News Around the World
Guillermo Parada points 2015 world champion Azzurra upwind during this year’s TP52 Worlds in Puerto Portals. Azzurra conceded the 2019 title to (owner-driver) Harm Müller-Spreer’s Platoon but went into the last Super Series round in Sardinia with a handy 6pt lead over her German rival. This fleet is still hitting new levels of competitiveness – Azzurra fitted new foils last winter to improve acceleration and her ability to hold a lane but the team later refused to share even the identity of the design office that created them
is a shape sculpted by natural forces, like a river rock smoothed by centuries in the stream. Fluid motion is the name of the game, both in the water and in
the air, and the moulded nature of the hull shape reveals the enormous effort that has gone into hydrodynamic and aerodynamic efficiency. ‘We address aerodynamics and hydrodynamics quite differently,’ said design co-ordinator Dan Bernasconi. He did not reveal which has priority, but went on to say the ultimate objective was full flight all the way around the track. That might imply aerodynamics is king, but achieving sufficient
acceleration to overcome drag in displacement mode and lift off as fast as possible is also crucial, so hydrodynamics can’t be far behind. This juggling act between water and air poses the major challenge in solving the foiling equation and will keep all the design groups sweating the theory and crunching the numbers throughout their campaigns. The catamarans of the previous two cycles revealed the enormous
cost of every second off the foils. If anything, that may be even more expensive with the monohulls, which have the added com- plication of losing stability at slow speeds. ‘These boats will definitely be more difficult to sail than the catamarans,’ Bernasconi acknowl- edges. ‘The pre-starts will be massively interesting, because there is a huge penalty for getting stuck in the water. ‘If you have unmatched boats the faster one will do everything
in its power to stay away from the competition. Meanwhile, the slower one will be trying desperately to engage and get the faster boat head to wind and stopped. You could easily lose the race on the startline, with one boat heading away at 30kt and the other one wallowing at 1kt, because the acceleration phase is really difficult.’ This quest for acceleration explains the distinctive narrow belly
running down the centreline on the underside of the ETNZ hull. ‘As soon as you begin to get lift on the foils you start reducing weight in the hull,’ says Bernasconi. ‘The hull starts to lift so it is running on the belly, which now presents a shape like the underside of a catamaran hull. You are trying to minimise wetted area and get as much of the boat up and out of the water as fast as possible. Every square metre of wetted area is friction and that delays acceleration.’ As always there are trade-offs. ‘That deeper belly sacrifices some
stability,’ Bernasconi explains, ‘so at slow speeds this boat is definitely going to be quite tender.’ This requirement to master two elements, water and air, is
24 SEAHORSE
reminiscent of dolphins – one minute torpedoing below the surface, the next soaring above it. They have named the boat Te Aihe, Maori for dolphin. Perhaps there’s room for a bit of poetry after all. The connection is also embodied in the reverse sheer of the
deck, which curves like a dolphin’s back as it leaps from the water. Here again aerodynamics play a big part, with the grinders positioned well below the airstream in two deep fore and aft trenches either side of the centreline. Much speculation centred on how the grinders would transfer
from one side to the other in tacks and gybes, but the odds are they will not move at all: the time spent shifting weight of minimal assistance to righting moment would be better utilised providing uninterrupted power. The afterguard of helmsman, main and headsail trimmer will slip
easily across the back of the cockpit to new positions on the wind- ward side, but only a privileged few will have a view of what is going on around the track… Helmsman Peter Burling laughs at the sug- gestion that only the driver will know where they are going. ‘I am sure you will see some heads pop up, but it is important they are not taking the full brunt of the wind.’ If grinder heads do pop up chances are it will be only to gulp
some air before bending to their task again. ‘The power requirements of getting the boat around the track are huge,’ says wing trimmer Glenn Ashby. ‘The horsepower the grinders put out is phenomenal. Aero-wise, nothing happens without them.’ In Bermuda the grinders, or in ETNZ’s case the cyclors, were
pumping hydraulic oil to power the foils and wing. This time the foil arms are electric, but everything else still relies on human power. Hydraulics are clearly going to be the principal power supply once again. Although Ashby says he will occasionally have a rope in his hand, the demand for hydraulic oil pressure will be constant. The transitions between displacement and flight will be dramatic
and fast. ‘When the boat starts accelerating the foils are immediately generating a huge amount of power, so it almost turns into a different boat,’ Ashby says, describing the first stage of lift onto that narrow centreline belly. ‘Then, when full lift-off onto the foils is achieved, it becomes an aircraft.’ The power in the rig has to come on quickly and the grinders
have to shift a lot of oil to achieve take-off, then the sailplan has to be instantly reshaped again to accommodate the sudden increase in apparent windspeed and angle. ‘You need to get those sails
NICO MARTINEZ
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