"Pushing Oil" to Victory
Since the day the AC72 design rules were unveiled, it’s been a given that controlling these waterborne beasts would be a challenge for their 11-man crews. In contrast to the 33rd America’s Cup, when Oracle and Alinghi employed engines to control their massive rigs, human power alone is allowed this time around, creating a situation that has been further exacerbated by the advent of full foiling.
“The team that maneuvers best wins,” says Oracle performance director Ian “Fresh” Burns. “I can’t overstate how significantly the crew interact with these control systems. In a flying condition, especially, instantaneous control is key to stability.”
To solve this problem, all four teams have plumbed their boats with sophisticated hydraulics, powered by grinding pedestals, that do everything from trim the wing to raise, lower and adjust the daggerboards. When you see the crews all spinning like mad on their aerodynamically sculpted pedestals they’re not turning winches so much as “pushing oil,” driving the pumps that send highly pressurized hydraulic fluid to various rams and motors on board.
Augmenting these efforts is a little noted, but very important aspect of the AC72 rule that allows the use of electric actuators to direct this energy, as opposed to the simple valves and lines used on America’s Cups boats in the past. This means the flow of hydraulic fluid can be controlled from different points around an AC72 at the touch of a button, as opposed to having to be controlled right at the source (think the valve located on the housing of a conventional hydraulic backstay). It also means being able to forego all kinds of secondary plumbing, which in turn means a much more streamlined system and less weight: no small consideration aboard a boat designed to spend as much time in the air as it does on the water.
“A parallel concept would be Formula 1 [and]buttons on the wheel vs. pushing the clutch and shifting gears manually,” says Mark Wiss, point man for the America’s Cup at Harken Inc. “It’s basically taking the mechanical systems that we’ve had and instead of activating them with a piece of string or a mechanical foot button, they’re now using an electric switch.”
Wiss adds that the central role played by hydraulics is evident in the way the campaigns have worked to integrate the systems into their overall boat designs. “A lot of the boats were designed around our equipment and how they’re using it,” says Wiss, whose company is the sole provider of hydraulics to Oracle and is also deeply involved with all three challengers. “In the old days they would design a boat, build a boat and then they would say, ‘Alright, where are we going to put the winches and blocks and stuff?’ Now they’re coming to us and saying, we need to integrate your equipment into our boat so you need to be part of the design process from day two, not on the end.”
Of course, installing a bunch of hydraulics and hardware is one thing, making the stuff actually work is another—especially aboard boats going 40-plus knots on a racetrack where a bad gybe or rounding can cost you not just a boat length or two, but hundreds of yards.
To fine-tune these sophisticated systems the syndicates employ a variety of different analytic tools, which they use in combination with crew feedback. For example North Sails, in addition to building 3Di headsails for all four campaigns, has been providing analytic help with the rest of the design process via its proprietary sail design software.
“If your focus is on performance and engineering and designing something that is right at the limit, then you need this type of information,” says North’s JB Braun. “As you start climbing to the pinnacle, to either stay there or achieve more performance gets harder and harder. You are trying to integrate all the pieces together to work together better, and there’s still a lot of unknowns.”
It’s the same thing with the many sensors found on Harken’s top-end winches and pedestals, and the hundreds of optic sensors embedded in each boat’s hulls, shrouds, crossbeam and underwater appendages.
Indeed, the sophistication of the various systems onboard an AC72 are such that the boats are almost like living creatures: the sensors and electronics serve as a kind of nervous system, the hulls and crossbeams as a kind of skeleton, the winches and lines as muscles, and the hydraulics as a kind of circulatory system.
“It’s almost like the boat is alive, in lots of ways,” says Braun. “When you put the wing up it’s alive, it just wants to go. When you turn the boat on, the boat measures everything…basically you flip a switch, and the thing turns on and it starts communicating with you. It’s an amazing accomplishment.”
Photo coutesy of AC43/Gilles Martin-Raget