‘That’s weather, right?’ Ex-Cup sailor on conditions and reliability of forecasting

Jon Bilger knows all too well how unreliable the weather can be.
Spending 10 years managing the weather department with Alinghi in the America’s Cup, including their successes in 2003 and ‘07 and their loss in 2010, the New Zealand sailor has seen just how crucial a proper understanding of conditions is.
Weather has been among the many intriguing factors of the 37th edition of the America’s Cup in Barcelona this year, with light breezes and storms causing disruptions to racing through the Louis Vuitton Cup round-robin stages.
“There’s a saying that goes for any sailor that has been to lots of different regattas, often the comment is made that ‘oh, it’s never normally like this’,” Bilger tells the Herald.
“With the America’s Cup in 2007 and the Challenger Series, [there] was really poor weather; the conditions were very atypical [in Valencia] and at Alinghi, I was involved in the selection process for the venue and we looked at 20-30 years of climate averages, and this was just out-of-the-box different.
“That’s weather, right? There’s the averages, then there’s what you get on the day. We haven’t had the strong sea breezes that we would often expect. It’s going to be interesting to see how the rest of the series works out with the Louis Vuitton Cup.”
After his time with Alinghi, Bilger went on to develop a weather-forecasting app called PredictWind, which is now the official provider of weather data to the America’s Cup.
While each team has its own meteorologist team, they interpret data from PredictWind – and likely other reliable models – to best assess the situation on the water.
The app isn’t limited to team use, though, and is easily accessible to fans who want to track the conditions on the course, or to everyday sailors who want peace of mind before heading out or while on the water.
For this year’s America’s Cup, Bilger’s team are using weather stations along the coastline in Barcelona to give them a good idea of what’s going on, with webcams on two of the hotels near the waterfront providing a live look over the water.
During Bilger’s time in America’s Cup competition, the forecast played a big role in planning race strategies and the weather teams were sizeable.
Back then, the crews still had a man up the mast looking for wind, with teams out on the water relaying information of the conditions back as well. Weather boats on the course are not a feature of the regatta anymore.
Having an accurate forecast still plays a big role, helping teams to decide how to set up their AC75s before racing, but Bilger said times have changed in terms of how teams are looking at that data.
“Back in those days, we would actually make a call on which side of the course was favoured, if it was going to be a big gain or a small gain, the confidence, because the first beat was 25 minutes long and a three-mile, and when you had a man up the mast you could only see a mile and a half,” Bilger said.
“The whole game’s changed now. The boats go so fast, you’re at the top mark in next to no time. But it’s more like a weather decision of what sort of conditions we’re going to have for the day. Do we have the right headsail on? Do we have the right mainsail on? And to really get the mindset of what to expect from the conditions.”
Bilger said the model his team used was “pretty good” in the three-to-five-day range, which could extend to a week. However, trying to predict anything more than 10 days in advance was simply crystal-ball gazing.
“That’s a big thing with weather. You’ve got to realise the limitations of the technology. We don’t get it right every time but at the same time, if you look at what we do now compared to 20 years or 30 years ago, it’s quite incredible.
“People really understand how complex weather is and how complex the models are, it’s amazing how accurate they can be.”
Christopher Reive joined the Herald sports team in 2017, bringing the same versatility to his coverage as he does to his sports viewing habits.