Abstract:
A method of manufacturing a ship deck and a prefabricated ship deck element for manufacturing the ship deck. The ship deck comprises a surface layer with an exposed upper side, e.g. of teak, being supported upon a carcase existent in the ship and having a surface that has protruding irregularities. The prefabricated ship deck element comprises said surface layer and an underlying layer of cellular plastic, and is applied upon the carcase by attaching the free lower surface of the cellular plastic layer to the carcase, such that the irregularities occurring on the surface of the carcase sink into the cellular plastic and the exposed surface layer remains essentially unaffected by said irregularities. In this way, a great surface finish can easily be achieved, at the same time obtaining significant savings of weight, subduing of footsteps and thermal insulation.

Description:
[0001]     This application claims priority and benefit from Swedish Patent Application No. 0401338-9, filed May 25, 2004, the entire teachings of which are incorporated herein by reference. This application also claims priority from PCT/SE2005/000769 filed May 24, 2005, the disclosure of which is incorporated here by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention refers to a method of manufacturing a deck structure for boats and ships allowing achievement of great finish on an exposed top surface preferably made of teak, and a prefabricated ship deck element for executing the method.  
       BACKGROUND OF THE INVENTION  
       [0003]     When manufacturing a deck on boats and ships, a top surface layer is typically applied on a supporting carcase, e.g. made of metal plate, having a surface layer that is exposed during use. In the following description, the generic term “ship” is used for the sake of simplicity to represent boats and ships of any kind and size having such a deck. “Carcase” implies a supporting and mainly inelastic foundation, forming an integral part of the existing ship structure. Ship decks having an exposed surface layer made of teak are of frequent occurrence, and it is generally regarded as being a functional and visually attractive material in the context of ships. Typically, ships of a multitude of different types and sizes are provided with such a teak deck, ranging from pleasure boats to huge cruise liners.  
         [0004]     However, when manufacturing teak decks it is a significant problem to achieve great smoothness on the teak top surface or similar. Particularly in the yacht industry, extremely high demands are often made on the surface finish of the deck.  
         [0005]     The supporting carcase, often being an existing foundation in the ship structure made of metal plates of aluminium or steel welded together, nearly always has a rugged and wavelike surface upon which a teak deck is to be applied. In particular, welding seams protruding from the surface occur when plural metal plates are welded together. Typically, these welding seams must not be ground away in order not to jeopardize the strength of the carcase. Moreover, the plates per se are often more or less embossed and rugged, thereby resulting in that the carcase surface presents randomly occurring variations in height and protruding parts, in addition to said welding seams.  
         [0006]     In order to avoid that the exposed surface on a teak deck applied on the carcase presents corresponding irregularities and variations in height, one must initially make sure that the foundation becomes even and smooth before the teak layer is applied thereon. Previously, this problem has been solved either by initially filling and grinding the surface of the carcase to achieve smoothness, or by applying a layer of glue, sometimes together with a piece of plywood, being sufficiently thick so as to cover all irregularities and weld joints on the carcase. A thick layer of, e.g., liquid polyurethane glue is then applied on the carcase, which is thereafter levelled by wiping with a batten or the like, such that all irregularities and protruding parts of the carcase, particularly occurring weld joints which may be 5-10 mm in height, are bridged over by the glue. After that, the teak layer can be applied on the glue layer to provide a good result.  
         [0007]     However, these previous manufacturing methods and deck structures are associated with a number of problems and drawbacks. When using either glue or putty filler, a substantial amount of such material must be applied on the carcase in order to eliminate all its irregularities. This addition of material results in considerable costs and increased weight that may be in the magnitude of tens of tons for large yachts or ships. If the gluing method is utilized for a large ship having, e.g., a 4000-5000 m 2  deck surface, the addition of glue results in a weight increase that may reach 30-40 tons. Using the putty filler method, a substantial grinding work is typically also added, in order to achieve a desired surface finish. Using the known methods, it is also relatively difficult to achieve the great smoothness always being demanded.  
         [0008]     Furthermore, a deck manufactured according to the prior art is somewhat hard and stiff to walk upon, and has also inferior insulating characteristics with respect to both temperature and noise/vibrations.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to obtain a simple yet reliable solution for achieving great surface smoothness on ship decks, such as teak decks, without causing a significant increase in weight and/or requiring extensive workload during the manufacture.  
         [0010]     Another object of the invention is to provide a ship deck with great qualities that is, among other things, pleasant and soft to walk upon, further having a great thermal and acoustic insulating capacity.  
         [0011]     These objects and others are obtained by a method of manufacturing a ship deck according to claim  1 , said ship deck comprising a surface layer with an exposed upper side, e.g. of teak, being supported upon an essentially inelastic carcase existent in the ship and having a surface that has protruding irregularities, e.g. welding seams. Prefabricated ship deck elements, comprising said surface layer and an underlying layer of cellular plastic, are applied upon the carcase by attaching the free lower surface of the cellular plastic layer to the carcase, such that the irregularities occurring on the carcase surface sink into the cellular plastic and the exposed surface layer remains essentially unaffected by said irregularities.  
         [0012]     According to one embodiment, the ship deck element is pressed, by using some force, against the carcase such that at least some of said protruding irregularities on the carcase surface sink into the cellular plastic by being depressed therein by local deformation of the cellular plastic.  
         [0013]     According to another embodiment, an impression is initially produced on the cellular plastic with markings corresponding to at least some of the irregularities of the carcase, whereupon a suitable amount of cellular plastic material is removed from the cellular plastic surface at the markings, e.g. by liquefaction, milling or cutting, in order to produce recesses in the cellular plastic surface. Then, corresponding irregularities sink into the cellular plastic by being received in respective recesses as the cellular plastic layer is attached to the carcase surface. The carcase surface may be provided with a colouring substance or the like, in order to produce such an impression on the cellular plastic.  
         [0014]     Alternatively, the positions of at least some of the protruding irregularities of the carcase to the cellular plastic may be located by measuring, whereupon a suitable amount of cellular plastic material is removed from the lower surface of the cellular plastic at corresponding locations, e.g. by liquefaction, milling or cutting, in order to produce recesses in the lower surface of the cellular plastic. Then, corresponding irregularities sink into the cellular plastic by being received in respective recesses as the cellular plastic layer is attached to the carcase surface.  
         [0015]     As the cellular plastic layer, polythene or polypropylene having a specific gravity of approx. 20-60 kg/m 3 , may be used.  
         [0016]     Furthermore, the surface layer may be supported, via the cellular plastic layer, upon a carcase in the shape of a together-welded plate structure of metal, such as aluminium or steel.  
         [0017]     The invention further encompasses a prefabricated ship deck element according to claim  7 , for manufacturing a ship deck comprising a surface layer with an exposed upper side, e.g. of teak, being supported upon an essentially inelastic carcase that has protruding irregularities, e.g. welding seams. The prefabricated ship deck element comprises said surface layer and an underlying layer of cellular plastic, and is adapted to be applied upon the carcase by attaching a free lower surface of the cellular plastic layer to the carcase, such that the irregularities occurring on the surface of the carcase sinks into the cellular plastic and the exposed surface layer remains essentially unaffected by said irregularities.  
         [0018]     The surface layer of the ship deck element may comprise a plurality of prefabricated modules of a web structure with seams between the webs. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The present invention is described below in more detail and with reference to the attached drawings:  
         [0020]      FIG. 1  is a schematic cross-section of a ship deck being manufactured according to an embodiment of the present invention.  
         [0021]      FIG. 2  is a schematic cross-section of a ship deck element being applied on a carcase during a phase in an alternative embodiment of the present invention.  
         [0022]      FIG. 3  is a perspective view of the underside of the ship deck element after the phase according to  FIG. 2 .  
         [0023]      FIG. 4  is a schematic cross-section of the ship deck element applied on the carcase during another phase following after the phase shown in  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0024]     The present invention will now be described with reference to the attached drawings, in which  FIG. 1  shows a cross-section of a ship deck, e.g. as seen in the latitudinal direction of the ship, during its manufacturing according to one embodiment. In the figure, the deck has a somewhat arched shape, although it may of course have any shape and size and may further be located anywhere on the ship, within the scope of the invention. The deck may preferably be made as web shaped sections of teak battens having a seam substance between each batten, and being supported by a glued carrier made of woven glass or thin plywood.  
         [0025]     According to the invention, the starting product is one or more prefabricated ship deck elements  100  to be applied on a supporting carcase  102 , existent in the ship. A ship deck element  100  of this kind comprises a surface layer  106  having a top surface to be exposed as the actual deck surface, and an underlying layer of expanded plastic  108 . The surface layer  106  is preferably made of teak, although other choices of material are conceivable for the surface layer, within the scope of the invention. For example, the surface layer  106  may be built up from a plurality of segments or battens made of teak on a fibreglass fabric or thin plywood, e.g. in a manner described in the patent document U.S. Pat. No. 4,351,256, wherein the expanded plastic  108  is attached to its underside by gluing. Preferably, the expanded plastic may be polythene or polypropylene having a specific gravity of approx. 20-60 kg/m 3  and having closed cells counteracting retention of water.  
         [0026]     The carcase  102  upon which the ship deck element  100  is being applied is typically a chiefly stiff together-welded plate structure metal, such as aluminium or steel. In reality, the surface of the carcase  102  is more or less irregular, which is schematically illustrated in the figure as protruding parts  104  that may include welding seams when plural plate segments have been welded together side by side. Such welding seams  104  should rather not be grinded away with respect to strength. Even though the surface of the carcase in the figure is shown smooth besides the welding seams  104 , also other more or less randomly protruding irregularities and bosses of varying size and shape may of course be present thereon, typically occurring during the manufacture and/or handling of metal plates. Such irregularities may primarily occur when the plate contracts along its edges after being welded.  
         [0027]     The upper side of the surface layer  106 , to be exposed as the deck surface when in a finished state, may even from the outset be designed with a desirable surface finish that remains unimpaired during the entire production process, thanks to the present invention.  
         [0028]     The ship deck is manufactured by gluing the free lower surface of the expanded plastic  108  of the ship deck element  100  against the carcase  102  existent in the ship, after applying a glue layer on the expanded plastic and/or carcase. According to a first embodiment, during this phase, the free surface of the expanded plastic is applied by a certain force against the irregular carcase  102 , such that the expanded plastic is deformed locally at the irregularities mainly protruding from the surface, in this example the welding seams  104 . In the figure, this force is illustrated by three arrows directed downwards.  
         [0029]     By making the expanded plastic layer  108  sufficiently thick, the irregularities protruding from the carcase, particularly the welding seams  104 , will then sink into the expanded plastic without reaching the outside surface layer  106 , e.g. made of teak. By means of this procedure, the resulting exposed surface of the surface layer  106  will remain undeformed after the manufacture, thus still having the original surface finish. It is also possible to add a certain amount of expanded plastic material at locations where the carcase buckles inwards/downwards. Furthermore, gluing the expanded plastic layer against the carcase may be done using a effervescent glue filling up irregularities that the expanded plastic material does not manage to fill up. However, in practice, it is in most cases necessary to initially make the main surface of the carcase fairly level and smooth in a so-called levelling process using a putty and/or glue. However, in this case, the same amount of such levelling material as in previous solutions is not required, since not all of the protruding irregularities need to be bridged over by this material.  
         [0030]     According to an alternative embodiment, the deck may be manufactured in a slightly modified manner, which is illustrated in  FIGS. 2-4 . As in the first embodiment, a prefabricated ship deck element  200 , comprising a surface layer  206  and an underlying layer of cellular plastic  208 , is applied on a carcase  202 .  
         [0031]     According to one embodiment, at least some of the protruding irregularities of the carcase  202 , in this case two protruding welding seams  204   a  and  204   b , may initially be provided with a colouring substance or the like, in order to provide, in a following phase, an impression on the cellular plastic marking these irregularities, i.e. the welding seams  204   a ,  204   b . Thereafter, the free surface  208   a  of the cellular plastic layer is applied against the irregular carcase  202 , which is illustrated by arrows directed downwards in  FIG. 2 , and is lightly pressed thereon. Thus, the applied force should be sufficient so as to produce an impression on the cellular plastic corresponding to at least some of the irregularities of the surface, but in this case it does not have to be so great as to make the protruding irregularities sink into the plastics.  
         [0032]     Thereafter, the ship deck element  200  is lifted off the carcase  202 . In  FIG. 3 , the lower surface  208   a  of the cellular plastic layer is illustrated after the impression executed according to  FIG. 2 , where two markings  210   a  and  210   b  have been produced by contacting the welding seams  204   a  and  204   b , respectively. In a next step, a certain suitable amount of cellular plastic material is removed from the cellular plastic surface  208   a  along the markings  210   a ,  210   b , e.g. by liquefaction, milling or cutting, such that two recesses are produced chiefly corresponding to the welding seams  204   a ,  204   b . If the cellular plastic material is removed by liquefaction, e.g. using a hot-air gun, the formation of volatile chips and fragments of waste cellular plastic can be avoided. Moreover, the removal by liquefaction can be executed relatively quickly and easily.  
         [0033]     According to an alternative embodiment, the positions of the welding seams  204   a ,  204   b  to the cellular plastic can be located by measuring, wherein the positions, shapes and directions of the welding seams  204   a ,  204   b  is initially measured on the carcase  202 , whereupon material is removed from the cellular plastic surface  208   a  at corresponding locations.  
         [0034]     Finally, the cellular plastic surface  208   a  is glued upon the carcase  202 , wherein the protruding welding seams  204   a ,  204   b  sink into the cellular plastic by being received in the formed recesses, e.g. according to the markings  210   a ,  210   b  shown in  FIG. 4  that were produced by either impression or measuring.  
         [0035]     Naturally, the cellular plastic layer may in this step be pressed against the surface of the carcase  202  using a certain force so as to make smaller protruding irregularities, which have not caused any corresponding removal of cellular plastic, sink into it in the same manner as in the first exemplary embodiment. Hence, it may be beneficial to initially remove cellular plastic material for the most rough irregularities, and then have any remaining smaller irregularities penetrating the cellular plastic under local deformation by applying a sufficient force as the cellular plastic surface  208  is glued upon the carcase  202 . However, this force can be considerably smaller as compared to the case when no cellular plastic material at all would have been removed.  
         [0036]     The above-described invention presents a number of benefits as compared to the prior art. By using a cellular plastic layer that bridges over protruding irregularities occurring on the carcase, it is not necessary to cover the carcase surface with any smooth layer of a putty or glue covering all such irregularities, before the surface layer is applied. Cellular plastic is a material of a significantly lower weight than glue or putty, and this solution therefore results in significant savings of weight.  
         [0037]     In addition, a ship deck manufactured according to the invention presents a number of advantageous characteristics. The cellular plastic layer of the invented prefabricated ship deck elements serves as an excellent insulator in the ship deck, both thermally and acoustically, as compared to conventionally manufactured ship decks.  
         [0038]     Furthermore, the relatively soft cellular plastic layer provides a somewhat resilient basis that is both pleasant and quiet to walk upon.  
         [0039]     Of course, further modifications and combinations of the above-described embodiments are conceivable within the scope of the present invention. Thus, the invention is not exclusively limited to the described embodiments, being generally defined by the following claims.