US3556170A

US3556170A - Mooring and fluid-transferring method

Info

Publication number: US3556170A
Application number: US839362A
Authority: US
Inventors: Peter J Bily
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1964-01-10
Filing date: 1969-07-07
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19

Abstract

An apparatus and method for mooring a floating marine vessel from a single offshore point, and for transferring fluid between the vessel and an onshore location. The apparatus includes an elongate rigid fluid-conducting conduit pivotally anchored at one end to the ocean floor, and connecting at the other end to a pallet that is raised and secured to the hull of the vessel, and articulated loading arms to conduct fluid from the pallet to the vessel''s manifolds. The method includes aligning the vessel with the conduit, raising and securing the pallet to the vessel''s hull, and connecting the loading arms to the manifolds.

Description

United States Patent Inventor Peter J. Bily Sunset Beach, Calif. Appl. No. 839,362 Filed July 7, 1969 Division of Ser. No. 336,906, Jan. 10, 1964, Patent No. 3,472,293. Patented Jan. 19, 1971 Assignee FMC Corporation San Jose, Calif. a corporation of Delaware MOORING AND FLUlD-TRANSFERRING METHOD 6 Claims, 17 Drawing Figs.

1 14/230 1111.01 .L 1363b 21/50 Field ofSearch 9/80.P.;

114/230; 137/236, 236(08), 6l5;-l4l/1, 279, 387, 388; 214/14, (Cursory) [56] References Cited UNITED STATES PATENTS 3,093,167 6/1963 McCammon 114/230x 3,155,069 11/1964 116mm 141/230 FOREIGN PATENTS 1,097,258 l/l968 GreatBritain Primary Examiner-Laverne D. Geiger Assistant Examiner-Edward J. Earls Anomeys-Francis W. Anderson and C. E. Tripp ABSTRACT: An apparatus and method for mooring a floating marine vessel from a single offshore point, and for transferring fluid between the vessel and an onshore location. The apparatus includes an elongate rigid fluid-conducting conduit pivotally anchored at one end to the ocean floor, and connecting at the other end to a pallet that is raised and secured to the hull of the vessel, and articulated loading arms to conduct fluid from the pallet to the vessels manifolds. The method includes aligning the vessel with the conduit, raising and securing the pallet to the vessels hull, and connecting the loading arms to the manifolds.

PATENTEUJANI 9|7| SHEET 1 nr 6 INVENTOR PETER J. mu

ATTORNEYS the terminal with the prevailing wind,aligning-thewessel with 1 MQDRING AND FLUID-TRANSFERRING METHOD CROSS REFERENCE TO RELATED APPLICATION This application is a division of applicants copending application Ser. No. 336,906, filed Jan. 10, I964, and entitled Mooring and Fluid Transferring Method and Apparatus now US. *Pat.

BACKGROUND OF THE INVENTION The field of art to which the present invention pertains includes methods for mooring floating marine vessels to a single offshore anchor facility that is also capable of transferring fluid, such asa petroleum cargo, between the vessel and an onshore storage terminal. I I I As is reflected by the prior art,:i t has beenproposed to moor .a :floating marine vessel toan offshore, above-waterterminal by flexible lines thatrun between the vessel'and the terminal, and also between the vessel and anchorsat strategically placed positions. Establishing fluid communication between the vessel and the terminal by a flexible hose system also has been proposed, there being fluid linesonthe ocean floor whichextend from the terminal to .a storage facility, usually on anadacent shore.

These systems, .however, have several disadvantages. For example, the terminal is subject'to stormdamage and is a navigational hazard since :it permanently projects above the water. Another disadvantage is that the flexible hoses are .dif-

ficult to handle andare subject to the corrosive action of salt water, which can render them unusable in a relatively short periodof time. Still another disadvantage is that the mooring lines do not allow sufficientmovement .of the vessel nor do theysatisfactorily accommodate normal .mooringIforces. Ad-

ditional disadvantages of the previous systemsinclude the dif- 3 5 I ficulty involved in positioning theymarine vessel properly in order :to connect up to the :mooring and fluid-transferring equipment, the problems that are incident to maintenance of this proper position duringthefluidntransfer operation, especially during inclement weather, and the not infrequentdif- .40

ficulty of casting off from these systemswithsafety as wellas speed. r

The present invention solves these problems anddifficulties by providing a quick, safe, and :uncomplex procedure for mooring the vessel, andffor transferring thejfluid to or from it.

SUMMARY OF'TI-IE' INVENTION This invention comprises .a ,method :formooring :a floating marine vessel to a submergedoffshore terminal :by orienting an imaginary path over the terminal, :moving the vessel along the path toward the terminal, and maintaining the vessel in the proper position for subsequent fluid transfer operations. .The

method involves ,pivoting .a submerged mooring structure about its anchor at the oceanfloor untilitis oriented properly, guiding the vessel into the desired alignment with the,structure, moving the vessel along a designated path toward the anchor of the submerged ,mooringstructure until it is in a desired berthing area, and holding it in this berthing area by connecting it to strategically. placedmooring members.

Accordingly, an object of the invention is toprovidewa method for mooring a floating marine vesselso that it can .move about a given point with freedom, yetsecurelymaintainingit in the required fluid transferposition;Another object of this invention is toprovidea method for mooring afloating marine vessel to an offshore single point terminal with a "minimum of trouble, even under badweather conditions, and then to cast off from'its mooring quicklyand safely.

BRIEF DESCRIPTION OF THE. DRAWINGS FIG. 1 is a plan of a-mooringand fluid transferring apparatus for usein earr yingrout the subject invention, with portions of the apparatus being broken.away, with the full lines with the phantom lines indicating how part of theapparatus looksin a mooring position when it is connected to a vessel.

FIG,. 2 is a side elevation of the apparatus shown in FIG. I with the full lines showing the apparatus in its rest position and the phantom lines showing the apparatus in a transitory position between rest and mooring positions.

FIG. 3 is an enlarged fragmentary plan as viewed from a position indicated by "line 3-3 in FIG. 2.

FIG. 4 is a vertical section taken on line 4-4 in FIG. 3.

FIG. 5 is an enlarged fragmentary plan of anotherportion of the apparatus shown in FIG. 1 and with parts being broken away. I

FIG. 6 is a transverse vertical section taken on line 6-6 in FIG. 5.

, FIG. 7 is alongitudinal vertical section taken on line 7-7 in FIG. 5 and with portions being brokenaway.

FIG. 8 is an enlarged front elevation of still another portion of the apparatus shown in FIG. 1 and with portions being 'broken away, 'it being noted that this portion of the apparatus is shown in said transitory position.

FIG. 9 is a sidelelevation, reduced in scale, of the apparatus I shown in FIGS as viewed from aposition on the left of FIG.:8,

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. 1 and 2, amooring and fluid-transferring apparatus 25 for use -in carrying out the present inventionis shown in a rest position, in full lines, lying on the'bed 26 of the ocean 27. Althoughgthe subject apparatus isdescribed herein as beingllocated in theocean, it is equally as usefulin other bodies of .water. The apparatus includes an anchor 30 partially embedded in and fixed on the seabed :by anchor'lines 31 and deadman anchors 32 connected to the outer ends of the lines; other types of anchors could be employed.

The subject apparatus 25 also includes a verticalforward coupling .housing 35 (FIG. l-4). It is to be "noted thatthe terms forward" and f rearward" are used .with reference to the orientation of a vessel 36 (FIG. 13.).above the apparatus during operation of the latter.'The coupling housing (FIG. 4,)

is secured to the anchor 30 by bolts 401and includes a lower outer swivel joint enablingrotation of the housing-aboutafior- .ward vertical axis 42 (FIG. 3).

A supply pipe '45 (FIGS. 2-4) lies in the seabed .26 and has an offshore end 46 in the anchor 30. The supplypipegalsmhas anopposite end, not.shown,-which leads to .astorage-facility,

also not shown, but usually located on an adjacent shore this nected :to -opposite ends.of the pipe coupling, andlateral elbows-56 are respectively connected to the lateralswivel joints.

Also included :in the subject apparatus .25 is .a metallic;

preferably steel, conduit structure 60 FIGS. :1. and 2) that has a rigid longitudinal lowersection 62 connected to the forward .eoupling housing '35 and projecting rearward therefrom, a

rigid transverse intermediate seetion 64 pivotally connectedto showingthe apparatusin its restpositio non the seabed, and the lower section, and rigid longitudinal upper sections-66 pivotally connected to opposite ends of the intermediate section. The intermediate and upper sections are also referred to herein as a U-shaped pallet.

The lower section 62 of the conduit structure includes a rigid reinforcing tube (FIGS. 1, 3, 4 and 5) having a mounting end portion 71 and an opposite coupling end portion 72 provided with outwardly facing concave end walls, as 73. The reinforcing tube is divided into a plurality of compartments 75 (FIG. 1) some or all of which are flooded or partially flooded with water in order to regulate the weight of the lower section; normally, in any given installation of the apparatus, the weight desired is predetermined and selected compartments are filled with water and sealed. Rims 76 are secured to the tube in longitudinally spaced relation therealong, and lateral blocks 77 are secured on opposite sides of the tube and project endwardly from the mounting and coupling end portions thereof. Forward and rear I-beam elements 78 are secured to the blocks and likewise project from the end portions of the tube. The forward I-beam elements are connected to the lateral swivel joints 55 on the coupling housing 35 so that the reinforcing tube is mounted for elevational adjustable movement about a horizontal axis 80 (FIG. 4). A lower stop 82 (FIGS. 5- 7) is secured to the upper surface of the reinforcing tube at its coupling end portion immediately rearward of the rearwardmost rim 76; the purpose of this stop will be subsequently described.

The lower section 62 of the conduit structure 60 also includes lower conduits 85 (FIGS. 13) having mounting end portions 86 individually connected to the lateral elbows 56 and opposite coupling end portions 87 adjacent to the coupling end portion 72 of the reinforcing tube 70. The conduits extend along opposite sides of the tube and are rigidly connected thereto by braces 88 which are connected to the rims 76 as well as to the conduits. Thus, the lower section of the conduit structure is mounted for swiveling movement about the axes 42 and 80. Also, the lower conduits are in fluid communication with the supply pipe 45 through the forward coupling elbow 48, the swivel joint 52, the pipe coupling 54 and swivel joints 55, and this fluid communication is maintained notwithstanding swiveling movement of the section.

The intermediate section 64 of the conduit structure 60 (FIGS. 1, 5-7) includes a main frame having forward and rearward

upper tubes

96 and 97 and a lower tube 98, which tubes, as viewed in FIG. 7, are in triangular relation with each other. These tubes are connected in this relation by main upper and lower struts 99 and by diagonal struts 100. Furthermore, the main frame includes tubular end portions 102 (FIGS. 1 and 8) which project from opposite ends of the

tubes

96, 97 and 98. Since one of the functions of the intermediate section is to provide a predetermined amount of weight, the tubes may be compartmented like the reinforcing tube 70, and water may be placed in these tubes to add weight if needed.

The main frame 95 of the intermediate section 64 also includes vertical support plates 106 (FIG. 7) depending from the forward and

rear tubes

96 and 97. Laterally spaced mounting channels 107 (FIG. 5) are secured to the support plates and have rear ends 108 under the rearward tube 97 and forward ends 109 projecting forward from the forward tube 96. An upper stop 110 interconnects the forward ends of the mounting channels and is in overlying relation to the lower stop 82. In addition, the main frame 95 includes central webs 112 which extend between and are connected to the lower tube 98 and to the mounting channels.

With particular reference to FIGS. 5 and 7, an upstanding rear coupling housing 116 is supported by and bolted on a plurality of brackets 118 which are fixed to the mounting channels 107 and which define a rectangular opening that receives the rear housing. This rear coupling housing includes an upper outer swivel joint 120 that enables relative rotation between the rear housing and the main frame 95 about a rearupright axis 122. A rear coupling elbow 123 projects downward within the rear housing and is connected to a T-coupling 125 within the housing. Rear lateral swivel joints 126 are connected to this Tcoupling and lateral elbows 128 (FIGS. 5 and 6) individually interconnect the rear lateral swivel joints and the coupling end portions 87 of the Iower'conduits 85. Furthermore, the rear I-beam elements 78 are individually secured to the outer portions of the rear lateral swivel joints so that the intermediate section 64 is connected to the lower section 62 and so that the rear housing and therefore, the entire frame 95 can tilt down and back, that is clockwise, from the position illustrated in FIG. 7.

The intermediate section 64 of the conduit structure 60 also includes intermediate conduits (FIGS. I and 57) extending lengthwise of the main frame 95 and having inner ends 136 connected to the rear coupling elbow 123 by a T-coupling 138. The intermediate conduits also have outer ends 140 (FIGS. 1 and 8) that project through the tubular end portions 102. Outer swivel joints 142 are individually connected to the outer ends of the intermediate conduits, and elbows 143 are respectively connected to these outer swivel joints.

It will be understood froin the foregoing description that the intermediate section 64 of the conduit structure 60 is mounted on the lower section 62 thereof for pivotal movement about the upright axis 122 and about a substantially horizontal axis 145 (FIG. 7). Counterclockwise pivoting of the intermediate section about the axis 145 is limited by engagement of the upper stop 110 with the lower stop 82, this limiting position being the position wherein a plane containing the forward and rearward

upper tubes

96 and 97 is substantially parallel to a plane containing the lower reinforcing tube 70.

Pivoting movement of the intermediate section 64 about the axis 122 is limited by guy lines 148 (FIG. 1) which have rear ends connected to eyelets 149 at opposite ends of the forward upper tube 96 and forward ends connected to the anchor 30. Preferably the guy lines permit pivotal movement of the intermediate section about axis 122 within an angle of about 15 both forward and rearward of a neutral position wherein the intermediate section is perpendicular to the lower section 62 or, in other words, a 30 total range of pivoting movement; this angle is given by way of example only since the invention is not limited to any particular angle of pivoting movement of the intermediate section.

Cushions 150 (FIG. 1) are mounted on the forward and rearward

upper tubes

96 and 97 on opposite sides of the centerline of the lower section 62 of the conduit structure 60. Each of these cushions includes a bracket 151 secured to its respective tube and a plurality of annular resiliently compressible pads 152, such as rubber tires, mounted on the brackets. The pads are rotatable on the brackets and project upward therefrom as shown in FIG. 2.

Each of the upper section 66 (FIGS. 1 and 8) of the conduit structure 60 includes inboard and outboard support tubes and 161 having lower bushings 162 rotatably fitted on the adjacent tubular end portion 102 of the intermediate section and opposite upper bushings 163. Tubular ribs 164 rigidly interconnect the support tubes in parallel relation with each other.

Each upper section 66 also includes an upper conduit 168 having a lower end 169 connected to its associated lateral elbow 143 and an upper end 170 connected to an upper elbow 171. A cross duct 173 extends through the upper bushings 163 of each upper section, and'an outer swivel joint 174 interconnects an outer end of this cross duct with the associated upper elbow 171. Furthermore, an inner swivel joint 174 is connected to an inner end of the cross duct. A spring clamp 176 is mounted on the inb'oard support tube 160 adjacent to the cross duct.

Each upper section 66 of the conduit structure 60 includes a buoyancy tank 180 (FIGS. 8--10) of generally cylindrical shape and which has an internal sleeve bearing 181 concentric with the minor axis of the tank and journaled in the upper bearings 163. The cross duct 173 of the associated upper section projects through this sleeve bearing. The buoyancy tank is mounted between the inboard and

outboard support tubes

160 and 161 for swinging movement about an axis substantially parallel with the axes 80 and 145 and the axis 182 (FIG.

2) of pivotal movement of the upper sections with respect to the intermediate section 64. Each tank has an upper air fitting 184 and a lower water fitting 185 both of which communicate with the otherwise fluid-tight interior of the tank. In addition, each tank has forward and rear eyelets 186.

Associated with each buoyancy tank 180 is a buoyancy control pipe 190 having a dual upper portion 192 connected in fluid communication with the water fitting 185 by upper swivel joints 193 and having a single lower portion 195 connected to the upper portion by lower swivel joints 196 and terminating in an open lower end 197. U-shaped straps 199 are connected to a pair of the ribs 164 and loosely extend about the lower portion 195 of each buoyancy control pipe; these straps support the buoyancy control pipe on the ribs during pivoting of each upper section into its rest position, as illustrated in full lines in FIG. 2, and yet accommodate longitudinal movement of the lower portion 195 of the pipe during swinging movement of the buoyancy tank between a position with its major axis substantially normal to the plane of the sup port tubes 160, 161(FIG. 9) and a position withthis major axis in substantially the same plane as the plane of the support tubes (fulllines in FIG. 2).

Buoyancy control buoys 205 (FIGS. 1 and 2) float in the water 27 above the conduit structure60 and include valves 206. The valves are individually connected to the air fittings 184 of the buoyancy tanks 180 by flexible buoyancy control hoses 208. If the tanks are above the lower ends 197 of the buoyancy pipes 190 and the valves are open. the air fittings 184 of the buoyancy tanks are opento the atmosphere and water is hydrostatically forced into the tanks through the buoyancy control pipes 190, causingthe tanks and thus the upper sections 66 of the conduit structure to submerge into their rest positions, as shown in full lines in FIG. 2. The tanks will stabilize at a submerged position just above the open lower ends 197 of their respective pipes so that the greater pressure at these lower. open ends maintains water in the tanks. When it is desired to raise the upper sections,air is forced into the tanks through the valves and hoses, expelling water from thetanks, andrendering the tanks buoyant so that they raise the. upper sections into positions extending upward from the intermediate section 64. Vertical upwardly extending fluid-transferring positions (FIG. 13), the loading arms remain positions of the upper sections, as shown in phantom in FIG. 2, t

are merely transitory, however, since when the upper sections are connected to a vessel 36, the upper sections project rearward from the intermediate section, as illustrated in phantom in FIG. 1. The valves 206. are closed to capture air in the tanks so that the tanks remain buoyant and in upper positions until the valves are opened and the air is forced out by water rushing in through the buoyancy control pipesl90.

The subjectmooring and fluid-transferring apparatus 25 also includes articulated metallic. loading arms 215 (FIG. 2 and 8-10). Each loading arm has an inner conduit 216 connected by inner swivel joints 217 and elbows 218 to the inner swivel joint 174 on its associated upper section 66. Each inner conduit is connected to an intermediate conduit 220 by an intermediate swivel joint 221, and an outer conduit 223 is connected to the intermediate conduit by

outer swivel joints

225 and 226 and elbows 227. The outer conduit 223 has a coupling 230 adapted for connection to one of the manifolds (FIG. 1])232 on the vessel 36.

The I loading arms 215 have folded positions (FIG. 8) wherein theirintermediate conduits 220 are releasably held within the clamps 176. In addition to the clamps 176, clamps 235 releasably connect the intermediate conduits to their respective outer conduits 223 adjacent to the couplings 230.

The loading anns are movable from their folded positions into projected positions (FIG. l3, l5 and 17) wherein they can be connected to the manifolds 232. In the folded positions of the loading arm (FIG. 8), the intermediate conduits overlap the inboard support tubes 160 and the intermediate swivel joints 221 are above the intermediate section 64 of the conduits structure 60. Therefore, when the upper sections 66 pivot between their rest positions (FIG. 2 in full lines) and their folded against the upper sections (that: is, do not swing relative to the upper sections) and thejoints 221 do not contact the intermediate section of the conduit structure.

The present apparatus 25 also includes an anchor marker buoy 240 (FIG. 2) that is connected to the forward coupling housing 35 by a line 241. This marker lbuoy projects out of the water at all times and, of course, indicates the position of the anchor 30. Furthermore, bow connecting lines 245 have lower ends secured to the anchor 30 and upper ends connected to bow line buoys 246. Shackles 247 are fastened to the bowconnecting lines. Also, auxiliary lines. 248 are connected to the eyelets 149 on the main frame and are releasably fastened by shackles 249 to the front eyelets 186 on the tanks 180.

OPERATION When not being used in a fluid-transferring operation, the conduit structure 60 and loading arms 215 lie submerged'on the seabed 26 as in full lines in FIGS. 1 and 2. Insofar as the apparatus 25 is concerned, only the

buoys

205, 240 and 246 are visible from the surface of the water. Since the buoyancy tanks are filled with water, this fully submerged rest position is maintained so that the apparatusdoes not constitute a navigational hazard, is not subject to wind damage, and yet can readily be spotted since the buoys are visible.

When it is desired to moor a tanker or other vessel 36 for purposes of transferring fluid to or from the vessel, a launch 250, on which is provided an air compressor 251, motorsout air in the tank and cause it to remain buoyant. The air com pressor is disconnected from this valve, and the launch motors to thev other control buoy whereupon, by repeating the described operation, the other buoyancy tank and upper section are made to rise into vertical position. Such upward movement of the buoyancy tanks and upper sections lifts the intermediate section 64 off the seabed 26 intothe position illustrated in FIG. 12. In this position of the apparatus, the tanks are of course visible on the surface of the water.

Next, tow lines, not shown, on the launch 250 are con:

nected to the rear eyelets 186 on the tanks 180 andftliecon duit structure 60 is swung about the axis 42 until the'lowefl section 62 is in alignment with the direction W of the pi-evail ing wind and projects rearward from the anchor 30 in the same direction as the direction of the prevailing'wind.

With the tanker 36 (FIG. 11) headed into tliei'prevailijrig' marker" wind, thetanker is maneuvered toward the anchor h buoy 240 and on a path which extends between the now v ble buoyancy tanks 180. Before the bowof thetankeiiis" between the tanks, the ships bow lines 260,which"are con-1 nected to bow line winches 261, are individually connected to the anchor bow lines 245, and the tanker is pulled toward the anchor 30 by operation of the bow line winches.

When the tanker's bow is between the tanksusogsiii s' mooring lines 265, which are connected"to'aftwinches 266'," are individually connected to the aft eyelets 186oni the buoyancy tanks on their respective sides ofth ehsh ip." By operating the aft winches, the ship's mooring lines are tensioned, which in turn pivots the uppersections-661rearvard and lifts the intermediate section 64 (FIG. 13) thereby tensioning the conduit structure, in order to pull the ship forward until it is spotted over the conduit structure 60 (FIG. 13), that is, until the ship's manifolds 232 are just aft of the tanks. It will be noted that as the tanker moves into this fluid transferring position, the bow lines 260 become slack. Next, ships auxiliary lines 270, which are connected to auxiliary winches 271 between the bow and

aft winches

261 and 266, are connected to the auxiliary lines 248, the latter being disconnected from the tanks 180 at this time. These auxiliary lines are provided to restrict forward movement of the ship in the event of a sudden reversal of the wind direction, W.

A hoist 280 on the tanker 36 is then employed to lift the loading arms 215 on board the ship, and the arms are connected to the manifolds 232. A signal is communicated to the storage facility, not shown, and the transferring operation begins, either loading fluid into the ship or unloading the fluid from it. Iffluid is being loaded onto the ship, it travels from the supply pipe 45 (FIG. 1) through the forward coupling housing 35 (FIG. 4) into the lower conduits 85 (FIG. 5), through the rear coupling housing 116 into the intermediate conduits 135, thence into the upper conduits 168 (FIG. 8), and finally through the loading arms 215 (FIG. 17) into the manifolds 232 of the tanker; if fluid is being unloaded, the flow is reversed as will be understood.

During transfer of fluid, the tanker 36 remains moored to the anchor 30 but can move about while fluid-tight integrity of the connections between the loading arms 215 and the manifolds 232 and between the

various conduits

45, 85, 135 and 168 is maintained. That is fore and aft movement of the ship due to varying intensity of the wind force W are accommodated by the conduit structure 60 and the articulated loading arms. Rocking of the ship is accommodated by the inner and

outer swivel joints

225 and 226 of the loading arms 215, and skewing of the ship from side to side is accommodated by pivotal movement of the intermediate section 64 about the axis 122. Furthermore, pitching of the ship is accommodated by the swivel joints 174 and 221 as well as the pivotal connections between the

sections

62, 64 and 66 of the conduit structure. In addition, the ship can range full-circle about the axis 42 (through the anchor 30) so as always to remain headed into the prevailing wind.

Since the prevailing wind will, therefore, almost always act on the tanker in a direction from the bow to the stern, as indicated by arrow W, the lower and

upper sections

62 and 66 of the conduit structure 60 and the mooring lines 265 are maintained constantly under tension between the aft winches 266 and the anchor 30.'As the total rear wind force F (FIGS. 13 and 15) on the ship increases, the lower section and the upper section and mooring line on each side of the ship move toward a colinear relation (phantom lines in FIG. 15), and as this force decreases, they move into a more angulated relation (full lines in FIG. 15).

The reason whey the associated upper and

lower sections

66 and 62 and the mooring lines 265, on their respective sides of the tanker 36, do not assume a straight line relationship at all times while under tension should be noted. With reference to FIG. 14, the load L, which is primarily the weight of the lower and

intermediate sections

62 and 64, tending to submerge the apparatus 25, may be regarded as being concentrated at and directed downward through the axis 122 (FIG. 5). The tanks 180 (FIG. 14) have a capacity sufficient to buoy up the upper ends of the upper sections 66 at positions above the lower ends thereof with a total force B equal to the load L. Therefore, the upper sections are urged toward straight-up positions by the tanks but are held in rearwardly upwardly projecting positions by the mooring lines. Tension forces in the lower and upper sections and mooring lines are indicated by T1 and T2. As a specific example, if T2 is 100,000 pounds on each mooring line 265, the total tension TI on the lower section is 200,000 pounds. Furthermore, if the load L is 20,000 pounds, the buoyancy force B is also 20,000 pounds.

Assuming a constant wind force W, the tension forces T2 (and thus T1) vary as the draft of the ship 36 changes. As the draft increases, that is as the ship goes down under an increasing cargo load, T2 decreases because the force F decreases; the force F decreases under these conditions because as the ship goes down in the water, there is less area of the ship exposed to the wind force W and, therefore, less total force F imposed on the ship. These changes are illustrated by observing the changed positions of the apparatus 25 from FIG. 13 to FIG. 15 wherein it will be noted that since T2 decreases, the buoyancy tanks 180 (full lines) move forward and upward and the intermediate section 64 moves downward. When the draft decreases on rising of the ship as a cargo is removed therefrom, the reverse action takes place.

An important advantage of this apparatus is that the intermediate section 64, or rather the cushions thereon, does not come into contact with the bottom of the ship 36, except perhaps in a storm wind of great force. This is true even though the buoyancy tanks and the intermediate section move up and down in the water in the manner described above. If such contact does occur, as illustrated in phantom lines in FIG. 15, the contact occurs gradually and gently and with a force considerably less than the forces T2 on the mooring lines 265. FIG. 16 is a force diagram showing various forces in effect when contact with the bottom 36 of the ship does occur. The force U is the vertical component of the force T2 acting at the illustrated angle on the intermediate section so that the force U may be approximately one third of the force T2. Furthermore, the total resultant upward force acting on the bottom of the ship is the difference between the force U and the load L, and this total force is distributed over the bottom of the ship among the several cushions 150, the force exerted at each cushion being identified by the letter C. Therefore, if contact with the bottom of the ship does occur, the force C acting upward at any of the cushions is only a small fraction of the force T2 and one which can easily be withstood by the hull without any adverse effect.

Another important advantage of the apparatus 25 is its ability to absorb or cushion-mooring forces or, stated otherwise, to avoid abrupt imposition of stress on the conduit structure 60 (FIG. 13), the mooring lines 265, the anchor 30, and the ship 36 as it surges back and forth. In understanding this advantage, it is helpful to regard the lower section 62, the upper sections 66, and the mooring lines 265 as an articulated linkage which interconnects a fixed point (the anchor 30) on the seabed 26 and movable points (the tanker's winches 266) and which includes upper pivot points (where the mooring lines connect to the buoyancy tanks 180) and lower pivot points (where the upper sections connect to the intermediate and thus to the lower section). It is believed that this linkage is readily apparent by observation of FIGS. 1315. This linkage yieldably resists elongation into a colinear condition with a resistance which progressively increases as the tanker 36 moves rearwardly away from the fixed anchor point. Therefore, an abruptly increasing force F is gradually, rather than abruptly, imposed on the anchor, the conduit structure 60, the mooring lines 265, and the ship. Furthermore, this linkage is maintained under constant tension by the oppositely acting forces L and B imposed on the linkage so that the ship remains dependably moored in its fluid-transferring position.

After the transfer of fluid has been completed, the loading arms 215 are disconnected from the manifolds 232, lowered by the hoist 280, and clamped in their folded positions. The ships auxiliary lines 270 are disconnected, and the apparatus auxiliary lines 248 are again connected to the buoyancy tanks 180. Still further, the bow lines 260 are detached from the anchor bow lines 245, and the mooring lines 265 are disconnected from the buoyancy tanks 180. The launch 250 moors alongside of the ship 36 so that the crew can open the valves 206 on the buoyancy control buoys 205, allowing air to bleed out of the buoyancy tanks whereupon water rushes into the tanks causing the same to submerge. It is to be noted that the tanks are manually directed to swing downward in a forward direction so that they return to the illustrated rest positions adjacent to the seabed 26. The ship 36 then leaves under its own power.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

I claim:

l. A method of mooring an d transferring fluid to or from afloating marine vessel, having a bow and a stern, in a berthing area which includes an anchor and a mooring structure connected to the anchor, the mooring structure including a first member pivoted to the anchor. a second member connected to the first member and extending transversely thereof; third members individually pivoted to and projecting upwardfrom the second member and spaced on opposite sides of the first member, and a pair of buoyant marker members individually connected to the third members andvisible from the surface of the water and spaced on opposite sides of a path passing over the anchor, said method comprising:

a. pivoting the first member about the anchor until the path is aligned in a preselected direction;

b. aligning the vessel with the path;

c. moving the vessel along the path toward the anchor and between the marker members until. the members are located between the bow and the stern of the vessel; and

d. maintaining the vessel in the berthing area by connecting it to the mooring structure.

2. The method of claim 1 wherein the vessel is first moved betweeri the marker members and then over the anchor in positioning the vessel in the berthing area with the marker members disposed between the bow and stem.

3. The method-of claim 1 wherein the vessel is moved between the marker members by connecting a line between the anchor and the vessel and then-applying tension to the line.

4. The method of claim 1 wherein the vessel is maintained against movement out of the berthing area in the preselected direction by connecting it to the marker members.

5. The method of claim 4 wherein the vessel also is maintained against movement out of the berthing area in a direction generally opposite to the preselected direction by connecting it to the second member. v

6. The method of claim 1 including the'additional step of e. establishing a fluid-transferring connection between the vessel and the marker members for conduction of fluid between the vessel and a remote storage facility.

Claims

1. A method of mooring and transferring fluid to or from a floating marine vessel, having a bow and a stern, in a berthing area which includes an anchor and a mooring structure connected to the anchor, the mooring structure including a first member pivoted to the anchor, a second member connected to the first member and extending transversely thereof, third members individually pivoted to and projecting upward from the second member and spaced on opposite sides of the first member, and a pair of buoyant marker members individually connected to the third members and visible from the surface of the water and spaced on opposite sides of a path passing over the anchor, said method comprising: a. pivoting the first member about the anchor until the path is aligned in a preselected direction; b. aligning the vessel with the path; c. moving the vessel along the path toward the anchor and Between the marker members until the members are located between the bow and the stern of the vessel; and d. maintaining the vessel in the berthing area by connecting it to the mooring structure.

2. The method of claim 1 wherein the vessel is first moved between the marker members and then over the anchor in positioning the vessel in the berthing area with the marker members disposed between the bow and stern.

3. The method of claim 1 wherein the vessel is moved between the marker members by connecting a line between the anchor and the vessel and then applying tension to the line.

5. The method of claim 4 wherein the vessel also is maintained against movement out of the berthing area in a direction generally opposite to the preselected direction by connecting it to the second member.

6. The method of claim 1 including the additional step of e. establishing a fluid-transferring connection between the vessel and the marker members for conduction of fluid between the vessel and a remote storage facility.