US3470841A - Anchor - Google Patents

Description

Oct. 7, 1969 A k, flqus 3,470,841

ANCHOR Filed March 20, 1968 2 Sheets-5heet POSITION "All POSITION "BIO INVENTORI RAFAEL FERNANDEZ LUOUE" /zuw Y HIS ATTORNEY R. F. LUQUE ANCHOR Oct. 7, 1969 Filed March 20, 1968 2 Sheets-Sheet 2 INVENTORZ RAFAEL FERNANDEZ LUQUE,

HIS ATTORNEY United States Patent 3,470,841 ANCHOR Rafael Fernandez Luque, Rijswijk, Netherlands, assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Mar. 20, 1968, Ser. No. 714,658 Claims priority, application Great Britain, May 15, 1967, 22,423/ 67 Int. Cl. B63b 21/32 US. Cl. 114-206 6 Claims ABSTRACT OF THE DISCLOSURE A light-weight anchor which has a high-holding power in relatively soft soil comprising a curved plate having a plane of symmetry end connection means suitable for connecting an anchor line to the plate lying in the plane of symmetry and attached to the plate.

The present invention relates to anchors suitable for anchoring marine structures at a marine location and, more particularly, to ship or barge anchors adapted to be readily worked in soft, unconsolidated soil on the sea floor to securely anchor a drilling rig barge or other type vessel. The anchor may also be used to stabilize marine structures sitting on the sea bed, such as platforms carried on legs.

The present anchor is applicable for use with any type of ship, vessel, or barge where an anchor with highholding power is desired for use in relatively soft soil conditions on the sea floor. The principal disadvantage of anchors presently in general use is that they depend at least partially on their weight to obtain high-holding power and are expensive. Additionally, the flukes normally found on such archors are not designed or arranged so as to cause penetration in a soft, muddy sea bottom, and the area of bearing surface is insufiicient to develop high-holding power in soft soil conditions.

Summary of the invention It is, therefore, a primary object of the invention to provide an anchor of extremely simple design, which can be manufactured at low costs.

It is a further object of the invention to provide a light-weight anchor which has a high-holding power at relatively soft soil conditions.

These objects have been attained in the present invention by providing an anchor for anchoring marine structures at a marine location which is characterized by a smoothly curved plate having a plane of symmetry, the cross-section of the plate along the plane of symmetry as well as the cross-sections of the plate along planes parallel to the plane of symmetry substantially being bounded by circle arcs having their centers lying along an imaginary straight line which is rectangular or at right angles to the plane of symmetry, and connection means suitable for connecting an anchor line to the plate lying in the plane of symmetry and attached to the plate.

The point at which the connection means are attached to the curved plate may be near or in the center of gravity of the curved plate.

The radii of corresponding arcs in parallel planes may be equal to each other.

The boundary of the cross-section of the plate with planes passing through the center line may comprise two curved lines. These curved lines may be formed by circle arcs.

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Description of the drawing The invention will be further described with reference to the drawing which shows by way of example some embodiments of the invention, wherein:

FIGURE 1 is a diagrammatic view showing a vertical section of an anchor according to the invention, which is illustrated as having been moved from a position on the marine bottom to an anchoring position in this bottom;

FIGURE 2 is a plan view of an anchor according to the present invention;

FIGURE 3 is a cross-sectional view taken in the plane of symmetry of the anchor according to FIGURE 2 along line 3-3 of FIGURE 2;

FIGURE 4 is a cross-sectional view taken along the line 4-4 of FIGURE 2;

FIGURES 5, 6 and 7 are plan and cross-sectional views corresponding to FIGURES 2, 3, and 4, respectively, but of an anchor construction which is alternative to the anchor shown in FIGURES 2, 3 and 4;

FIGURES 8, 9, and 10 are plan and cross-sectional views of still another form of anchor according to the invention;

FIGURE 10A is a view similar to that of FIGURE 10 but illustrating still another alternative form of anchor according to the present invention;

FIGURE 11 shows a plan view of still another form of anchor according to the present invention;

FIGURE 12 is a cross-sectional view taken in the plane of symmetry of the anchor according to FIGURE 11 along line 12-12 of FIGURE 11;

FIGURE 13 is a cross-sectional view along line 13-13 of FIGURE 11;

FIGURE 14 is a cross-sectional view of a connection means suitable for connecting an anchor cable to an anchor; and

FIGURE 15 is a cross-sectional vietw taken along the line 15-15 of FIGURE 14.

The anchor as shown in FIGURE 1 comprises a curved plate 1 and a connection means 2 which is fixed to the positively curved side of the plate and may consist of an eyebolt or a pivoting rod provided with an eye, suitably for connecting thereto one end of an anchor cable or chain 3 which at the other end thereof is connected in a suitable manner (e.g. by means of a winch) to a ship (not shown) floating on the surface of the water overlying the sea bottom or ocean floor 4.

In posiltion A, the anchor is shown in FIGURE 1 to be resting on the sea bottom 4 and the anchor line 3 is kept taut by the ship. On pulling of the anchor line, one end of the anchor will be dragged into the bottom 4 and on further pulling, the Whole anchor will slide into the bottom and reach a position B along a path 5 which has the form of a circle arc with radius R. As will be seen heerinafter, the radius R of the path 5 is equal to the radius of the cross-section of the anchor in its plane of symmetry.

The anchor design as shown in FIGURES 2, 3 and 4 comprises a simple curved plate 6 provided with a ring or eye 7 welded thereto, this ring or eye being suitable for connecting thereto a chain or cable. The plate 6 is curved in the form of part of an imaginary cylinder having a radius R as can be seen in the plane of symmetry as shown in FIGURE 3, which shows a cross-sectional view of the anchor taken along the line 3-3 in FIGURE 2. FIGURE 4 shows a cross-sectional view of the anchor taken along tthe line 4-4 in FIGURE 2. This crosssection has an upper and lower boundary comprising two parallel lines 8 and 9. It will be appreciated that, since the anchor plate 6 forms part of a cylinder, all the crosssections of the anchor taken in planes parallel to the plane of symmetry along the line 3-3 will have boundaries comprising circle arcs having their centers on an imaginary straight line rectangular or at right angles to the plane of symmetry. This imaginary line will be referred to hereinafter by the expression center line. The point 10 (FIGURE 3) coincides with the point of intersection of the plane of symmetry and the center line and forms the center of an imaginary circle With the radius R.

On being connected to a chain or cable, the anchor will move into the sea bottom when tensile force is exerted on this chain or cable, provided that the chain or cable is in the plane of symmetry of the anchor, and the angle between the chain or cable and the sea bottom is not too great. The anchor plate 6 will then be displaced over the surface of the imaginary cylinder which has a radius R and has the center line of the anchor plate as its central axis. The anchor will thereby cut its way into the sea bottom 4 to a position B in which the relative positions between anchor cable and anchor plate are such that this cable is approximately rectangular to the plate.

Another design of an anchor according to the invention is shown in FIGURES 5, 6, and 7. The anchor plate 14 has a substantially rectangular top or plan view (FIG- URE 5). The cross-section of the plate 6 in the plane of symmetry is shown in FIGURE 6. The section of the plate taken along the line 7-7 of FIGURE 5 has a boundary comprising two sets of parallel lines 11, 11' and 12, 12'. The centers of the boundary lines of the cross-sections in planes parallel to the plane of symmetry lie on a center line (cf. point of intersection 13 with this plane of symmetry). Consequently, the plate 14 of the anchor forms part of the surface of two cones which have a common axis (being the center line) and a common base (lying in the plane of symmetry). The anchor as shown in FIGURES 5, 6 and 7 will be displaced over the surface of these two cones to reach an anchoring position cf. position B in FIGURE 1) when being loaded by an anchor cable.

FIGURES 8, 9, and show an alternative of the anchor construction according to FIGURES 5, 6, and 7. It differs from this former construction in that the crosssections taken in planes passing through the center line of anchor 14a (vide point 15 being the intersection of this line with the plane of symmetry in FIGURE 9) have boundaries comprising curved lines 16 and 17 forming circle arcs (vide FIGURE 10). The radii of these circle arcs (FIGURE 10) are shown as being smaller than the radii of the circle arcs (FIGURE 9) forming part of the boundary of the cross-section of the anchor plate taken in the plane of symmetry, however the radii may be substantially equal if so desired as shown, for example, in FIGURE 10A.

The anchor as shown in FIGURES 11, 12, and 13 has in plan view thereof a shape which is approximately equal to one half of an ellipse. The curvature of the anchor plate 18 in a direction rectangular to the plane of symmetry (section 1313) is of the same type as shown in the anchor in FIGURES 8, 9, and 10. Connection means comprising lever 19 for coupling an anchor cable or chain to the anchor plate 18, is pivotally attached to this plate 18 near the center of gravity thereof.

Since this center lies at the negatively curved side of the plate 18, a slit-like opening 20 is arranged in the plate through which the lever 19 protrudes. This lever has two openings, the opening 21 being used for coupling the lever to the plate by means. of a pin 22 passing through the support means 23 which are attached to the lower side of the curved plate 18, and the opening 24 being suitable for connecting an anchor cable thereto by any suitable means such as a D-shackle.

An alternative construction of connection means is shown in FIGURES 14 and 15. The connection means as shown in these figures comprises a housing 24' enclos ing a smoothly curved, groove cable carrier 25 around which one end of the anchor cable can be laid with both ends of the cable (not shown) passing through passageway 26 defined by the housing. The carrier 25 has an opening 27 therein the axis of which coincides with the axes of openings 28 in the housing 24. A pin such as pin 22 (FIGURE 13) is passed through openings 27 and 28 and support means such as support means 23 (FIG- URE 13) to secure this alternate form of connection means to an anchor plate similar to plate 18 (also FIG- URE 3). Since the anchor cable is to be connected to the lever 19 by means of a D-shackle or other similar arrangement, the combination consisting of the anchor plate 18, the lever 19 and the D-shackle will have a higher center of gravity than the arrangement consisting of the anchor plate 18 provided with the connection means according to the FIGURES 14 and 15. The chance of toppling over of the latter construction on being dragged into the marine bottom will consequently be smaller than in the arrangement being provided with the lever 19.

It will be appreciated that the present invention is not limited to the particular types of anchors having crosssections as shown in the FIGURES 4, 7, 10 and 13, but that without departing from the scope of the invention, other types of cross-sections may be applied. If desired, the anchors may be provided with guiding plates or fins which are connected to the anchor plate and extend in planes parallel to the plane of symmetry.

For obtaining a sufiicient grip of the anchor on the marine bottom, the radius R should not be too small. A radius of more than 12 feet, and preferably on the order of sixty feet, may be applied depending on conditions.

The radii of the circle arcs in the cross-sectionof the anchor as shown in FIGURES 10 and 13 may be at least six feet or more. In applying a radius R (vide FIGURES 9 and 12) of about sixty feet, these latter radii are preferably about thirty feet.

To orient the anchor in the correct position when it is placed on the sea bottom in the position A as shown in FIGURE 1, the trial and error method may be applied, by lowering the anchor on to the sea bottom by means of the anchor cable 3. This method, however, is only applicable if the visibility in the water is sufficient or if a diver is available to report on the position of the anchor. In another manner, two lines may be connected to the anchor, each line being connected to a point of the anchor plate, these points being arranged symmetrically with respect to the plane of symmetry of the anchor plate and arranged on the convex side of the anchor plate on or near that edge of the anchor plate which is trailing in view of the direction of movement when the anchor is being pulled into the sea bottom. By connecting the anchor cable 3 to the marine structure to be anchored and by connecting equal lengths of the two lines to a tugboat, the anchor will automatically be positioned such the plane of symmetry thereof contains the anchor cable 3. By lowering the two lines simultaneously by equal amounts, the anchor will be placed on the sea bottom in the correct position. If desired, the two lines may be disengaged from the anchor by a diver after the anchor is placed on the sea bottom. It is also possible to abandon these lines or to connect the end thereof to a buoy.

I claim as my invention:

1. An anchor of high-holding power in sea bottoms characterized by relatively soft soil conditions, said anchor Comprising:

a smoothly curved plate of a substantially rigid construction and of a size capable of withstanding substantial force being applied thereto, said plate having a convex side and a concave side, said plate further having a plane of symmetry, with the crosssection of the plate along the plane of symmetry as well as the cross sections of the plate along the planes parallel to the plane of symmetry substantially being bounded by circle arcs having their centers lying along an imaginary straight center line which is perpendicular to the plane of symmetry; and

connection means suitable for connecting an anchor line to the plate lying in the plane of symmetry and attached to the plate near the center of gravity of said plate with at least the major portion of said connection means extending outwardly from the convex side of the plate.

2. The anchor according to claim 1 wherein said plate is provided with an opening therein and centrally disposed with respect thereto and wherein said connection means is attached to said plate by support means afiixed to the concave side of said plate near the center of gravity of said plate, said connection means comprising a lever which extends from said support means and is pivotally mounted thereon, said lever passing through said opening in said plate so that the major portion of said lever is disposed on the convex side of said plate, sald opening being of a size permitting pivotal movement of said lever.

3. The anchor according to claim 1 wherein the radii of corresponding circle arcs in said parallel planes are equal to each other.

4. The anchor according to claim 1 wherein the crosssections of the plate taken in planes passing through the center line are bounded by two curved lines.

5. The anchor according to claim 4 wherein the curved lines are circle arcs having radii smaller than the radii of the circle arcs forming corresponding parts of the boundary of the cross section of said plate taken along the plane of symmetry.

6. The anchor according to claim 4 wherein the curved lines are circle arcs having radii substantially equal to the radii of the circle arcs forming corresponding parts of the boundary of the cross section of said plate taken along the plane of symmetry.

References Cited UNITED STATES PATENTS 1,319,419 10/ 1919 Reynolds 114-206 1,325,693 12/ 1919 Deam 114206 2,721,530 10/ 1955 Vorenkamp 1l4-206 TRYGVE M. BLIX, Primary Examiner

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