SE538099C2

SE538099C2 - A mooring system

Info

Publication number: SE538099C2
Application number: SE1350466A
Authority: SE
Inventors: Per-Anders Åkerström; Christer Wockats
Original assignee: Bassoe Technology Ab
Priority date: 2013-04-12
Filing date: 2013-04-12
Publication date: 2016-03-01
Also published as: BR112015025395A2; WO2014168572A1; CN105377687A; US20160059936A1; SG11201507956XA; CN105377687B; SE1350466A1

Abstract

11 ABSTRACT A mooring system (1) comprising a first and a second object (2, 3), whereinat least said first object (2) is floating, and wherein said mooring system (1)further comprises a hawser (4) with a first end adapted to attached to saidfirst object (2), and a second end adapted to be attached to said secondobject (3) , c h a r a c t e r i s e d i n that the hawser (4) comprises at leasttwo rope segments (10, 10”) with an intermediate chafing member (9)arranged between the at least two rope segments (1 O, 10”), wherein theintermediate chafing member (9) runs via a fairlead (6) and said fairlead (6) isadapted to be arranged adjacent a side (7) of said first object (2) facing thesecond object (3) and said first end being attached to an attachment point ofsaid first object (2), which attachment point being distanced to said fairlead (e). Figure for publication: 1

Description

The present invention relates to a mooring system for mooring a floatingobject to another object, the mooring system comprising a hawser and the hawser comprising two rope segments.

BACKGROUND Hawser is a nautical term for a thick cable or rope used in mooring or towing.Mooring refers to any means of attaching a vessel to an object such as abollard, pier, quay, other floating object/vessel or a mooring. One of the mostimportant factors in offshore mooring is using a hawser that is long enough toprovide sufficient elastic to allow the vessel to move due to movements inwaves. lf a boat is tied with a short and/or stiff hawser while offshoremooring, it cannot move when in large waves and could be swamped or itcould result in excessive loads in the mooring hawsers. A more elastichawser will allow movement both up and down as well as significant sidemovement to avoid to become swamped or to avoid excessive loads in the mooring hawser.

SUMMARY OF THE INVENTIONThe object of the present invention is to provide an improved mooringsystem. This object is achieved by the mooring system as set forth in the appended claims.

The present invention discloses a mooring system comprising a first and asecond object, wherein at least said first object is floating. Said mooringsystem comprises a hawser with a first end adapted to be attached to saidfirst object, and a second end adapted to be attached to said second object,such that the hawser thereby moors the two objects to each other. Thehawser comprises at least two rope segments with an intermediate chafingmember arranged between the at least two rope segments, wherein the intermediate chafing member runs via a fairlead and said fairlead is adaptedto be arranged adjacent a side of said first object facing the second objectand said first end being attached to an attachment point on said first object,which attachment point is arranged distanced to said fairlead. The secondend of the hawser is inevitably attached to the second object.

The rope segments is adapted to have an inner elasticity in relation to saidchafing member, whereby the relation between the rope segments elasticityand the chafing members elasticity is such that the chafing member can beconsidered to be stiff and the rope segments to be elastic.

The chafing member is adapted to have a high friction durability in relation tosaid rope segments, whereby the relation between the chafing member”sfriction durability and the rope segments durability is such, that said chafingmember can withstand friction loads without any substantial damages, whichfriction loads would wear down said rope segments.

A relation between the length of the intermediate chafing member and thedistance between the intermediate chafing member and the attachment pointis such, that it allows a stretching of the rope segment compensating fornormal motions of the first object and still maintaining the intermediatechafing member within the fairlead.

Further, the distance between the fairlead and said attachment point is such,that at least the length of the rope segment between the intermediate chafingmember and the attachment point, at least corresponds to the length of theintermediate chafing member. Further, the distance between the intermediatechafing member and the attachment point is such, that it allows a stretchingof the rope segment compensating for the stiffness of the chafing member,such that the elasticity of the inventive hawser at least corresponds to singlerope hawser with the length corresponding of the first rope segment and the intermediate chafing member of the present invention. However, the construction of the inventive hawser with an intermediate chafing memberallows the second rope segment to be longer, due to that it can be attachedfurther away from the side of the first object facing the second object,whereby a greater elasticity in the hawser can be achieved than in previouslyknown hawsers, due to the increased total length of rope segments.

The fairlead creates a joint in which side forces upon the hawser is absorbedwhen the first and the second objects careers relative each other. Thefairlead thereby enables that the rope segments on each side can besubjected to lengthwise directed forces only and further that the first end canbe attached at a point of the first object located distanced from the sidefacing the second object. With distanced is meant; the distance along thesecond rope segment from the intermediate chafing member to theattachment point, whereby the rope segment might pass guiding points,changing the direction of the rope segment, on its way to the attachmentpoint. The hawser can thereby become an increased length that in mostcases is close to twice the length compared to prior art solutions. The ropesegments having some elasticity will thus totally give a more elastic mooringin this system. Further, a rope is generally more elastic than a cable or chainand the hawser will thus have added elasticity with two rope segments.

The invention combines the advantages with mooring with a rope, whichprovides elasticity with the advantages with mooring with a more durable hawser member such as a chain or wire.

Also the second object can be provided with a fairlead in correspondingmanner, whereby the hawser is provided with another intermediate chafingmember adapted to run via said fairlead upon the second object and having athird rope segment attached thereto in order to attach to the second object.The elasticity of the hawser can thereby be increased even more due to theadded length of stretchable rope.

According to one aspect of the present invention the chafing member of thehawser is a chafing chain. The part of the hawser in contact with the fairleadwill apart from the pulling force have a friction load and it will thus beadvantageous to have a chain instead of a rope and thereby increasing thelifetime of the hawser. Alternatively the chafing member of the hawser is achafing cable which will also extend the lifetime as compared to a rope.

According to a further aspect of the present invention the rope is made fromnylon or polyester. Nylon and polyester presents increased elasticity as wellas being lighter than a wire or chain.

According to yet another aspect of the present invention the fair lead is ahawser pipe arranged such that the hawser runs through the pipe. A pipe donot require that much maintenance as for instance with a pulley and a hawser pipe can also be made quite light.

According to yet a further aspect of the present invention the systemcomprises two hawsers. This allows for better control of the lateral balance ofthe object with the main part of the hawser system. lf further strength isdesired the mooring system could be made using two pairs of hawsers.Further hawsers could of course be added if the required strength is veryhigh.

By adding longer or more rope segments a higher elasticity can be achieved,wherein a parallel arrangement of a plurality of inventive hawsers increasesthe strength of the mooring system. ln one aspect of the invention a pluralityof inventive hawsers are arranged parallel with each other between the firstand second object, especially is a pair of hawsers arranged parallel or a two pairs of hawsers.

According to an additional aspect of the present invention the mooringsystem comprises a bridle holding the fairlead and that is fastened to the object by using pad eyes or other means of fastening. Pad eyes can beproduced using different methods.

According to another additional aspect of the present invention the floatingobject is a semi-submersible platform. Preferably the bridle holds the fair leadunderneath the deck-structure and is at least fastened to columns of thesemi-submersible platform located on the side closest to the other object.

According to yet an additional aspect of the present invention the floatingobject is a ship-shaped structure, such as a ship or a barge. ln this case themooring system is preferably arranged on the sides of ship. Thus, accordingto one aspect the bow or stern of the floating object is positioned towards theother object, the fairlead is arranged adjacent the end of the ship-shapedstructure facing the other object and wherein the hawser run along the side ofthe ship-shaped structure and having one end attached to the farther half ofthe ship-shaped structure.

According to another aspect of the present invention the hawser runs within apipe along the side of the ship-shaped structure. l\/lore preferably is of courseto have hawsers on both sides of the ship-shaped structure and thus pipes on both sides.

The other object is according to one aspect of the present invention also afloating object.

According to one aspect of the present invention the other object is a tensionleg platform.

According to yet another aspect of the present invention the surface of thehawser pipe has a coating for either decreasing the friction or protectionagainst corrosion or both of these. This could for instance be applied using hot spraying the hawser pipe with thermal spraying and zinc/aluminiumpowder or cold and hot spraying of polymeric solutions.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further disclosed with reference to the accompanying drawings.

Figure 1 is a schematic bottom view of a mooring system used in an embodiment with the floating object being a platform.

Figure 2 is a schematic side view of a mooring system according to the invenﬁon.

DISCLOSURE OF PREFERRED E|\/|BODll\/IENTS Figure 1 shows an inventive mooring system 1 for mooring a floating object 2to another object 3. ln the shown embodiment the mooring system comprisesthe first and the second object 2, 3 and four hawsers 4 which are attached toa first and the second object 2, 3 with their first and second end 13, 14respectively. ln the shown embodiment the floating object 2 is a platformequipped with the fairleads in the form hawser pipes 6. The hawsers 4 runthrough of hawser pipes 6, thereby creating a joint about which the hawsercan bend when the first and the second object 2, 3 moves relative eachother. The hawser 4 comprises two rope segments 10, 10' which are made ofan elastic material such as a nylon or polyester rope. The two rope segments10, 10” are separated by a chafing chain 9. The chafing chain 9 is moredurable concerning the friction against the hawser pipe 6 than the ropesegments 10, 10”. The hawser 4 has its second end 14 attached to thesecond object 3 and the first end 13 is attached to the first object 2 adjacentthe side 8 facing away from the second object 3. Thus, compared to prior art solutions, the hawser 4 of the present invention is longer by as much as thefirst object allows, i.e. decided by the length of the object 2.

What also is shown in figure 1 is that there are two pairs of parallel hawsers 4for increased strength of the mooring system. The hawser pipes 6 are held together laterally with bridles 11 and fixed at both sides using pad eyes 12. ln figure 2 can be seen a side view of the mooring system 1.

The foregoing is a disclosure of an example practicing the present invention.However, it is apparent that modifications and variations of the mooringsystem will be obvious to one skilled in the art. lnasmuch as the foregoingdisclosure is intended to enable one skilled in the art to practice the instantinvention, it should not be construed to be limited thereby, but should beconstrued to include such modifications and variations as fall within thescope of the claims. For instance, the positioning of the mooring system inthe shown embodiment is underneath the box bottom of a platform.However, if the floating object is a ship the hawsers will be placed on thesides of the ship or possibly on deck. Further, it is also possible to havearrangements with fairleads on both the floating object and the other object,thus having two chafing members for each hawser leading to an even greater elasticity and flexibility in the mooring system.

Claims

1. A mooring system (1) comprising a first and a second object (2,3), wherein at least said first object (2) is floating, and wherein saidmooring system (1) further comprises a hawser (4) with a first end (13)adapted to attached to said first object (2), and a second end (14)adapted to be attached to said second object (3) ,c h a r a c t e r i s e d i n that the hawser (4) comprises at least two ropesegments (10, 10') with an intermediate chafing member (9) arrangedbetween the at least two rope segments (10, 10'), wherein theintermediate chafing member (9) runs via a fair|ead (6) and said fair|ead(6) is adapted to be arranged adjacent a side (7) of said first object (2)facing the second object (3) and said first end (13) being attached to anattachment point of said first object (2), which attachment point beingdistanced to said fair|ead (6), wherein said first end (13) is attached tosaid first object (2) adjacent the opposite side (8) of said first side (7) ofthe object (2). A mooring system (1) according to c|aim 1, wherein the intermediate chafing member (9) is a chafing chain or cable. A mooring system (1) according to any of the preceding claims,wherein the rope segments (10, 10') are made from nylon or polyester. A mooring system (1) according to any of the preceding claims,wherein the fair|ead (6) is a hawser pipe arranged such that the hawser (4) runs through the hawser pipe. A mooring system (1) according to any of the preceding claims,wherein the system comprises two parallel arranged hawsers (4) or two pairs of parallel arranged hawsers (4). 10. 11. 12. A mooring system (1) according to any of the preceding claims,wherein a bridle (11) holds the fairlead (6) and is fastened to the firstobject (2) by using pad eyes (12). A mooring system (1) according to any of the previous claims,wherein one of the first object (2) is a semi-submersible platform. A mooring system (1) according to c|aim 7, wherein the mooringsystem is arranged underneath the deck structure of the semi-submersible platform. A mooring system (1) according to c|aims 7 and 8, wherein abridle (11) holds the fairlead (6) underneath the deck-structure and is atleast fastened to the columns of the semi-submersible platform locatedon the side closest to the other object. A mooring system (1) according to any of the c|aims 1 to 6, wherein the first object (2) is a ship-shaped structure. A mooring system (1) according to c|aim 10, wherein a bow or astern of the first object (3) is positioned towards the second object (3), thefairlead (6) is arranged adjacent the end of the ship-shaped structurefacing the second object (3) and wherein the hawser (4) run along theside of the ship-shaped structure and having one end attached to the halfof the ship-shaped structure furthest away from the second object (3). A mooring system (1) according to c|aim 10, wherein the hawser(4) runs within a pipe along the side of the ship-shaped structure. 5 13. 14. A mooring system (1) according to any of the previous claims,wherein the second object (3) also is floating. A mooring system (1) according to any of the previous claims,wherein said second object is a tension leg platform.