US3899990A - Systems for anchoring ships at sea - Google Patents

Abstract

The anchoring system includes an arm hinged on a base fixed to the sea-bed, this arm being capable of resting at the bottom of the sea in the position for which there is no anchoring. For anchoring, the arm must be raised, which takes place by a buoy, which is of adjustable buoyancy controlled by remote control, such as through a pneumatic pipeline. When the operation is terminated, the buoy is again allowed to fill with water and drop with the arm to the sea-bed. The arm is spared the effects of swell in both the lowered and raised positions and can thus be of light structure. The invention is particularly useful for anchoring oil tankers.

Description

United States Patent Lecomte Aug. 19, 1975 1 SYSTEMS FOR ANCHORING SHIPS AT SEA 3,409,055 11 /1968 Bily 9/8 P X 3,472.293 10/1969 Bily 114/230 X [75] lhvemor- Claude 90mm, 3,479,673 11 /1969 Manning 114/.5 R Femehay-aux-Reses, Franee 3,722,223 3/1973 Gratz 9/8 P x [73] Assignee: Entreprise dEquipements FOREIGN PATENTS OR APPLICATIONS Mecamques flydraul'ques 1,097,258 l/1968 United Kingdom 114 230 E.M.H., France 22 Ffl d; J 16, 1973 Primary ExaminerTrygve M. Blix Assistant ExaminerEdward R. Kazenske [2H Appl' 379317 Attorney, Agent, or Firm-Stevens, Davis, Miller &

Related U.S. Application Data Mosher [63] Continuation of Ser. No. 146,127, May 24, 1971,

abandoned [57] ABSTRACT The anchoring system includes an arm hinged on a [30] Foreign Application Priority Data base fixed to the sea-bed, this arm being capable of June 10. 1970 France 70.21365 resting at the bottom of the Sea in the Position for which there is no anchoring. For anchoring, the arm 52 U.S. c1. 114/230; 9/8 P; 61/46 must be raised, Whieh takes Place by a buoy, which is 51 Int. Cl. B63b 21/04 of adjustable buoyancy Controlled y remote control. 58 Field of Search 114/230, 15 T, 125, 16 E, Such as threugh a Pneumatic P p when the p 5 9 p; 61/46, 4 ation is terminated, the buoy is again allowed to fill with water and drop with the arm to the sea-bed. The [56] References Cited arm is spared the effects of swell in both the lowered UNITED STATES PATENTS and raised positions and can thus be of light structure. The invention is particularly useful for anchoring oil 1,373,329 3/1921 Hoar 114/16 E tankers 1,488,067 3/1924 Schneider..... 114/16 E 7 2,955,626 10/1960 Hartley 9/8 P X 3 Claims, 8 Drawing Figures PATENTEB AUG-Y 9 I975 sum 5 BF 5 NRA.

SYSTEMS FOR ANCHORING SHIPS AT SEA This is a continuation of application Ser. No. 146,127, filed May 24, 1971, now abandoned.

The invention relates to a system of the type enabling the anchoring or mooring of ships in the open ocean (or on a lake, etc.), especially petrol tankers.

It will be recalled firstly, on this subject that it has already been proposed to anchor ships to a platform or to an anchoring buoy, which platform or buoy is connected to the ocean floor by a column or by an arm articulated on a base fixed to the ocean floor.

It may be desirable, at least in certain cases, to lighten these systems. It will be noted also, more particularly in the case of buoys connected to the submarine base by an arm held especially inclined and orientable along any given azimuth that the arm is subject to flexion under the combined forces of the traction on the anchoring cable, and of the hydrostatic pressure on the buoy, whence the necessity of suitably reinforcing said arm.

It has been devised, according to the invention, to constitute the anchoring system essentially by an arm connected in articulated and pivoting manner on the base anchored to the sea-bed, and to combine with the free end of this arm, a buoy whose role is only that of marking the said extremity to enable the anchoring thereto of a ships cable each time this is desired.

In particular, the arm may be provided for, in the absence of anchoring, resting on the sea-bed, the said buoy being able, either, according to a first embodiment, to be rigidly attached to the end of the arm and combined with means which, actuated for example from the coast by a pneumatic or other system, enable the unballasting at least momentarily the buoy to make it reascend with the arm, or, according to a second embodiment, to be normally floating and connected by a cable at the end of the said arm which can, outside the period of use, rest on the sea-bed.

There can also be provided at the end of the arm a light buoy which, normally, enables the arm to be lifted, with a hydrostatic thrust exactly necessary for this purpose, so that, when the ship is anchored, there is a possibility for the buoy to be depressed under the action of the anchoring traction, the arm being oriented towards the ship.

This orientation of the arm towards the ship can be easily obtained in each of the above-mentioned cases, so that the said arm only works in practice in traction.

The invention comprises, apart from these features, certain others which are preferably used at the same time and which will be more explicitly described below, especially:

a feature relative to installations of the type concerned for which a transfer of liquid is provided between the ship and the base, anchored to the sea-bed, of the anchoring system, which base is itself connected by submarine pipes to a coast installation or to a submarine production or storage installation which to effect the connection with the ship, has at least one flexible pipe connected to the base by a rotary joint.

This flexible pipe can then be treated like a pipe resting normally at the bottom of the sea, and of which the free end will be for example connected to a marking buoy provided with a coupling system enabling the said end to be raised in order to ensure its connection with the ship coming up to the anchoring system.

This last'feature is advantageous, since it enables the avoidance of a floating pipe, always dangerous by -reason of the effects of swell.

The invention relates, more particularly, to certain methods of application (especially those for which it is applied to installations for anchoring petrol tankers), as well ascertain embodiments, of the said features, and it relates, more particularly also and this by Way of new industrial products, the systems of the type concerned including application of these same features, as well as the special elements designed for their construction.

The invention will in any case, be well understood with the aid of the drawings and description which follows, which are, of course, given primarily by way of example and are not to be regarded as limiting.

In the drawings:

FIGS. 1 and 2 show diagrammatically, in elevation, respectively in an anchoring position and in a position resting on the sea-bed, an anchoring system constructed according to the invention;

FIG. 3 shows, on a larger scale and in part, the said system with means of ballasting and deballasting, according to the invention;

FIG. 4 illustrates in elevation another embodiment of the system according to the invention, of the same type;

FIG. 5 illustrates in elevation another embodiment of a system according to the invention, with a flexible connecting pipe resting on the sea-bed;

FIG. 6 shows in part, on a larger scale, a portion of the embodiment of FIG. 5; and

FIGS. 7 and 8, lastly, show in elevation, respectively in two different positions, another embodiment of an anchoring system constructed according to the invention.

According to a preferred embodiment of the invention, in order to construct for example an anchoring system anchored to the submarine bed, with a view especially to enable ships B (FIG. 1) to be anchored near the coast or for transfer of oil or any other fluid it being understood that this does not constitute a limiting particular application the procedure is as follows.

This system is constituted essentially by an arm I which has been articulated on a base 2 anchored to the sea-bed, and this in such manner that the said arm can be inclined at will and, at the same time, oriented in any azimuth, for example by means of a double articulation 3 enabling the pivoting around a ZZ axis, as wcil as articulation around a horizontal axis, and, with this arm which should normally rest on the sea-bed 4, as seen in FIG. 2 or FIG. 4, means are made to cooperate which enable, atleast momentarily, that is to say when it is desired to effect the anchoring of a ship, the lifting of the arm with a view to this anchoring.

These means will for example be effected in one of the manners indicated below.

In the embodiment which is illustrated in FIGS. 1 to 3, the said means are constituted for example by a float device 5 which can play the role of a buoy, which device has been fixed to the free end of the arm 1 and which has been provided with means adapted to enable the ballasting or deballasting at will, these means being actuated if necessary from the coast by remote control systems, which can be of any suitable type, for example pneumatic, hydraulic, mechanical or other.

The manipulations with a view to anchoring a ship will consist of effecting, from the said means, the emptying at least partially of the water which is contained in the buoy 5 for the lowered position of FIG. 2, so as to create a hydrostatic thrust which can be just sufficient to lift the arm 1 and ensure its floating, as indicated in FIG. 1, or slightly more.

Under these conditions, the assembly having been brought to the position of FIG. 1, the anchoring of the cable 6 coming from the ship can be easily effected on the anchoring device 7 which the buoy includes.

As a result, the traction exerted on the cable 6 can bring the assembly into an oblique direction such as that represented in discontinuous line in FIG. 1 for which the buoy 5 is immersed. It will be noted in any case that for this position, given the slight hydrostatic thrust on the buoy 5, the arm 2 is practically unsubjected to tensile forces, so that it can be made of light material.

In addition, the effects of swell on the buoy are avoided. As regards means for ensuring the deballasting of the buoy 5, they are provided for example in a manner which is illustrated in FIG. 3, for which it is assumed that said means use a pneumatic control consisting essentially of a pipeline 8 coming from the coast, ending at the base 2 and then running along the arm 1.

Compressed air, arriving through this pipe 8, would have for example the function of controlling one or several valves such as 9, 10, intended to enable the expulsion of air or water, according to the nature of the operations to be effected, and this possibly in combination with at least one orifice 11 provided at the bottom of the buoy.

In the position for which the assembly rests on the bottom, it is assumed that the whole of the float is filled with water.

When it is desired to make the assembly reascend, the compressed air is placed under pressure in the pipeline 8 and ends at 12 through a pipe provided with a non-return device 13. At the same time, the valves 9 and 10, actuated at 14 and 15 by the compressed air arriving through a pipe 16, are brought into a closed position. The compressed air arriving at 12 and drives out the liquid which can be expelled through the orifice 11 and this to a level which enables the component of gravity of the arm 1 to be compensated.

When this has been obtained, the introduction of compressed air through the pipeline 8 is discontinued.

For the reverse operation, that is to say when it is de sired to make the assembly again rest on the sea-bed, it suffices to purge the pipeline 8 from the control situated on the coast. The air which is in the buoy 5 is then expelled through the valve 9 which opens under the effect of the purge, and water again enters through the orifice 11 as well as through the valve 10 to fill the buoy. Due to the said valve, the filling can be done fairly rapidly.

Of course, any other means could be envisaged for the same purpose.

In any case, there is obtained an assembly which is light, due to the fact that the arm 1 is never subjected to large flexing forces, and which in addition is spared the effects of swell since either, when there is no anchoring, the device rests on the sea-bed, or, when there is anchoring. The assembly is in an immersed but partially raised position, such as that shown in discontinuous line in FIG. 1.

In the embodiment shown in FIG. 4, it is assumed that the assembly included simply an articulated arm, as above, on the base 2, that the end of the arm at 17 was connected by a cable 18 to a very light buoy 19 floating normally on the sea. The end of the cable 28 ends at an anchoring device 20, after having traversed the buoy 19 in a central conduit 21.

In this embodiment, when the anchoring cable 6, coming from the ship, is attached, the assembly takes an inclined but immersed position, as was the case in FIG. 1 (position in discontinuous line).

In the embodiment which is shown in FIGS. 7 and 8, there is provided the fixing on the arm 1 of a buoy 5 which floats constantly but which is just sufficient to counterbalance the component of gravity of the arm 1.

Under these conditions, the assembly acts in the same manner as that of FIG. 1, as is seen in FIG. 8 where it is shown that the cable 6 tends to incline the arm 1 into a position for which the buoy also 5 is immersed.

Here again, and at least for the anchoring position, the assembly is spared thereby from the effects of swell.

The invention includes also the following feature, relative to means for enabling the transfer of fluids to be ensured between the ship 1 and the coast or a submarine installation, by passing through the anchoring system, which arrangement is seen also to spare the assembly from the effects of swell.

In known installations, the pipelines coming from the coast or from the submarine installation are made to end at the buoy itself, and there must then be provided a floating pipe between the buoy and ship. The effects of swell on such a floating pipe are often dangerous.

' In the abovesaid arrangement, recourse is had to a flexible pipe resting normally on the bottom and coming from a rotary joint arranged on the anchoring base suchas 2. l

Such an arrangement is shown in FIGS. 5 and 6, where there is seen a pipeline 22 arriving from the coast or from the submarine installation to a shaft 23 around which is mounted a rotary joint 24; it is onto this joint that is connected the flexible pipe 25 capable of ensuring the connection to the ship.

Due to this rotary joint, the ship can be positioned in any azimuth. As for the manner of connecting to the ship the free end 26 of the flexible pipe 25 (which could be a bundle of pipes, if the transfer of several liquids such as fuel for the engines, fresh water supply, etc., have to be envisaged), there is provided for example the attachment of this end 26 to a marking buoy 27 provided with means, such as a hook 28 and cable 29, to enable its lifting each time attachment to the ship is to be effected.

FIG. 6 show with several details how the articulation of the arm 1 on the shaft 23 is ensured, with pivoting at 30 and horizontal articulation at 31.

The fluid passes from the shaft 23 into the rotary joint 24 through ports 32.

Such an assembly is completely spared the effects of swell.

As a result of which, whatever the embodiment adopted, there can be produced systems whose operation emerges sufficiently from the foregoing for it to be unnecessary to-dwell on this subject, and which have, with respect to preexisting types, numerous advantages, especially:

that of enabling a light structure, given that the arm 1 is subject in practice only to tractive forces,

and that of being able to be easily spared the effect of swell, as regards both the anchoring system proper and the one or more liquid transfer pipes.

As is self-evident, and as emerges already from the foregoing, the invention is in no way limited to those of its methods of application, nor to those of its methods of production of its various parts, which have been more especially considered; it encompasses, on the contrary, all variations.

I claim:

1. A device for the surface mooring of a ship on a body of water comprising:

a. a base anchored to the bottom of the body of water;

b. an arm having a free end with the other end pivotally connected to the base;

c. a hollow interior buoy secured to the free end of the arm so that when the buoy is floating at the surface of the water substantially all of the arm is normally below the surface and extends diagonally to the base, said buoy and arm having means for mooring a ship thereto;

d. means on the buoy and arm for ballasting and deballasting the buoy so as to arcuately move the free end of the arm from an upper position near the surface of the water to a lower position near the bottom;

e. said means for the ballasting and deballasting comprising: a pipe for fluid coming from a distant control station and capable of being pressurized or discharged, said pipe extending along the arm and connected to the buoy to be in communication with its interior, a hole formed in the bottom of the buoy to establish communication between the interior of the buoy and the body of water, at least one normally open valve at the upper part of the buoy positioned to form a communication between the buoy interior and the ambience, this valve being connected to the pipe to be actuated by said pressure so as to be closed when the pipe is pressurized and to open when the pipe is not pressurized.

2. The device of claim 1, comprising, in addition to said valve an additional valve at the base of the buoy connected to form a communication with the body of water, this valve being closed when the pipe is pressurized and opened when the pipe is not pressurized.

3. The device of claim I in which said pipe is connected to the buoy through a non-return device.

Claims (3)

1. A device for the surface mooring of a ship on a body of water comprising: a. a base anchored to the bottom of the body of water; b. an arm having a free end with the other end pivotally connected to the base; c. a hollow interior buoy secured to the free end of the arm so that when the buoy is floating at the surface of the water substantially all of the arm is normally below the surface and extends diagonally to the base, said buoy and arm having means for mooring a ship thereto; d. means on the buoy and arm for ballasting and deballasting the buoy so as to arcuately move the free end of the arm fRom an upper position near the surface of the water to a lower position near the bottom; e. said means for the ballasting and deballasting comprising: a pipe for fluid coming from a distant control station and capable of being pressurized or discharged, said pipe extending along the arm and connected to the buoy to be in communication with its interior, a hole formed in the bottom of the buoy to establish communication between the interior of the buoy and the body of water, at least one normally open valve at the upper part of the buoy positioned to form a communication between the buoy interior and the ambience, this valve being connected to the pipe to be actuated by said pressure so as to be closed when the pipe is pressurized and to open when the pipe is not pressurized.

2. The device of claim 1, comprising, in addition to said valve an additional valve at the base of the buoy connected to form a communication with the body of water, this valve being closed when the pipe is pressurized and opened when the pipe is not pressurized.

3. The device of claim 1 in which said pipe is connected to the buoy through a non-return device.

Images