Bullet Proof

Advanced Boat Building

FSF Staff September 24, 2010

Boat builders are constantly on the hunt for a competitive edge. Whether it’s the most technologically advanced construction techniques or highest grade building materials, any advantage or enhancement that will leave the contenders in their wake is welcomed. For years, fiberglass remained the go-to material for boat manufacturers and although it will likely never be phased out, times are changing.

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The founding father of all composites, fiberglass is still widely in use today due to its proven track record and inherent rot-resistant and cost-to-strength benefits. While fiberglass gets the job done and will continue to do so for many years to come, new fibers offer key advantages to technology oriented boat builders. It’s important to understand that Kevlar is a trademark from Dupont on a material called aramid. There are numerous aramid providers; however only Dupont calls it Kevlar. While Kevlar and carbon fiber are extremely lightweight, durable and stiff, they are also very expensive. Because they are so costly, the use of these materials has historically been limited to technical poling skiffs where weight is critical and materials are limited.

For years, fiberglass remained the go-to material for boat manufacturers and although it will likely never be phased out, times are changing.

Egret is one of the premier manufacturers of shallow water flats skiffs and has been utilizing carbon/Kevlar for years. While they still manufacture skiffs with traditional fiberglass laminates, carbon/Kevlar is the ultimate hull material that’s desired by angling’s most elite clientele. While skiffs have been Egret’s mainstay, they’ve stepped it up a notch with the 306 Offshore. Not your typical center console, Egret offers an option to have the 306 Offshore built with carbon/Kevlar. With this enhancement anglers can expect to reduce overall weight by 600-pounds, which will provide increased performance and fuel efficiency.

Because it is so expensive, it makes perfect sense that builders of the largest sportfishers would only utilize advanced fibers selectively to reinforce the hull and deck. Weaver Boatworks, a leader in the custom sportfish market utilizes layers of Kevlar for its inherent strength benefits, not weight. Weavers are some of the fastest custom convertibles available. To achieve the structural integrity required to push a 70-foot yacht upwards of 50-knots the legendary builder utilizes Kevlar to reinforce the interior and exterior of each cold-molded hull. Utilizing triple-planked Okoume plywood, Douglas fir stringers, and a heavy-duty hull outfitted with a layer of Kevlar, these offshore battlewagons are designed to take on whatever Mother Nature can dish out. In the event of a serious impact, the Kevlar reinforcements will stretch, where traditional e-glass would simply fracture.

While Kevlar and carbon fiber are becoming increasingly popular, as technology continues to grow builders have been looking beyond the marine industry. Kevin Fenn of East Cape Skiffs is dedicated to producing cutting-edge flats boats. While East Cape offers technical poling skiffs with carbon fiber and Kevlar laminates, Kevin has recently been experimenting with Innegra, a polypropylene material designed for composite fabrication. A portion of the material is actually recycled soda bottles. In recent years, Innegra has been used in Formula-1 racecars as a replacement for carbon fiber. Innegra has the strength and all of the benefits of higher-grade fabrics without the brittleness. Perhaps the greatest benefit is that it costs 33-percent less than carbon/Kevlar while retaining the same attributes.

When it comes to a high-quality finished product, advanced construction techniques are the second part of the equation. Legend Custom Yachts has over 20-years of experience building boats with advanced composites. Legend is currently the only company building semi-custom sportfish yachts out of pre-impregnated resinous material reinforced with multi-directional carbon/Kevlar fabrics. “With pre-preg you don’t have to mix anything and the process is absolutely precise. The material is delivered at 3° below zero. When we order pre-preg material we specify the exact amount of resin content and the engineers at the factory consider the desired performance, durability and flexibility when confirming what amount of resin content is optimum. The only way pre-preg can be accomplished is with specialized computer driven impregnators. Each layer is vacuum bagged with the last step involving a final vacuum bagging with a 180° post cure for over 20-hours. This liquefies the gummy resin, which perfectly flows through the material. It’s the same process that’s used to manufacturer F-22 Raptor fighter jets.” Says Scott Gerber, President of Legend Custom Yachts.

With manufacturers constantly exploring new-age materials and construction techniques, recreational boaters can only benefit. Boat builders are looking for new ways to capture clients and advanced construction processes coupled with space age materials including high-tech fabrics, resins and coring materials are paving the way for the most high-performance vessels of all time.

Suck It Up

While pre-preg may be the future, vacuum bagging and resin infusion are two commonly used techniques with resin infusion offering greater control. Vacuum bagging is a clamping technique that utilizes a bag and a series of pumps to suck out excess resin and air to achieve a solid laminate. This technique is highly dependent on the technicians, as the amount of vacuum pressure is critical. Too much suction will draw out too much resin, while not enough suction will result in a weak bond. Vacuum infusion differs in that the process uses the sealed bag to draw resin through the fabric and into the mold at different locations. It’s a more controlled method that maximizes the fiber/resin ratio while offering perfect adhesion to core materials.

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