Title: Dredging Vessel

The invention related to a dredging vessel.

According to the present invention there is provided a dredging vessel comprising: a) a floating member to float in ambient water, said floating member having a front end and a rear end, and propulsion means adjacent the rear end, b) a head connected to the floating member forward of the propulsion means and to move along the water bed upon movement of the floating vessel relative to the water bed, said head supporting at least one water outlet, and c) a water pump having an inlet connected to ambient water and an outlet connected to the or each head water outlet, in use said water pump delivering water under pressure to the or each head water outlet to disturb particulate material on a water bed whereby it mixes with ambient water, and said propulsion means drawing disturbed particulate material mixed with ambient water up towards the floating member, and said propulsion means ejecting disturbed particulate material mixed with ambient water to the rear of the vessel.

Preferably the head is connected between one first end of a pair of arms, the other second end of the pair of arms being connected to the floating vessel, said pair of arms keeping the head in a fixed position relative to the floating vessel. Preferably the pair of arms is pivoted to the vessel. Preferably the pair of arms extends forward from the rear end of the vessel.

Preferably the head comprises a first bar having along its length water outlets in the form of a plurality of nozzles. Preferably the nozzles are each connected to the water pump through hoses. Preferably the first bar can rotate relative to the pair of arms whereby to adjust the angle or the nozzles relative to the pair of arms. The first bar may be rotated using a hydraulic ram.

Preferably the head further comprises a second bar having along its length water outlets in the form of a plurality of nozzles. Preferably the nozzles are each connected to the water pump through hoses. Preferably the second bar can rotate relative to the pair of arms whereby to adjust the angle or the nozzles relative to the pair of arms. The second bar may be rotated using a hydraulic ram.

The first and second bars may be rotated independently.

Preferably jets of water from nozzles from both first and second bars form a "V" to disturb the particulate material with maximum effect.

An embodiment of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows a side view of a dredging vessel,

Figure 2 shows a perspective view of part of Figure 1 with a head with first and second bars on a pair of arms.

Referring to the drawings there is shown a dredging vessel 1.

Vessel 1 has a floating member in the form of a barge 2 adapted to float in ambient water. Barge 2 has a bow 2A and stern 2B. Barge 2 has adjacent its stern 2B propulsion means in the form of a propeller 3 to drive and manoeuvre the barge 2. In addition one or more bow thrusters 4 may be provided.

A pair of arms 1 OA, 1 OB is pivoted at one second end to the stern 2 A of barge 2. Arms 1 OA, 1 OB extend forward from the stern 2B, and can be raised or lowered using a wire 11.

A head in the form of first and second of rotating bars 12,13 are provided between first ends of arms 1OA, 1OB forward of the propeller 3. Bar 12 has a lever 12A at one end connected to a hydraulic ram 12B. Bar 13 has a lever 13A at end connected to a hydraulic ram 13B. Operation of hydraulic rams 12B13B rotate bars 12,13.

Bars 12,13 are kept in a fixed position relative to barge 2 by means of wire 11. Bars 12,13 can be raised or lowered so they are adjacent the water bed by lengthening or shortening a wire 11. Bars 12 and 13 each support a plurality of nozzles 14 each connected by a hydraulic pipe 15 to outlet of high pressure water pump 16. Pump 16 has an inlet 16A connected to ambient water. Bars 12,13 move along the water bed upon movement of the barge 2 relative to the water bed.

In use, the water pump 16 delivers water under pressure to the nozzles. Jets of water emerge from the nozzles to disturb particulate material on a water bed whereby it mixes with ambient water. As barge 2 moves and as shown by the arrows in Figure 2, propeller 3 draws disturbed particulate material mixed with ambient water up towards the barge 2, and the propeller 3 ejects disturbed particulate material mixed with ambient water to the rear of the vessel where it can move out of the area as the water flows (e.g. as a river or with the tide).

In use bars 12,13 are rotated so that the jets of water from nozzles 14 from both bars 12 and 13 form a "V" to disturb the particulate material with maximum effect. Bars 12 and 13 are rotated into different positions to accommodate different angles of pair of arms 1OA, 1OB relative to barge 2. In this respect it will be seen that the nozzles from bar 13 may direct jets of water backwards and the nozzles from bar 12 may direct jets of water forwards.

A single hydraulic motor 17 (or other mechanical or electrical or electronic power source) may be used to power pump 16 and propeller 3.

It has been found that keeping the head around Vi metre above the waterbed disturbs the particulate material with maximum effect.

The force of water from the twin spray-bar action (bars 12 and 13) undercuts and dislodges particulate material from the waterbed. This is particularly effective when used on hard-packed mud or silt where a single spray-bar or bar with low pressure water jets may have limited impact. The twin spray bars break up chunks of mud or silt into small particles through the pulverising action of the two interlocking spray streams.

The forward bar 13, which angles spray towards the rear of the barge, acts additionally to accelerate the stream of water containing particulate material towards the rear of the barge where the action of the barge propeller moves the particulate material into the ambient current or outgoing tidal stream.

The pressure of water fed to each bar 12,13 from the water pump 16 can be varied to accentuate the undercutting effect, the pulverising effect or to flush water containing particulate material in suspension towards the rear of the barge, according to the operational requirement.

It is evident that the arms connected to the spray bars, and which pivot at the stern of the barge, must be raised and lowered according to the depth of water the barge is operating in. It follows that, in order to maintain the optimal angle of the V-spray to the waterbed, the spray-bars must be capable of being rotated independently as the arms are raised or lowered, and this may be a key part of the design.

The invention may take a form different to that specifically described above. For example the head could comprise just a single bar 13. The nozzles 14 could be adjusted or selected for controlling flow rates of water.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.