WO1992018699A1

WO1992018699A1 - Bridges for providing access from a water-borne craft to the shore

Info

Publication number: WO1992018699A1
Application number: PCT/GB1992/000738
Authority: WO
Inventors: John Rose
Original assignee: ARNPRIOR HOLDINGS Ltd
Current assignee: ARNPRIOR HOLDINGS Ltd
Priority date: 1991-04-23
Filing date: 1992-04-22
Publication date: 1992-10-29
Anticipated expiration: 1993-10-23
Also published as: AU1677692A; GB9108618D0

Abstract

A hinged flap (130) located at the ship end of a ship-to-shore bridge for vehicular access to a ferry vessel is adapted to receive a ramp (136) lowered from the vessel. The angle of inclination of the flap (130) is adjustable by means of hydraulic cylinders (134), and is placed under automatic control so as to maintain an optimum transition angle between the flap (130) and the ramp (136). Angle sensing means (140) are temporarily located on the ramp (136) to monitor the transitional angle, the output from the sensor (140) controls operation of the cylinders (134). A further angle sensor (148) may be located on the main deck of the bridge to monitor the angle between the deck and the flap (130), and may be used to control variable ballast means varying the buoyancy of the ship end of the bridge to maintain an optimum angle between the deck and the bridge. Also described are embodiments of floating bridge structures incorporating automatically controlled buoyancy tanks adapted to maintain the shore end of the deck level with an adjoining quay and automatically controlled shore end deck flaps adapted to maintain the flaps parallel to the quay.

Description

"Bridges for Providing Access from a Water-Borne Craft to the Shore"

The present invention relates to bridge structures for the roll-on-roll-off (Ro-Ro) loading and unloading of ships, providing vehicular access between a quay and a vessel lying alongside.

One example of this type of bridge is known as a linkspan, which comprises a bridge extending outwardly from the quay, having, its shore end pivotally supported on the quayside and its ship end supported by means of a buoyancy tank or tanks. The buoyancy of the tank or tanks may be variable, allowing the freeboard of the ship end of the bridge to be varied to suit the freeboard of the ship. Bridges of this type are described in British Patent No 1,333,592. Such ship-to-shore bridges are well known and are commonly used in association with Ro-Ro ferries having stern or bow doors. However, bridges of this type are not suited for all types of berth and are relatively static in their location once installed.

A further problem encountered in many types of ship to shore bridges, in use, is the maintenance of suitable transition angles between ramps and the deck of the bridge owing to relative vertical movements between the ship and the bridge.

It is a first object of the present invention to provide ship-to-shore bridge incorporating means for automatically controlling such transition angles.

It is a further object of the present invention to provide a ship-to-shore bridge offering greater mobility, a wider range of applications and greater flexibility of use than existing types. The invention also provides the potential for multi-lane vehicular access to wide-beam catamaran ferries, thereby allowing loading and unloading times to be reduced so that the high spsed and correspondingly reduced passage times of such craft can be more fully exploited.

In accordance with a first aspect of the invention (applicable to ship-to-shore bridges according to the second aspect of the invention set out below and to other types of ship-to-shore bridges), a ship-to-shore bridge comprises a main deck having a shore end and a ship end and is provided with a.ship end flap hinged transversely to the ship end of the deck and adapted to receive a ramp lowered from an adjacent vessel, means for varying the angle of inclination of said ship end flap, first sensor means for monitoring the angle between said ship end flap and said ramp and for generating a control signal, and automatic control means responsive to said control signal for varying the angle of inclination of said ship end flap so as to maintain a desired angle between the ship end flap and the ramp. Preferably also, the bridge includes means for varying the freeboard of the ship end of the deck, second sensor means for monitoring the angle between the deck and the ship end flap and for generating a control signal, and automatic control means responsive to said control signal for varying the freeboard of the ship end of the deck so as to maintain a desired angle between the deck and the ship end flap.

Preferably, said first sensor means comprises a portable housing adapted for temporary attachment to the end of the ramp lowered from the vessel. The temporary attachment of the housing may suitably be accomplished by means of a magnet or magnets.

The angle of inclination of the ship end flap is preferably varied by means of hydraulic cylinders under the control of said automatic control means.

According to a second aspect of the invention, there is provided a ship-to-shore bridge comprising a floating structure including a main deck having a shore end and a ship end, buoyancy means for supporting said deck, shore ramp means whereby vehicles may be transferred between the shore end of the deck and the shore, and variable ballast means adapted to vary the buoyancy of the structure such that the shore end of the deck may be maintained at a desired level with respect to an adjacent quay.

Preferably, the buoyancy means comprises at least one buoyancy tank located at the shore end of the deck and at least one buoyancy tank located at the ship end of the deck. Preferably also, the variable ballast means is adapted to vary the buoyancy of said at least one tank at the shore end of the deck.

Preferably also, the variable ballast means is further adapted to vary the buoyancy of said at least one tank at the ship end of the deck.

The shore ramp means preferably includes a generally rectangular shore end flap hinged transversely along one edge to the shore end of the deck and means for varying the angle of inclination of the flap with respect to the deck, such that the flap may be maintained substantially parallel to the adjoining quay as the angle of inclination of_ the deck varies.

Preferably also, the bridge includes automatic control means- adapted to maintain the shore end of the bridge at said desired level and to maintain said shore end flap substantially parallel to the quay.

Preferably also, the shore ramp means further includes a plurality of finger flaps hingeably connected to at least one of the three free edges of said shore end flap and adapted to extend across the gap between the rectangular flap and the adjoining quay.

Preferably also, the automatic control means includes means for monitoring the angle of inclination of one of said finger flaps located adjacent the hinge of said shore end flap to generate a control signal for controlling the level of the shore end of the bridge.

Preferably also, the automatic control means includes means for monitoring the angle of inclination of one of said finger flaps remote from the hinge of said flap to generate a control signal for controlling the angle of inclination of the shore end flap.

A number of variations are possible at the ship end of the deck. The deck may simply project beyond the buoyancy means at the ship end to receive a ramp lowered from the ship. A plurality of hinged finger flaps may project from the ship end to rest on the ledge on the ship. In this case the finger flaps may be movable transversely with respect to the deck and may also be capable of receiving a ramp lowered from the ship. A generally rectangular ship end flap may be provided hinged transversely along one edge to the ship end of the deck, and means provided for varying the angle of inclination of the ship end flap with respect to the deck. The freeboard of the ship end of the bridge may be varied by variable ballast means, by use of a ship end flap, or both. Where a ship end flap is employed its angle of inclination may be controlled by automatic control means in order to maintain an optimum transition angle between the flap and a ship's ramp resting thereon, in accordance with a a first aspect of the invention defined above. Variable ballast means controlling the buoyancy of the ship end of the bridge may also be placed under automatic control to maintain a desired angle between the ship end flap and the ship end of the deck.

The angles of inclination of the shore and ship end flaps are preferably varied by means of hydraulic cylinders.

The beam of the bridge is preferably sufficient to allow multi-lane vehicular access to broad beam vessels such as high speed catamarans.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Fig. 1 is a schematic plan view of a ship-to-shore bridge in accordance with the second aspect of the invention; Fig. 2 is a side view of the bridge of Fig. 1; Fig. 3 is a side view of an alternative embodiment of the bridge of Fig. 1 suited for use in exposed berths; Fig. 4(a) is a side view of the bridge of Fig. 1 with its ballast and flaps adjusted for low water and/or for a vessel of low freeboard; Fig. 4(b) is a side view of the bridge of Fig. 1 with its ballast and flaps adjusted for high water and/or for a vessel of high freeboard; Fig. 4(c) is a side view of an alternative embodiment of a ship-to-shore bridge in accordance with the second aspect of the invention, adjusted for low water; Fig. 4(d) is a side view of the bridge of Fig. 4(c), adjusted for high water; Fig. 4(e) is a side view of still another embodiment of a ship-to-shore bridge in accordance with the second aspect of the invention, adjusted for high water and/or for a vessel of high freeboard; Fig. 4(f) is a side view of the Bridge of Fig. 4(e), adjusted for low water and/or for a vessel of low freeboard; Fig. 5 is a schematic illustration of the use of the bridge of Fig. 1 with a stern, quarter ramp or side loading vessels in different berthing configurations; Fig. 6 is a schematic plan view of a ferry terminal utilising the bridge of Fig. 1 with a broad beam Ro-Ro catamaran having five vehicular access lanes; Fig. 7 is a detailed plan view of ship-to-shore bridge similar to that of Figs. 4(e) and 4(f); Fig. 8 is a ship end view of the bridge of Fig. 7; Fig. 9 is a shore end view of the bridge of Fig. 7; Fig. 10 is a side view of the bridge of Fig. 7; Fig. 11 is a side view of an automated ship end flap of a ship-to-shore bridge in accordance with a first aspect of the invention; Fig. 12 is a schematic diagram illustrating the automatic control system of the flap of Fig. 11; Fig. 13 is a fragmentary side view illustrating the movement of the flap of Fig. 11; and Fig. 14 is a schematic side view illustrating the variations of the position of the flap of fig. 11 in response to relative vertical movements of the bridge and an adjacent vessel.

As illustrated in Figs. 1 to 4(b), a ship-to-shore bridge in accordance with the invention is a floating structure providing a roadway from a Ro-Ro ship lying alongside to the quay. One end of the bridge is maintained at the same level as the quay and the other is preferably adjustable to the threshold of the vessel using it.

The structure is in the form of two buoyancy tanks 10 and 12, one at either end of a torsionally rigid integral bridge or deck section 14 spanning between them. Each of these tanks is ballastable. The tank 12 nearest to the ship is set at a freeboard to suit the vessel using it. In general terms the depth of the tank is sufficient to allow it to adjust at all stages of the tide for vessels between 1 metre and 3.5 metres of freeboard, although this range can be extended by increasing the depth of the tank up to 6.50 metres to suit catamaran ferries.

The link between the bridge at the top of the ship end tank 14 and the vessel can either be in the form of relatively small flaps 16 that rest on the ship and accommodate any movement between the ship and the structure due to waves or the passage of vehicles. If the vessel has its own ramp then these flaps are stowed in a lowered position and provide a sloped platform on to which the ship's ramp can be landed.

The ballast of the shore end tank 10 is automatically controlled by suitable control means to maintain the shore end of the deck 14 at the desired level with respect to the quay. Control systems suitable for the purposes of the invention are well known and will not be described in detail herein.

The depth of the shore end buoyancy tank 10 is dependent on the range of tide. The overall height must be such that at very low tide, completely free of ballast, it is still level with the quay. The end of this pontoon is fitted with a levelling platform 18 hinged transversely at its inboard end and projecting longitudinally beyond the end of the tank. This platform is elevated by hydraulic rams 20 or other suitable means to ensure that whichever angle the structure is tilted at, it remains parallel to the quay. Finger flaps 22 which rest on the quay can be fitted either to one, two or three of the non-hinged sides of the platform. The angle of inclination of the finger flap 22f. nearest the hinge of the levelling platform is monitored to provide a control signal for the tank 10 to ballast/deballast. As the tide goes down the angle on this flap 22f. will become too steep and it will signal the automatic ballast control system to start deballasting the tank 10. On a rising tide, when the gradient of this flap 22f becomes too excessive in the opposite direction, it provides a signal to the auto control to ballast the tank 10.

The angle of inclination of the flap 22a (located at the corner of the levelling platform away from the hinge) is monitored to provide a further control signal which actuates the hydraulic cylinders 20 to lift the levelling platform 18. As the tide goes down and the structure tilts, this flap 22a will signal to the auto control system of the elevating jacks 20 to raise or lower in order to maintain the platform parallel to the quay.

The angles of the flaps 22a and 22f_ may be monitored by means of limit switches or other suitable sensors, as will be apparent to those skilled in the art.

The floating Ro-Ro structure is moored to the adjacent quay by backsprings 24 to restrain fore and aft movement and alongside the quay by counterweighted breast ropes 26. The whole structure is fendered off the adjacent quay, the type of fendering 28 being dependent upon the structure of the quay. Wherever possible wheel fenders are preferably used, with their axles horizontal. At the ship end of the structure the flaps 16 that link to the ship may be adjusted transversely along a shaft 30 to line up to the centre line of vessels which vary in beam thus ensuring that they centre on the centre line of the ship. The hinge arrangement of the flaps 16 is such that it can absorb berthing shocks.

The box structure of the bridge section can contain fuel, fresh water and sullage tanks 32, 34 and 36 and any other tank or pipework required to service the vessel using it.^' Although the structure is primarily intended for use by catamarans, it can also equally accommodate normal general purpose Ro-Ro ferries and Ro-Ro trailer ships.

In exposed berths where waves will create pitching and possible rolling of the Ro-Ro pontoon, the configuration of the tanks may differ as shown in Fig. 3. The tanks can be made up of large diameter tubular legs 38, 40 connected-to rectangular tanks 42, 44 at their base to reduce movement due to waves and swell. The rectangular tanks 42, 44 produce a dampening effect. The legs and the submerged rectangular tanks may also be fitted with wings which will further reduce any movement.

Figs. 4(c) and 4(d) show an alternative embodiment of a ship-to-shore bridge in accordance with the invention, having a generally wedge-shaped hull 200 tapering from its shore end 202 to its ship end 204. The interior of the hull is divided into a plurality of ballast tanks 206, 208, 210, 212, allowing the buoyancy of the hull and the angle of inclination of the main deck 214 to be adjusted between low and high water. An automatically controllable shore end flap 216 is included as before. In this example there is no adjustable ship end flap, the ship end of the deck 214 merely being extended to provide an overhang 218 to accommodate bulbous bows of vessels. A ship end flap, could, however, be incorporated if desired.

Figs. 4(e) and 4(f) shows a further embodiment, again being generally wedge shaped but in this case comprising a main deck section 300 interconnecting ship and shore end ballast tanks 302 and 304 respectively. As illustrated, the structure includes adjustable ship and shore end flaps 306 and 308 respectively.

The various structures described above can be used in a number of different ways to suit berths of differing configurations as shown on Fig. 5, which illustrates the bridge in use with stern, quarter ramp and side loading vessels. It will be appreciated that it could equally be used with bow loading or other types of vessel, and that numerous other configurations are possible. The structure is totally independent from the shore -with the exception of a power supply, although this can be provided by an on-board generator. It can be easily moved and redeployed in other areas when not required either at the end of a season or when a ferry operator wishes to move to an alternative route or a Port Authority to a different berth.

Fig. 6 shows the structure in use with a catamaran 60, and the general layout of a terminal suitable for cars and coach type operation, including a boundary security fence 46, traffic access control 48, traffic lanes 50 and customs control 52 for disembarking vehicles, parking space 54 for vehicles awaiting embarkation and a traffic control signal gantry 56. The broad beam of the structure permits multi-lane access to the catamaran (five lanes in this example), allowing vehicles to embark and disembark simultaneously. This provides the potential for loading and unloading times to be reduced, so that the benefits of the high speed of catamaran vessels can be more fully exploited. The on-board storage tanks 32, 34 and 36 allow fuel and fresh water to be supplied to a vessel and sullage discharged while vehicles are loading and unloading. The storage tanks may then be refilled/emptied before the arrival of the next vessel.

A more detailed example of a ship-to-shore bridge in accordance with the invention is illustrated in Figs. 7 to 10.

This embodiment consists of a twin hulled bridge, typical overall dimensions being 55 metres long x 24 metres wide. The hulls 100, 102, each typically having a waterplane area of 360 metres², are located at either end of an inclined rigid box girder bridge section 104.

At the quay end of the facility, the shore side hull 100 is covered by a ramp 106 (typically 13 metres x 22 metres) which is hinged at the top of the bridge section 104 and is maintained level with and parallel to the quay by ballast and supporting hydraulic cylinders, as in the previous example.

The ship end hull 102 is subdivided into watertight compartments and is not used for ballast in this embodiment. The deck is stiffened and may be fixed in line with and at the same inclination as the bridge to provide a fixed freeboard. An overhang (typically of 3.5 metres) is provided to ensure that any contact made by the vessel will be above the water on a fendered face and not to the buoyant section of the ship end hull 102. This is particularly important with bulbous bow vessels, and the overhang may extend up to 6 metres.

Although the deck of the ship end hull 102 may be fixed in position, it is preferred that, as illustrated, it comprises a ramp 108 hinged 11 metres inboard of the hull and projecting 3.5 metres beyond the hull face. When being used in a 903 berth with an axial ramp ship, this ramp will be hydraulically raised to and be maintained in the horizontal position. This will ensure that the ship's ramp can be landed without twist when used in the axial position.

This ship end ramp 108 is fully load supporting using hydraulic cylinders 110. When vessels of varying freeboard use the facility end on it will be possible to optimise the angle at the point where the ship's ramp lands to achieve the smoothest transition curve.

The ramp 106 on the shore end hull 100 is hinged 14 metres inboard and has flaps 110 hinged on the remaining three sides. These flaps 110 are shaped so as to provide a smooth transition from quay to shore end ramp 106. Their arc of movement is about 1103 and when stowed upright in the locked position will create a crash barrier, as seen in Figs. 9 and 10.

The angle of inclination of the flap 110a nearest to the hinge on either side is monitored and is used to activate the ballast system in the shore end hull 106 as previously described. This ballast system may maintain the level at about 200 millimetres above the quay level.

The outboard end of the ramp 106 away from the hinge is supported on two hydraulic cylinders mounted within two rectangular columns 112. The angle of inclination of the outer flap 110b on the side of the ramp 106 is monitored and is used to activate these supporting cylinders in such a way as to maintain the ramp 106 parallel and level with the quay. Within the shore end ballast tank 100 there are two cofferdams in each corner which provide reserve buoyancy in the event of damage to this tank. The ballast pump and valves are contained in one of these cofferdams so as to be easily accessible from the towers 112 supporting the cylinders.

In circumstances when the facility is lying alongside, normal mooring lines to mooring bits and fairleads may be used. These will typically consist of one head line, one stern line, two backsprings and two breast ropes. Care must be taken to ensure that the whole structure will not drift off the quay under wind, current or tractive and braking forces from the passage of vehicles. Breast lines, 20 metres apart, will be the main method to hold the facility tight to the quay. To ensure that these maintain a reasonable angle throughout the tide, mooring points for them are located 6 metres inboard from the quay on plinths built up to the optimum height to ensure that at no time is the angle of the mooring too steep.

All mooring lines may suitably consist of a combination of a wire and synthetic rope. The wire may be fitted with a soft eye for attaching to the mooring bollards on the shore. This will prevent chafe over the edge of the quay. The rope tail will provide a certain amount of spring as well as making it simple to belay it to the mooring bits of the facility.

Optionally, the two breast lines may be attached onboard the facility to the ends of hydraulic cylinders 114. When not in use these cylinders 114 working in accompaniment with a hydraulic accumulator will maintain a constant tension even through the hydraulic power pack is switched off. When the flaps 110 are down and traffic is operating, the tension on these cylinders will increase to ensure that the whole of the structure is held firmly against the quay. This variation requires the use of wheel fenders, described in more detail below.

The outer end of the ship ramp 108 is fendered with orange coloured, high abrasive resistant polymer fendering.

On either side of the structure and at the inshore end there is a steel belting to ensure that any contact with the quay or passing ship- will be on this rather than on the main shell plating.

In places where this belting makes contact with the sheet pile wall it will be faced with low friction UHMWPE facing.

In addition to the static fendering, it is preferred that wheel fenders 116 (such as type Trellex Burleigh 42-1-FX) be mounted with their axles horizontal. These allow smooth vertical movement of the structure due to the tide, even when the breast ropes are tensioned. They can also absorb the component of berthing energy normal to the quay.

In the illustrated example no provision has been made for self-propulsion. Mooring and fendering are symmetrical. When moving to a new berth the lines will be let go in a normal manner and the pontoon towed by a tug made fast to the mooring bits. It may either tow alongside or from either end. Once it has arrived at the new berth with the breast ropes adjacent to the bollards on the shore, these may be secured and the rest of the mooring lines set up accordingly. Winches should be not required.

The power cable must be disconnected prior to starting the unmooring. A security interlock may be attached to a breast line to ensure that power supply is disconnected prior to it being let go.

If the facility is to be move_i frequently, it will be an advantage to duplicate the mooring ropes on either side of the structure. In this case, those not in use may be stowed in proper boxes to keep them clear of the deck.

The controls and power pack for the hydraulics, electrics and ballast system may be contained within a standard ISO container 118 mounted and secured on the deck in the location indicated on the drawings.

When not in use all systems can be switched off with the exception of the main power source which will remain on while the facility is secured in the berth to provide the following:- (a) Power to navigation lights 120 (12 volt).

(b) Heaters for hydraulic oil.

(c) Driers for the power pack.

All flaps 110 may be hoisted and hydraulically locked off in the vertical position isolating the facility from access by unauthorised personnel.

When in use, no operator will be required. To make the facility operational, all that is necessary is for the power to be switched on and the selected flaps 110 to be lowered on to the quay. Once this is done the ballast and hydraulics will automatically maintain the facility at the correct level with the quay throughout the tidal cycle. This is achieved by signals sent to the main control PLC from the two flaps 110a and 110b on the shore end ramp 106. The flap 110a nearest to the hinge of the ramp 106 will activate the ballast to ensure that the freeboard of the shore end hull 100 is maintained-at a height of approximately 200 millimetres above the level of the quay. The outboard flap 110b will activate the hydraulic cylinders supporting the ramp 106 to ensure that it is always parallel to the quay.

The only manual operation required will be on the ship end ramp 108, which will initially be set to suit the ship's freeboard immediately the vessel has berthed and lowered its ramp 122. A single lever positioned locally to the ship end ramp 108 can be raised or lowered to operate the ramp 108 to optimise the height in relation to the ship's ramp 122. This would normally be undertaken by any unskilled operator or the mooring gang.

As a further option an angle-sensing control box, magnetically attached to the end of the ship's ramp 122 once it has been lowered, will maintain the angle between the ship's ramp 122 and the ship end ramp 108 of the facility. It will therefore adjust for freeboard and trim change of the vessel automatically. The control panel for this will be located in a small locked cabinet built into the container housing. This option is described in greater detail below and may also be used with other types of ship to shore links.

Roll trailers are particularly susceptible to abrupt changes of gradient which are likely to occur mainly at the interface between the ship's ramp 122 and the landing point of the facility and also, but to a lesser extent, at the change of angle between the ship end ramp 108 and the main bridge section 104. There is also to a lesser extent a change of angle between the bridge section 104 and the shore end ramp 106.

At the first interface this can be minimised by the incorporation of the actuated ship end" ramp and angle sensor previously mentioned. At the next interface between the ship end ramp and the bridge transition flaps 124 2 metres long may be provided which will halve the change of angle creating a curve at the interface between the two planes. At the final interface between the ship and the shore there may be a fixed curve at the top 2 metres of the bridge 104 where it hinges to the shore end ramp 106. In this way it is ensured that there is a smooth passage between the ship's deck and the quayside which is particularly important for the rapid loading and discharging of vessels particularly where low ground clearance dockside equipment is in use.

The deck of the facility may be illuminated by floodlighting, arranged to minimise glare to drivers of vehicles. Frequent low-powered, low-level lighting is preferred to single overhead high intensity units.

The steel plating of the structure is preferably not less than 10 millimetres thick, except for trapezoidal stiffeners under the deck which may be 8 millimetres thick as they are sealed on one side so that corrosion is limited to one face only.

The plating on the bottom of the pontoon hulls and the first metre of side plating which is permanently submerged should preferably be increased to 12 millimetres. This will reduce the need for dry-docking to between 7 and 10 years. Cathodic protection may also be employed.

Navigation lights 120 are located at all four corners of the facility, those at the ship end being mounted on retractable masts to ensure that they can be lowered clear of the ship's ramp when a ship is using the facility. The colour and characteristics of the lights will be as required by the port in question. The lamps are electrically operated with battery back-up.

The lights and motors for the ballast system and hydraulics are powered from shore via an armoured cable. If the facility is to be frequently moved then duplicate power cables may be provided on either side.

The automated ship end flap referred to above is illustrated in Figs. 11 to 14, and may be incorporated in other types of ship-to-shore bridge in addition to those described herein.

When a Ro-Ro vessel berths at a quay and its cargo is discharged via a ship-to-shore bridge (either of the type described herein or by an existing type of linkspan) the gap between the ship's deck and the bridge is closed either by fingers on the end of the bridge lowered on to the ship's sponson or by the drawbridge ramp of the ship lowered and rested on the end of the bridge.

The ship end of a floating bridge will move while in the berth. This movement can be divided into two types. .

(a) Long period movement such as tidal changes and increase in freeboard due to the ship discharging its vehicles. This long period movement can be followed by raising and lowering the outer end of the bridge.

(b) Short period movement may result from any of the following:-

(i) Pitching of ship or bridge due to waves

(ii) Change of trim due to vehicular movement

(iϋ) Heave due to waves

(iv) List or roll

These short period movements are taken up by the fingers or the ship's ramp. If these are only short the angle at their hinge or the point where they make contact with one another very soon becomes critical and results in vehicles grounding.

With longer ramps or fingers the total movement can be greater. However, the problem of grounding of vehicles can better be overcome by providing an automated flap 130 on the end of the bridge 132 on to which the ship's ramp is lowered, in accordance with a first aspect of the invention.

The aim of the automated flap 130 is to maintain the angles between the ship's deck and the bridge 132 such that any change due to movement between the bridge 132 and ship is corrected by movement of the flap 130 so as to minimise the risk of vehicles grounding.

The actuated flap 130, hinged at its inshore end can be raised and lowered by a number of hydraulic jacks 134.

The ship's ramp 136 is lowered and rested on to this flap 130 and the bridge 132 is lowered sufficiently to ensure that the ship's ramp 136 slopes upwards from the car-deck 138. The flap 130 is raised/lowered until the angle between the ship's ramp end and the point where it lands on the flap 130 is the optimum angle; i.e. where angles between the ship's deck/ship's ramp, ship's ramp/flap and flap/bridge are as near equal as possible.

A magnetically attached portable signal box 140 is then placed on the ship's ramp 136 at its outer end. This signal box 140 has a freely rotating shaft 142 through it on to one end of which is attached an arm 144. This arm is telescopic and on its outer end it has a small wheel 146 which rests on the surface of the automated flap. As the ship rises, the angle of the deck/ramp and ramp/flap increases. This increase will be registered by a rotation of the shaft 142 in the signal box 140.

This rotation will signal the hydraulic jack 134 to raise or lower to maintain the angle between the ship's ramp 136 and the automated flap 130 at the angle set initially. This signal box 140 is connected by a wire plugged into the'console of the hydraulic power pack of the bridge 132.

If at the same time as the short term movements are taking place the ship is slowly rising/falling with the tide, the angle between the automated flap 130 and the bridge 132 will reach a point where it becomes critical. As soon as it nears this point a contact will be made signalling for the bridge 132 to be raised or lowered by variation of the ship end ballast to once again optimise the transition angles between the bridge and the ship's deck. A fixed sensor 148, similar to the portable sensor 140, may be fixed to the bridge 132 for this purpose.

The control of the automated flap 130 is indicated schematically in Fig. 12. The sensor 140 controls the circulation of the fluid in the hydraulic cylinder via solenoid-actuated valves connecting the cylinder chambers to the fluid reservoir.

The angle sensors 140 and 148 may utilise rotary shaft encoder means or other angle sensing arrangements as will be apparent to those skilled in the art. The invention thus provides, in its first aspect, an automated ship end flap for use with ship-to-shore bridges to maintain an optimum transition angle between the ship end of bridge surface and a ship's ramp resting thereon; and, in its second aspect, a ship-to-shore bridge which is mobile, flexible in use and substantially automatic in operation.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

1. A ship-to-shore bridge comprising a main deck having a shore end and a ship end, and including a ship end flap hinged transversely to the ship end of the deck and adapted to receive a ramp lowered from an adjacent vessel, means for varying the angle of inclination of said ship end flap, first sensor means for monitoring the angle between said ship end flap and said ramp and for generating a control signal, and automatic control means responsive to said control signal for varying the angle of inclination of said ship end flap so as to maintain a desired angle between the ship end flap and the ramp.

2. A ship-to-shore bridge as claimed in Claim 1, further including means for varying the freeboard of the ship end of the deck, second sensor means for monitoring the angle between the deck and the ship end flap and for generating a control signal, and automatic control means responsive to said control signal for varying the freeboard of the ship end of the deck so as to maintain a desired angle between the deck and the ship end flap.

3. A Ship-to-shore bridge as claimed in Claim 1 or Claim 2, wherein said first sensor means comprises a portable housing adapted for temporary attachment to the end of the ramp lowered from the vessel.

4. A ship-to-shore bridge as claimed in Claim 3, wherein said housing is removably attached to said ramp by magnetic means.

5. A ship-to-shore bridge as claimed in any preceding Claim, wherein the angle of inclination of the ship end flap is varied by means of hydraulic cylinders under the control of said automatic control means.

6. A ship-to-shore bridge comprising a floating structure including a main deck having a shore end and a ship end, buoyancy means for supporting said deck, shore ramp means whereby vehicles may be transferred between the shore end of the deck and the shore, and variable ballast means adapted to vary the buoyancy of the structure such that the shore end of the deck may be maintained at a desired level with respect to an adjacent quay.

7. A ship-to-shore bridge as claimed in Claim 6, wherein the buoyancy means comprises at least one buoyancy tank located at the shore end of the deck and at least one buoyancy tank located at the ship end of the deck.

8. A ship-to-shore bridge as claimed in Claim 7, wherein the variable ballast means is adapted to vary the buoyancy of said at least one tank at the shore end of the deck.

9. A ship-to-shore bridge as claimed in Claim 8,wherein the variable ballast means is further adapted to vary the buoyancy of said at least one tank at the ship end of the deck.

10. A ship-to-shore bridge as claimed in Claim 6, wherein the shore ramp means includes a generally rectangular shore end flap hinged transversely along one edge to the shore end of the deck and means for varying the angle of inclination of the flap with respect to the deck, such that the flap may be maintained substantially parallel to the adjoining quay as the angle of inclination of the deck varies.

11. A ship-to-shore bridge as claimed in Claim 10, wherein the bridge includes automatic control means adapted to maintain the shore end of the bridge at said desired level and to maintain said shore end flap substantially parallel to the quay.

12. A ship-to-shore bridge as claimed in Claim 11, wherein the shore ramp means further includes a plurality of finger flaps* hingeably connected to at least one of the three free edges of said shore end flap and adapted to extend across the gap between the rectangular flap and the adjoining quay.

13. A ship-to-shore bridge as claimed in Claim 12, wherein the automatic control means includes means for monitoring the angle of inclination of one of said finger flaps located adjacent the hinge of said shore end flap to generate a control signal for controlling the level of the shore end of the bridge.

14. A ship-to-shore bridge as claimed in Claim 12, wherein the automatic control means includes means for monitoring the angle of inclination of one of said finger flaps remote from the hinge of said flap to generate a control signal for controlling the angle of inclination of the shore end flap.

15. A ship-to-shore bridge as claimed in Claim 6, wherein the deck projects beyond the buoyancy means at the ship end to receive a ramp lowered from a ship.

16. A ship-to-shore bridge as claimed in Claim 6, wherein a plurality of hinged finger flaps project from the ship end of the deck to rest on a ledge of a ship.

17. A ship-to-shore bridge as claimed in Claim 16, wherein said finger flaps are movable transversely with respect to the deck.

18. A ship-to-shore bridge as claimed in Claim 6, further including a generally rectangular ship end flap, hinged transversely along one edge to the ship end of the deck, and means for varying the angle of inclination of the ship end flap-with respect to the deck.

19. A ship-to-shore bridge as claimed in Claim 18, including automatic control means whereby the angle of inclination of said ship end flap is controlled in order to maintain an optimum transition angle between the flap and a ship's ramp resting thereon.

20. A ship-to-shore bridge as claimed in Claim 19, wherein the bridge includes variable ballast means for varying the buoyancy of the ship end of the bridge and further automatic control means for controlling said buoyancy to maintain a desired angle between the ship end flap and the ship end of the deck.

21. A ship-to-shore bridge as claimed in any of Claims 10 to 14 or Claims 18 to 20, wherein the angles of inclination of said shore and ship end flaps are varied by means of hydraulic cylinders.