No stopping! How the lives of America’s Cup grinders have changed

You have all had a chance to see by now how the new AC75 America’s Cup flying boats work. Forget traditional roles, everything is different on board. Luca Bassani hit the nail on the head when, during the first episode of The Cup Newspaper, he ironically pointed out how we have “gone back to slaves at the oars of galleys” with grinders.

THE HARD LIFE OF THE GRINDER ON THE AC75

Indeed, the lives of grinders (i.e., winch men) have changed dramatically on AC75s. After the “cycling” interlude of last year’s America’s Cup, it’s back to working with arms. But all the time, and we explain why.

Harkenhas been working hard on this, and here’s how Harken True Clutches, clutch systems for changing function and ratio on winches, have revolutionized the lives of America’s Cup grinders.

How much of the total surface area of the hull and appendages, on the new America’s Cup boats, is submerged in water? Less than 2%. AC75s “fly,” not sail in displacement or glide, as it has always been. The world of the America’s Cup has changed, a revolution for all to see. Keen observers will also have noticed, however, that much has changed in the lives of grinders.

The men at the handcuffs make movements quite different from what we were used to seeing. Theynever stop, do not change direction of rotation to scale in the reduction ratio, or to switch from one function to another (e.g., to act first on a sheet and then on a steering wheel). Now the goal is to “grind” at a constant speed: 80 rpm.

The new technology that enables them to do this is an invention of Harken. It is called True-Clutch and it came on board the AC75 more than a year ago, but until now it has been kept strictly secret.

Traditional “pedestal” systems, the columns that act on the winches of large racing boats to change gears, use so-called “dog clutches” (gear and tooth systems) as clutches that can be activated using a button, lever, switch, or simply by reversing the direction of the handles.

Whichever way it happens, the entire grinder team must still stop working while the clutch is engaged. Which inevitably results in a loss of efficiency. This has always been the case, even in regattas at the highest levels. But with the advent of large “full foiling” hulls, everything has changed. Stopping and losing inertia can be fatal. Let’s see why.

Each pedestal must act on a very wide range of functions: mainsail sheet and carriage, jib sheets, barber, steering wheels, cunninghams, flaps and rudder vanes, halyards, and more. The reaction times of the trimmers must then be much faster (given the speed of the boats) and their adjustments occur at the same time with those in control of managing the “flight” of AC 75s. Both teams must rely on the power coming from the same source, the pedestals, and at the same time. In addition, adaptations (switching from one function to another and ratio changes) happen at a very high frequency: to get an idea during a 90-second gybe it happens a dozen times.

Already on the AC 50s that battled it out in the 2017 Cup edition in Bermuda, the goal was to never lose pressure in the oil flow in the transmission, and even then there was already talk of True-Clutches. Harken had created a team of engineers from its departments in both the U.S. and Italy, headed by Michele Cazzaro, R&D and Engineering Manager, who worked alongside Team Oracle.

One could not simply “steal” a clutch idea from the automotive industry; nothing suitable existed. On America’s Cup boats, you start with the power provided by the human body and then adapt it to a transmission, plus weight containment is a more critical factor not to mention that you are working over a different torque range (the True-Clutch can handle more than 1,000 Nm of torque and the whole system weighs only 1 kg).

Several solutions were considered, but in the end the one identified by Michele Cazzaro and his team is as simple as it is efficient and effective, more like a motorcycle clutch: A stack of composite friction discs and a spring-loaded pressure plate in its own housing box, particularly thin and light, also made of composite. But unlike a motorcycle clutch, which is manually activated, the True-Clutch uses small electric servomotors to control its activation.

DISCOVER HARKEN PAVILION AT MILAN YACHTING WEEK

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