The invention relates to a single skin construction method for building a vessel. The method may be used for constructing vessels of different shapes and sizes.

Other methods for constructing boats are previously known: US Patent 3832745 describes a method wherein a single whole mould is used for constructing the hull. The disadvantage with this method is that the mould has a constant dimension, so that only vessels of the same size can be produced. The preparation of moulds of this kind is expensive and time-consuming, and this method requires therefore the mass production of boats in order to be economically viable. British Patent 1578534 describes a construction method wherein regular, profiled materials are used. US Patent 3593354 describes a sandwich construction with a frame which may be removed. This method is restricted, in the main, to lightweight boats. US Patent 2758321 makes use of a reinforced plastic structure for the hull, and an inner support structure (ribs) which are fixed in the hull during the entire construction process.

The advantages of the method in the present invention in comparison to the aforementioned methods are that the invention provides a more flexible and economically favourable method. In the method in the invention a pre- prepared mould is not used, but the inner support structure of the vessel is used as a mould. Thus, there is great flexibility with regard to, for example, the length and shape of the hull. The method is therefore particularly suitable for building vessels in small series.

According to the invention, the method of building vessels

which are constructed of an inner structure and a ski consisting of several layers which together constitute single laminate, is characterized in that the inne structure is built first and a thin plate is attache thereafter to the inner structure in such a way tha together they form a mould for the skin.

The method is further characterized in that:

(i) the skin is laminated on the outside of th mould; (ii) the mould and the skin are separated; (iii) the thin plate is removed from the inne structure; (iv) the inner structure and the skin are joined.

The method is further characterized in that said thin plate constitutes one or several layers in the skin laminate where the other layers are laminated directly on to the thin plate which is placed on the inner structure.

The method is further characterized in that the mould is divided into sections in such a way that steps (ii) to (iv) in the method described in claim 2 take place section by section.

The method is still further characterized in that the thin plate constitutes one or several layers of the skin laminate, and that the other layers of the skin are laminated directly on to the outside of the thin plate after said plate has been placed on the outside of the inner structure.

The method is yet further characterized in that the skin is laminated on the outside of the mould, whereupon the thin plate is removed.

The method is still further characterized in that th building of the inner structure, the application of th thin skin plate and the lamination of the skin take plac whilst the vessel is upside down.

The invention will be explained in detail with referenc to the drawings where:

Figure 1 shows the inner structure which consists o transverse ribs and longitudinal braces on t which is applied a thin plate of the desire shape, a slip film and skin.

Figure 2 depicts a completed hull where the thin plat and the slip film have been removed and the ski has been attached to the inner structure.

The inner structure consists of longitudinal braces (2) which are mounted on transverse ribs (1) .

Thin plates (3) are laid between the longitudinal braces, said plates preferably being glass fibre reinforced. Initially the plates are flat and are bent into the right shape when they are attached to the inner structure. Spacers may be positioned between the transverse ribs (1) in order to maintain the correct shape of the plates. A foil/slip film (4) is placed over these plates and shall ensure that the skin releases after moulding. The actual skin laminates (5) , of the desired quality and thickness, are placed on the mould.

Once the skin laminates have been cured, the mould (braces (2) and the thin plate (3)) and the skin laminate (5) are separated. First the thin plates are removed, and thereafter the inner structure is joined to the skin laminate (5) .

Alternatively, the thin plates may remain as an integrated part of the skin laminate, ie, they are not removed.

A further alternative method is that the thin plates are removed without it being necessary to separate the skin and the inner structure.

The entire method in the invention takes place preferably in that the work is carried out section by section in the hull, and whilst the vessel is upside down.