The present invention relates to a method for constructing a ship. The invention also relates to a construction panel for constructing a ship or components of a ship. The invention moreover relates to a ship.

For safety and environmental reasons use is increasingly being made nowadays of ships provided with a double-walled hull. In the possible case of leakage or damage to one of the walls of the hull the second wall prevents the ship being holed and for instance the outflow of liquid cargo such as oil (products) .

A double-walled ship has the drawback relative to a single-walled ship that the double wall makes the ship heavier and therefore reduces the cargo capacity of the ship. Double-walled ships moreover have the problem that water is usually present between the walls of the hull and, among other problems, this causes stability problems and the danger of corrosion.

In addition, an explosive mixture may result in the hollow space, with all the risks this entails. In order to prevent this in the case of tankers the space is often filled with nitrogen, which leaks out slowly again and has to be replenished.

It is moreover a drawback that a steel ship is heat conductive and that the cargo is thereby heated or cooled, so that for instance oil products have to be heated during the whole transport in order to keep the oil liquid.

Another drawback of double-walled ships is that they are more difficult and therefore more expensive to construct. US RE 38, 697 describes for instance a ship with a double-walled hull wherein a foam is arranged in the space between the walls. Arranging the foam takes place in the assembled state of the ship. DE 19914420 describes a sandwich panel which can be used in shipbuilding. It is an object of the present invention to improve the existing double-walled ships and to at least partially solve at least one of the above stated problems.

Provided for this purpose according to the invention is a method for constructing a ship, comprising the steps of:

manufacturing at least two construction panels by placing an inner plate and an outer plate at a distance, arranging a plurality of transverse beams and at least two longitudinal beams between the inner plate and the outer plate, wherein at least one of the transverse beams protrudes beyond at least one of the outer longitudinal beams, and arranging and curing a foam-like material in a space between the outer transverse beams, the outer longitudinal beams and the inner plate and the outer plate; and

- mutually connecting the two construction panels, wherein the two protruding transverse beams of the two construction panels are connected so as to form a frame section.

Calculations and simulations have shown that it is possible to suffice with thinner inner and outer plates compared to the thickness of the walls of conventional double-walled hulls. The method according to the invention moreover enables a modular structure of a ship. The construction panels can for instance be produced at a location other than where assembly of these panels takes place. The manufacture of the construction panels, including the arranging of the foam-like material therein, therefore preferably takes place prior to the mutual connection of the plates for the purpose of forming (part of) a ship. With such a construction a weight-saving is moreover obtained so that at low water the ship can sail for longer because it has a smaller draught and at high water can transport more cargo. In contrast to conventional ships, a ship constructed using the method according to the invention has intrinsic buoyancy.

Owing to weight being saved fuel is also saved because it is less often necessary to sail, and if the cargo is the same there is less water displacement and so less resistance than in the case of a conventional ship. A ship according to the invention moreover requires less maintenance because interior spaces need not be maintained. It has also been found that the construction has a better collision resistance than a conventional ship. According to a preferred embodiment, at least one midship extending between a bow and a stern is manufactured with the construction panels. The midship preferably has an at least substantially equal cross-section along the length. It is however also possible for the stern and the bow to be manufactured from construction panels according to the invention.

According to a further preferred embodiment, the inner plate and the outer plate are manufactured from steel and have a thickness between 4 and 25 mm, preferably between 3 and 15 mm. The inner and outer plates preferably have a length of between 8 and 16 metres, and more preferably a length of about 12 metres, in particular 12.24 metres, this distance being slightly greater than twice the length of a standard container (TEU) . The width of a plate, and thereby the width of a construction panel, is preferably smaller than the length of the construction panel.

The transverse beams and the longitudinal beams preferably take a plate-like form and are manufactured from steel. The height of the beams preferably corresponds to the distance between the outer plate and the inner plate. The inner plate and the outer plate preferably lie at a distance of between 0.2 and 1.0 metre from each other.

For the manufacture of a construction panel a framework or lattice-work is assembled from transverse and longitudinal beams preferably connected to each other by welding. The outer beams here define the outer periphery of the space which is to be filled with the foam-like material. By having at least one of the transverse beams extend outside this space, an outer end of this transverse beam is left free after the foam-like material has been arranged. This enables easy connection of the panels.

The transverse beams and the longitudinal beams are preferably connected, preferably by means of welding, to the inner or outer plate. The plate arranged as second plate can for instance be connected by slot welds. Ά stiff assembly is provided by connecting the beams to the inner and outer plate.

The outer plate, the inner plate, the outer transverse beams and the outer longitudinal beams form a closed space here which is filled with a foaming material. The outer beams preferably extend close to the peripheral edges of the inner plate and the outer plate. When two panels are connected the outer beams lie at a distance from each other so that a chamber is formed. Since these outer teams enclose the space in which foam is received, no foam is present in these chambers. This therefore makes this chamber suitable as welding chamber for the purpose of connecting the outer ends to be connected by welding. In order to provide for a good distribution of the material, at least one of the transverse beams or the longitudinal beams is provided with passages for passage of the material when the foam-like material is arranged. The foam-like material is preferably introduced under pressure into the space. When cured, the foam-like material preferably strengthens the connection between inner and outer plate and, after filling and curing, the space is preferably completely filled without empty spaces. The arranging of foam-like material between the outer and inner plates prevents liquids being able to penetrate therebetween. The arranged foam moreover has the result that, despite the use of thin plate material, the skin remains taut since the skin is supported over the whole surface by the foam-like material.

The foam-like material is preferably a thermoset. In the case of fire the construction panel hereby retains its strength. The foam-like material more preferably comprises at least one material chosen from the group of polyurethane and

polyisocyanurate .

The foam-like material preferably as a weight after foaming of less than 150 kg per cubic metre, more preferably the foam-like material has a weight after foaming of between 55 and 65 kg per cubic metre. This provides for a light construction panel.

As already stated above, it is possible according to the invention to construct a ship from plate material which is thinner than the plate material of conventional (double-walled) ships. If plate material with a thickness according to the invention were to be used in conventional ships, this plate material would then bend outward and/or buckle. This is prevented according to the invention by arranging foam-like material between the plates of a construction panel. The plates are supported here by the foam, whereby buckling and outward bending are prevented. A stiff panel is hereby nevertheless provided despite the use of these thin plates.

According to a further preferred embodiment of the method, the construction panels are manufactured in a casing in order to prevent outward bending of the inner plate and the outer plate during arranging of the foam-like material. Since use can be made according to the invention of an inner plate and an outer plate which are thin such that without support they bend outward, it is advantageous to make use of a casing, or a template or formwork. This prevents outward bending of the plates under the influence of the introduced foam-like material and through other causes . For the purpose of connecting two panels two outer ends of separate panels free of foam-like material are connected so as to form a frame section, or an athwartship support beam.

According to the invention it is not necessary to provide an additional supporting construction since the connected panels, and in particular the connected transverse beams, impart sufficient stiffness to the ship. In order to connect the panels not only is a transverse beam preferably connected, but the upper plates and the lower plates of adjacent construction panels are also connected, preferably by welding. All transverse beams of two panels are preferably connected to each other.

It should be noted that in this context the term ship must be interpreted broadly. A ship is particularly understood to mean among others an inland navigation vessel and a sea-going ship such as a tanker, but also a pontoon or a tug-pushed barge. The term transverse, as in transverse beams, relates here to a direction perpendicularly of the longitudinal direction, or the direction of movement, of the ship. The transverse beams lie here substantially perpendicularly of the longitudinal beams.

According to the invention the term frame section should be understood to mean a cross bracing in a ship. A frame section is a strengthening beam here, constructed according to the invention from a plurality of coupled beams extending over the whole width of the ship. A preferred embodiment of the method comprises of manufacturing at least three construction panels, wherein at least two of the construction panels comprise wall panels and wherein at least one construction panel comprises a bottom panel, wherein at least one of the transverse beams of the bottom panel protrudes on either side beyond the outer longitudinal beams for connection of construction panels on either side thereof, wherein the wall panels are arranged at an angle to a bottom panel. At the bottom panel outer ends of a transverse beam protrude here on either side. Transverse beams of the wall panels can then be connected to these transverse beams. The transverse beams of the wall panels and the bottom panel preferably extend here at an angle, more preferably at an angle of about ninety degrees . Since the side walls are upright, it is possible here to speak of uprights.

It should be noted here that is also possible to mutually connect for instance two bottom plates, wherein wall panels are arranged on either side of the coupled bottom plates. A wider ship can for instance thus be constructed.

A bottom panel and a wall panel preferably have a length as described above of about 12 metres. A bottom panel preferably has a width corresponding to a multiple of 2.5 metres, the width of a container. A bottom panel preferably has a width of between about 5 and 10 metres, preferably about 5 metres.

A wall panel preferably has a width of between about 2 and 8 metres, preferably about 4.5 metres. This width substantially corresponds to the height of the side walls of the ship.

One of a plurality of transverse beams of a bottom panel is preferably connected to a transverse beam of a wall panel in order to form a frame section. One of two, preferably one of three of the transverse beams of a bottom panel is more preferably connected to a transverse beam of a wall panel in order to form a frame section. A number of the transverse beams of a bottom panel do not run all the way to the top of the wall panels. These transverse beams do however contribute toward the structural integrity of the bottom, this enhancing the cargo capacity of the ship. It may be the case here that at least one of the two, preferably one of the three transverse beams of the bottom panel protrudes outside the outer longitudinal beam, while the other transverse beams do not protrude beyond this longitudinal beam. The transverse beams of a wall panel are more preferably arranged at a mutual distance which is twice, preferably three times greater than the distance between the transverse beams of a bottom panel. This imparts sufficient strength to the walls of the ship, while weight is hereby saved.

According to a further preferred embodiment of the method according to the invention, only two outer longitudinal beams are arranged for the construction of a wall panel. The beams extending in longitudinal direction of the ship in the wall panels then serve as delimitation of the space to be filled. It has been found that a thus obtained wall panel is sufficiently strong. It is moreover advantageous that no further additional stiffeners need be used according to the invention in the wall panels, since the construction with the foam-like material between the plates already imparts sufficient stiffness. A further weight-saving is thus achieved.

According to a further preferred embodiment of the method, the transverse beams of the bottom panels are placed at a mutual distance -greater than at least 1.5 times, preferably at least twice the distance between the transverse beams in conventional shipbuilding. The transverse beams in the bottom panels preferably extend at a distance of about 1 metre from each other. The transverse beams in the wall panels preferably extend here at a distance of about 3 metres from each other. According to a further preferred embodiment according to the invention, at least one of the longitudinal beams protrudes beyond at least one of the outer transverse beams, wherein two construction panels are connected in the longitudinal direction by mutually connecting the protruding longitudinal beams. This enables efficient connection of panels in the longitudinal direction of the ship. Each longitudinal beam preferably protrudes on either side beyond the outer transverse beams for connection in the longitudinal direction.

According to the invention athwartship modules are preferably constructed first by connecting two wall panels and at least one bottom panel. The thus obtained athwartship modules can then be connected in the longitudinal direction in order to form a ship's hull. At least a middle part of a ship extending between a bow and a stern is preferably constructed in such a manner. This method provides for a modular construction of a ship. The panels can first be individually manufactured, after which athwartship modules can be constructed from these panels. A hull can finally be assembled by connecting a plurality of athwartship modules in longitudinal direction.

It is however also possible to first connect construction panels in the length to form an overall wall length or bottom length, and to then connect the thus obtained components in the width direction in order to form a hull.

According to a further preferred embodiment, connection of the beams comprises of arranging the beams of two construction panels adjacently and fixedly welding the beams. The beams do not overlap each other here. In this way a strong connection is provided with less chance of fatigue. According to an alternative preferred embodiment of the method, connection of the beams comprises of arranging the beams of two construction panels in overlapping manner and fixedly welding the beams. In this way a strong connection is provided with a simple dimensioning.

Because the outer ends of the beams are free of the foam-like material, it is possible to connect these outer ends by welding. The foam-like material is hereby not damaged.

A further preferred embodiment of the method also comprises of: manufacturing at least one hatch panel by placing an inner plate and an outer plate at a mutual distance, arranging at least two transverse beams and at least two longitudinal beams between the inner plate and the outer plate and arranging and curing a foam-like material in a space between the outer transverse beams and the outer longitudinal beams; and

using the hatch panel to form a closure for the space formed by the wall panels and the bottom panels.

The structure of a hatch preferably corresponds substantially to the structure of a construction panel. Making use of thus manufactured hatches for the purpose of being able to close the loading space formed by the wall panels and the bottom panels saves weight. A thus manufactured hatch also has an intrinsic buoyancy and will therefore not sink if it falls overboard.

The invention further relates to a construction panel adapted for constructing a ship, wherein in lying position the panel comprises :

an outer plate extending a distance from an inner plate; at least two transverse beams and at least two longitudinal beams extending between the inner plate and the outer plate, wherein at least one of the transverse beams protrudes beyond at least one of the outer longitudinal beams; and an intermediate layer of foam-like material extending in the space enclosed by the inner plate, the outer plate and the outer transverse beams and the outer longitudinal beams .

Such a panel is stiff and enables simple mutual connection for the purpose of efficient construction of a ship' s hull as discussed above.

According to a preferred embodiment of the construction panel, at least one of the longitudinal beams protrudes beyond at least one of the outer transverse beams. This enables efficient connection of the panels in longitudinal direction. Both outer ends of the longitudinal beam preferably protrude beyond the outer transverse beams and both outer ends of the transverse beam preferably protrude beyond the outer longitudinal beams. In this way the panels are easy to connect in the width and length directions .

According to a further preferred embodiment, the outer end of a protruding beam extends at a distance from the peripheral edges of the inner plate and the outer plate as seen in the plane of the inner plate and the outer plate. The peripheral edge of the upper plate more preferably extends at a distance from the peripheral edge of the inner plate. The connections between the beams and the plates do not lie in one line here as seen in the plane of the panel. This provides for a strong connection. The outer plate, the inner plate and the mutually connected beams are still more preferably arranged offset relative to each other. Separate panels can in this way be connected to each other easily and substantially without join.

According to a further preferred embodiment, a beam extends beyond the peripheral edge of the inner plate. When two panels are now connected, the outer plates of the two panels will lie against each other, while the upper plates extend at a mutual distance. Owing to this distance it is possible to connect the beams efficiently, preferably by welding. A cover plate is then arranged between the upper plates for the purpose of closing the opening between the upper plates of the panels. Such a closing plate moreover imparts additional stiffness to the connection.

The invention also relates to a ship constructed from a plurality of mutually connected construction panels manufactured particularly with the method according to the invention, wherein transverse beams of mutually connected construction panels are connected in order to form frame sections of the ship. Such a ship is very light compared to conventional ships while the cargo capacity is increased.

It should be noted that the application is not limited to ships constructed solely from construction panels according to the invention. It may thus be possible to construct a ship wherein only a part of the ship is constructed from the panels. It is moreover possible for an existing ship to be modified by applying construction panels according to the invention, for instance as already stated above by applying the hatches. Furthermore, it may for instance be possible for only the bottom of a ship to be constructed from the panels according to the invention, while conventional wall parts are used to form walls.

The present invention is further illustrated with reference to the following drawing, which shows a non-limitative preferred embodiment of a ship according to the invention constructed using a preferred embodiment of the method according to the present invention, and in which:

Figures 1A and IB show respectively a schematic side view and top view of a ship; Figure 1C is a schematic top view of another embodiment of the ship;

Figures 2A and ^" 2B show respectively a schematic

cross-section and a perspective view of a middle part of the ship;

Figure 2C shows a schematic cross-section of the ship of figure 1C;

Figure 3 shows schematically a wall panel and a connected bottom panel;

- Figure 4 shows schematically an assembly of two bottom panels and two wall panels;

Figure 5 shows in cross-section a connection between a wall panel and a bottom panel;

Figure 6 shows a schematic cross-section of a connection between two bottom panels;

Figure 7 shows schematically a formwork for manufacturing a panel; and

Figure 8 shows schematically a panel in (over) loaded state. Figures 1A and IB show a first embodiment of an inland navigation vessel 1 according to the invention with a bow lb and stern la. The loading space of ship 1 is formed by midship lc. Midship lc is assembled from five modules 2 , each forming a cross-section of midship lc. Such a module 2 is shown in figures 2A and 2B.

Modules 2 have a length xl of 12.24 metres, whereby the overall length of the middle part is 61.20 metres. The overall length of ship 1 is 86 metres. The width x6 of ship 1, see figure 2A, is 9.56 metres.

A module 2 is assembled from three panels, i.e. two wall panels 3 and a bottom panel 4. The thickness of panels 3 is 0.78 metre, whereby the width x3 of the loading space is 8.0 metres. The height x2 of panels 3 is 3.7 metres and the height x4, including gangway, is 4.60 metres. The thickness of the bottom panel x5 is 0.40 metre.

Figures 1C and 2C show another variant of the inland navigation vessel, wherein the bottom is constructed in the width from two bottom panels 4. Such a ship has a length of 110 metres, wherein the middle part has a length of about 80 metres. Modules 2 each have a length of 12.24 metres. The width of the loading space x3a as indicated in figure 2C is 10.25 metres, while the overall width x6a is 11.45 metres. The height x2a of a wall panel 3 is 5.60 metres. The thickness x5a of a bottom panel is 0.50 metre, while the thickness x7a of a wall panel 3 is 0.60 metre. The width of a single panel 4 is 5 metres. In order to construct a ship the panels 3 and 4 are first manufactured and subsequently connected to each other to form the modules 2 as shown in figure 2A. Situated between panels 3 and 4 are welding chambers 15 which will be discussed in more detail below. Modules 2 are then connected in longitudinal direction to form midship lc. The bow lb is connected on the front side while the stern la is connected on the rear side.

The structure of panels 3 and 4 is shown in more detail in figure 3. A bottom panel 4 is constructed from an outer plate 6 of 6 mm S355 steel, an inner plate 5 of 8 mm hardened steel. Steel beams 7 and 8 are arranged between plates 5 and 6. The beams have a thickness of 5 mm. Transverse beams 7 lie transversely of ship 1 at a distance x6 of 0.98 metre from each other. Longitudinal beams 8 lie at a distance x7 of 2.47 metres from each other in the bottom panel. Beams 7 and 8 are welded to outer plate 6 and inner plate 5. Outer beams 7a and 8a extend close to the peripheral edges of plates 5 and 6 so that they enclose a large part of the surfaces of plates 5 and 6. Transverse beams 7 are provided with passages 73 close to inner plate 5. The outer transverse beams 7a and longitudinal beams 8a form together with plates 5 and 6 a closed space which is filled with PIR foam 13 having a weight after foaming of 60 kg per cubic metre. The foam here completely fills the space between outer beams 7a and 8a and plates 5 and 6.

Transverse beams 7 protrude on both sides beyond the outer longitudinal beams 8a so that outer ends 71 are left clear. Longitudinal beams 8 similarly protrude on both sides beyond the outer transverse beams 7a so that outer ends 81 are also left clear. Both outer ends 71 and 81 are provided with recesses 72 and 82 in the central area.

As shown, outer plate 6 is arranged offset in both the length and width directions relative to the framework or lattice-work formed by beams 7 and 8. On the left in figure 3 the outer ends 81 protrude for instance beyond the peripheral edge of lower plate 6, while on the right the peripheral edge protrudes beyond outer ends 81. The same applies for transverse beams 7. Outer ends 71 and 81 protrude beyond the peripheral edge of upper plate

6 on all sides.

A wall panel 3 is constructed from two longitudinal beams 8a and five transverse beams 7. Beams 7 lie at a distance of 2.9 metres from each other. Outer plate 6b is a steel plate with a thickness of 6 mm and the inner plate is a steel plate of 5 mm thickness. Foam 13 is arranged in the space between the plates and beams

7 and 8a. Figure 5 shows a cross-section of the connection between a wall panel 3 and a bottom panel. For connection of a wall panel 3 to a bottom panel 4 transverse beams of the two panels are connected. On wall panel 3 an additional plate 16 is connected between longitudinal beam 8a and an additional longitudinal beam 8a in order to form the chine. Foam is arranged between these two longitudinal beams 8a. The outer end 71b of wall panel 3 which forms an angle protrudes beyond this outer longitudinal beam 8a. Outer end 71a of bottom panel 4 also protrudes beyond the outer beam of bottom panel 4. The free outer end 71b of wall panel 3 is welded to outer end 71a of the bottom panel with welded joint 10. No foam is present at the position of the connection since the two outer beams 8a of wall panel 3 and bottom panel 4 are situated a distance from each other in order to form a welding chamber 15.

The distance between inner plates 5a and 5b is closed with a cover plate 11 which is welded to both inner plates.

As shown in figure 3, one of three transverse beams 7 of bottom panel 4 is connected to a transverse beam of a wall panel 3 to form fully continuous frame sections situated at a distance of 2.9 metres from each other in the wall panels.

Figures 4 and 6 show the connection between two bottom panels 4a and 4b, wherein longitudinal beams 8 of both panels are connected. The connection between two wall panels 3a and 3b is also shown in figure 4. Outer ends 81a and 81b are connected with a welded joint 10. No foam is present at the position of the connection since the inner spaces of panels 4a and 4b are bounded by the outer beams 7a lying at a distance of 0.42 metre from each other. A welding chamber 15 is thus formed. The welding chambers 15 between two panels here form as it were a box frame section, as shown best in figure 4. Also shown is that outer plates 6b and 6a are arranged offset so that they fit together when connected. Connection 9 between plates 6a and 6b is situated here at a distance from the plane of connection 10. Situated between plates 5a and 5b is an opening which is sealed with a cover plate which is connected by welding. By making use of the method to construct the shown ship 1 according to the invention a weight-saving is achieved of about 33% per metre of midship relative to a conventionally constructed ship of the same dimensions. By way of comparison, a midship of a conventional ship has a weight of about 4500 kg per metre, while the ship according to the invention has a weight of about 3000 kg per metre. This means that 91 tons of extra cargo can be transported, entailing an improvement of 6%. Calculations and simulations have shown that inter alia in the case of a light cargo, in the case of a maximally loaded ship with a uniform distribution and in the case where the cargo is distributed non-uniformly in the ship, the locally occurring stresses lie within the permitted range.

Figure 7 shows a formwork 12a,b for manufacturing a panel according to the invention. Inner plate 5 and outer plate 6 with the framework of beams 7 and 8 therebetween are arranged in formwork parts 12a, b. Figure 6 shows only transverse beams 7. Foam is then arranged in the space between beams 7 and plates

5 and 6. Parts 12a and 12b of the formwork prevent plates 5 and

6 bulging outward under the influence of the curing foam.

Figure 8 subsequently shows a panel according to the invention in loaded state. When an object 14 makes contact with a ship provided with panels according to the invention from a direction I, the foam between plates 5 and 6 will distribute the load, whereby a strong panel is obtained despite the relatively thin plates 5 and 6. Outer plate 6 of the hull will eventually collapse. However, the foam prevents water being able to flow between plates 5 and 6 so that, despite the damaged outer plate 6, no leakages occur.

The present invention is not limited to the shown embodiments but also extends to other embodiments falling within the scope of the appended claims. It is thus also possible with the method according to the invention to make a pontoon which can be used to transport cargo. Such a pontoon has for instance dimensions of 200 x 75 metres or 110 x 30 metres. The panel thicknesses can be greater here than 0.5 metre. Such a pontoon has for instance a maximum load of 12 tonnes per square metre.