The Noose Tightens

A look at why ETNZ is the faster boat at the America’s Cup.

September 13, 2013

America’s Cup 34

Did the Kiwis build a better boat? It’s possible that their domination on San Francisco Bay is a result not of better boat handling, but of better construction. David Schmidt

Depending on what flag you’re waving in this America’s Cup, today was either a massive victory or an enormous setback. Oracle Team USA, the Defenders of the 34th America’s Cup, suffered a bludgeoning on Tuesday and promised change. It arrived today in the form of an afterguard rotation. John Kostecki, the team’s ace tactician, stood down, replaced by Sir Ben Ainslie, history’s most decorated Olympic sailor. Unfortunately for Oracle, this change failed to alleviate their problems.

Oracle got off the line of Race Six in the lead, which they held for the first two legs, with both boats demonstrating nearly identical speeds. The two AC72s scorched through the leeward gate, sheets hardened and—several tacks later—Emirates Team New Zealand (ETNZ) rolled Oracle. Pole position changed hands twice more, with ETNZ painfully dialing down the Americans on their last crossing. The Kiwis rounded the upwind mark first and promptly lit their afterburners in the light breeze, horizoning the Americans.

ETNZ 5, Oracle -1.


Then, ETNZ owned Race Seven. The Kiwis won the start and rounded the first mark two seconds ahead of Oracle. The two boats stayed in touch through the leeward gate, again exhibiting similar speeds, until it was time punch back upwind. ETNZ whistled through the weather gate first, leapt onto their foils and instantly compounded their lead to almost comical proportions, ultimately winning by one minute and six seconds.

ETNZ 6, Oracle -1.

Careful readers will remember that both boats exhibited virtually identical numbers through the first two legs. So why was ETNZ able to once again hammer Oracle?


I learned some key answers this morning during a tour of ETNZ’s base as a guest of Vesper Marine. While ogling over the ETNZ backup wing, one of the Kiwi shore crew casually mentioned that their wing is far more adjustable than the Americans’. Critically, the Kiwis can purportedly articulate the bottom section of their leading wing element (ballpark, the lower 30 percent), which influences the shape and twist of the wing’s top section. While both teams can twist their trailing element, Oracle’s forward element is reportedly static.

The design differences go far deeper: ETNZ’s second-generation boat was always designed to foil, so the Kiwis employed diagonal bracing to ensure torsional rigidity when airborne and higher-volume bows as nosedive insurance. In contrast, Oracle uses two parallel main beams, and their bow sections are considerably finer. When these factors are tallied, ETNZ’s adjustable forward wing element allows them to power out of maneuvers faster, while their stiffer platform allows them to press their boat much harder when foiling, and their full bows play goalie should calamity strike.

In both races, ETNZ and Oracle stayed in touch until the bows pointed to weather. Then, tacking duels and match-racing tomfoolery ensued, all of which rewarded the more nimble boat. The Kiwis gained small bits of real estate on virtually every maneuver, which—critically—allowed them to reach the top of the windward leg first and light up their foils, while Oracle kept struggling to weather.


Back to Kostecki and Oracle’s mystifying decision to change horses in midstream: Given Oracle’s disastrous results today, it’s obvious that the team’s problems lie in their design and their boat-handling skills, not in their afterguard. Change is desperately needed, but I’m afraid that this can’t be sorted out through simple crew rotations or new foils.

Oracle now faces the miserable reality of do-or-die wins. Otherwise, the Cup will go antipodean, possibly as soon as Sunday.


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