GB2155881A - Temporary mooring point structure - Google Patents

Abstract

A temporary mooring point structure, e.g. for an artificial harbour or port comprises a plurality of floating units or pontoons having vertically disposed passages 8 through which legs 6 forming mooring posts (4) are vertically movable by lifting means on the units from a sea bed engaging position for rapid dismantling and 12 transportation to a new site. The legs terminate in spikes 20 which penetrate the sea bed and a dead-weight anchor 16 is mounted between the bases of the legs. A plurality of the units may be connected by a causeway to the shore, with flexible bridges providing vehicle transportation surfaces linking the units. <IMAGE>

Description

SPECIFICATION Temporary mooring point structure This invention relates to a temporary mooring point structure and in particular to the quick construction of temporary floating facilities that may be towed into and out of position.

According to the present invention there is provided a temporary mooring point structure comprising: a floating unit; a plurality of substantially vertically disposed passages through the floating unit; a mooring post passing through each said passage; and lifting means on the floating unit to lift each mooring post from a sea bed engaging position to a retracted position, for movement of the structure to a new location.

It is preferred that each mooring post comprises a plurality of legs and a deadweight anchor mounted between the bases of the legs. The deadweight anchor may be a rigid structure mounted between the bases of the legs. Preferably the underside of the floating unit is formed with recesses to receive the deadweight anchors in the retracted position of each mooring post. Each leg may terminate in spike means below the deadweight anchor.

It is desirable that roller guide means are mounted on the unit to engage each mooring post and guide its movement. When the mooring post is, as previously discussed, constituted by a number of legs, each leg may be engaged by roller guide means: each leg is preferably of circular cross section and is engaged by three or more rollers equally spaced around its circumference.

The invention may advantageously be employed to provide an effective temporary port or harbour facility which combines fast straightforward construction with easy removal.

Thus, in accordance with the invention there is provided a temporary harbour or port comprising: a plurality of floating units; a plurality of substantially vertically disposed passages through the floating units; a corresponding number of mooring posts extending upwards from a sea bed engaging position, each said passage receiving a mooring post and the floating units being free to rise and fall with the sea; lifting means on the floating units to lift each mooring post from its sea bed engaging position to a retracted position for dismantling of the port or harbour to allow movement to a new location; a causeway connecting the floating units to the shore; and flexible bridges linking the floating units, and at least one floating unit and the causeway.Preferably each bridge comprises a plurality of independent fingers disposed in side by side relation to form a vehicle transportation surface, and joint means at each end of each finger, connecting the finger to a said unit, each joint means allowing relative movement between the finger and the unit whereby movement of the fingers, common or differential, accommodates relative movement between the units.

The invention will now be further described, by way of example, with reference to the accompanying drawings in which; Figures 1 to 3 are front, side and plan views of a temporary mooring point structure, according to the invention; Figure 4 is a side view of a mooring post arrangement employed in the structure of Figures 1 to 3; Figure 5 is a front view of the structure of Figures I to 3, showing winching apparatus; Figure 6 is a view from above of an operational port according to the invention; Figure 7 is an enlarged view of part of the handling region of the port shown in Figure 1; Figure 8 is a side elevation of a flexible bridge between two pontoons of the port of Figs. 6 and 7; Figure 9 is a detail on section A-A of Figure 10, of one end of a finger, forming part of such a bridge; Figure 10 is a plan view, partially cut away, of the finger; and Figure 11 shows a reinforced edge region of a pontoon, for attachment to a flexible bridge.

Referring to Figures I to 3, the temporary mooring point structure consists of a floating pontoon 2 having two mooring posts 4, each with four commonly extensible and retractable legs 6 of tubular section extending vertically through the body of the pontoon 2 and being configured in a square (or rectangle). The posts 4 are at opposite ends of the pontoon. Referring to Figure 4, the legs 6 are free to move up and down their respective passages 8 through the pontoon, each being constrained to run true to the vertical by a set of guide rollers 10, the rollers being mounted to the bulkhead 12 surrounding the passage 8 via energy absorbing devices 14 such as springs.The rollers 10 for each leg are arranged at three mutually equidistant positions about the leg 6 with two rollers being mounted, as shown in Figure 4, one above the other, with their axles perpendicular to the axis of the leg, and two single rollers being mounted at the other two positions. The bases of the legs 6, of a particular mooring post are fixed to a common deadweight anchor 16, for example of 1000-3000 tonnes, which forms a rigid horizontal web between the legs 6. At the end of each leg, extending below the flat base 18 of the anchor,is a spike 20.

The topmost ends of the legs 6 of a mooring post are stiffened by girders 22 fixed around the boundary of the square shaped array of legs. Referring to Figure 5,mounted on the deck 24 of the pontoon above a stowing recess 26 for each deadweight anchor is a windlass 28 from which a plurality of cables 30 is dropped through holes 32 similar to those formed to accommodate the legs 6 but of smaller dimensions, and anchored to mounting eyes 34 on the upper surface of the deadweight anchor. By this means a deadweight anchor 16 and corresponding legs 6 may be raised and lowered to assume retracted and sea bed engaging positions, respectively.

In its sea bed engaging position each deadweight anchor 16 lies on the sea bed 36 having been lowered by virtue of the windlass 28 and the force of gravity. The pontoon is thus constrained from drifting by the deadweight anchors 16, extra purchase being gained by the spikes 20 having penetrated the seabed. The pontoon is free to move up and down the legs 6 to accommodate the rise and fall of the sea, such rise and fall having been accounted for by the slackening off of the cable 30 attached to the deadweight anchor. The pontoon provides a basis, for example in conjunction with other pontoons, for any temporary facility (e.g. a port or harbour), until such time as it is no longer required.Then, the deadweight anchor and mooring post assembly may be raised to its retracted position in which the deadweight anchors are stowed, residing in the recesses 26 in the hull of the pontoon, so as to present a smooth keel to the water apart from the spikes remaining proud of the profile. With the pontoons so configured they may be towed to a required destination and rapidly set up there.

In other embodiments each mooring post is associated with a hydraulic take-up mechanism to allow the pontoons to rise and fall with the sea and/ or to lift the mooring posts.

An artificial port embodying the units of Figures I to 5, has as shown in Figure 1, a handling region 38 linked by a causeway 40 to the shore 42. The handling region comprises an array of six floating pontoons 2, arranged as two side by side rows each of three pontoons arranged lengthwise. Thus the array is generally rectangular and the length wise direction of the rectangle is at right angles to the causeway. A sheltered region 46 is thereby formed between the handling region 38, the causeway 40 and the shore 42.

As previously described, each pontoon is secured in place by two mooring posts passing through the pontoon.

Each pontoon is linked to each of its neighbour ing pontoons by a flexible bridge 48. One pontoon 2 is linked by a flexible bridge 50 to a 'roll on-roll off' pontoon 52 which is located at the port end of the causeway 40. The roll-on roll-off pontoon 52 is connected to the causeway by a ramp 54 hinged at respective ends to the causeway 4 and the pontoon 52. The pontoon may carry a swing bridge for connecting the pontoon 52 to a ship.

Each pontoon is a flat-bottomed structure having a plurality of ballast chambers (commonly 16) formed by watertight compartments. When a pontoon is being loaded on one side a chamber on the opposite side may, under automatic control, be filled with water to keep the deck horizontal, and subsequently automatically emptied when the bal lasting is no longer required.

The causeway 40 comprises a semi-submersible structure with a large bottom chamber from the longitudinal sides of which smaller leg chambers extend upward. Water is admitted to the bottom chamber until just the ends of the legs remain above the surface of the sea. A roadway is then constructed and secured at each transverse edge to one of the legs. The causeway shown has a roadway 55 and a walkway 56. The causeway may employ liftable weighted legs penetrating the sea bed, in the manner of the pontoons.

The bridges 48 and 50 connecting the pontoons must be able to accommodate various relative movements of the pontoon they link, e.g. the rising of one pontoon with respect to the other or the rising of just one part of a pontoon, causing the bridge to twist.

Each flexible bridge 48 comprises a number of independent fingers 57 arranged side by side to form a structure suitable for goods vehicles. As is shown in Figure 10, each finger 57 is formed in this embodiment by three I-beams 58 welded together along their length. Each I-beam has welded to each end a rugged plate 59 formed with a downwardly-facing U-shaped recess 60 (see Figure 9). Each recess engages a respective hinge pin 61 carried between a pair of plates 62 which are welded to the side 63 of a pontoon. The hinge pins at one end of a given bridge are axially aligned along the side of the pontoon, as shown in Figure ll,and are perpendicular to the length of the fingers. The three pins of each finger end act as hinge members allowing the end to swing about the member for example when the other end rises and falls.The pins are moveover a slightly loose fit in the recesses and, therefore, a slight twisting movement of each finger with respect to the pins, and hence the pontoon, is permitted. The up and down and twisting movements can combine, so that each finger can swivel to a limited extent with respect to the other fingers and the pontoon. The bridge formed by a plurality of fingers as described above may undergo a considerable overall twist compounded from relatively small differences in the orientation of adjacent fingers, and is substantially torsion free within the limits to which it is subjected in use.

Figure 11 shows in section the edge region 63 of a pontoon adjacent a bridge and in particular shows detail of local stiffening and support structure, comprising an array of stiffening plates 64, extending parallel to one another between the side 63 of the pontoon and an internal wall 65 parallel to the side 63, and cross-plates 66 between the stiffening plates 64. As is clearly shown in Figure 7, the pin-carrying plates 62 are welded to the side 63 at positions at which it is supported by the stiffening plates 64. Also as shown, one cross-plate 66 is fixed between each adjacent pair of plates 64 such that cross-plates extending from opposite faces of a given plate 64 are staggered from each other, being spaced from the side 63 by approximately one third and two-thirds respectively, of the distance from the side 63 to the wall 65.

The port described is made up from a number of modules which are easy to assemble and disassemble. Thus, it may be used in one place and when no longer required may be dismantled and towed to a new location, and rapidly re-assembled there. Each pontoon has a number of towing bollards 68.

It will be appreciated that although this specification has referred to use of temporary mooring point structures in the sea, such structures could also be used in lakes and rivers.

Claims (14)

1. A temporary mooring point structure comprising: a floating unit; a plurality of substantially vertically disposed passages through the floating unit; a mooring post passing through each said passage; and lifting means on the floating unit to lift each mooring post from a sea bed engaging position to a retracted position for movement of the structure to a new location.

2. A structure according to claim I wherein each mooring post comprises a plurality of legs and a deadweight anchor.

3. A structure according to claim 2 wherein each deadweight anchor is a rigid structure mounted between the bases of the legs.

4. A structure according to claim 3 comprising recesses formed on the underside of the floating unit to receive the deadweight anchors in the retracted position of each mooring post.

5. A structure according to any of claims 2 to 4 wherein each leg terminates in spike means below the deadweight anchor.

6. A structure according to any preceding claim further comprising roller guide means mounted on the platform and engaging each mooring post to guide its vertical movement.

7. A structure according to any of claims 2 to 5, further comprising roller guide means mounted on the platform and engaging each mooring post to guide its vertical movement, each leg being of circular cross section and the roller guide means for each leg comprising three or more rollers equally spaced around the circumference of the leg.

8. A transportable harbour or port comprising: a plurality of temporary mooring point structures according to any preceding claim; a causeway connecting the floating units to the shore; and flexible bridges providing vehicle transportation surfaces linking the floating units and at least one floating unit and the causeway.

9. A harbour or port according to claim 8 comprising a plurality of ballast chambers within each floating unit, and water admission means to admit water to a ballast chamber on the opposite side of a unit to that on which a load is applied.

10. A harbour or port according to claim 8 or 9 wherein the floating units are arranged in an array extending transversely to the causeway to form a sheltered region between the floating units, the causeway and the shore.

11. A harbour or port according to any of claims 8 to 10, wherein each bridge comprises a plurality of independent fingers disposed in side by side relation to form a vehicle transportation surface and joint means at each end of each finger, connecting the finger to a said unit, each joint means allowing relative movement between the finger and the adjacent unit, whereby movement of the fingers, either common or differential, accommodates relative movement between the floating units.

12. A bridge according to claim 11 wherein each joint means comprises a pin transverse to the finger, and a pin retaining conformation, movement of the finger perpendicular to the pin being hinging movement about the pin, and limited movement of the finger in other senses being accommodated by play between the pin and the retaining conformation.

13. A temporary mooring point structure substantially as hereinbefore described with reference to the accompanying drawings.

14. A transportable port or harbour substantially as hereinbefore described with reference to the accompanying drawings.