FIELD OF THE INVENTION

The present invention relates to a boat hull for marine vessels, ships or vehicles according to the preamble of claim 1 , and more particularly to a boat hull comprising an inner surface layer, an outer surface layer and an intermediate core layer between the inner surface layer and the outer surface layer. The present invention further relates to a marine vessel, ship, boat or vehicle according to the preamble of claim 21 , and more particularly to a marine vessel, ship, boat or vehicle comprising a hull with a sandwich structure having an inner surface layer, an outer surface layer and an intermediate core layer between the inner surface layer and the outer surface layer.

BACKGROUND OF THE INVENTION

Boats and boat hulls are nowadays usually manufactured fiberglass. Fiberglass may be easily manufactured into complex shapes which especially true for recreational boats. Fiberglass is also particularly desirable as it is strong, durable and corrosion resistant. Traditionally fiberglass boat hulls are manufactured by laying a number of layers of fiberglass on a female mould. In this manner a laminate of layers of glass fiber is formed to a desired shape for the boat hull. The boat hull manufactured from fiberglass further is provided additional structural elements or stiffeners for achieving necessary structural rigidity for the boat hull.

However, fiberglass hull production requires a great amount of labor to laminate the hull and this work is mainly carried out by handwork. Fiberglass hull production requires also use of a tool or mould where to laminate the glass fiber against and obtain the desires shape. This mould represents one of the biggest investments in the construction of a boat and it has a limited life cycle. Materials, such as fiberglass, Kevlar and carbon fiber, used for forming the fiberglass hull are extremely expensive materials. Furthermore, as fiberglass hulls require use of bulkheads and reinforcement for achieving necessary strength and rigidity, the manufacturing process and the hull construction becomes complex. Fiberglass has also disadvantages as material. Fiberglass hull production requires two components, the fiberglass itself and an impregnation material. This last one of these is highly flammable which represents com- promises the safety of the users and crew. Even through the use of fire retard- ants, the fumes produced are highly toxic and the propagation of the fire is a high risk while sailing and at the marina, posting a great threat to the rest of the vessels. Fiberglass hull materials are non-degradable and thus generate great amounts of hazardous waste. Although, fiberglass hulls are strong and dura- ble, they are also very brittle and will easily break if they sustain an impact.

Furthermore, surface quality of current fiberglass hulls is given by the amount of effort and money invested in the mould surface finish. Even with a high-end mould quality, over time and during the life time of the mould, the surface finish will deteriorate and require high maintenance. Additionally, fibers and fiber layers have to be laid by hand on the mould which may induce errors and compromise precision.

It is also known in the prior art to build aluminium boat hulls from sheet aluminium. Such aluminium boats may be made of one or two aluminium sheets. Aluminium sheets are also used in sandwich boat hull structures in which at least an outer skin layer of the sandwich structure is made of aluminium sheet. The inner skin layer of the sandwich structure may also be formed from aluminium sheet or some other sheet material. Use of aluminium provides light constructions with excellent resistant to corrosion. In the known sandwich structures a core layer between the inner and outer skin layers is manufac- tured from polymer material, such as polyurethane.

However, aluminium sheets do not provide sufficient rigidity to the boat hulls as such and not even in the sandwich structure together with the polymer core layer. Therefore, the boat hull has to be provided additional stiffened or structural elements for providing necessary rigidity for the hull. These additional structural elements increase the weight of the hull makes the manufacturing process and the hull construction complex and time consuming. Aluminium sheets are also subjected to micro and macro cracks upon forming the shape of the aluminium sheets. Forming the core layer and attaching the outer and inner skin layers to the core layer causes additional production steps, as the polymer core layer has to be formed into the shape of the outer aluminium skin layer. The polymer core layer also generates non-degradable waste which has to be handled in the manufacturing process and also at the end of the life of the boat hull.

BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide a boat hull and marine vessel as to overcome or at least alleviate the above prior art disadvantages. The objects of the present invention are achieved by a boat hull according to the characterizing portion of claim 1 . The objects of the present in- vention are also achieved with a marine vessel, ship, boat or vehicle according to the characterizing portion of claim 20.

The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the idea of providing a composite or sandwich struc- ture for a boat hull. The composite structure of the boat hull comprises an inner surface layer, an outer surface layer and an intermediate core layer between the inner surface layer and the outer surface layer. According to the present invention the intermediate core layer is manufactured from aluminium and has a cellular structure. Furthermore, the intermediate core layer has a continuous structure extending between the inner surface layer and the outer surface layer. The cellular structure of the aluminium intermediate core layer means that it comprises cavities, pores or the like. According one embodiment of the present invention the intermediate core layer is provided from aluminium foam having pores for forming the cellular structure. In another embodiment of the present invention the intermediate core layer is provided from aluminium sheet or plate formed by bonding aluminium strips together, the aluminium sheet or palte having a honeycomb structure comprising cells for forming the cellular structure. The aluminium sheet or plate maybe provided from aluminium strips attached together. In an alternative embodiment the intermediate core layer is provided from a profiled aluminium sheet or plate forming the cellular structure together with one or both of the inner surface layer and the outer surface layer.. The inner surface layer and the outer surface layer are attached to the intermediate core layer for forming the composite or sandwich structure. Accordingly the hull of the boat is manufactured from one or more panels having the composite structure. The composite or sandwich panels are joined together for providing the boat hull and the shape of boat hull. The outer and inner skin layers of the may be provided from aluminium, wood, fiberglass, carbon fiber, stainless steel or the like, preferably at least the outer layer is manufactured from aluminium. In the present invention the whole hull may be constructed from sandwich structure according to the present invention. Alternative, only part of the hull may be constructed from the mentioned sandwich structure. The present invention concerns any kind of boats and marine vessels, such are motor boats, sailing boats, row boats, canoes, fishing boats, kayaks, jet skis, rafts or the like. Furthermore, the present invention also concerns floating stationary houses, floating isolated and stationary recreational platforms or spaces or the like floating stationary marine constructions for human activities.

When the composite panels according to the present invention are used to build the boat hull there exist no need for special tool or mould for forming the shape. This reduces required labour and enables automation of the production of the boat hull. Constructing hull from flat aluminium panels enables all the cutting and machining to be done by computer aided machinery that will introduce excellent construction tolerances. Joining of the panels may therefore meet an extremely tight fit. The nature of the mechanical rigidity of the aluminium panels allows excellent flatness and straight joining. A boat hull built with aluminium core may be constructed to be completely recyclable. The boat hull having the composite structure in which the aluminium intermediate core layer with cellular structure provides a self-supporting structure and thus additional stiffeners, structural elements or internal reinforcements may be omitted. This makes the boat hull very light in respect to conventional fiber- glass boat hulls and boat hulls having aluminium layers with polymer core layer. Furthermore, the aluminium composite panels according to the present invention will not break during an impact, but they deform and absorb the energy of an impact maintaining the surface sealed. In case of hull damage repairing is easy through the replacement of panels at the damaged zone. The alumini- urn does not burn in solid state and it dissipates the heat quickly enough to prevent fire propagation providing fire safety.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached [accompany- ing] drawings, in which

Figure 1 is a schematic cross-sectional view of boat hull according to one embodiment of the present invention;

Figures 2A and 2B show schematically one embodiment of a sandwich structure according to the present invention;

Figures 3A and 3B show schematically another embodiment of a sandwich structure according to the present invention; and

Figures 4A and 4B show schematically yet another embodiment of a sandwich structure according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a schematic cross-sectional view of a hull 1 of marine vessel, ship, boat or vehicle, named as boat hull 1 in the following. The present invention therefore concerns therefore any kind of boats and marine vessels, such are motor boats, sailing boats, row boats, canoes, fishing boats, kayaks, jet skis or the like. The boat hull 1 is manufactured from one or more composite or sandwich panels 10, 12, 14. The sandwich panels 10, 12, 14 provide a boat hull comprising an inner surface layer 4, an outer surface layer 2 and an intermediate core layer 6 between the inner surface layer 4 and the outer surface layer 2, as shown in figure 1 . Accordingly, each sandwich panel has the inner and outer surface layers 4, 2 and the intermediate core layer 6. Furthermore, the boat hull 1 may be manufactured from a single panel formed for shaping the boat hull 1 or from several panels joined together for shaping the boat hull 1 . The whole hull may be constructed from sandwich structure according to the present invention. Alternative, only part of the hull may be constructed from the mentioned sandwich structure.

The intermediate core layer 6 of the boat hull 1 is manufactured from aluminium. Furthermore, the intermediate core layer 6 has a cellular structure. The cellular structure of the intermediate core layer 6 in the context of this application means that the intermediate core layer 6 comprises cavities or pores or the like. The cavities or pores are preferably closed, at least by the outer and inner surface layers 4, 2. The thickness of the intermediate core layer 6 may be for example 3 mm to 500 mm, preferably between 5 mm to 50 mm. The cellular aluminium core provides very light and rigid structure, and further a self-supporting light weight boat hull 1 . The cellular structure provides light weight and rigid self-supporting structure as well as excellent buoyancy properties.

The intermediate core layer 6 has a continuous structure extending between the inner surface layer 4 and the outer surface layer 2. The continuous structure means that the intermediate core layer 6 is formed from a single structure, and not from separate or independent pieces or elements. There- fore, the continuous, or uninterrupted, structure of the intermediate core layer 6 extends over the whole surface area of the inner surface layer 4 and the outer surface layer 2. The intermediate core layer 6 may thus comprise a continuous bedding structure, or a continuous sheet structure, or a continuous plate structure. The continuous structure of the intermediate core layer 6 provides excel- lent rigidity and self-supporting structure for the hull 1 .

Figures 2A and 2B show schematically one embodiment of the present invention in which the boat hull 1 or the sandwich panel for the boat hull 1 comprises the inner and outer surface layers 4, 2 and the intermediate core layer 6 with a honeycomb structure 7 for forming the cellular structure. The honeycomb structure 7 comprises cells or cavities formed with honeycomb walls. The honeycomb walls and the cells extend between the inner surface layer 4 and the outer surface layer 2. Figure 2B shows a top view of the sandwich panel when the inner surface layer 7 is removed. The cross-sectional shape of the honeycomb cells may be rectangular, circular, elliptical, hexago- nal, square or any other geometrical shape. Accordingly, the closed cells or cavities are formed by the honeycomb walls and the inner and outer surface layers 4, 2. Cell size of the cellular structure may be for example 5 mm to 25 mm, preferably between 9 mm to 15mm. The cell size may be measured as the largest width of the cross-sectional view.

Accordingly, the intermediate core layer 6 may form the cellular structure by itself with the honeycomb structure. Alternatively, that the intermediate core layer 6 may form the cellular structure together with one or both of the inner surface layer 4 and the outer surface layer 2. Thus the intermediate core layer 6 may be attached or bonded to the inner surface layer 4 and/or the outer surface layer 2 such that a cellular structure is provided. The inner surface layer 4 and the outer surface layer 2 may be attached to the intermediate core layer 6 such that cells or cavities are closed. The intermediate core layer 6 may be welded or glued or otherwise attached to the inner and outer surface layers 4, 2.

The intermediate core layer 6 may be an aluminium sheet or plate formed by bonding separate aluminium strips together. The separate aluminium strips may be welded or glued or otherwise attached together for forming the continuous structure. After attaching the aluminium strips together the continuous structure may be stretched for forming honeycomb or cellular structure to the intermediate core layer 6. Honeycombs from aluminium may also be produced by an expansion process. Continuous processes of folding honey- combs from a single aluminium sheet comprises forming slits to the aluminium sheet and then continuous in-line production may be used for forming aluminium honeycomb using metal rolls by cutting and bending.

In an alternative embodiment the intermediate core layer 6 may be a profiled aluminium sheet or plate. The profiled aluminium sheet or plate may be a corrugated sheet or plate, or it may have wave-like form or point-like protrusions and depressions. It should be also noted that the aluminium sheet or plate or the aluminium strips may be embossed for increasing rigidity. The profiled aluminium sheet or plate may form the cellular structure together with one or both of the inner surface layer 4 and the outer surface layer 2. The aluminium sheet or plate may form the cellular structure together with one or both of the inner surface layer 4 and the outer surface layer 2 such that the cells are closed.

Figures 3A and 3B show schematically another embodiment of the present invention in which the boat hull 1 or the sandwich panel for the boat hull 1 comprises the inner and outer surface layers 4, 2 and the intermediate core layer 6 is provided with aluminium foam layer 8 for forming the cellular structure. The aluminium foam layer 8 comprises pores for forming the cellular structure. The pores may have pore size between 1 mm to 25 mm, preferably 1 to 10 mm and more preferably 1 to 6 mm. Aluminium foam layer may be manufactured by known method starting from liquid aluminium or from aluminium powder. In one embodiment the pore size may be 5 mm to 25 mm, and preferably between 9 mm to 15 mm.

The inner surface layer 4 and the outer surface layer 2 are attached to the intermediate core layer 6. The inner and outer surface layers 4, 2 may be glued to the intermediate core layer 6, or they may be attached mechanically, or by metal joint or by welding. The composite integral structure provided by the surface layers 2, 4 and the intermediate core layer 6 provides a very rigid, strong and self-supporting structure. The inner surface layer 4 and/or the outer surface layer 2 may be manufactured from aluminium, carbon fibre, fiberglass, wood or stainless steel. In one preferred embodiment the outer surface layer 2 is formed from aluminium, and in another preferred embodiment the outer and inner surface layer 4, 2 are formed from aluminium. The aluminium surface layers 2, 4 may be formed using aluminium sheets. The thickness of the inner and outer surface layer 4, 2 may be between 0,2 mm to 2,5 mm, preferably 0,5 to 1 ,5 mm. The inner surface layer 4 may be arranged to form an inner surface of the boat hull 1 . Further, the outer surface layer 6 may arranged to form an outer surface of the boat hull 1 . Figures 4A and 4B show schematically embodiment in which an additional skin layers 3, 5 are provided on the surface of the inner and/or outer surface layers 4, 2 for forming the inner and/or outer surface of the boat hull 1 . In the embodiment of figure 4A the boat hull 1 further comprises an outer skin layer 3 provided on the outer surface layer 2 and arranged to form the outer surface of the boat hull 1 . Figure 4B shows an embodiment in which the boat hull 1 comprises the outer skin layer 3 and further an inner skin layer 5 provided on the inner surface layer 4 and arranged to form the inner surface of the boat hull 1 . It should be noted that the boat hull may also comprise only the inner skin layer 5. The inner skin layer 5 and/or the outer skin layer 3 may be manufactured from carbon fibre, fiberglass, wood or stainless steel.

Referring back to figure 1 , the boat hull 1 may manufactured from one or more sandwich panels 10, 12, 14 formed by the inner surface layer 4, the outer surface layer and the intermediate core layer 6 between the inner surface layer 4 and the outer surface layer 2, manufactured from aluminium and having the cellular structure. The sandwich panels 10, 12, 14 forming the boat hulM may be connected or joined abutting to each other by welding, laser welding, friction welding or friction stir welding. As shown in figure 1 , the hull 1 is formed of flat surfaces provided by the one or more sandwich panels 10, 12, 14. Accordingly, each sandwich panel may be flat panel and the shapes of the boat hull 1 are provided by the joints between the adjacent sandwich panels. Alternatively, the hull 1 is formed of flat surfaces and the shapes of the boat hull 1 are provided by local deformations of the sandwich panels, or by the joints and the local deformations.

The present invention provides a marine vessel, ship, boat or vehicle comprising a hull 1 with sandwich structure having an inner surface layer 4, an outer surface layer 2 and an intermediate core layer 6 between the inner surface layer 4 and the outer surface layer 2. The characteristics of the hull 1 are achieved by the intermediate layer 6 of the hull 1 which is manufactured from aluminium and has a cellular structure. Accordingly the marine vessel, ship, boat or vehicle has a hull 1 according to the above mentioned formed with the sandwich structure according to the present invention.

The present invention also provides use of a sandwich structure comprising an inner surface layer 4, an outer surface layer 2 and an intermediate core layer 6 between the inner surface layer 4 and the outer surface layer 2, the intermediate core layer being manufactured from aluminium and having cellular structure, for forming a hull of a marine vessel, ship, boat or vehicle.

Figures 5A, 5B and 5C show examples of possible methods for joining aluminium panels 10, 12 according to the present invention. Figure 5A shows an embodiment in which a material is machined from one of the surface layers 2, 4 and from the core layer 6 at the end and end surfaces of the panels 10, 12 for forming oblique end and machined area 21 between panels 10, 12 to be joined. The machined end surfaces are placed against each other and they may be glued or welded to together along the core layer 6. The oblique ends enable forming a bend or corner between the joined panels 10, 12. A connector plate 22 is also attached to the inner surface of corner for reinforcing the joint and attaching the panels 10, 12 together. The connector plate 22 may be glued or welded to the surface layer 2, 4 of the panels 10, 12. Figure 5B shows a similar joining method but in this embodiment the joint is reinforced with a connector plate 23 which is riveted with rivets 24 to the panels 10, 12. Otherwise the joint may be similar to the joint of figure 5A. It should be noted that the joining method shown in figures 5A and 5B may also be used for form- ing a bend or corner in one single panel. In that case one of the surface layers 2, 4 is removed from a corner area and the core layer 6 is machined, as shown in figure 5A. The other surface layer 2, 4 is left unbroken. Then the panel is bent such that the end surfaces of the core layer at the machined area 21 are against each other. The end surfaces at the machined area 21 may be for ex- ample glued or welded together.

Figure 5C shows another embodiment in which core layer 6 is removed from both panels 10, 12 and the end or end surface. A connector element 25 is placed between the panels 10, 12 and inside the area in which the core layer is removed, as shown in figure 5C. The connector element 25 also has a part arranged on one of the surface layers 2, 4 for attaching the panels 10, 12 together also at the surface layers 2, 4. Alternatively, the connector element 25 comprises only the part provided inside the core layer 6. The connector element 5 may be glued, welded or riveted to the panels 10, 12.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.