WO2018174722A1

WO2018174722A1 - Apparatus and methods related to loading material onto a vessel and preparing the material for transport

Info

Publication number: WO2018174722A1
Application number: PCT/NO2018/050084
Authority: WO
Inventors: Helge-Ruben Halse
Original assignee: Viking Dredging As
Priority date: 2017-03-23
Filing date: 2018-03-21
Publication date: 2018-09-27
Also published as: SG10201702393VA

Abstract

A method of loading dredged material onto a vessel (1) for subsequent transport, a related method of retrofitting or preparing the vessel, a base (20) and apparatus for providing the base. Dredged material comprising solids mixed together with water may be loaded onto a base of a cargo space (12) of the vessel, wherein the base may comprise a topography (22) which is retrofitted onto a pre-existing flat deck or floor of the vessel, and at least one filter (24, 24) may be arranged to interface with the cargo space. Fluid comprising the water from the mixture may pass through the filter and separate from the dredged material. The separated fluid from the filter may then be collected in a containing structure (24), from which the separated fluid may be removed through an outlet, e.g. by suction, to leave a remainder of the dredged material comprising solids in the cargo space in condition for transport after the loading has taken place. The topography can collect and guide the fluid toward the filter where it may be separated.

Description

APPARATUS AND METHODS RELATED TO LOADING MATERIAL ONTO A VESSEL AND

PREPARING THE MATERIAL FOR TRANSPORT

The present invention relates in particular to loading and transport of materials on cargo vessels at sea. More specifically, the invention relates to methods of loading material onto a vessel for subsequent transport, methods of retrofitting or preparing a vessel to obtain a base for a cargo space, a base for a cargo space and related apparatus for providing such a base. Particular embodiments relate in particular to applications in dredging operations, such as dewatering a dredged material to prepare the material for transport where it is loaded onto the base in fluidic form.

In the loading and preparation for transport of cargo on a cargo vessel, it can be convenient to load cargo such as solid particulates in a fluidic mixture with a fluid. It may then be desired to remove the fluid from the mixture once loaded, in order to transport the solid particulates in "dry" form.

In the dredging and land reclamation industry, dredged material from the seabed at sea may be loaded into a cargo hold of a vessel for transport to another location. In land reclamation activities for example, the dredged material may be taken from the seabed in one location and then transported to another location where it is dumped or otherwise discharged e.g. into the sea or onto land, to produce "new" land.

Multi-purpose vessels which can perform dredging, store, and transport dredged material are well known. An example of such a vessel is a trailing suction hopper dredger (TSHD).

Bulk carriers or barges may be used in order to transport dredged material. The material may be transferred into a cargo space of the bulk carrier or barge from an adjacent dredger vessel while dredging is ongoing. It may be convenient and efficient to load the dredged material into a cargo space of the vessel in the form of a slurry, e.g. a mixture containing sand and seawater as is typically recovered from the seabed. However, the content of water in the slurry can impose challenges. For instance, the water content occupies a proportion of the overall payload capacity of the hold when it is of interest primarily for the hold to contain only the dredged solids. Furthermore, for long distance transport on a bulk carrier, marine standards require the material in the cargo holds to be transported in "dry" condition.' Therefore, when dredged material is contained in the hold in the form of slurry, it may be sought to de-water the dredged material before commencing transport. A known solution is to let the dredged material settle in the hold to result in a layer of water in the upper part of the cargo space from which the water can then overflow or be siphoned away, e.g. through a hose lowered into the top of the cargo hold. A drawback in this technique may be the waiting time needed for the settling of the slurry to take place and potential need to terminate any further loading of the hold until the water has been siphoned off. This may delay the overall process. In addition, the dredged material even when settled may not be sufficiently dry and may contain water which may be difficult or impossible to access or extract from the hold by way of the hose. The water may for example be very heavily laden with solids making it practically difficult to extract. In addition, the pumps which may be typically used to draw fluid through the hose may not be able to function effectively in cases where solids remain in mixture with the water. In addition, the hoses may only access a limited portion of the hold at a time, and it can be time consuming or difficult to effectively manipulate an end of such a hose to an appropriate position in the hold for accessing extractable fluid parts and extracting those parts of the dredged material, in particular when holds are large or many. Vessels such as bulk carriers or barges as may be utilised for transport of dredged material may also have other challenges. The decks or floors of cargo holds on which the dredged material may be stored during transport are often flat and of large expanse. For instance, a typical flat deck area may be 80 x 25 m. The fluid may thus spread and/or distribute under gravity across the deck area, which can be problematic under extraction. The type of solids may also affect extraction of fluid, where fine grained solids, such as fine sand or muds, can hinder existing dewatering solutions, such as using suction pipes acting at discrete locations in the cargo space, where fluid may be sought to be extracted through the stored volume of dredged material from one region to another. It is an aim of the invention to obviate or at least mitigate one or more drawbacks or difficulties associated with the prior art. Another aim of the invention is to provide improved solutions for de-watering or fluid removal from fluid cargo on cargo vessels in general, in particular on flat decks or floors of such vessels. Yet another aim is to provide more improved, e.g. more efficient, solutions for loading and preparing dredged material on vessels for transport of such material, According to a first aspect of the invention there is provided a method of loading dredged material onto a vessel for subsequent transport, wherein the method comprises:

loading dredged material comprising solids mixed together with water, onto a base of a cargo space of the vessel, the base comprising:

a topography which is retrofitted onto a pre-existing flat deck or floor of the vessel; and

at least one filter arranged to interface with the cargo space, whereby fluid comprising the water from the mixture passes through the filter and separates from the dredged material, the separated fluid from the filter being collected in a containing structure, from which the separated fluid is removed through an outlet, to leave a remainder of the dredged material comprising solids in the cargo space in condition for transport after the loading has taken place;

wherein the topography is arranged to collect and guide the fluid toward the filter so as to be separated.

The topography of the base may include at least one surface which is sloped for guiding the fluid toward the filter, where the fluid may drain from the mixture in the cargo space under gravity. The surface may be sloped with respect to the pre-existing flat deck or floor by an angle of 15 degrees or more, or by an angle of 30 degrees or more.

The fluid which passes through the filter may typically comprise water, e.g. seawater. In some cases, the fluid which passes through the filter may also include some small-diameter solids, e.g. combined with or carried in the water. The topography may comprise at least one block of material in contact against the flat deck or floor, the inclined surface being a surface of the block. The block of material or blocks of material may contact the deck by an area or areas of contact together being 50% or more of the total area of the pre-existing flat deck or floor. The block of material may have a flat bottom in contact with the flat deck or floor.

The topography may comprise at least one element which is arranged on the flat deck or floor, defining a volume inside the element which is filled with material, the filled volume arranged to support a load of the material in the cargo space against the sloped surface, and/or to transmit the load to the flat deck or floor. The filled volume or element may have a flat bottom in contact with the flat deck or floor. The material may preferably be cellular concrete, although may comprise any other suitable light-weight material for providing the strength necessary for supporting the load on the base. The material may have lightweight elements embedded therein, and the embedded elements and may have a density lower than the material in which they are embedded. The lightweight elements may for example be granules, or small pieces of material. For example they may comprise expanded polystyrene (EPS) beads. The material in which the lightweight elements may be embedded may be concrete. The lightweight elements may for example be foam elements or beads. The material in which they are embedded may comprise a matrix which may bond the lightweight elements together when the material is set.

The material may have a density lower than the material of the element defining the volume which the material fills or is embedded. The element may comprise a structure of metal, which structure may include cross plates, corrugated sheeting, and/or pipes, joined together. The topography may be supported on the flat deck or floor by at least one area of contact, the area or areas of contact together being 50% or more of the total area of the pre-existing flat deck or floor.

The fluid mixture may be loaded by entering the mixture into the cargo space. The loaded mixture may pass through the filter, separate from the dredged material, and be removed from the containing structure during entry of the mixture into the cargo space.

The vessel may be a bulk carrier. The mixture may then be loaded by entering the mixture into the cargo space through a top hatch of a cargo hold of the bulk carrier. The floor may be a floor of the hold. The floor may be the top tank of the vessel.

The vessel may be a flat top barge. The flat top barge may be equipped with side boards to provide a cargo hold. The side boards may be arranged in upright configuration and may provide walls for the hold. The fluid mixture may be obtained by another vessel and the method may include transferring the fluid mixture from the other vessel into the cargo space to load the mixture onto the base. The deck may be a deck of the barge. The barge may be a pontoon.

The outlet may comprise a drainpipe, which may comprise slits, slots or perforations in a wall of the drainpipe for letting through separated fluid to be removed via the drainpipe. The other vessel may be a dredger, and the method may include performing dredging using the dredger to obtain the fluid mixture to be loaded onto the cargo space.

The method may further comprise operating a suction generating device for producing suction in the containing structure or at or in the outlet to extract the fluid from the containing structure through the outlet. The device may be a pump of any design, or an ejector.

The separated fluid may be removed from the vessel via the outlet. The containing structure is preferably arranged to receive fluid from the filter, the fluid draining under gravity from the cargo space through the filter.

The topography may be provided by one or more topographic blocks or elements, for guiding the draining fluid toward the filter. The sloped surface may be an upward facing surface of the topographic block or element. The topographic block or element may be constructed, e.g. by casting in situ on the flat deck or floor, or may be constructed in advance, e.g. by pre- casting, prior to locating the block or element on the flat deck or floor.

The filter may comprise gravel material or other particulates. The filter may comprise an element arranged to separate the fluid, such as matting, porous fabric, membrane, mesh sheet, or the like. The element may prevent the intended solids of the dredged material to be transported from passing through into the containing structure. The element may be supported by gravel material or other particulate on the base. The containing structure may be a channel, e.g. in a bottom of the base. The containing structure may include, e.g. be packed or filled with, gravel or other filler or particulate material, and the element may be laid over the gravel or filler or particulate material. In particular, the containing structure may contain gravel or other particulate material, and a filter may be laid over the gravel or filler or particulate material, so as to be supported by the gravel or filler or particulate material, the filter configured to separate the fluid from the dredged material, the containing structure being arranged to receive fluid from the filter, the fluid draining under gravity from the cargo space through the filter.

The method may include operating a device for producing suction in the containing structure for extracting the fluid. The device may be a pump or an ejector. The pump may be of any design. The remainder of the dredged material contained in the storage space may comprise solids, such as sand, mud, and/or other particulates or aggregates dredged from a seabed, to be transported in the cargo space. The containing structure may be arranged to receive fluid from the filter, the fluid draining under gravity from the cargo space through the filter.

The method may further comprise operating a suction generating device for producing suction in the containing structure for extracting the fluid from the containing structure through an outlet to lead the extracted fluid off the vessel. The suction generating device may be a pump or an ejector.

According to a second aspect of the invention, there is provided a method of retrofitting or preparing a vessel to obtain a base for a cargo space for subsequent loading, preparation, and transport of dredged material, wherein the dredged material when loaded comprises solids mixed with water, the method comprising the steps of:

providing a vessel comprising a pre-existing flat deck or floor;

arranging a filter to interface with the cargo space, the filter operable to allow fluid comprising the water to be separated from the mixture;

arranging and fitting a topography onto the pre-existing flat deck or floor, the topography being configured to collect and guide the fluid toward the filter; and

providing a containing structure arranged to collect and contain the separated fluid in the containing structure, and further arranged so that the separated fluid can be removed from the containing structure through an outlet, in order to allow a remainder of the dredged material comprising solids to remain in the cargo space in condition for subsequent transport.

The method may include filling a channel with gravel and laying an element over the gravel to obtain a filter arranged to separate the fluid. The method may include inserting a topographic block or element onto a deck or floor of the vessel to obtain the topography, wherein a surface of the topographic block may be arranged to guide the fluid, when draining under gravity, toward the filter. The method may further include performing casting of the topographic block or element in situ, or alternatively pre- casting the topographic block or element before inserting the casted topographic block or element onto the flat deck or floor. According to a third aspect of the invention, there is provided Apparatus for providing a base for a cargo space on a vessel, the base to be loaded with dredged material comprising solids mixed together with water, and configured to facilitate preparing the dredged material for subsequent transport, the apparatus comprising:

a filter configured to be arranged in the base to interface with the cargo space for separating fluid comprising the water of the mixture, from the dredged material;

a containing structure for collecting the separated fluid from the filter;

an outlet for removing the collected fluid from the containing structure; and a topography configured to be retrofitted onto a pre-existing flat deck or floor of the vessel, the topography being arranged to collect and guide the fluid toward the filter so as to be separated.

The topography may include at least one surface for guiding the fluid along a slope of the surface toward the filter. The angle of the slope with respect to the pre-existing flat deck or floor may be 15 degrees or more or 30 degrees or more.

The topography may comprise at least one block of material configured to be placed in contact against the flat deck or floor. The surface for guiding the fluid along the slope may be a surface of the block.

The block of material or the blocks of material may contact the flat deck or floor by an area or areas of contact together being 50% or more than the total area of the pre-existing flat deck or floor. The block of material may have a flat bottom in contact with the flat deck or floor. The topography may comprise at least one element which is configured to be arranged on the flat deck or floor, the element being configured to define a volume inside the element when on the flat deck or floor, the volume being filled with material, the filled volume being configured to support, and/or transmit to the flat deck or floor, a load from the dredged material which may bear against the sloped surface in use. The filled volume or element may have a flat bottom configured to be placed in contact with the flat deck or floor.

The material of the block or element may preferably be cellular concrete, or may be another suitable lightweight material or filler capable of transmitting load between the inclined surface and the flat deck or floor.

The material may have lightweight elements embedded therein, and the embedded elements and may have a density lower than the material in which they are embedded. The lightweight elements may for example be granules, or small pieces of material. For example they may comprise expanded polystyrene (EPS) beads. The material in which the lightweight elements may be embedded may be concrete. The lightweight elements may for example be foam elements or beads. The material in which they are embedded may comprise a matrix which may bond the lightweight elements together when the material is set.

The material may have a density lower than the material of the element defining the volume which the material fills or is embedded.

The topography may be supported on the flat deck or floor by at least one area of contact, the area or areas of contact together being 50% or more of the total area of the pre-existing flat deck or floor. The filter may comprise an element arranged to separate the fluid selected from the group comprising: a perforated screen; matting, porous fabric; porous textile or membrane; mesh sheet.

The apparatus may further comprise at least one topographic block for the base, the topographic block being arranged to be fitted in place on a deck or floor of the vessel, and have a sloped surface for guiding the fluid toward the filter.

According to a fourth aspect of the invention, there is provided a base for a cargo space of a vessel, the base being retrofitted onto a pre-existing flat deck or floor of the vessel, the base configured to be loaded with dredged material comprising solids mixed together with water, and further configured to facilitate preparing the dredged material for subsequent transport, the base comprising:

a filter configured arranged to interface with the cargo space for separating fluid comprising the water of the mixture, from the dredged material;

a containing structure arranged to collect the separated fluid from the filter;

an outlet for removing the collected fluid from the containing structure; and a topography supported upon the flat deck or floor, the topography being arranged to collect and guide the fluid toward the filter so as to allow the fluid to be separated. According to a fifth aspect of the invention, there is provided a cargo vessel provided with the base of the fourth aspect. According to a sixth aspect of the invention, there is provided a method of loading material onto a vessel for subsequent transport, wherein the method comprises:

loading material comprising solid particulates in a fluidic mixture, onto a base of a cargo space of the vessel, the base comprising:

at least one filter arranged to interface with the cargo space, whereby fluid from the mixture passes through the filter and separates from the mixture, the separated fluid from the filter being collected in a containing structure, from which the separated fluid is removed through an outlet, to leave a remainder of the material comprising solid particulates in the cargo space in condition for transport after the loading has taken place;

According to a seventh aspect of the invention, there is provided a method of retrofitting or preparing a vessel to obtain a base for a cargo space for subsequent loading, preparation, and transport of material, the material when loaded comprising solid particulates in a fluidic mixture, the method comprising the steps of:

providing a vessel comprising a pre-existing flat deck or floor;

arranging a filter to interface with the cargo space, the filter operable to allow fluid from the mixture to be separated from the mixture;

providing a containing structure arranged to collect and contain the separated fluid in the containing structure, and further arranged so that the separated fluid can be removed from the containing structure through an outlet, in order to allow a remainder of the material comprising solids to remain in the cargo space in condition for subsequent transport.

According to a eighth aspect of the invention, there is provided apparatus for providing a base for a cargo space on a vessel, the base to be loaded with material comprising solid particulates in a fluidic mixture, and configured to facilitate preparing the dredged material for subsequent transport, the apparatus comprising:

a filter configured to be arranged in the base to interface with the cargo space for separating fluid the material;

a containing structure for collecting the separated fluid from the filter;

an outlet for removing the collected fluid from the containing structure; and a topography configured to be retrofitted onto a pre-existing flat deck or floor of the vessel, the topography being arranged to collect and guide the fluid toward the filter so as to be separated. According to an ninth aspect of the invention, there is provided a base for a cargo space of a vessel, the base being retrofitted onto a pre-existing flat deck or floor of the vessel, the base configured to be loaded with material comprising particulates in a fluidic mixture, and further configured to facilitate preparing the dredged material for subsequent transport, the base comprising:

a filter configured arranged to interface with the cargo space for separating fluid from the dredged material;

a containing structure arranged to collect the separated fluid from the filter;

an outlet for removing the collected fluid from the containing structure; and

a topography supported upon the flat deck or floor, the topography being arranged to collect and guide the fluid toward the filter so as to allow the fluid to be separated.

According to a tenth aspect of the invention, there is provided a cargo vessel provided with the base of the ninth aspect. In any of the sixth to tenth aspects: the material may be dredged material; the solid particulates may be in mixture with water, e.g. seawater, e.g. which may be mixed and recovered together with solids during dredging; the vessel may be a bulk carrier or barge.

Any of the above aspects of the invention may include further features as described in relation to any other aspect, wherever described herein. Features described in one embodiment may be combined in other embodiments. For example, a selected feature from a first embodiment that is compatible with the arrangement in a second embodiment may be employed, e.g. as an additional, alternative or optional feature, e.g. inserted or exchanged for a similar or like feature, in the second embodiment to perform (in the second embodiment) in the same or corresponding manner as it does in the first embodiment.

Various advantages of the invention and its features are described and will be apparent from the specification throughout. There will now be described, by way of example only, embodiments of the invention with reference to the accompanying drawings, in which: is a perspective view representation of an interior of a hold on a bulk carrier vessel;

is a representation of part of a base of a cargo space in a hold of a cargo vessel according to an embodiment of the invention;

is a sectional representation of a separating structure in the base of the cargo space of Figure 2, in larger scale;

is a sectional representation of an alternative separating structure according to another embodiment of the invention;

is a sectional representation of another alternative separating structure according to an embodiment of the invention;

is a perspective view representation of an interior of a cargo hold on a bulk carrier vessel with another alternative separating structure, according to an embodiment of the invention;

is an end-on view of the separating structure of Figure 6 in larger scale; is a perspective view of pipework in the cargo hold of Figure 6 in large scale;

are perspective representations of a pipe end structure for the pipework of Figure 8;

is schematic sectional representation of a part of a barge with a base of a cargo space for dredged material configured for separating seawater, according to another embodiment of the invention;

is an end-on representation of a hold of a bulk carrier containing dewatered solids ready for transport, according to an embodiment of the invention;

is a block diagram representation of a method of use of a vessel according to an embodiment of the invention;

is a perspective view of a cargo vessel according to another embodiment of the invention;

is a perspective view of a construction element for the base of the cargo space of the cargo vessel of Figure 13, in close up;

is a perspective view of one of the holds of the cargo vessel of Figure

13 in close up showing construction elements of the base;

is a perspective view of another of the holds of the cargo vessel of

Figure 13 in close up after construction of the base;

is an end on view of the cargo hold of Figure 16;

is a perspective close up view of a separating structure of the base of the cargo vessel of Figure 13; Figure 19 is a perspective view representation of a hold of cargo vessel with an alternative base for the cargo space according to another embodiment of the invention; and

Figure 20 is a perspective view representation of the hold of Figure 19, the base being loaded a fluid mixture of dredged material.

With reference first to Figure 1 , there is illustrated part 1 of a bulk carrier showing in particular the interior of a cargo hold 10. The cargo hold 10 is one of a number of cargo holds in the hull of the bulk carrier. The cargo hold 10 provides a cargo space 12 for cargo in the form of dredged material.

A base 20 of the cargo space 12 is prepared with sloped topographic blocks 22 which are inserted and arranged to add topography onto a flat floor of the hold 10. The blocks 22 in this example are formed of concrete and are arranged to define, in this example, a number of parallel channels or valleys 24 in the base.

In embodiments of the invention, such a hold 10 is loaded by dumping a raw mixture of dredged material and seawater from the seabed into the cargo space 12. As will be explained further in the following description, the base 20 can be configured to facilitate removing seawater from the loaded mixture. The indicated zones 25 indicate example areas for providing a 'dewatering' or separating structure (not specifically shown in Figure 1 ) for allowing seawater to be separated from the mixture.

Turning now to Figures 2 and 3, an example separating structure 30 for the base 20 is provided in a valley between inserted blocks 22. The separating structure 30 has a filter 32, which is supported on a bed of coarse particulate, in this example a bed of gravel 33. In other variants, the coarse particulate may comprise coarse sand.

The mixture 5 of dredged material and seawater is loaded into the cargo space 12 above the filter 32. Seawater from the mixture drains under gravity and passes through the filter 32 as indicated by the arrows. The filter 32 is configured such that dredged solids, e.g. sand particulate or other solids, do not pass through the filter 32. Hence, the seawater by passing through the filter 32 is separated from the mixture so as to leave behind a remainder of dewatered material comprising solids in the cargo space 12. The filter 32 in this example is a porous fabric such as a layer of geotextile, matting, or porous sheeting. The fabric may be rolled out or otherwise provided onto the top of the bed of gravel 33. The separating structure 30 is arranged so that seawater passes into a region below the filter and is collected and contained in a container 34. The container 34 in this case is in the form of a channel or trench, which extends the length of the valley in the base of the hold. As can be seen, the container 34 has sidewalls 35 which extend upward from a container bottom 37, which in this example is constituted by a portion of the floor of the hold (top tank of the vessel), providing surfaces for containing the seawater in the container 34.

In this example, the container 34 is provided alongside or between inserted blocks 22, and the sidewalls 35 are formed by surfaces of the blocks 22 on opposing sides of the valley, or by a surface of the blocks 22 on one side and a vertical sheet of steel on the other. The container bottom 37 is formed by a surface of the floor of the hold 10.

The bed of gravel 33 for supporting the filter 32 is also contained in the container 34. The gravel 33 is a coarse, 'loosely packed' particulate, which is very highly permeable to seawater, so as not to provide any significant restriction to seawater entering the container 34 through the filter 32. Other coarse particulates such as coarse sand may be used instead of or in addition to gravel. The seawater entering the container 34 is contained in the interstitial spaces between and around the particles of gravel or other particulate. In this way, the gravel 33 is confined in the container 34 and provides the necessary support for the filter, whilst the seawater can enter and permeate freely in the bed of gravel 33.

The seawater drains through the cargo space under gravity, and meets a sloping surface of the blocks 22. The sloping surface is angled so that the seawater drains, following the slope, toward the filter in the separating structure 30.

An outlet 40 is arranged for extracting the seawater from the container 34. The outlet 40 is exemplified as including an opening to a pipe for leading the seawater off the vessel, although in general may be an outlet of any suitable form for extracting the seawater from the region of container 34, away from the hold 10, and off the vessel. As described in other embodiments further below, the outlet may be in the form of permeable drainpipe which has slots or perforations which allow entry of seawater into the drain pipe but prevents the gravel or other particulate in the mixture from entering.

Figure 4 illustrates a variant of the separating structure 30, which differs in that a filter 132 is provided in the form of rigid mesh instead of a flexible fabric as in the filter 32. The filter 132 does not require support from any substrate of gravel 33 hence no bed of gravel 33 is used in the variant of Figure 4. The container 34 into which the seawater passes through perforations 132p in the filter is free from gravel 33, and therefore has a greater volume available for collecting and containing water which drains from the dredged mixture during loading. The filter 132 in this variant is supported in place by shoulders 137 on the sidewalls of the containing structure. The filter 132 is sufficiently rigid to resist deformation under the load of the dredged material so as to maintain the configuration substantially as illustrated in the figure during use.

It will be appreciated that in other embodiments, the filter 132 could be fastened in place to the blocks e.g. through appropriate fasteners such as screws, bolts, or the like. In yet another embodiment, a container may be provided in the form of a cassette or cartridge, which is inserted into a pre-configured space in between the blocks 22. The cassette may comprise the sidewalls, floor, and a filter 132 fastened between the sidewalls at the top of the cassette. The cassette is adapted to provide a snug fit in the pre-configured space in the base of the hold. Thus, the filter can be configured prior to installation and simply inserted into the base of the hold by insertion of the cassette to place the filter and container in position ready for use.

In Figure 5, the base includes a first separating structure 30 as described above in bottom of the valley between blocks 22. In addition, a second separating structure 50 is provided on a valley side. The second separating structure has a filter 52 through which seawater is received in a container 54. The filter 52 is arranged upslope from the first separating structure 30, and intercepts draining water guided by the block 22 on an uphill side of the filter 52. The additional collecting structure 52 facilitates collecting a portion of the total amount of water to be drained from the mixture, such that not all of the water needs to be accommodated by just a single separating structure in the base, and this can therefore facilitate more efficient drainage and separation of the seawater of the total volume of dredged material.

The filter 52 is a mesh sheet with perforations and is supported on shoulders 57. The container 54 is not gravel packed in this example. The separating structure 50 functions similarly to the separating structure 30 so that seawater passes through the mesh, while solids with grain sizes greater than the diameter of the perforations of the mesh do not pass and remain in the cargo space. The seawater is contained in the container 54, from which it can then be extracted and offloaded from the vessel.

In this example, an inclined duct 58 connects the container 54 with the container 34. The water contained in the container 54 is led, under gravity, through the duct 58 to the container 34 of the first separating structure 30. The seawater from both the filter 52 and the filter 32 is combined in the container 34 from where it can be extracted through the outlet 40. The duct 58 is arranged inside the block 22. Turning now to Figures 6 to 9 an alternative implementation in the cargo hold 10 is shown. They show a particular arrangement of separating structures in the base of the cargo space 12. Various pipework and related components are also installed inside the hold 10 and are employed for helping to extract separated seawater off the vessel. Features of specific implementations which corresponding to those in earlier-described embodiments herein are referenced using the same numeral in the drawings. Features which are generally similar, but which vary from earlier-described embodiments and are referenced in the text, use the same numeral but incremented by a multiple of one hundred. More specifically, the arrangement of Figures 6 to 9 has a main separating structure 230 in the valley between blocks 22, and further separating structures 250 arranged upslope from the main separating structure 230 on the valley sides. The further separating structures 250 have containers 254 which are connected with the container 234 of the main separating structure 230 by way of connecting ducts. Thus, seawater that drains through the filter 252 of the further separating structures 250 passes through the filter 252 and then drains through the ducts into the container 234 of the main separating structure. The container 234 is in communication with an outlet 40 in the form of a mouth to an extraction pipe 80. The seawater is led away through the extraction pipe and overboard from the vessel into the sea. In order to extract the separated seawater from the container 234, an ejector 82 is utilised. In other embodiments, a pump, generally of any design, may be used instead of the ejector 82. The ejector 82 comprises a pipe section e.g. a venturi, having an internal restriction arranged to generate suction on the upstream side of the restriction. The pressure is thus lowered at the outlet and in the region near the outlet 40 in the container 234, producing a suction effect. Thus, the seawater is drawn out of the container 234 and led through the extraction pipe 80 by operation of the ejector 82. In order to operate the ejector 82 and produce the necessary suction, an operating fluid is pumped through a supply pipe 86 and is driven through the restriction in the ejector 82. The seawater from the container 234 is lifted through the outlet, flows into the ejector 82 where it combines with the operating fluid and is driven through the extraction pipe 80 and off the vessel. The operating fluid may

conveniently be seawater. The pipework also includes pipes 90, 92, 94 for use in removing dredged solids from the cargo hold, when offloading is to take place. Further fluid can then be supplied and added into the hold at the bottom of the cargo space 12 through the pipes 90, 92, 94. The added fluid flows through pipes 90, 94 and is jetted into the cargo space through nozzle outlets 96, 98. The fluid added from the nozzle outlets 96, 98 combines with the solids of the dredged material in the bottom of the cargo space 92 to produce a new mixture, which then can be removed from the hold 10. Further fluid can also be supplied through pipes 92 and jetted into the hold through supply outlets 97. The offloading of the new mixture can take place by use of the ejector 82, through a second outlet 41 . The added fluid to create the new mixture is conveniently seawater, and can be supplied through the pipes 90, 92, 94 by means of a pump.

As seen in Figure 9A and 9B, the outlets 40 and 41 are contained in a pipe end structure 83. The pipe end structure 83 is arranged at the base of the cargo space so that the outlet 40 is aligned with the container 234 so as to allow the seawater from the container to pass into the outlet 40.

The outlet 40 communicates with the container 234 for extracting separated fluid during loading. The second outlet 41 is utilised for extracting, during offloading, the generated new mixture of solids and added fluid. The pipe end structure 83 has an opener/closer 89 for selectively closing or opening up communication for the generated mixture to enter into the second outlet 41 and be extracted through the ejector 82 and off the vessel. The

opener/closer is in the form of a hinged flap in the example of Figures 9A and 9B. A suitable activation mechanism (not shown) may be provided for activating the opener/closer 83 appropriately. During loading, the opener/closer 83 is closed against communication through the outlet 41 . During offloading, the opener/closer 83 is opened to allow communication of the generated new mixture through the outlet 41 to extract the slurry via the ejector 82.

Although an ejector 82 is described in the above, in other variants, this can be replaced instead by a motorized pump, which may be of generally any suitable design, and which can be operated to produce the necessary suction at the outlet 40 for extracting the separated seawater.

It should also be appreciated that the dual outlet of the pipe end structure 83 is merely an example, and that in other embodiments, separate outlets and pipes may be provided for removing separated seawater when loading and for removing the fluid mixture of solids when offloading. In Figure 6, the level of solids in the cargo space 12 during loading is marked and denoted 'S'. A top layer of seawater will tend to form above fluid more heavily laden with solids due to relative densities. The level of the seawater layer above the solids is indicated and denoted W. During loading, seawater drains under gravity through the filters 232 and 252 in the base of the cargo space 12. However, seawater in the top layer of seawater may additionally be extracted from the hold by means of a cofferdam of the hold or by inserting an open end of a pipe 47 into the top layer of seawater to siphon the seawater from the top layer out of the hold through the open end. Alternatively, a pump (of any design) may be connected to extract the seawater through the end of the pipe 47. This may facilitate to remove seawater more quickly and increase the speed of loading and dewatering.

It can further be appreciated from the examples that the area of the filter can be adapted according to requirements. In the examples shown, the filter may extend from one end of the hold to the other. The width and total area may be provided accordingly. In the Figure 6 example, the main separating structure 230 has two filter screens tilted at an angle on either side of a ridge. The tilted arrangement can increase the area of filter facing the volume of dredged material for a given distance across the cargo hold. Thus, the amount of seawater that may be drained simultaneously may be controlled by appropriate choice and

arrangement or dimensioning of the filters.

While the above embodiments have been described particularly in relation to a cargo hold 12 on a bulk carrier, it can be noted that the separating structures may be employed similarly on other types of vessel. In Figure 10, a part of a flat top barge 301 is illustrated where dredged material 305 is being loaded onto a base 320 of a cargo space 322. The base 320 comprises topographic blocks 22 installed on a flat top deck 306 of the barge 301 . The deck is supported on a hull in the sea. Separating structures 330, 350 comprise respective containers with filters, such as those described above in relation to the bulk carrier, for allowing seawater to separate from the solids component of the dredged material, by passing through the filters. The slope of the blocks 322 facilitates directing the seawater toward the location of the filters. 'Free' seawater at the top of the volume may wash over the sides as the dredged material is loaded onto the base 320. Seawater entrained in the solids, will drain under gravity as indicated by stippled arrows through the volume and be led toward the filters so as to separate out and be extracted through outlets (not shown).

In certain variants, the outlets for the separated seawater from the containers may consist merely of openings or pipe leading through the side of the vessel, allowing for seawater water to be extracted from the containers and drain overboard as the containers fill up with separated water, without requiring any applied suction from pumps or the like.

When loading is complete, the cargo space may contain substantially dry 'dewatered' solids of the dredged material, the top level indicated as 'DW as illustrated in Figure 1 1. The solids are contained in the cargo space in condition ready for transport.

It can be appreciated that the barge 301 may be self-propelled or non-propelled. Although the embodiments above refer to "sea" and "seawater", these terms also include fresh water and reference to use of the vessel in the "sea", the term sea includes any body of water in which the vessel may be employed, including lakes, rivers, or other waterways.

With reference to Figure 12, an example method 500 of use of the vessel, e.g. the barge or bulk carrier, is described in the following steps, denoted S1 to S7 below and in the figure:

S1 . A base is provided which includes a filter and a container (a containing structure). The filter and the container are arranged such that fluid which passes through the filter and is separated from the mixture to be loaded onto the base is collected in the container. From the container, the separated fluid can communicate with an outlet and be removed from the vessel. For instance, topographic elements may be placed to define valleys therebetween. A 'loosely' packed particulate may then be provided in the valley with a porous filter supported on top, providing part of the base, facing the cargo space. The valley sides may then provide a containing structure from which fluid from the filter can be contained. S2. Material is dredged from the seabed producing a fluid mixture (e.g. slurry) comprising solids and seawater. The mixture may be suctioned from the seabed.

53. The mixture is pumped into the cargo space of the vessel. For instance, while the mixture is being suctioned from the seabed, it may pass directly through a delivery pipe, possibly equipped with a spreader pipe to the cargo space of the vessel. The dredging may be performed by a separate dredger vessel.

54. During the loading of the vessel, while fluid is entering the cargo space, fluid from the mixture drains through the filter, and may simultaneously flow through an overflow.

Topographic elements on the base of the cargo space provide surfaces which guide the mixture toward the filter. S5. Optionally, suction is applied to extract fluid from the container. After loading, the remainder (solids unable to pass through the filter, e.g. due to large diameters than allowable to pass) is substantially free from fluid, allowing it to be transported. S6. The dredged material is transported in the cargo space to a destination.

S7. The transported material is then offloaded at the destination, e.g. dumped onto the seabed or directed onto shore where "new" land is required. Offloading is performed by adding fluid to the cargo space. This produces a new fluid mixture of the dredged material and the added fluid. The new fluid mixture can then be offloaded through pipes, e.g. by pumps (of any design) or ejectors, applying suction in the cargo space at or adjacent to the base to extract the material from the cargo space. Optionally, the same pipework and suction generating devices can be used both for removing the separated water during loading, and for removing the new fluid mixture during offloading.

The above described solution is advantageous in that the dewatering can take place during loading through a configuration of the base which lets the water drain while retaining the solids in the cargo space. "Dry" material for transport on bulk carrier or barges can be obtained swiftly and efficiently at low cost. The filters and topographic can be of simple construction and materials so as to facilitate quick installation and cost effective provision.

Referring now to Figure 13, a cargo vessel 401 is depicted. The cargo vessel 401 has a number of cargo holds 410a-410c separated by bulk heads extending widthways across the vessel 401 . Each cargo hold 410a-410b has a cargo space 412, and arranged to contain a mixture of dredged material (not shown in Figure 12) on a base 420 of the cargo space 412, such as may be loaded onto the cargo space 420 in fluid form.

The base 420 has separating structures 430 in valleys 424 between sloped surfaces of topographic elements 422. The separating structures 430 have a filter (described further in the description below) through which fluid from the dredged material can pass, so as to separate the fluid from mixture, which due to for instance the diameter of the solids being greater than that of pathways through the filter, remain in de-watered condition in the cargo space 420 for transport. The maximum angle of the slope of the surfaces in the direction of the valley bottom, indicated by letter T, may be 15 degrees or more, or more preferably 30 degrees or more. This can facilitate guiding the draining seawater from the mixture downslope toward the valley bottom and toward the filter of the separating structure 430. The separating structure 430 in this case is provided at or near the bottom of the valley 424.

The manner of construction of the base 420 will now be described in further detail, where this may provide for obtaining a suitable base 420 for the cargo space of the vessel in a convenient and cost effective manner, by retrofit construction on a pre-existing flat deck.

In Figure 14, a topographic element 422m for the base 420 is illustrated prior to installation. The element 422m has a structure comprising a plurality of cross-members 422x arranged in parallel and spaced apart from one another along a length of the structure. The cross- members 422x are thin plates arranged to stand edgeways and upright from the flat floor of the hold. Pipes 422p, 422q extend horizontally along the structure. The cross-members 422x are joined and intersect at right angles with the central long axis of the pipes 422p, 422q on a plane perpendicular to the pipes. The arrangement of cross-members 422x and pipes 422p, 422q provide a frame structure to define a tillable volume when located on a flat deck or floor. The cross-members 422x are triangular, and have bottom edges 422b arranged to rest parallel against a floor of a deck, and sloped supporting edges 422e, which extend upward at an angle from the bottom edge. A corrugated sheet 422c is joined to and supported on the sloping edges 422e of the cross-members. The corrugated sheet 422c thus can provide a sloped surface 422z for the topographic element 122. The sloped surface 422z may then face the cargo space and guide draining water from the mixture downslope, when in use.

In order to construct the base 420, the element 422m is first provided and then placed on a pre-existing floor 407 of a cargo hold 410c, with the bottom edges 422b of the cross members 422x bearing against the floor 407. As seen in Figure 15, several such elements 422m are placed on the flat floor 407, and are arranged to obtain a topography including generally V or U-shaped valleys 424. The valleys 424 are defined between adjacent topographic elements 422m placed onto the floor, with the sloped, upper surfaces of the corrugated sheets facing one another and being angled toward the valley bottom. When placed on the floor 407, a hollow space is provided inside the element 422m, underneath the corrugated sheet 422c.

Once arranged in the appropriate position on the floor 407, the hollow space or volume inside the element 422m is filled with a filler. The interior of the pipes 422p, 422q is un-filled, remaining hollow so as to save weight. The filler adds structural strength to the element 422m, so that it may withstand greater loads, and transmit an applied load to the sloping surface to the floor, e.g. when the dredged mixture is loaded onto the base and is supported on the filled topographic elements 422. The filler may typically comprise material such as concrete or more preferably cellular concrete which can have a particularly high stength-to- weight ratio. The filler is poured directly in 'wet' form into the space defined inside the topographic element, and is contained inside the element 422m between the floor 407 and internal walls of its structure. Thus, the element 422m provides in effect a mould or cast for the inserted filler. The inserted filler is trapped by the structure of the part 422m and left to set and harden in place. The filler may adhere to the floor to secure the topographic element 422 in place on the floor.

Building the topography as described above can be advantageous, in particular in terms of convenience and cost whilst also providing the necessary strength to resist loading. The lightweight cellular concrete is cast, in situ, directly on the deck of the vessel. The elements 422m for forming the topography can be prefabricated at a ship yard, and placed as a unit onto the pre-existing flat deck or floor of the vessel, where it then can provide a cast for the concrete which is then poured into the inside of the element 422m. The cellular concrete can be easy to remove (e.g. using an excavator or similar) after a project is finished.

The topography, provided such as in the manner described above, can allow for easy mobilization and demobilization onto any vessel having a flat deck (prior to retrofit).

By virtue of construction from corrugated thin-walled pipes and plates, the filled topographic elements 122 that are formed on the deck to provide the topography can be light in weight. The use of pipes provide for obtaining an interior cavity which is e.g. open to air or gas or filled with material that is less dense than the cellular concrete that fills the element 122m around the outside of the pipes. Thus, compared with an element only of concrete, the provision of pipes in this manner can facilitate to limit or reduce the amount of cellular concrete (less cost and less weight) that may be needed in the final filled topographic element 122. Typically, the thickness of the material of the corrugated sheets and the wall thickness of the pipes is in the range of 1 .5 mm to 2.5 mm. Typically, the material of the pipes 122p, 122q, plates 122x, and corrugated sheet 122c comprises metal e.g. steel, or aluminium or another metal. In other embodiments however, any one or more of these components may be plastic or other material that suits the purpose. When the cellular concrete is emplaced in the volume inside the element, thus filling the trapped volume provided by the structure of the element 122m on the deck, the cellular concrete can take all compression. The structure of thin-walled corrugate plates and pipes will stay in place (not be removed). The topographic element 122 that is formed can take all compression load from the dredged material cargo space. Even if the cellular concrete breaks up or has small air pockets, the total volume of concrete is always kept within the structure between the corrugated sheet, plates, and outer surfaces of the pipes. The outer corrugated plate conveniently provides a wear and tear layer. If the corrugated sheet 122c is worn from previous use, an additional wear plate may be added to the topographic element.

As can be appreciated from the above, the topography of the base can be formed by retrofitting to a pre-existing flat deck of the vessel. The vessel before retrofitting may not be purpose built, but can made fit for purpose upon being fitted with the base, including the topography and the filter, onto the flat deck of the vessel, or onto a pre-existing flat floor of a cargo hold of the vessel, as described above. The topography can consist of lightweight materials. It may cover 50% or more of the pre-existing flat deck or floor of the vessel (which may for instance be a flat-top barge, bulk carrier, etc). The topographic elements may be formed by filling concrete into a predefined volume of a part which is placed on the floor or deck, being designed so that loads can be distributed appropriately to pre-existing deck beams, without requiring additional special steel construction.

The provided topography and separating structures of the base may thus be advantageously be combined to collect and help direct draining seawater under gravity toward the filters of the separating structures, so as to allow the seawater to separate and be removed from the cargo hold.

Figures 16 and 17 show an arrangement once the filler is set and the topographic element 422 is formed, with reference to a second one of the holds 410b. The topographic element 422 of the base 420 is constructed in the same way as the hold 410a described above. The part 422m remains in place in the topographic element 422 together with the set filler 422f, supporting the load from the dredged material upon the base 420. The outer surface of the corrugated sheet 422c faces the cargo space 412, which the dredged material bears against and contacts when loaded in the cargo space 412. The surface 422z can protect the topographic element against abrasion and wear from the dredged material in the cargo space.

As can be seen more clearly with further reference to Figure 18, the base 420 includes a separating structure 430, which is arranged to extend along the edge of the topographic elements 122 at the valley bottom, along the full length of the hold. The separating structure 430 has a filter 452 in the form of an element with perforations 452p extending therethrough to let draining seawater, as indicated by arrows A, pass through from the cargo space into a container 434 below. The sloping corrugated surface 422 is inclined toward the filter and the valley bottom to direct seawater, draining under the force of gravity, toward the filter 452. A drainpipe 440 provides an outlet for the separated seawater from the filter 452. In this example, the drainpipe 440 is arranged inside the container and extends along the length of the separating structure 430. The drainpipe 440 may be connected to a suction generating device, e.g. a pump, an ejector or the like, to encourage the separated fluid into the drain pipe and lead the seawater out of the cargo hold. In certain variants, the drainpipe 440 may pass through a wall of the bulkhead, and valves and/or pumps or the like may be connected to the drainpipe on an opposite side of the wall of the bulkhead, in a separate non-cargo containing region where the valves and/or pumps can be more readily accessed and controlled. The container 434 is also filled with a course particulate to provide support for the filter 452. The drainpipe 440 may be provided with perforations, slits, or other small openings through the wall of the pipe 440. The separated seawater from the filter 452 may thus pass into the drainpipe 440 through the perforations, slits, or other small openings at locations spread along the length of the pipe 440. The seawater can enter into the drain pipe along the full length of the cargo hold. This may facilitate swift removal of the separated seawater, and may improve the overall speed of dewatering and loading.

With reference to Figure 19, the vessel 401 has an alternative configuration where a base 620 of the cargo space 412 has topographic elements 422 on each side which are retro-fit constructed and secured in place on the pre-existing floor of the hold in the manner described in the examples of the base 420. However, the central topographic element 622 differs somewhat in that it does not have a corrugated sheet facing cargo space. Rather, the topographic element 622 has flat, sloped planar surfaces facing the cargo space. The sloped surfaces 622z such as may be provided by a moulded structural material, e.g. same material as the filler in the elements 422, i.e. cellular concrete, or other lightweight, high strength material. The interior of the element 622 may comprise a hollow pipe 622p or tube arranged horizontally, for providing structural support. The region around the pipe 622p comprises the structural material moulded to the required shape. Figure 20 illustrates the cargo space 412 when the fluid mixture 405 of dredged material is loaded onto the base 620. Seawater from the mixture drains through the separating structures and is removed from drainpipes 440. It can be noted that the loaded mixture 405 initially has generally flat upper surface, as indicated in Figure 20, due to it being loaded in fluidic form. Stratification of the mixture may take place to produce a top layer of seawater which may be removed by siphoning or dumping over the side of the hold, e.g. through side outlets or hoses or the like.

The cargo hold 41 Ob of the vessel 401 is provided with pipework to facilitate offloading the remainder of the dredged material after transport. The pipework inlcudes fluid supply pipes 490 provided with nozzles for supplying fluid into the cargo space for fluidising the dredged material. The fluidised material may then be extracted through other pipes to remove the transported dredged material from the hold.

The solutions described above based on bulk carriers or barges for transport of the dredged material may be preferable over TSHDs or other multi-purpose dredger vessels, at least for certain types of material and transport distances. The multi-purpose vessels of the prior art may have drawbacks in that they are purpose fitted with equipment for the various different functions of dredging, loading, offloading, and transport which may often be required over large distances across the sea. As a result, they can be expensive to build and commission, and may not be available at short notice. Furthermore, the equipment on board the vessel may remain redundant for large periods of the cycle time, while other activities in the process are carried out. The solutions described herein may mitigate or eliminate such drawbacks.

Moreover, the base of the cargo space can be constructed easily and from lightweight, but strong materials, for supporting and withstanding the loads imparted by the dredged material in the cargo space. The base with the separating structures, and also the pipework for removing separated seawater during and for offloading solids, can be conveniently retrofitted to the pre-existing configuration of the hold.

Various modifications and improvements may be made without departing from the scope of the invention herein described. Although embodiments have been illustrated where the deck of the cargo hold is provided with topography and separating structures along the full length of the hold, it will be appreciated that in other variants only part of the length of the cargo hold may be provided with such topography or structures. Furthermore, the solutions describe above may be applicable to other types of vessel with pre-existing flat decks or floors, and may be used to separate and remove fluid from other kinds of material comprising solids loaded in a fluidic mixture with water or other fluids.

Claims

1 . A method of loading dredged material onto a vessel for subsequent transport, wherein the method comprises:

2. A method as claimed in claim 1 , wherein the topography of the base includes at least one surface which is sloped for guiding the fluid toward the filter, the fluid draining from the mixture in the cargo space under gravity.

3. A method as claimed in claim 2, wherein the surface is sloped with respect to the preexisting flat deck or floor by an angle of 15 degrees or more.

4. A method as claimed in claim 2 or 3, wherein the surface is sloped with respect to the pre-existing flat deck or floor by an angle of 30 degrees or more.

5. A method as claimed in any of claims 2 to 4, wherein the topography comprises at least one block of material in contact against the flat deck or floor, the sloped surface being a surface of the block.

6. A method as claimed in claim 6, wherein the block of material or blocks of material contact the deck by an area or areas of contact together which is 50% or more of the total area of the pre-existing flat deck or floor.

7. A method as claimed in claim 5 or 6, wherein the block of material has a flat bottom in contact with the flat deck or floor.

8. A method as claimed in any of claims 2 to 4, wherein the topography comprises at least one element which is arranged on the flat deck or floor, defining a volume inside the element which is filled with material, the filled volume arranged to support a load against the inclined surface, and/or transmit the load to the flat deck or floor.

9. A method as claimed in claim 8, wherein filled volume or element has a flat bottom in contact with the flat deck or floor.

10. A method as claimed in any of claims 5 to 9, wherein the material is cellular concrete.

1 1 . A method as claimed in any of claims 5 to 10, wherein the material has lightweight elements embedded therein, the embedded elements having a density lower than the material in which they are embedded.

12. A method as claimed in any preceding claim, the topography being supported on the flat deck or floor by at least one area of contact, the area or areas of contact together being 50% or more of the total area of the pre-existing flat deck or floor.

13. A method as claimed in any preceding claim, wherein the fluid mixture is loaded by entering the mixture into the cargo space.

14. A method as claimed in claim 13, wherein the loaded mixture passes through the filter, separates from the dredged material, and is removed from the containing structure during entry of the mixture into the cargo space.

15. A method as claimed in any preceding claim, wherein the vessel is a bulk carrier, and the mixture is loaded by entering the mixture into the cargo space through a top hatch of a cargo hold of the bulk carrier.

16. A method as claimed in any preceding claims, wherein the vessel is a flat top barge.

17. A method as claimed in any preceding claim, wherein the fluid mixture is obtained by another vessel and the method includes transferring the fluid mixture from the other vessel into the cargo space to load the mixture onto the base.

18. A method as claimed in claim 17, wherein the other vessel is a dredger, and the method includes performing dredging using the dredger to obtain the fluid mixture to be loaded onto the cargo space.

19. A method as claimed in any preceding claim, which further comprises operating a suction generating device for producing suction in the containing structure or at or in the outlet to extract the fluid from the containing structure through the outlet.

20. A method as claimed in claim 19, wherein the device is a pump or an ejector.

21 . A method as claimed in any preceding claim, wherein the separated fluid is removed from the vessel via the outlet.

22. A method as claimed in any preceding claim, wherein the filter may comprise sand or gravel material or another fluid-permeable particulate.

23. A method as claimed in any preceding claim, wherein the filter comprises an element arranged to separate the fluid selected from the group comprising: a perforated screen; matting, porous fabric; porous textile or membrane; mesh sheet.

24. A method as claimed in claim 23, wherein the element may be supported by sand, gravel material or other coarse particulate.

25. A method as claimed in any preceding claim, wherein the containing structure comprises a channel.

26. A method as claimed in any preceding claim, wherein the containing structure contains gravel or other particulate material, and a filter is laid over the gravel or particulate material, so as to be supported by the gravel or particulate material, the filter configured to separate the fluid from the dredged material, the containing structure being arranged to receive fluid from the filter, the fluid draining under gravity from the cargo space through the filter.

27. A method as claimed in any preceding claim, wherein the remainder of the dredged material is stored in cargo space, on the base thereof, and comprises de-fluidised or de- watered dredged solids.

28. A method of retrofitting or preparing a vessel to obtain a base for a cargo space for subsequent loading, preparation, and transport of dredged material, wherein the dredged material when loaded comprises solids mixed with water, the method comprising the steps of:

providing a vessel comprising a pre-existing flat deck or floor;

arranging and fitting a topography onto the pre-existing flat deck or floor , the topography being configured to collect and guide the fluid toward the filter; and

29. A method as claimed in claim 28, which includes filling a channel or valley with gravel or other particulate, and laying an element over the gravel or other particulate to obtain the filter to separate the fluid.

30. A method as claimed in claim 28 or 29, which includes inserting a topographic block or element onto the pre-existing flat deck or floor of the vessel, to obtain the topography, wherein a surface of the topographic block or element is sloped to guide the fluid, when draining under gravity, toward the filter through which the fluid may pass to separate the fluid from the mixture.

31 . Apparatus for providing a base for a cargo space on a vessel, the base to be loaded with dredged material comprising solids mixed together with water, and configured to facilitate preparing the dredged material for subsequent transport, the apparatus comprising: a filter configured to be arranged in the base to interface with the cargo space for separating fluid comprising the water of the mixture, from the dredged material;

a containing structure for collecting the separated fluid from the filter;

an outlet for removing the collected fluid from the containing structure; and

a topography configured to be retrofitted onto a pre-existing flat deck or floor of the vessel, the topography being arranged to collect and guide the fluid toward the filter so as to be separated.

32. Apparatus as claimed in claim 21 , further comprising at least one suction generating device for extracting the collected fluid from the containing structure via the outlet.

33. Apparatus as claimed in claim 21 or 22, wherein the filter comprises an element arranged to separate the fluid selected from the group comprising: a perforated screen; matting, porous fabric; porous textile or membrane; mesh sheet.

34. Apparatus as claimed in any of claims 21 to 23, wherein the topography includes at least one sloped surface for the base, for guiding the fluid toward the filter.

35. Apparatus as claimed in claim 34, wherein the surface configured to be sloped with respect to the pre-existing flat deck or floor by an angle of 15 degrees or more.

36. Apparatus as claimed in claim 34 or 35, wherein the surface is configured to be sloped with respect to the pre-existing flat deck or floor by an angle of 30 degrees or more.

37. Apparatus as claimed in any of claims 34 to 36, wherein the topography comprises at least one block of material configured to be placed in contact against the flat deck or floor, the sloped surface being a surface of the block.

38. Apparatus as claimed in claim 37, wherein the block of material or blocks of material contact the deck by an area or areas of contact together being 50% or more than the total area of the pre-existing flat deck or floor.

39. Apparatus as claimed in claim 37 or 38, wherein the block of material has a flat bottom in contact with the flat deck or floor.

40. Apparatus as claimed in any of claims 34 to 39, wherein the topography comprises at least one element which is configured to be arranged on the flat deck or floor, and define a volume inside the element which is filled with material, the filled volume arranged to support a load against the inclined surface, and/or transmit the load to the flat deck or floor.

41 . Apparatus as claimed in claim 40, wherein filled volume or element has a flat bottom configured to be placed in contact with the flat deck or floor.

42. Apparatus as claimed in any of claims 37 to 41 , wherein the material is cellular concrete.

43. Apparatus as claimed in any of claims 37 to 42, wherein the material has lightweight elements embedded therein, the embedded elements having a density lower than the material in which they are embedded.

44. Apparatus as claimed in any of claims 37 to 42, the topography being supported on the flat deck or floor by at least one area of contact, the area or areas of contact together being 50% or more of the total area of the pre-existing flat deck or floor.

45. Apparatus as claimed in any of claims 31 to 43, wherein the topography comprises topographic blocks, and the containing structure is disposed between the topographic blocks.

46. Apparatus as claimed in any of claims 31 to 44, wherein topography comprises topographic blocks arranged to have a valley therebetween, and wherein the containing structure is arranged adjacent to a topographic block at or near a side of the valley.

47. A base for a cargo space of a vessel, the base being retrofitted onto a pre-existing flat deck or floor of the vessel, the base configured to be loaded with dredged material comprising solids mixed together with water, and further configured to facilitate preparing the dredged material for subsequent transport, the base comprising:

a containing structure arranged to collect the separated fluid from the filter;

an outlet for removing the collected fluid from the containing structure; and

48. A cargo vessel provided with the base as claimed in claim 47.