When Boston Whaler wanted to build a bigger boat, the Edgewater, Fla.-based company faced a problem. The boat’s weight would be too great for its manufacturing facility to handle. Boston Whaler overcame that challenge thanks to advanced composites engineering, and its biggest boat ever – the 42-foot-long 420 Outrage – hit the waves in September. The company teamed with long-time partner Marine Concepts, a composites manufacturer, on the project. Two other industry companies contributed: Composites supplier Gurit and infusion specialist Composites Consulting Group.

Boston Whaler builds six models of fishing and pleasure boats using vacuum infusion to fabricate fiberglass liners and hulls. These are bonded together with a high-density foam sandwiched in between, making the resulting boats almost indestructible, says Chris Wachowski, director of product development at Boston Whaler.

However, going bigger than a 40-foot hull for its new 420 Outrage boat presented difficulties. To fit within existing Boston Whaler manufacturing capabilities, the hull and liner molds had to weigh less than 60,000 pounds. “That is the weight of our 370 Outrage, which was our previously largest Whaler,” Wachowski says. “If we built our tools with our traditional design practices, the new hull and liner molds for the 420 Outrage were predicted to weigh over 90,000 pounds.”

This slimming down in weight, though, could not take place at the expense of strength. During production, the liner is maneuvered into the hull and bonded to it, with a hollow space between the two. Into this space, a robot gun injects a two-part structural foam core that expands, creating an unsinkable foam-fiberglass construct, according to the company. During expansion, the foam creates tremendous pressure on the liner and hull, so material strength is critical.

Previously, Boston Whaler used a steel frame and steel bulkhead/grid construction. This frame system was attached to the hull and liner molds, providing the rigidity needed to prevent them from swelling and perhaps exploding due to the pressure of the expanding foam, says Todd Biddison, project manager at Marine Concepts in Cape Coral, Fla. However, the company’s traditional method would not work for boat lengths beyond about 37 feet. “We had to find an alternative construction method,” Wachowski says.

In searching for a solution, the closest comparable designs Boston Whaler could find were wind turbine blades. As much as 300 feet long, these blades are typically formed by two-part closed molds that must be strong and lightweight. So, the company turned to Gurit USA, which had experience in this area.