Building a Class40: the first stages

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Building a Class40: the first stages


From design to launch: constructing a Class40 for a solo ocean race means building a solid, light, performing and reliable customized boat, one which – in a nutshell – is better than the others. In La Trinité-Sur-Mer, at the JPS shipyard, the building work is progressing at a fast pace and with great precision: Alberto Bona takes us on a journey through the first three construction phases, the basic ones.

“Everything obviously starts from the project”, explained Alberto, “which we work with great precision. Then, with the drawings and data, we enter the shipyard, where we start from the construction of the hull by creating the mold, or the “box” in which the boat will come to life, which is a structure of wood and fiberglass.

This mold is called female, because it is the internal part on which the fiberglass cloth – an actual fabric – will be laid down. We then move on to the preparation of what in slang is called a sandwich, which is nothing more than a compound in which the fiberglass cloths are positioned one above the other, with an ultra-light foam material in the middle. The sandwich consists of a layer of fabric, the foam and another layer of fiberglass fabric. This determines the solidity of the structure, while ensuring maximum lightness. The difficulty lies in predicting where mechanical resistance will be needed more (or less), in order to adjust the quantity and concentration of fabric. For example, in the area near the keel, the foam will be completely replaced by fabrics, which will create a compact and very resistant layer, to prevent stress or any collisions from affecting the structure.

The skill needed in order to build a resistant and light boat lies in correctly dimensioning the various areas subject to mechanical stress: too much fabric means too much resin, and therefore more weight, the major enemy of a racing boat. Putting the designer’s ideas into practice is far from easy, and it takes years of experience and a highly skilled workforce. The next process is the infusion of the resin, which penetrates and consolidates this mechanical structure between the fiberglass and the foam. Infusion is a very fast process, and is done under vacuum. Once the resin has solidified, the hull is ready.

The process continues with the construction of the bulkheads – the backbone of the boat – which are necessary to provide rigidity. In actual fact, they are large panels that are adapted to the shape of the hull in all the right places. The bulkheads are the internal structures that ensure the mechanical rigidity of the hull along the three axes: without these, our hull would not last long in the midst of the waves. The construction of the bulkheads – an extremely important step – is characterized by two factors: on the one hand the structural calculations, on the other the shipyard’s experience in obtaining a light, rigid and reliable boat.

Concomitantly with the hull and the reinforcements, the deck is built: the construction method is the same, and maximum precision is needed so that the two parts – the hull and the deck – fit together”.