Vacuuming carbon for the new Bermuda 50Oct 2, 2015
A Hinckley Bermuda 50 during construction.
One of the keys to a speedy boat is building it lightweight. For pure race boats, this has meant carbon fiber construction and spare interior spaces. Most racer/cruisers, however, are built with more of an eye toward comfort. The latest Hinckley design, the Bermuda 50, takes an approach to building light and strong by using a cored hull of carbon fiber. This plan yielded the impressive hull of the Bermuda 50, a modern racer/cruiser with offshore capability.
Peter Smith is Hinckley’s senior product engineer for the Bermuda 50 and he is a key player in Hinckley 50 construction. Building a different type of sailboat compared to what Hinckley has made in the past was a departure for the Hinckley team. “It’s a new product, so it was exciting,” Smith said. “We’ve completed one and are about to launch the second.”
In addition to the design departure of a more modern, racer/cruiser hull shape, a different layup was used for the B50. Most Hinckley vessels are built using a group of materials that Hinckley calls DualGuard, which is a combined Kevlar/E-glass outer skin, coring and then a carbon fiber inner skin. For the B50, Hinckley switched to an all-carbon sandwich with carbon outer skin, an M-series Core-Cell SAN foam (SAN is styrene acrylonitrile, a different and improved chemical mix compared to the polyvinyl chloride mixtures based on older technology used in earlier coring materials) and a carbon fiber inner skin. In all, each boat uses 22,000 square feet of carbon fiber to complete the hull layup.
Why the switch to all carbon? According to Smith, the move was due to the tall 81-foot rig on the B50 and the mechanical stresses that produces. “With the high bending loads,” Smith said, “we wanted extra stiffness. The strength to weight and the stiffness to weight of the carbon is very good.”
Fiberglass has been around for a long time and most sailors have had some experience using glass cloth to make repairs. Carbon fiber has become widely used in a variety of products, but the shiny black material does retain some of its exotic reputation. It might seem there is a big difference working with tens of thousands of square feet of carbon compared to a material like E-glass. According to a boatbuilder like Smith, however, the difference is minor. “It was virtually the same. It involved handling dry fabric just like fiberglass. And we used the same SCRIMP process for the carbon.”
A simplified look at the SCRIMP process.
SCRIMP is also a mature technology in use by the boatbuilding industry. The acronym stands for Seemann Composites Resin Infusion Molding Process. The technique was developed by Bill Seemann, a builder of boats and other fiberglass products. In the early 1960s, Seemann had a small boat repair company called Leda Boat Works. He began building Olympic-class Finn racing dinghies and eventually larger custom sailboats. With this experience, Seemann became even more interested in finding ways to improve boatbuilding techniques. His search for solutions led him to invent and patent C-Flex, a system that uses longitudinal rods embedded in the fiberglass fabric. In 1970 he founded Seemann Fiberglass and investigated vacuum processing. In 1987, he started another outfit called Seemann Composites to further develop the SCRIMP concept. In 1990, Seemann was awarded a patent for the SCRIMP method.
Using plastic bagging, SCRIMP employs a vacuum pump to produce a near-vacuum at several points along the hull layup. This low pressure draws the resin through the fiberglass or carbon fiber material in a controlled, uniform way. One of the big advantages of using SCRIMP compared to hand layup is a big reduction in volatile organic compound (VOC) emissions, which in the past few decades have come under strict supervision by Federal and state environmental agencies. The process also leads to lighter, stronger parts with more predictable resin to cloth ratios.
Peter Smith agrees that SCRIMP was the way to go for the B50, which uses vinylester resin for wetting out the carbon fiber. “It means a much better workshop environment. And it produces a more consistent laminate that is lighter, stronger and stiffer.”
So not only does the B50 reflect the latest ideas in a modern racer/cruiser, its SCRIMPed and cored carbon fiber hull is produced with state-of-the-art techniques and materials — just like the original Bermuda 40s built in 1959 from solid fiberglass when it was still a new material.