Material World

New composites and how they are used are making boats lighter, stronger and faster
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High-tech materials and techniques are often proven on raceboats before being applied to recreational vessels.

High-tech materials and techniques are often proven on raceboats before being applied to recreational vessels.

Gino Morrelli and his partner Pete Melvin have been at the leading edge of composites technology in the boating industry for decades. They helped design and build America’s Cup boats and parts for the Stars & Stripes syndicate in 1988, worked with Oracle Team USA a decade later, and have drafted numerous power and sail designs. They’ve spent more time working with carbon and other high-tech materials than many boatbuilders have with fiberglass.

When asked where composites are headed, Morrelli had an interesting answer: “To me, it’s glass.”

Morelli is talking about Gorilla Glass, which Corning makes and is similar to what is used for smartphones. It’s a multilayer, clear laminate that Morrelli believes will eventually be used as a supporting structural element in boats because its properties are superior to conventional float glass for curving, tinting and gluing in ways that designers want for today’s boats.

“The driving force is to make the outside available to the inside,” he says. “Putting in bigger windows is a big driver for recreational boats and charter boats.”

Gorilla Glass is used on Boeing’s 787 Dreamliner and Airbus’ A380 aircraft. Lights can be integrated into the glass and dimmed, and television can be projected through the glass. On the 787 Dreamliner, each window has its own dimming switch.

If glass on a boat can be dimmed, then the need for external eyebrows and blinds, for shade inside, is eliminated. Large windows provide great views, but they also let in sunshine. That necessitates eyebrows on the outside of boats and blinds on the inside. “If we can get the glass to dim, we can get rid of the valances and eyebrows and all the weight,” Morrelli says. “We’re doing the math on a daily basis with suppliers.”

Carbon is King

Though the concept of see-through hull sides remains a longer-term vision, the current state of the art in composites for Morrelli and Melvin is the use of carbon and epoxy resins. Ultra-high-modulus carbon, like the stuff used for aircraft, costs about $200 a pound, but Morrelli says the carbon he uses on boats prices out at about $25 a pound. “Carbon’s so cheap it’s crazy not to use it,” he says.

Ultra-high-modulus carbon will be in play for the upcoming America’s Cup, but since the rules have put a cap on autoclave pressure that can be used for constructing parts, it limits the level of carbon quality required to make the parts. “Once you cap autoclave, you put a cap on the stupidity,” Morrelli says, explaining that otherwise, teams could be spending a quarter million dollars on a few pounds.

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The infusion process ensures that the precise amount of resin is evenly distributed throughout the part.

The infusion process ensures that the precise amount of resin is evenly distributed throughout the part.

Still, as with any high-tech material, there are compromises with carbon. “Airplanes have bird-strike problems, but we hit whales, kelp and debris,” Morrelli says. “We build a boat with 2 millimeters of carbon around a foam core that is plenty strong, but it can’t take a bump at the dock.”

He continues: “We’re struggling and still working on finding the best compromises between all the conflicting requirements and make it halfway affordable.”

Eric Goetz, chief technology officer at Goetz Composites in Bristol, R.I., says that because carbon is finding its way into more projects, the price is coming down. Production of aircraft-grade material trickles down to more commercial-grade material that a custom boatbuilder would use. That brings down costs.

Morrelli adds that the cost of a boat is about more than its price. It’s also about retaining value over time. Before building a boat, Morrelli asks the owner: “What’s your escape plan? Will you own this boat and pass it on to your grandchildren?” If a boat isn’t pure carbon, he tells them, it’s going to have second-class resale value.

Steve French, director of operations at Garlington Landeweer Yachts and president and owner at French Yachts and at Applied Concepts Unleashed, says buyers seek out those brands because of their resale value. It is not unheard of, he says, for a Garlington 44 built 30 years ago to sell for twice as much as its original price. “The economy of a French yacht and the economy of a Garlington is the longevity,” he says. “If you have a boat that doesn’t last very long and it has maintenance and repair issues, it’s not going to have good resale.”

French calls his manufacturing process Lifetime Construction Technology, and as the name implies, it focuses on building boats that last. In the custom fishboat world, he says, few builders are using infusion because it is best done with molds, and most manufacturers use jigs or cold molding. French Yachts and Garlington both use epoxy resins and 17- and 18-ounce multidirectional woven fiberglass. French uses wet infusion for wetting out the laminate, while Garlington uses dry vacuum-bagging and some wet bagging.

Garlington is moving toward infusion, French says. During infusion, the dry fabric and core material are laid into a hull, deck or part, and then a vacuum draws the resin through the part. As long as there are no vacuum leaks, infusion is considered the best way to arrive at the proper amount of resin for optimum saturation without excess. In vacuum-bagging, the laminate and resin are all applied, and then the bag is pressurized. The pressure spreads the resin through the fabrics, forcing out excess to provide maximum strength and minimum weight.

For ultimate curing, manufacturers post-cure a boat’s laminate in a huge oven called an autoclave. Outerlimits Offshore Powerboats in Bristol, R.I., does this for its 100-plus-mph high-performance boats, which sell for close to or in excess of $1 million. Goetz introduced Outerlimits founder, the late Mike Fiore, to carbon, epoxy resin and post-curing when Fiore was looking for a way to save weight on an engine hatch. Fiore became so enamored of the process that he started building entire boats with the materials. Outerlimits remains the only high-performance powerboat builder to use carbon and epoxy and post-cure on every hull and deck.

The interior module of a boat is readied to be dropped into the hull.  The yellow panels are infused composite.

The interior module of a boat is readied to be dropped into the hull.  The yellow panels are infused composite.

There’s a difference, Goetz says, between a laminate being post-cured to reach its optimum properties and one that needs to be cooked for the preimpregnated laminate to cure. Costs are also an issue, French says. “Autoclave to do a 60-foot hull, just the real estate and maintenance would put people out of business,” French says.

On the French 54, as many parts as possible are infused; even the cabinet panels have a carbon-fiber grid. French Yachts builds its 34- and 54-footers from the keel to the hardtop with carbon-fiber tape on joints and chemical bonding. “It lowers maintenance by doing everything that can be done in composite and gluing it together instead of screwing it together,” French says.

Just as the America’s Cup helped improve sailboat design and construction methods, offshore powerboat racing has done the same for high-performance boats. The builder that has dominated one of the sport’s most competitive classes is High-Tech Composites in Melbourne, Fla. The company builds 32-foot catamarans with enclosed cockpits that race in the twin-outboard SuperStock class. The boats are powered by identical engines and run at speeds exceeding 100 mph in calm conditions.

Modern processes result in efficiencies in the plant and on the water.

Modern processes result in efficiencies in the plant and on the water.

Doug Wright, managing partner of High-Tech Composites, says his company uses E-glass with substantial carbon reinforcements, including a 3/8-inch-thick stringer cap in the sponsons and on top of the bulkheads. He uses Gougeon epoxy resin and Airex closed-cell cross-link PVC foam coring for its adhesive properties. “You can’t rip glass off it,” Wright says.

Instead of infusion, High-Tech uses a resin impregnator to get a glass-to-resin ratio that includes about 65 to 70 percent glass. The laminate is then vacuum-bagged before it is post-cured at 140 degrees for 12 hours. “We’re making the boat as light as we can,” Wright says. “The only way to get the boat as light and strong as we can is to vacuum-bag it.”

Lighter and Stronger

It wasn’t long ago that boatbuilders preferred 2408 woven roving. The 24 stands for ounces. Today, most builders use 1708 and 1808, a 30 percent or so reduction in fabric weight alone. Infusing or vacuum-bagging helps further reduce weight by eliminating excess resin, and it results in a stronger part.

Where things get tricky is when vertical or angled surfaces come into play. A builder must get the resin to stay on those surfaces. Even the highest-tech resins won’t do any good if they run off a part. Fillers made from manmade or natural materials added to the resin help get it to stay put. French likes to use rubber-toughened epoxy for strength and flexibility.

“It’s not the adhesion, but the right amount and kinds of fillers that have to stay on the surface and not run out,” French says.

The darker material is carbon, and the lighter is closed-cell foam.

The darker material is carbon, and the lighter is closed-cell foam.

JB Currell, owner of JNJ Composites and Coatings in Holderness, N.H., says the difficulty in using carbon correctly in an infusion application is getting a complete wet-out of the fiber, because of carbon’s color. It’s black, and the epoxy resin is clear, so it’s difficult to see.

“In a standard glass layup, I can dye it and see that I have complete wet-out of the glass,” he says. “With carbon, I weigh the carbon and weigh the resin, and I know it’s all gone into the part somewhere.”

The use of chemical adhesives such as 3M 5200 and Plexus continues to become more widespread in the marine industry. The goal is to use fewer large parts that are bonded together, instead of mechanically fastening smaller parts.

“We’re big on longitudinal stiffeners made out of carbon, stringers, chines, tied-together cabinetry and structures with carbon strap,” French says. “I expect to see more high-strength adhesives, more modular assemblies, more of a culture of making boats that become one piece.”

Currell says the most critical thing with materials is understanding how they work and what is actually needed. “It’s understanding the orientation of the fiber and that carbon isn’t always required,” he says. “You can substitute carbon with S-glass.” Currell adds that E-glass, which many builders use, was designed for electrical insulation, and that S-glass, which is more for structural applications, is a better choice for boatbuilding.

French had a builder come to him because the company’s 55-foot power cruiser was flexing too much in the water and had excessive stress fractures in the deck. French recommended running a carbon-fiber cap the length of the stringers and bonding it with epoxy resin. It stiffened the boat, eliminating the stress cracks.

French used epoxy because polyester doesn’t have good adhesive properties. Currell says the lack of adhesion is a major cause of delamination because polyester doesn’t bond well to cores. It doesn’t stick to the substrates. He prefers a high-density, closed-cell foam or honeycomb for interior bulkheads. The foam can be shaped by being heated.

Additionally, builders must understand at which angles to place the fabric, based on the loads. “It’s understanding where the load is going to be and where the fiber is going be,” Currell says. “If you don’t want the hull to twist going through waves, use a plus or minus 45, put it over a stringer so the stringer is the 0 in the axis, and the plus or minus 45 would crisscross each other.”

High-Tech Composites uses vacuum-bagging to produce the lightest, strongest hulls possible.

High-Tech Composites uses vacuum-bagging to produce the lightest, strongest hulls possible.

A quad-directional glass runs longitudinally, laterally and at opposing 45-degree angles. When a builder lays them down, there is less resin in the outermost layer, resulting in less print-through on the boat’s exterior.

Experts say that temperatures play a key role in laminates, as well. Builders should store high-end materials and resins in climate-controlled areas. If fiberglass and cores are stored in an open area in a humid climate, they will absorb ambient moisture.

Madness to the Method

French says he’s encouraged by the increase in manufacturers using computer numerical control equipment. “The beauty of CNC is that people will trust the modeling,” he says. “You’re going to have boats that will be built better.”

Morrelli & Melvin employs experts with doctoral degrees in finite element analysis and computational fluid dynamics to help identify high-stress areas and develop the best laminates in real time, while a boat is being designed. “We can use FEA to define the load paths, and we have enough real-world results that we can go out and test the boats against the FEA results for deflection,” Morrelli says. “It makes the laminate and the structure more precise, and because it’s much more reliable, now we can trust it.”

Because of the advances in materials made in the past decade, Morrelli says boatbuilders at the leading edge are now improving construction methods.

For example, when using chemical adhesives to bond larger, heavy parts, most builders are concerned about a “kiss-off.” After a bed of adhesive is placed, when the two parts come together they will force out the glue between the pieces if some sort of gap isn’t created for the glue to remain. Fixtures equipped with springs and clamps that connect to the parts and maintain that gap are required to avoid that issue.

“Getting boat manufacturers to invest in fixtures like these is that game-changing last step,” Morrelli says. “Improvement in these methods will let us benefit from some of the materials in much better ways.”

This article originally appeared in the February 2019 issue.

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