Opposite: it’s 2014 and early days in developing the new cats that will contest the 35th America’s Cup in Bermuda but already Luna Rossa helm Chris Draper – now with Team Japan – is using a handheld remote to fine-tune the foils on his AC45F development boat. These two boats, along with a considerable hoard of development data, were handed over to Team New Zealand when Luna Rossa withdrew from the Cup in 2015. Simpler – but probably no easier – during the 1920 Cup (above) when you just pulled things… hard
effectively a hydraulic ‘battery’ where
excess power from the grinders can be stored. In addition, this time hydraulic pressure has been limited to the relatively low figure of 5,000psi. This is aimed at containing costs by allowing teams to use off-the-shelf accumulators, rather than having them waste resources in developing custom gear.
While teams have worked hard to evolve hydraulic set-ups, Harken have been run- ning their own in-house R&D programme and are supply ing three of the six Cup teams, much of the gear custom-designed specifically for the AC50s and, in the case of the rams, all fabricated in titanium. Among the items the Wisconsin-based manufacturer has conjured up this time is a new rotary pump, the vital element of the hydraulic set-up that converts the crew’s grinding effort into hydraulic pressure as smoothly and efficiently as possible. Mark Wiss, director of business development at Harken, explains why this development has been necessary: ‘Most hydraulic pumps are driven by engines, so Harken are in a unique position where we’ve devel- oped an efficient pump that’s designed specifically to be driven by human hands. ‘Hydraulics companies all employ rotary hydraulic pumps, but those pumps are very inefficient when used at a very low RPM with input that’s provided by human beings. The Cup teams all have elaborate test benches and do their own head-to- head testing, and they have come back to us saying that Harken’s pump is today the most efficient that’s available.’
The operating pressure of the hydraulics
has also required new developments to be made, as, by modern grand prix yachting standards, 5,000psi is low compared to the 10,000psi used on the AC72s or even to the 7,500psi on a TP52 hydraulic installa- tion. One downside of a relatively low- pressure hydraulic system is that it requires slightly larger rams to be used, which in turn require more hydraulic fluid to oper- ate them and, as a result, a less welcome aspect: more pumping by the crew… For Harken it also caused a momentary hesitation as developing specialist lower- pressure hydraulic kit was likely to have less trickledown into other classes. Nonetheless, involvement at the sharp end of the America’s Cup being part of their corporate DNA, they opted to press on. As Bill Faude, Harken’s creative director, observes: ‘We’re passionate about it. We have to be at the front – that’s our culture.’ Under the AC Class rule one hydraulic accumulator can be used to control the rake (fore and aft rotation of <12°) adjust- ment of the daggerboards, while two others are used for the boards’ deployment and retraction.
Accumulators have been permitted this time to prevent the helmsman running out of hydraulic ‘juice’ to operate the all- important trim of the foils. But even so the amount of available hydraulic power will still have its limits. Thus optimising every aspect of the hydraulic systems, from grinder fitness and strength, to improved design of the rotary pump and so on, will all help maximise the number of man - oeuvres (or of hydraulic adjustments) that can be made during a race. This represents
a fundamental area of AC50 performance development for the teams. As Mark Wiss says: ‘With the human input they want to make sure they’re utilis- ing as much of that power as possible. We did a lot of in-house testing at the request of the teams to provide them with efficiency reports on basically every component of the systems that we’ve supplied, whether it’s a winch, a gearbox, a pump, a pedestal, hydraulic tubes – that all forms a part of their decision-making process. Fortunately we’d done all that previously, and continue to do it, and it’s showing that we’re always in the high 90 percentile of efficiency.’ Use
of accumulators should also
sharpen up the speed with which the trimming of the foils and the wing or man - oeuvres can be carried out. For example, raising or lowering the daggerboards isn’t left to the buoyancy or weight of the board as is largely the case on a less manoeuvre- critical offshore multihull. On AC50s both up and down functions are now performed hydraulically and are lightning fast. As Wiss observes: ‘They go down in the blink of an eye – like a guillotine.’
The rams operating the daggerboard up/down are also the longest, most highly powered onboard, given that if the boat is foiling at the time they need to be oper- ated, they may be supporting the majority of the boat’s 2,332-2,432kg weight. ‘They require the most oil and have to be the fastest-activating cylinders on the boat,’ advises Wiss. ‘Getting the board down faster in manoeuvres is key. And then you want to pull it up without having to expend that much energy.’
SEAHORSE 35
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