Technical Field

This invention broadly relates to a method of making sail membranes for use in the manufacture of sails for vessels such as yachts, boats and sailboards. In particular, the invention relates to a method of making sail membranes which are particularly suitable for the manufacture of reinforced three dimensional sails.

Background of the Invention

The following references to and descriptions of prior proposals or products are not intended to be and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the following prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but can assist in the understanding of the inventive step of the present invention, of which the identification of pertinent prior art proposals is but one part.

Traditionally, sails were constructed from a number of panels cut from various woven or laminated cloths and joined by sewing or adhesive. The cloth panels were cut and joined in such as way as to impart the desired three dimensional shape to a finished sail.

Over the past twenty-five years, there have been considerable advances in sail making. Manufactures have been manufacturing sails using new techniques to produce sails commonly known as 'load path sails' or 'string sails'. These sails are constructed from multiple layers of material being laminated together. Typically, these sails include base and top layers of polyester film and an inner layer of reinforcing means comprising threads or strips of various high strength fibres.

For instance, US patent No. 5,097,784 discloses a method of producing laminated sails using a three dimensional convex mould and laying reinforcing fibres continuously from corner to corner, corner to edge, and/or edge to edge of the sail membrane. Subsequent to the grant of the US patent, The shape of the convex mould was modified to be adjustable via a hydraulic mechanism such that the shape of the base layer of the sail membrane may be changed to impart a desired three dimensional shape. This method of manufacturing however has the shortcomings in that the convex mould is expensive to produce and the shape adjustment process is time consuming.

It is an object of the present invention to overcome or substantially alleviate one or more of the above shortcomings, or at least to provide a useful alternative.

Disclosure of the Invention

Accordingly, in one aspect, the present invention provides a method of making sail membranes, the method including the steps of:

removably and substantially sealing at least a margin of a base layer to a surface; inflating the base layer;

laying a first reinforcing layer on a first surface of the inflated base layer under pressure; and

bonding the reinforcing means to the inflated base layer.

The invention also includes a sail made using the method of the present invention.

The first reinforcing layer is preferred to include a plurality of reinforcing means in the form of any one or more of the following: threads, fibres, yarns or tapes.

Preferably, topical pressure is applied on each of the reinforcement means as they are laid on the inflated base layer. As such, each reinforcement means is pressed against the inflated base layer to enhance the bond.

It is preferred that each reinforcing means is bonded to the inflated base layer using an adhesive to provide a reinforced base layer. Preferably, the method of making sail membranes includes the pre-steps of:

cutting one or more panels out of a sheet; and

joining the panels together to form the base layer.

The sheet may be made of a polyester film or any other suitable sail membrane base material.

Conveniently, the method of making sail membranes includes a yet further step of using the broadseeming technique to impart a desired three dimensional shape to the base layer.

The base layer preferably includes a margin. The margin is preferred to extend beyond an intended outline of a finished sail membrane to facilitate attachment of the base layer to the surface. The sealed margin may define a substantially air tight cavity between the base layer and the surface. The margin may be sealed to the surface by sealing means such as adhesive tapes.

The inflation of the base layer preferably involves providing an inlet within the sealed margin, the inlet being connected to an air supply. To inflate the base layer, the air supply may be activated to blow air into the substantially air tight cavity. As such, apart from the margin, the base layer is not in contact with the surface.

Preferably, the sealed margin includes an outlet for exhausting air. The outlet may be used to control the degree of inflation or to deflate the base layer.

In a preferred embodiment, the method of making sail membranes of the present invention includes the further step of laying a top layer on the reinforced base layer and bonding the top layer to the reinforced base layer to provide a partially covered sail membrane. The top layer may include on its underside a layer of adhesive to effect the bond.

The top layer may be made of one of the following: a film, fabric, and a film and fabric laminated cloth. In another preferred embodiment, the method of making sail membranes includes yet further steps of:

turning the partially covered sail membrane over such that a second surface of the base layer is exposed;

removably and substantially sealing the margin of the partially covered sail membrane to the surface;

inflating the partially covered sail membrane;

laying a second reinforcing layer on the second surface of the inflated partially covered sail membrane under pressure;

bonding the second reinforcing layer to the inflated partially covered sail membrane;

laying a second top layer on the further reinforced partially covered sail membrane; and

bonding a second top layer to the further reinforced partially covered sail membrane to provide a fully covered sail membrane.

Optionally, each of the first and second reinforcing layers has a reduced thickness or density.

It should be noted that the reinforcing layers mentioned herein need not cover the entire surface of the base layer ahd the reinforcing means which form the reinforcing layers may be discrete.

Accordingly, in another aspect, the present invention provides a sail making surface adapted to support a base layer which includes a margin removably sealed to the surface, the margin defining an air tight cavity, the surface having one or more inlets adapted to blow air into the cavity to achieve inflation of the base layer.

Brief Description of the Drawings

The invention may be better understood from the following non-limiting

description of a preferred embodiment, in which: Figure 1 is a perspective view of a base layer of a reinforced sail membrane attached to a surface, the sail membrane being made in accordance with a method of the present invention;

Figure 2 is a schematic cross sectional view of a partially covered sail membrane including the reinforced sail membrane of Figure 1 and a top layer;

Figure 3 is a schematic cross sectional view of an inflated partially reinforced sail membrane of Figure 1 illustrating the reinforcing means being attached to the base layer in the manufacturing process.

Detailed Description of the Drawings

It should be noted that the sail membrane to be made by the method of the present invention is for the manufacturing of a sail.

Referring to Figure 1, a sail membrane 5 includes a three-dimensional and non- planar base layer 10 consisting of joined panels 12 and 14. The base layer 10 has a substantially triangular outline 16 and a margin 18 which is designed to cover the outline 16. The margin 18 extends beyond an intended outline of the finished sail membrane 5 in order to facilitate attachment of the base layer 10 to a surface which is a floor 20 in the present embodiment. The margin 18 is removably and substantially sealed to the floor 20 by adhesive tapes 22. The sealed margin 18 defines a substantially air tight cavity between the base layer 10 and the floor 20.

An inlet 24 is provided within the sealed margin 18 of the base layer 10. Connected to the inlet 24 is one end of a conduit 26 which is connected at an opposite end to an air supply which is an air blowing machine.

The sealed margin 18 includes outlets 28 for exhausting air. The outlets 28 are used to control the degree of inflation or to deflate the base layer 10, as desired. In an alternative embodiment, one or more inlets are provided to form integral parts of the surface. In this case, the inlets are configured to blow air into the cavity for the inflation of the base layer 10.

The method of making a sail membrane will now be described. The first step is to prepare the base layer 10 which involves cutting and assembling panels such as 12 and 14 to form the base layer 10. Panels such as 12 and 14 of desired shapes and sizes are cut from a sheet made of material such as polyester film, fabric or laminate. The panels, for example 12 and 14, are cut and joined together in such a way as to produce a base layer having the desired three dimensional shape and configuration. A technique generally known as 'broadseeming' is used to impart the desired three dimensional shape to the base layer 10.

Referring to Figures 1 and 3, once the base layer 10 is prepared, it is attached to the floor 20 in preparation for attachment of a reinforcing layer consisting of a plurality of reinforcing means in the form of reinforcing fibres 30. The margin 18 of the base layer 10 is sealed to the floor 20 with the inlet 24 connected to the air blowing machine (not shown) via the conduit 26. The air blowing machine is then activated to continuously blow air into the cavity 32 (see Figure 3) defined by the margin 18 thereby inflating the base layer 10. As a result, the majority of the underside of the base layer 10 is not in contact with the floor 20.

The reinforcing means may be in the form of threads, yarns, fibres, tapes or strips made of a suitable reinforcing material. Turning to Figures 2 and 3, laying of the reinforcing fibres 30 is carried out by a specifically designed machine 34 (see Figure 3) designed to run over the surface of the base layer 10 in passes. Each pass is designed to lay one or more reinforcing threads or fibres and each sail membrane requires multiple passes to form a reinforcing layer. The machine 34 is also capable of applying an adhesive 36 (see Figure 2) to the reinforcing fibres 30 and pressing the reinforcing fibres 30 already laid on the base layer 10 against the base layer 10 towards the floor 20 under pressure to facilitate bonding of the reinforcing fibres 30 to the inflated base layer 10.

Referring to Figures 2, in another embodiment, a top layer 40 is laid on the reinforced base layer 10, and bonded to the reinforcing fibres 30 and upper surface 38 of the base layer 10 respectively by a layer of pressure sensitive adhesive 36 to provide a partially covered sail membrane. The top layer 40 may be made from a polyester film, or a woven or laminated fabric, or a combination of both the film and fabric, to protect the reinforcing fibres 30 and further strengthen the sail membrane 5. The top layer 40 is assembled from individual panels having similar sizes and shapes similar to the panels 12 and 14 forming the base layer 10.

It is contemplated that an alternative embodiment of the method of the present invention involves the inclusion of two reinforcing layers and two top layers to a single base layer. This embodiment involves removing the partially covered sail membrane described above from the floor 20 and turning it over such that a second surface 42 (see Figure 3) of the base layer 10 is now exposed facing upwards. The margin of the partially covered sail membrane is then removably and substantially re-sealed to the floor 20 with the already attached first top layer 40 facing downwards. The partially covered sail membrane is then reinflated. A second reinforcing layer and a second top layer are subsequently laid and attached to the surface 42 (see Figure 2) of the base layer 10 (which is now facing upwards) in a similar order and manner to that described above for the first reinforcing and top layers. It should be noted that in this embodiment, the thickness or density of each of the first and second reinforcing layers (ie. each reinforcing means) is preferred to be reduced considerably. As sometimes it can get cumbersome and messy to run a pass for the purposes of laying and pressing down the reinforcing means simultaneously, reducing the thickness or density of each of the reinforcing layers is beneficial in enabling the machine to run smoothly. Now that preferred embodiments of the present inventions have been described in some detail, it will be apparent to those skilled in the art that the method of making sail membranes may offer at least the following advantages:

1. it can be carried out without the assistance of expensive or complex

equipment;

2. it can be carried out and run at a very low cost; and

3. it can be carried out swiftly and easily to make sail membranes of different shapes and sizes.

It will be appreciated that the embodiments described above are not intended to be limiting on the scope of the invention and that variations and modifications may be made without departing from the spirit and scope of the invention.

Industrial Applicability

The present invention is industrially applicable in that it is capable of being carried out to manufacture sail membranes of different shapes of sizes in an economical and swift manner.