AU2001240336A1 - Method of manufacturing a watercraft - Google Patents

Description

METHOD OF MANUFACTURING A WATERCRAFT

TECHNICAL FIELD This invention relates to watercraft and methods of manufacturing same. BACKGROUND ART

Traditionally watercraft such as surfboards, surf skis, sail boards, body boards and the like have been manufactured from a foam (usually polyurethane) core which includes an internal stringer (usually a strip of plywood). The core materials are shaped and then coated with a composite of resins and fibreglass to form an outer skin.

Whilst such watercraft can be produced in varying shapes and designs and in attractive finishes there are a number of acknowledged disadvantages associated with the traditional methods of construction including:

1. Polyurethane-foam cores are inherently weak, not impact resistant, and the processing of the foams is generally wasteful.

2. Stringers used to reinforce the core materials have little resilience and are heavy compared with the overall weight of a craft. 3. Resins which are commonly used are solvent based, highly toxic and environmentally damaging.

4. Commonly applied fibreglass skins are brittle, relatively heavy and are readily damaged by impacts and collisions.

5. Fibreglass is highly toxic in its application and a potential cause of lung, skin and liver disorders.

6. The watercraft are 100% non-recyclable.

There are increasing pressures on industries to use eco-friendly and sustainable manufacturing techniques, to eliminate the use of toxic materials, and to maximise the use of natural recyclable materials. One natural material which is available in abundance is bamboo, a natural timber which is readily grown in tropical and semi-tropical regions of the world. Whilst bamboos are used for building purposes and for making furniture poles, etc. its field of use has been relatively limited.

Bearing in mind that bamboo is in abundant supply, is a relatively renewable inexpensive resource, can be readily worked, is naturally strong it is surprising that the material is not used more extensively than it is.

It is an object of the present invention to provide a method of constructing watercraft such as surfboards, utilising bamboo as a protective veneer.

Further objects and advantages of the present invention will become apparent from the ensuing description.

DISCLOSURE OF INVENTION According to the present invention there is provided a method of manufacturing a watercraft which comprises a foam inner core and an outer layer of natural bamboo veneer, the method comprising the steps of; (a) applying an adhesive to a plurality of sheets of bamboo veneer,

(b) placing the sheets on the inner core

(c) drawing the sheets onto the core under a partial pressure environment, (d) allowing the adhesive to cure.

The core material may be from any variety of foam including an extruded polystyrene foam.

The core material is unreinforced.

The sheets of bamboo veneer are applied separately to the top and bottom major surfaces of the core.

The adhesive is cured whilst at an elevated temperature.

The elevated temperature can be approximately 60 degrees Celsius. The step of drawing the sheets onto the core under a partial pressure environment can be achieved within a flexible membrane.

According to a further aspect of the present invention there is provided watercraft manufactured according to the aforesaid method, the watercraft comprising a foam inner core protected by an outer layer of bamboo veneer.

The core material may be from any variety of foam including expanded polystyrene foam.

The core material is unreinforced.

BRIEF DESCRIPTION OF THE DRAWINGS Aspects of the present invention will now be described with reference to the accompanying drawings in which; Figure 1 is a cross-sectional drawing of a watercraft according to the present invention, and

Figure 2 is a partial perspective and plan view of the step of forming an elongate bamboo veneer from rolls, and

Figure 3 shows the elongate veneer of Figure 2 overlying core of a watercraft after shaping of the veneer, and

Figure 4 shows a watercraft core and veneer where the veneer has had adhesive applied and is taped at the edges to conform to the shape of the core, and

Figures 5 & 6 are side and sectional views of the process of creating a partial vacuum to draw the veneer onto a watercraft core prior to curing.

With respect to Figure 1 of the drawings a watercraft hull generally indicated by arrow 1 can be formed from a rigid foam core 2 protected by an outer veneer 3. The outer veneer 3 is formed from sheets of bamboo veneer.

The bamboo which is in sheet form is taken from the internal "timber" region of bamboo plants.

Depending on the parent material the bamboo sheet is provided in various sizes, approximately a millimetre thick. The bamboo sheet material can be applied to the core in a natural or preconditioned state.

The preconditioning of the sheet material can include the application of adhesives and/or resins and a partial pressure environment used to apply the sheet material to the core.

The process of manufacture can include the steps of shaping the core materials by hand or machine or by pre-moulding. Resin impregnated bamboo sheet materials are then applied as a veneer to the core preferably within a partial pressure environment (a vacuum chamber).

The partial pressure environment can be subject to elevated temperatures. The sheet materials are laid on a foam core and placed on a bed within the vacuum chamber, and when a vacuum is applied the sheets are drawn onto and adhere to the core.

The major surfaces of the hull may be covered in a two-stage process by the application of veneer to one side, allowing the adhesive to cure and then applying the veneer to the other side and allowing the adhesive to cure.

The completed hull can then be removed from the chamber and finished in a variety of ways.

Finishing may entail sanding, the application of epoxy varnishes, paints, lacquers and the like, and the fitting of accessories such as rope ties, fins, skegs, rudders and the like.

With respect to Figure 2 to 6 of the drawings the first stage of the manufacturing process is to form an elongate bamboo veneer 4 from smaller sheets taken from rolls of bamboo veneer 5 as is illustrated by Figure 2.

The veneer 5 is then shaped to conform to the shape of the core 2 as is illustrated by Figure 3.

Adhesive is then applied to the underside of the veneer 5 and extending edges 4a are taped onto the underlying edges of the core 2 whilst the core is supported by a rest 6 as is illustrated by Figure 4.

The veneered core 2 is then placed on a supporting table 7 atop a rigid template 8. A flexible top plate 9 is placed on the top surface of the veneered core 2 and the element formed is bagged within a flexible membrane and then the bag is evacuated.

The element is then placed within a heating chamber (not shown) for curing.

The temperatures within the heating chamber are approximately 60 degrees Celsius.

After curing the laminated core can be applied to the opposite side and similarly processed prior to sanding and finishing. The present invention has many advantages over conventional practices including;

1. Non-toxic foam (styrene), which vastly reduces waste and which is recyclable can be used.

2. Epoxy resins, which have fewer volatile organic compounds and less than 6% solvents can be used.

3. No stringer is used, which leads to a 15% overall weight reduction and increases performance for the same weight.

4. A bamboo veneer, which has twice the strength of fibreglass, for the same weight and is flexible, light, totally natural and non- toxic at all levels of manufacture.

5. Product produced utilising the methodology of the present invention has less toxicity, as it uses recyclable cores, organic substrates (bamboo) and epoxy resins.

6. Product is aesthetically appealing due to its natural appearance. 7. Easy blended repairs can be readily made.

Aspects of the present invention have been described by way of example only and it will be appreciated that modifications and additions thereto may be made without departing from the scope thereof, as defined in the appended claims.

Claims (12)

CLAIMS:

1. A method of manufacturing a watercraft which comprises a foam inner core and an outer layer of natural bamboo veneer, the method comprising the steps of; (a) applying an adhesive to a plurality of sheets of bamboo veneer,

(b) placing the sheets on the inner core

(c) drawing the sheets onto the core under a partial pressure environment, (d) allowing the adhesive to cure.

2. A method as claimed in claim 1 wherein the core material is an extruded polystyrene foam.

3. A method as claimed in claim 1 wherein the core material is unreinforced.

4. A method as claimed in claim 1 wherein the sheets of bamboo veneer are applied separately to the top and bottom major surfaces of the core.

5. A method as claimed in claim 1 including the step of allowing the adhesive to cure at an elevated temperature.

6. A method as claimed in claim 5 wherein the elevated temperature is approximately 60 degrees Celsius.

7. A method as claimed in claim 1 wherein the step of drawing the sheets onto the core under a partial pressure environment is achieved within a flexible membrane.

8. A method substantially as herein described with reference to the accompanying drawings.

9. A watercraft manufactured according to the method of claim 1 comprising a foam inner core protected by an outer layer of bamboo veneer.

10. A watercraft as claimed in claim 9 wherein the core material is an expanded polystyrene foam.

11. A watercraft as claimed in claim 10 wherein the core material is unreinforced.

12. A watercraft is substantially as herein described with reference to the accompanying drawings.