Building better boats

A new fibreglass moulding process that produces large, low volume pieces has recently been demonstrated by Minneapolis-based Genmar Holdings.

A new fibreglass moulding process that produces large, low volume pieces has recently been demonstrated by Minneapolis-based Genmar Holdings, who claim to be the world’s largest independent boat builder.

Eight 2001-model-year Larson and Glastron boat models from 17 to 21 feet will be built with the VEC (Virtually Engineered Composite) process, and plans are for all models 24 feet and under to be made in the VEC plant, a new 95,000 sq. ft. facility.

VEC replaces the traditional open-moulding process with a computer-controlled, closed-mould system that makes complex fibreglass parts of defined thickness and strength. Production takes place in an automated and self-contained cell. A two-part ‘floating mould’, supported by water pressure in a surrounding vessel, takes the place of complex steel-and-wood supports and open moulds used in the past.

VEC mould ‘skins’, the liners that vary relative to the parts being made, can be changed in about an hour, making it possible to produce a number of differently sized and shaped parts in the same VEC cell.

The VEC process begins with a spray of gelcoat on the mould. Then precut pieces of proprietary fibreglass material along with precision-moulded urethane foam sections are laid into the mould sections. The two mould halves are then joined together and a precise mixture of resin and catalyst are injected, under pressure, into the space between the mould halves. Water surrounding the mould supports it against this pressure and controls the temperature of the moulded parts as it cures.

Sensors inside the mould monitor every facet of the process and transmit data to a computer which controls more than 500 variables including temperature, viscosity, flow rates, mass density, gel times and peak exotherms. It automatically adjusts the components to produce a fibreglass part cured in consistently optimal conditions.

Every VEC cell is also linked to a central computer at Genmar’s VEC Technology, Inc. headquarters in Greenville, PA, where the system was developed and perfected, for quality control and trouble-shooting purposes. The system is so precise, tests have shown less than one-pound fluctuation in total hull weight among 1,000 hulls already manufactured.

In Genmar’s VEC process for boats, the hulls incorporate a stringer system and boat floor in a single part, with backing plates in place for mounting the engine and other hardware. A five-axis robotic router/driller precisely trims (to 1/1000th inch) the hull and deck, cuts openings for engine and drive mountings, and locates holes for mounting hardware. Hull and deck parts then proceed separately down an automated production line for final assembly before being moved to a staging area for shipping.

The VEC moulding process is claimed to be more precise and four times faster than traditional open moulding. It reduces styrene emissions from lamination by as much as 90 percent so that more parts can be built while complying with EPA regulations. The VEC floating mould technology also lowers tooling costs and permits more flexible production, with a variety of parts producible in the same VEC cell.

The closed-mould VEC system results not only in a cleaner environment, it also produces a stronger part since styrene that may escape in the traditional process now is infused within the laminate. VEC parts are also virtually wood-free, which reduces consumption of forest products and wood waste.

Genmar has announced that it already engaged in discussions with other companies worldwide, in various industries, relative to licensing its VEC technology.

www.genmar.com