News: Strong and light: the evolution of the epoxy infusion revolution
Specialist epoxies and innovative techniques have enabled boat builders to construct boats which are lighter and tougher than ever before. David Johnson looks at the evolution of infusion technology which does so much to reduce the compromises of boatbuilding.
Large boat/small boat? Cruiser/racer? Sail boat/motor boat? Aluminium/fibreglass? (Or wood? Or composite?) No matter what kind of boating you’re into and whether you’re an owner or a manufacturer, it is impossible to escape the seemingly endless decisions that have to be made and, with them, the inevitable compromises.
One of the most important and fundamental considerations is the relationship between weight and strength. An ideal boat, after all, would be engineered to combine both of these qualities.
Where a boat builder wishes to produce aesthetically exquisite, lightweight, durable and void-free process-controlled parts (large or small), then using vacuum resin infusion techniques with specialist epoxies has become the most obvious approach.
Unfortunately, that’s not always possible. For example, whilst it is possible to build extremely durable hulls using polyester or vinyl-ester resins, they are invariably as heavy as they are strong. For sailors, such boats will never be the fastest on the water. For motor boaters, they’re not going to be the most fuel efficient.
But not all manufacturers have had to compromise between weight and strength. To create components that are both strong and light, boat builders require low-viscosity epoxy systems that have been specially formulated for resin infusion. That’s exactly what was first developed in the 1970s by Gougeon Brothers, Inc., (GBI), an organisation founded by three brothers from Bay City, Michigan. Nearly fifty years of continuous development and testing later, the latest incarnations of these special epoxies are available today, manufactured by West System International and sold under the PRO-SET® epoxy brand.
The evolution of in-mould infusion
To get the very best from these specialist epoxies, new boat building techniques have been developed. The most important of these is the evolution of in-mould, vacuum bagged resin infusion techniques.
The delivery of epoxy within a mould via vacuum or pressure is a development of 50 years of experimentation that have their roots in the advent of polyester resin and glass laminates. The original idea was to control hazardous volatile organic compounds (VOCs) associated with open mould hand layup techniques, when using either polyester or vinyl-ester resins. Both Colin Chapman, who shared the manufacturing methods of Lotus cars with that of the Moonraker motor boats design and Jeremy Rodgers, with the classic Contessa range, can be credited with some of this early experimentation.
The method of infusion with epoxy is slightly more recent but was, none the less, developed many years ago. The process is driven by a desire to optimise quality whilst also being mindful of operator contact with the mixed epoxy. Where a boat builder wishes to produce aesthetically exquisite, lightweight, durable and void-free process-controlled parts (large or small), then vacuum infusion using specialist epoxies has become the most obvious approach.
Key benefits of using specialist epoxies with infusion techniques for boat builders include:
- Superior strength
These specialist epoxies are among the strongest available, ensuring that well engineered hulls are suitable for the complicated stress and loading on a marine structure and are protected against impacts and abrasion for longer.
- Lighter, better performing boats
Replacing polyester and vinyl-ester infusion with specialist epoxy formulated for infusion processes and using appropriate composite engineering, can significantly reduce the weight of hulls and improve the performance of boats. In addition, boat builders who use these epoxies can reduce the weight of components above the vertical centre of buoyancy (the superstructure) to minimise rolling and other performance issues.
- The right viscosity for infusion
These specialist epoxies have been formulated to have the perfect viscosity for infusion, allowing rapid processing.
- The correct gel and working times for successful infusion of the largest projects
Unlike polyester and vinyl-ester resins that require more hardener to speed up the process, infusion epoxy resin can be combined with a range of different hardeners to optimise the pot life and working times for successfully infusing a large or small component. Cure times can also be adjusted by blending the four available hardeners. This makes epoxy suitable for even the largest, most complex infusion projects, as well as for intricate, irregularly shaped components.
David Johnson is Technical Operations Manager at West System International. He can be contacted here.