Visitors to Charleston, S.C., often skip the tour bus and take in the city’s historic neighborhoods by horse-drawn carriage instead. A unique part of Charleston culture, these large, 16-passenger carriages have been rolling along the city’s streets for decades. One tour operator, Old South Carriage Company, recently put a modern twist on a longstanding tradition by converting its fleet of carriages from wood to composites.

According to Dick Williams, operations manager at Old South, wooden carriages require “excessive maintenance” including painting, tightening fasteners, replacing corroded parts and rebuilding each carriage with new wood every 10 to 12 years. So, about a year-and-a-half ago, the company began exploring alternative materials.

Old South considered aluminum but decided that it, like wood, would be subject to corrosion and difficult to keep coated. The company also explored epoxy wood systems but realized that laminated wood carriages would be too heavy. In the end, Williams says fiberglass composites were “a total stand out” in in terms of durability, lightness and the ability to reproduce identical components from the same tools.

Even so, Williams admits it was a far stretch for a carriage company to move away from wood. However, the attention surrounding Boeing’s new South Carolina facility helped him convince Old South’s owner. Part of his argument was “if it’s good enough for Boeing, it’s good enough for carriages.”

Old South sought out Cutting Edge Composites in Summerville, S.C., to discuss the idea. “I think they were a little bit shocked,” says Williams. “These guys are in the business of building composite components for military applications. They do some very high end stuff… and we roll in there one day with a carriage to see if they could build it.”

The two companies worked together for six months to design the body, roof, running boards and seats for the 6 x 12-foot carriages. There were several considerations to be made, starting with the strength of the vehicle. The carriages must carry a driver and 16 passengers totaling approximately 3,400 pounds.

Paul Pace, business manager at Cutting Edge, says the seats needed to be light, yet strong enough to support guests of all body types. The original wooden seats used support beams. The new seats feature an aluminum plate embedded in a fiberglass laminate and tapped so the components can later be fastened together.

The 8 x 15-foot roof also presented a challenge. The initial prototype used heavy laminates like those found in boat tops manufactured by Cutting Edge, but the result was far too heavy. The roof was then redesigned with a very low resin content, reducing its weight by one third.