Plastic fantastic
A revolution? A sometimes overused word. A new era? Without a doubt, even though metal had already started to replace wood for boatbuilding over the past century. Instead, it is more of a before and an after. Like the invention of the wheel or electricity, the sudden appearance of “plastic” in our everyday lives changed so many things that it is hard to imagine the before. For building recreational boats, this new material was truly disruptive, redefining the landscape and injecting fresh momentum and energy. It may not have completely replaced wood, steel or aluminum. But it did enable boatbuilding to make a real technological leap forward, the scale of which can still be difficult to understand today.
Firstly, it is interesting to note that the generic term “plastic” is not necessarily a perfect match with the properties of this new material. This term refers to a potential suppleness, a potential flexibility, and even an easily malleable element. However, “plastic” is something else entirely. It is the blend of plasticity, enabling you to give the future object the desired form, with the underlying structure that gives it rigidity and solidity. That is why its real technical name – glass-polyester laminate – is far more meaningful. This is a composite created specifically at the time when the object is produced. A resin – fluid, or… plastic before hardening – reinforced with glass fibers – gives the creation a definitive shape and resistance once it has dried.
New material created through chemistry
This ancient principle was revisited thanks to the progress made with chemistry in the 20th century. The invention of “polyester laminate” construction is attributed to two scientists in 1935. The first, the American Russel Games Slayter, was an engineer and fascinated by the properties of glass. In 1933, he invented glass wool, an exceptional insulating material. The second, Allan Dick, was a British chemist and specialist in new resins derived from the chemistry of petroleum and coal. Our two pioneers came up with the idea to create a homogeneous material by impregnating fiberglass layers with polyester resin. Initially, the electricity industry took a close interest in their work because it had a real need for effective insulating materials.
At the height of the Second World War, the American industrialist Owens Corning decided to commission a fiberglass-reinforced “plastic” hull for a motorboat. The industrialist had made Games Slayter one of his vice presidents, and his company – Corning Fiberglass Corp. – went on to become a giant in the glass industry. The prototype for this boat appeared in 1944. Other American chemical companies also took on this adventure. However, the invention of the first “plastic” recreational boat is still attributed to Corning and Slayter.
It is fascinating or somewhat mysterious to see that plastic boats are in fact made of… glass. Which might not be particularly reassuring for anyone who has ever broken a window by mistake. Is glass not inherently a “fragile” material? Well, not necessarily, especially when we are talking about “fiberglass”. This fiber is obtained by the high-speed stretching of molten glass beads – at very high temperatures – which pass through a sort of sieve to give filaments that are finer than hair (diameter of 9 to 15 microns). These filaments are then combined in bundles that are interlaced in various combinations. These glass fibers are then coated, which the resin will be able to attach to.
As far as the “fragility” of this fiber is concerned, its tensile strength is comparable with that of… steel! And its elasticity is comparable with aluminum. All with a lower density. While this might seem miraculous, we must clarify that the fiber’s exceptional properties depend to a great extent on how the strands are fitted together. If they are interlaced in two or even three directions – known as a “mat” – they will not have the same mechanical capabilities as if they are aligned in long continuous bundles and wound into coils, known as roving. For boatbuilding, the mat and roving techniques each have a specific use: the first is applied for planking for instance, with simple large panels, while the second is used for more contorted sections, like in the cockpit for instance. We also have “unidirectional” sections, aligned with the direction of the efforts needed to support specific loads.
Process adapted for series production
But let’s not get ahead of ourselves. With this new material, the glass would not be anything without the resin, and vice versa. The resin is a viscose, translucent liquid whose application requires a catalyst and hardener. The polymerization process makes it possible to obtain a rigid, light and solid form, after impregnating the flexible fiberglass fabrics with a liquid resin…
How can we compare this alchemy with the use of timber for thousands of years and metal for the past century, when this material already exists before it is implemented? The major benefit with “plastic” involves being able to create the exact forms we want, no matter how innovative, complex or even contorted they may be. Its use is also far less demanding in terms of know-how and working time than traditional building with timber, less technical than welding metal and easier to reproduce.
Looking at this process in detail, we start off by building a female mold from a master or a timber frame with the precise forms of the hull drawn by the designer. This mold is without a doubt the most delicate part of the whole operation. We need to ensure that it is held in place with metal external stiffeners and sand its internal surfaces as carefully as possible before coating it with wax. We then apply the “gel coat”, the hull’s waterproof outer layer which will look like traditional paint – which is why it is essential to have immaculate surfaces. We then lay the glass fabrics, which we coat with resin using rollers, brushes or even sprays, in successive layers or “strata”. In sections that are contorted or tucked away, we spray resin and fiberglass using guns that are specially designed for this operation and fed by the roving coils mentioned earlier. We then carry out the delicate phase to remove the hull from the mold before stiffening it and structuring it with partitions and counter-molds.
The benefits of building with fiberglass-reinforced polyester clearly stand out: we can give the hull and deck the exact forms that we want. We can reproduce as many identical hulls as we want from the same mold. “Plastic” is water-tight, solid and not affected by the elements. It does not rust, corrode or rot. If implemented correctly, it is not susceptible to delamination (separation of the various fiberglass layers). Admittedly, for an equivalent weight, its stiffness is significantly less than plywood. But it is far better at resisting punching and stamping work. It was discovered much later on that the gel coat can experience watertightness issues. But new resins resolved this. Above all, plastic supports series construction at speeds that are far quicker than with any other material. This is also reflected in its significantly lower costs and prices.
Pioneers with faith
Of course, these qualities were not enough on their own. This new material was widely mistrusted to begin with. Initially, experts at shows thought that it was just good for waterproofing wooden hulls. However, in the mid-1950s, the American yard Hinckley took the daring step to produce its first “plastic” hulls. Located in the State of Maine and renowned up until then for its exceptional woodwork and veneers, Hinckley promised that its new units would be lighter and more solid than their wooden predecessors. This of course led to uproar in more traditional corners: the new material did not have the noble features or qualities required for yachts, which must be both seaworthy and elegant. Hinckley persisted. And succeeded.
In France, the first plastic hull appears in 1952. This is a small dinghy with plans by the architect Pierre Staempfli. However, the true polyester pioneers are Costantini, Lanaverre, Jeanneau or Rocca.
Working out of La Trinité, the Costantini brothers, who are nevertheless plywood specialists, produce France’s first-ever plastic live-aboard sloop in 1956. This 7m unit leaves less of a mark on history than its neighbor in the yard. While the first sloops are taking shape, a young midshipman called Eric Tabarly is working tirelessly to bring back to life a black cutter from the end of the previous century. He uses its aging timber hull as a mold and applies seven layers of glass fabric soaked in polyester resin to create a new one. This cutter is the Pen Duick.
Slightly earlier, in 1955, a Bordeaux-based cooper or barrel-maker called Lucien Lanaverre, whose business was struggling, decides to make the switch to building boats. He first produces a 505 – a magnificent dinghy – in molded timber, then takes the daring step to create a little Moth – a tiny solo dinghy – out of polyester. When he meets the naval architect Christian Maury, this changes his destiny. Christian Maury designed a dinghy for the Socoa sailing school in the Basque Country. In 1958, the two pioneers decide to start building this model using polyester. This rapidly enjoys great success and becomes a star on waters around the world: they call it the 420. To begin with, their enthusiasm makes up for their lack of experience… which they gain through its phenomenal success.
At around the same time, the two sons of an Italian carpenter living in France decide to start building polyester motorboats. The first is called Oreste Rocca and is a huge fan of racing and other aquatic acrobatics. He finds that polyester hulls resist better than their timber counterparts when taking the boat up a ramp to fly through a circle of flames… His brother Louis Rocca handles the technical side of the construction process. In 1957, the Rocca brothers build 1,500 polyester motorboats. They consumed 80 tons of resin and 70 tons of glass fabrics.
In the same year, a young daredevil from Vendée, a fan of acrobatics, motorbikes and powerboating, creates a timber hull with which he leads the race around the first marker in the Paris Six Hours event. He sees this as a sign. His name is Henri Jeanneau. He has taken over the family hardware store in Les Herbiers, but he devotes most of his time to racing and designing speedboats. He does not believe in polyester. However, the following year, he agrees to produce a plastic hull “just to see”. He tests his prototype by throwing it at full speed onto pebbles, sand and even rocks. These experiences convince him. In his eyes, the new material is an unprecedented technological breakthrough. He builds a yard and launches the series production of “plastic” boats. All that is left now is to convince his clients.
And they will be very keen. From motorboats to sailing dinghies and, very soon, live-aboard boats, the pioneering polyester takes off across France. It opens up and accompanies a new era: converting an old rural country to the magic of the sea.