Sailing-The Spanish weatherman plotting Britain's path to glory

No expense has been spared in Britain's bid to win the America's Cup for the first time in its 173-year history, but all the state-of-the-art technology money can buy would be sunk without one age-old skill - meteorology.

When the first-to-seven series against holders New Zealand begins off the Barcelona coast on Saturday, one of the key members of the world-class team assembled at huge cost by British billionaire Jim Ratcliffe will not even be on the boat.

Meteorologist Miguel Sanchez Cuenca, known in the business as 'Capi', will be on a chase boat watching the action unfold, hoping the long hours spent analysing wind patterns and preparing weather forecasts have paid off.

"The hardest part for forecasting are the unstable days when weather models are totally inconsistent," the 59-year-old Sanchez Cuenca, a successful international sailor and CEO and meteorologist at Metwind sailing forecasts, told Reuters.

"The weather has been challenging in Barcelona for this America's Cup with models failing more than expected. Then it's about intuition and seeing the bigger picture.

"When I make a last-minute call in tricky conditions, it's exciting and if it helps the team, satisfying."

While wind is a sailor's best friend, it can also be fickle and what is expected to be a close-run battle between Ben Ainslie's British team and Pete Burling's Kiwis could come down to sail choice on the AC75 foiling boats.

The two competing crews must choose the size of their mainsail and hoist it 40 minutes before they leave dock while they can leave the decision on the smaller jib sail until around 20 minutes before the race.

Those decisions will depend on current wind strength and whether it is likely to increase or decrease during the hour of racing