Part and Parcel

As boaters demand lighter, stronger, and faster boats, what goes into the construction will matter more
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Goetz Composites built this  70-foot cataman using preimpregnated carbon fiber.  Here, it’s being rolled over so construction can be completed.

Goetz Composites built this 70-foot cataman using preimpregnated carbon fiber. Here, it’s being rolled over so construction can be completed.

When I look at technological advances in construction materials and techniques, I see a widening of the horizon. The building blocks of composite boats have remained constant throughout the past couple of dec­ades, but the demands put on those building blocks are increasing.

People want to go faster and try electric propulsion — in some cases it’s mandated — and they want to cruise to different parts of the world. These pressures have caused builders to respond with lighter, stronger, and tougher boats, as well as different approaches to increasing speed.

In terms of the building blocks, fiberglass, carbon and, to a lesser degree, Kevlar are the basic fibers. Polyester, vinylester and epoxy are the resins in use. Balsa, foam and honeycombs are the cores. Also in the mix are renewable natural fibers; these are now being used in small items such as sports helmets, surfboards and skis—and in some areas of boats.

Renewable fibers have variable sets of properties depending on sorting, harvesting and where they are cultivated. Some of the strongest of these, when properly sorted, have properties similar to fiberglass.

At the JEC World international composites show last March in Paris, our team saw ample evidence of other industries — automotive, furniture and consumer goods such as decking, siding and fencing — diving into alternative fibers made of materials such as flax and hemp. But we haven’t started using these in our facility.

More boatbuilders are accepting higher-tech resins, such as epoxies. Hinckley Yachts has gone to all epoxy, and MJM Yachts has been there since the company’s inception.

More companies are also moving away from polyester and vinylester resins. Fabricators are looking for resins formulated with materials other than oil-based compounds. Eco-friendly resin systems are not as fully developed as the natural fiber sector, but change is coming. Gougeon Brothers recently bought a company that produces plant-based—not petroleum-based—resins.

One new material that’s gaining popularity is a thermoplastic core made from recycled plastic milk jugs called polyethylene terephthalate (PET). Many boatbuilders are using it because it can be implemented in the same ways as conventional foam core, so there are no new processes to learn. We used it for creating a structural lid for a box inside a sailing catamaran. It’s a little heavier than foam, but it’s less expensive. Companies including Gurit, Diab Group and Composites One all supply PET.

The primary industries we look at for next-generation materials are automotive, aircraft and wind turbines. We observe automotive processes because they are developing so many parts so quickly. The aircraft and aerospace industries work so much with carbon fiber — the Boeing 787 has 98,000 pounds of carbon fiber in it — that we’re always on the lookout for process upgrades. We don’t build blades for wind turbines, but we have clients who insist on long life span and safety, so we use that industry’s extensive research.

We can use that kind of data with our customers who are looking for longevity in whatever we build them. There aren’t necessarily different materials used in wind, but there is a bit of different science.

For instance, when we’re making a part that contains a stock of carbon-fiber strips or pieces, we typically have to perform debulking to ensure that there are no air voids in the laminate. Usually we would have to do that by putting on a vacuum bag every ply or two. The wind industry figured out how to stack the pieces, apply resin and only bag it once at the end. That approach makes the process easier and reduces labor costs.

As materials and processes evolve, they are still driven by the desire for increased performance and payload. In sailboats, there is a move in the performance arenas to flying the boats on hydrofoils. It’s not just America’s Cup boats; French manufacturer Beneteau builds foiling sailboats for recreational use and has developed foiling powerboats, as well. This move requires increasing structural strength in areas of the hulls that are not normally as stressed. Bottoms, topsides and decks need to be engineered to accept foil loads.

If you’re foiling and the hull is out of the water, you essentially are suspending the boat by the area of the hull that the foil plugs into. We reinforce those areas, removing the core and substituting solid carbon laminate. If the foils retract using hydraulics, the hull needs to be engineered to anchor the rams.

In powerboats, we are seeing two diverging paths. One is making boats faster through the application of more horsepower, especially with outboards. There are boats with three, four and five outboards. Even heavy, overbuilt hulls respond to overwhelming horsepower.

The second path in powerboats is more sophisticated and recognizes the need for eco-friendly approaches. This starts with designs whose shapes reflect a greater understanding of advanced naval architecture. Combining these shapes and then relying on a more sophisticated, engineered approach to building, using more directional reinforcements and higher-performing resins to save weight and maintain or increase strength, makes for more easily driven, fast and relatively economical craft.

Whatever we can dream up, it’s coming. Embrace the changes. 

Eric Goetz is a worldwide leader in high-tech composites. The chief technology officer of Bristol, R.I.-based Goetz Composites, he was the first to build prepreg carbon racing sailboats in the United States and has built more than 100 custom boats, including nine America’s Cup racers, one of which won the 1992 contest.

This article originally appeared in the November 2019 issue.

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