March 22,2015. Leg 5 to Itajai onboard Team Alvimedica. Day 4. Charlie Enright on the helm as the clouds part for a momentary glimpse of sunlight with rain and squalls on the horizon. Conditions remain variable and puffy for the last 48 hours until the next low pressure system takes over,forecasted to bring a quick rise in wind and waves.
The role of weather in sailing
22:29 - Source: CNN
CNN  — 

There’s an old adage that says you can’t change the wind but you can adjust your sails.

It’s a lesson for life, but racing sailors have got this down to a fine art as they seek incremental gains in performance.

From dinghy sailors reading the wind as they race around a short course, to circumnavigators hitching a ride on pressure systems barreling around the planet, harnessing the weather is a fundamental principle in sailing. And knowledge equals power.

In the super high-tech world of the America’s Cup, micro analysis of climatic conditions is becoming increasingly important as hydrofoil technology becomes even more advanced.

And, although foiling fever has gripped the world of sailing over the last decade or so, the giant multihulls that rose out of the water to “fly” over the surface on hydrofoils at the 2013 America’s Cup in San Francisco were a game-changer.

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At the 2017 America’s Cup, raced in foiling AC50 catamarans in Bermuda, Emirates Team New Zealand trounced all-comers and demolished holder Oracle Team USA 7-1 to regain the Cup.

Much was made of the Kiwis’ revolutionary “cyclors” – using leg power to operate the winches rather than traditional arm grinders – but their in-depth analysis of the weather, applied to complex hydrodynamics data to determine which specific foil configurations to use, was one of the real keys, according to team chief Grant Dalton.

“The met [meteorology] was probably the unsung super gain that we had,” Dalton told CNN’s Mainsail.

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Dan Bernasconi, head of design for Emirates Team New Zealand, said the team had a number of design options for foiling appendages on any given day and would make their selections based on the information from the team meteorologist, Roger “Clouds” Badham.

“We had two different options for dagger boards and different options for rudders and elevators, so we had to develop our processes so we could make changes to the boat as late as possible, because it was absolutely crucial to the performance of the boat to have the right foils on for the right conditions,” said Bernasconi.

Dalton added: “These set-up changes made massive speed issues – 3-4 knots if we got it wrong.

“So Clouds was under the most pressure he’s ever been under in any campaign. Basically, we waited for him to tell us what boards we were going to race with. Whatever he called was what we’d do.”

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Emirates Team New Zealand helmsman Peter Burling and trimmer Blair Tuke and shore crew manager Sean Regan hoist the America's Cup in the Great Sound during the 35th America's Cup June 26, 2017 in Hamilton, Bermuda. / AFP PHOTO / Chris CAMERON        (Photo credit should read CHRIS CAMERON/AFP/Getty Images)
America's Cup: How Team NZ won in Bermuda
22:31 - Source: CNN

As winners, the Kiwis have taken the historic event back home and will host the next edition of the America’s Cup in 75ft foiling monohulls in Auckland in 2021.

Five separate race courses from the mouth of Auckland’s Waitemata Harbor into Hauraki Gulf will provide very different conditions.

A scientific knowledge of the wind and water state at any given moment during the short 20-minute races could be the difference between winning and losing the Cup.

“This is a city where you go out in 5 knots and it’s blowing 25 knots before you get to the race course,” added Dalton.

“That’ll affect your foil configuration and what jibs you have on board, and because we’ll go quickfire, we won’t have time for a three-hour build up. They’ll [meteorologists] have better tools but the interpretation will need to be even finer and you will take a gain if you get that right.”

When an America’s Cup campaign for 2021 will cost in excess of $140 million, you can’t afford to take your eye off the weather.

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For a more in-depth look at how sailors harness the weather, watch October’s edition of CNN Mainsail above.