaining member 307 shown at 90° from that shown in Fig 7A and thus groove 601 is not visible in this drawing.

Fig 7C schematically illustrates, in cross sectional view, an end elevation view along line E-E of Fig 7A.

On insertion of a given pile into the seabed misalignment of known padeyes is a common problem. On insertion of a given pile the padeye is intended to be in line with the tethering chain that is attached to the rig. Unfortunately with known piles the pile often rotates during insertion so that the padeye is no longer in line with the tethering chain emanating from the water-borne structure to be tethered. Such a situation is known as "misalignment" and the degree of misalignment that is considered acceptable with known padeyes is +/- 7.5 degrees (15 degrees total angle). In relation to the present invention it is important that the final link 308 of the tethering chain is not allowed to come into contact with the edges of plates 304, 305. Any such "touching" would create unwanted strains on plates 304, 307 and/or end link 308. Such unwanted strains would otherwise result in unwanted so-called out of plane bending of end link 308. In the preferred embodiment of the present invention the total angular separation between plates 304, 305 is therefore set at 40 degrees or less and in the best mode contemplated at 30 degrees or thereabouts. In conjunction with such a flared out structure comprising plates 304 and 305 groove 601 is configured so as to work in conjunction with channel 306 and thus to ensure that link 308 is not allowed to come into contact with plates 304, 305 when misalignment occurs. Thus in the best mode, that is using a channel of 30 degrees, any misalignment of up to +/- 15 degrees is allowed for thereby giving the engineers attending to insertion of a given pile a greater margin for error in the alignment direction of the pile. This saves a great deal of cost compared with the use of piles with existing prior art padeyes since the allowed tolerance is greater and therefore the chances of having to abandon a misaligned pile reduced. Those skilled in the art will appreciate that groove 601

P2063.spec acts as a pivot for the final chain link 308. It ensures that the tether has a specific location between planar members 304, 307 and thus aids in ensuring that link 308 does not come into contact with plates 304, 305. Groove 601 is splayed around the circumference of elongate connecting member 307 such that any misalignment of the water-borne structure being tethered and the pile can be accommodated without unwanted contact as between the sides of the end link and the inner surfaces of plates 304, 305. In this way out of plane bending of the end link is prevented. In order to avoid doubt, as will be appreciated by those skilled in the art, the use of the word 'prevented' is to be understood as also including 'substantially reduced' and/or 'substantially prevented'.

In the best mode contemplated groove 601 is located substantially mid way along the length of retaining pin 307 and the pin is cylindrical or substantially cylindrical. Suitably groove 601 extends around a portion of the circumference of said pin in a direction that is substantially perpendicular to the length of the pin.

In accordance with the present invention the attachment means 303 is preferably configured as part of a casting forming a section of a pile. However, in certain applications the attachment means maybe welded to or otherwise formed (preferably cast) as part of the wall of any suitable anchoring structure. Of course to tether something it must be anchored at a first end, such as to the bed of a body of water as hereinbefore described, and at a second end to the structure being tethered. It is to be understood that the attachment means described hereinbefore may be located at either end. Thus, for example, such an attachment means may be formed as part of the body of a ship or as part of a sea-borne oil rig or other floating structure as well as to an anchoring pile located in the sea bed or a suitably configured anchoring point such as on a harbor wall or rock formation located at the shore. In other words the attachment means may be used at either end of a given tether, but in the best mode contemplated the attachment means of concern in the present invention is formed as part of an anchoring pile.

P2063.spec The attachment means 303 described in relation to figures 3A-3C, 4A-4D comprising the substantially planar members 304, 305, channel 306 there between and connecting member 307 maybe described as a clevis arrangement for receiving an end of a given tether.

Those skilled in the art will realize that the prior art method of attaching a given tether to a water-borne structure and/or an anchoring structure located on the sea bed as depicted in Figs 1A-1 B and figs 2A-2D has been totally superseded by the present invention. Effectively the traditional padeye of Figs 1A-1 B and figs 2A-2D may be considered as having been split so as to form a channel between two opposing plates and such that the channel progressively widens to accommodate strict tolerances in the tethering process. The arrangement illustrated in the preferred embodiments of Figs 3A-3C, 4A-4D, 5A- 5B, 6A-6B and 7A-7C removes the need to use a prior art shackle type arrangement that has proved to be problematic in some of harsher sea and ocean type environments. The present invention is thus considered to provide enhanced safety compared with the prior art method and therefore to potentially save a great number of lives.

In accordance with the present invention there is also provided a method of anchoring a water-borne structure to the bed of a body of water using a tether, the method characterized by:

(a) forming an anchoring structure such as, for example, a pile or a hull of a ship, said anchoring structure having an attachment means located thereon, the attachment means comprising:

a first substantially planar member occupying a first plane and a second substantially planar member occupying a second plane, said substantially planar members disposed a substantially opposite to one another and separated by a channel there between; and

P2063.spec a connecting member extending across a said channel, said connecting member configured to attach a said tether thereto;

(b) attaching a tether to the attachment means; and

(c) locating the anchoring structure as required.

Thus the tether may be attached to the attachment means wherever the attachment means is located. The attachment means may be located on a given water-borne structure or, in the best mode contemplated, on an anchoring structure that comprises a sea-bed anchoring pile such as a suction pile or a driven pile.

A further preferred embodiment of the present invention concerns the inclusion of a further plate-like member substantially located below the substantially planar members 304,305. In the example of a sea bed pile such a plate is orientated relative to members 304,305 to provide a means of deflecting debris on insertion of the pile into the sea bed. Deflection in this way helps to ensure that rocks do not become lodged in channel 306. In order to aid insertion of the pile such a further plate suitably comprises one or more holes configured to allow debris of a small enough grain size, for example mud and sand, to pass through whilst preventing larger diameter debris to potentially become trapped in channel 306. The hole or holes thus aid insertion of the pile into the seabed since they reduce the resistance arising from the inclusion of the further plate. The further plate would substantially be parallel to the lower edges of members

304,305 and thus its plane would substantially follow the general direction of the chain attached to retaining pin 307.

P2063.spec