America’s Cup Yacht Sculpture

Design is beautiful when it works as intended and when properly executed with efficiency in its engineering. The awe of passersby tells us that we have succeeded in creating an amazingly surrealistic sailing sculpture, a work designed to educate and inspire. -Ross Weene, Design Engineer

BACKGROUND
Rodger Martin Design was contracted in Fall 2004 to provide options for displaying, in front of the Museum of Fine Arts Boston, the 1992 America’s Cup defender America3 and challenger Il Moro di Venezia, for the exhibition “The Things I love” – the many collections of William I Koch. Requirements were such that the display should highlight the boats; the sculpture of hull form, the artistry of their applied engineering. The support system in form must work efficiently – it should be as minimal as possible so as to not visually detract from the boats, it must be unique and interesting, museum-quality, and able to sustain winds up to 110 MPH (96 knots) to meet building code.

THE DESIGN
The supporting architecture for the boats was designed to be as light as possible in aesthetic, and, for the most part, invisible at first glance. Approaching the museum from the east one can almost miss seeing the network of wires and support masts designed to work around, and blend in with, existing trees. Inspiration was drawn from a visit to Günter Behnisch and Frei Otto’s 1972 Olympic Stadium in Munich – the system takes the main “windward” supporting wires (one per boat) to the top of compression spars then down to ground.

The two boats are heeled over at fifteen degrees, set on opposite tacks, and sailing upwind to the east, the direction of strongest anticipated winds. Heeling the boats also allows better viewing of the decks. Cyrus Dallin’s 1909 sculpture “Appeal to the Great Spirit” provides interesting juxtaposition and a “windward mark” which America3 is rounding to starboard, leading Il Moro which is ducking astern to then tack and round. Due to the constraints of the display area (in size and numerous underground utilities) – it is a close and exciting mark rounding!

The support rigging by Navtec / Hall Rigging is solid Nitronic 50 stainless steel rod with 316 stainless fittings. We drafted several suspension arrangements involving different numbers of wires and attachment points and then reduced the options to a few best solutions. Structural engineers Erik Egleston, Kirk Mettam, and Mike Davister at Robert Silman Associates then took a look at the options with Finite Element Analysis (FEA) software to assess stability and help optimize the system. The final wire locations reflect optimal structural stability with the minimum number of wires. The longest wire, attaching Il Moro’s midship windward side to the tip of a carbon spar, is a 175′ long single piece of -76 (76,000 lb. break) rod. America3 uses a 109′ length of -76 rod for her main support wire. The thickest wire, at Il Moro’s midship leeward side, is a length of -91 rod.

The 43’ custom woven carbon fiber compression spars by Ted van Dusen of Composite Engineering weigh only 300 pounds each minimizing additional stresses in the wires, and are build of the same high strength & stiffness / low weight material used in the yachts’ masts. They are built by weaving uniaxial carbon fiber from spools onto a custom milled mandrell. The fibers are then saturated with epoxy and autoclaved to cure. Theese spars are themselves a work of art.

ANCHORING THE YACHTS
Within the boats, the main midship supporting wires attach to the keel towers. The bow and stern tethers on both boats stabilize against pitching and yawing in heavy wind, and are attached to the forestay, runner, and mainsheet bulkheads via custom chainplates designed by SDK, the team that originally engineered America3 , and fabricated by Syd Janes of Syd Janes Metal.

The loads on the yachts and rigging are impressive under a 110 MPH wind, requiring a substantial anchoring system. Helical piles are used extensively for the tension wire anchors – there are fourteen total, installed by Solid Earth Technologies. These are a great solution, as they can be installed and removed without vibration – we could not risk damaging the museum’s exhibits if we were to jackhammer equivalent strength concrete anchors. The helicals, like giant corkscrews, are driven to depths of 15-20 feet below grade to engage a layer of clay. They are also used to anchor the concrete footings below each boats’ keel and below carbon support masts, provided by Skanska Construction. Loads in the rigging are monitored realtime via load cells in the main windward wires’ pins. Pretension in all other rigging elements is determined by measuring their harmonic oscillation, by Tripyramid Structures.

Below each ballast bulb is a ball-and-socket joint that allows the yachts to pivot if hit with a blast of wind, rather than bending and stressing their structures, and also take 70 tons compression experienced in a 110 MPH wind blast. These joints were also essential to the installation process – each boat was placed in its socket and atop two custom tipping cradles. Then the cradles were tipped fifteen degrees to the boats’ final positions and the rigging attached. Everything fit perfectly, even over the 230’ footprint of the installation – made possible by three-dimensional computer aided design.

FINAL THOUGHTS
The America’s Cup is a racing forum demanding the highest level of team organization, design and engineering perfection. Though the boats are now art objects and most likely past their sailing days, this project demanded us to fulfill those same requirements to be successful.

Our upmost gratitude goes out to Bill Koch for daring to engage in such a grand public display; to Peter Grubb, Bill’s yacht captain, our right-hand man in coordinating the project from the beginning, and to everyone on the team for their dedication and enthusiasm.

SETTING UP THE YACHTS  – Powerpoint ( 12 MB )