For nearly 30 years, 12-Meter yachts took center stage at the America’s Cup. The last 12-Meter was built in the late ’80s, but a meticulously restored fleet of “Twelves” continues to race in Newport, RI, thanks to a group of enthusiastic owners.

Enterprise (US 27), built in 1977, is the latest 12-Meter to undergo restoration. This includes adding a newly redesigned, fully optimized keel. Sparkman and Stephens was engaged to do a performance analysis and design the new keel; Symmetrix was brought in to create an accurate pattern.

The Symmetrix pattern will be used by the Broomfield foundry to create a cast concrete mold. Lead is poured into this mold to create the keel.

Twelve Meters race under a complex rating rule that takes many factors into consideration, including weight and volume of underwater surfaces. Precise shaping of the mold is critical; if it’s off by even a fraction of an inch, too much (or too little) lead will be used, throwing off the keel weight. Symmetrix’s precise CNC shaping of the pattern ensures that the molds are accurate, which in turn ensures that the keel meets the size and weight calculated by Sparkman and Stephens.

The refit of Enterprise will be completed this spring, in time for the 2018 racing season.