By Mike Broughton
February 26, 2003
Source: www.americascup.yahoo.com

How space age monitors have raised the game at predicting the shifts

Russell Coutts has been quick to recognize the part played by the weather team in Alinghi’s success so far. “Jon Bilger and his team have achieved great things out there and taught Brad and me things about the Hauraki Gulf that we didn’t know.”

In race three of the America’s Cup Match, with six minutes to go, just seconds before the communication lines are cut at the five minute gun, it was Bilger who relayed the vital call to the Alinghi afterguard to ‘go right’. That bold call helped tactician Brad Butterworth to plump for the right side of the race course and open a decisive 200 meter lead on Team Zealand in the first few minutes of the race.

The wind was out of the north and Bilger says that up until a last minute change of heart, he liked the left and it seemed like left was the obvious call. “For once it looked an easy choice, we thought ‘left-handers’ on the left would be the only way to go, despite that fact that there looked like more wind on the right. But one of our weather boats saw the big right hander and radioed in immediately.”

Bilger orchestrates a flotilla of eight Alinghi weather boats, placed strategically to monitor the wind on each side of the race course. Data from each boat is networked together and displayed before Bilger and meteorologist Jack Katzfey on their flag ship or nerve centre. Armed with fast intranet access and scrambled communications Bilger can also monitor a myriad of shore stations as well as view sophisticated radar to track shifts and wind patterns.

Team New Zealand has seven weather boats. Three weeks before the Cup, they increased their team from four to seven to match that of the Challenger. Roger ‘Clouds’ Badham remarks, “it is a cold war out there and we decided to match Alinghi’s weather flotilla a few weeks ago. Financial constraints would not allow us to have that many six months ago, but we have some great sailors out in our boats who all contribute a massive amount.”

In charge of the hardware at Team NZ is legendary round the world navigator, Mike Quilter. Ex Victory Challenge/illbruck forecaster, Chris Bedford recently bolstered the forecasting effort alongside Badham and helps feed information to another Illbruck sailor Ray Davis who is the link to the race boats. Badham compares the last few minutes of information to the onboard teams to that of working the stock market. “Ray Davis usually does the final ten minutes talking to the boat. The final fifteen minute period the stress levels go up. It is just like short term future trading. Ray Davis talks tactician to tactician to get the message across”.

Space Age Monitors

One of the most impressive of the America’s Cup forecasting monitors is the ‘wind profiler’, which is a huge 16 metre square array on Motutapu Island on the eastern side of the Hauraki Gulf. It is designed to monitor the lower layers of the atmosphere (up to 2000 meters) and help forecasters and air traffic controllers warn pilots of wind shear on the approach path to an airport. Utilized by NASA for wind information for the landing of the space shuttle, the massive aerial transmits vertically giving wind speed and direction at varying heights to enable a three dimensional picture to built up with time.

Built by Atmospheric Radar Systems Ltd (Atrad) of Australia, the company first installed a wind profiler at Sydney airport just prior to the Sydney Olympics. Atrad CEO, Rob Silva explains, “the wind profiler is a great tool for building up clear scientific picture of the wind over a small area. The data feeds into a meso-scale computer model and the computing power is usually the limiting factor given that with our transmitters we can achieve a definition of 75 metres with our UHF transmitters.” The transmitter on the Hauraki Gulf is VHF and achieves a definition of 150 meters and costs in excess of US$100 000.

The huge costs of some of the weather monitors have meant that the weather teams have clubbed together to share expenses. Team New Zealand and Alinghi share the information of the wind profiler (Prada and OneWorld were also bought in). Likewise the weather buoy information was bought by all of the teams, whilst a ‘secret SODAR’ monitor, (again discreetly placed on Motutapu Island) is again a joint programme between the top teams.

Sodar (Sonic detection and ranging) systems are used to remotely measure the vertical turbulence structure and the wind profile of the lower layer of the atmosphere (usually below that of wind profilers). Sodar systems are like radar (radio direction and ranging) systems except that sound waves rather than radio waves are used for detection and cover an arc of around fifteen degrees. Other names used for sodar systems include echo sounder and acoustic radar. A more familiar related term may be sonar, which stands for sound navigation ranging.

Sonar systems detect the presence and location of objects submerged in water (e.g. submarines) by means of sonic waves reflected back to the source. Sodar systems are similar except the medium is air instead of water and reflection is due to the scattering of sound by atmospheric turbulence and can replace the conventional ‘weather balloon’.

Most sodar systems operate by issuing an acoustic pulse and then listen for the return signal for a short period of time. Both the intensity and the Doppler (frequency) shift of the return signal are analysed to determine the wind speed, wind direction and turbulent character of the atmosphere.

‘Scary’ Lasers

A discreet, but exciting development for this America’s Cup has been the use of lasers by the OneWorld weather team, early in their program. Known as Lidar (Light Detection And Ranging) uses a similar concept to Sodar and is normally positioned vertically at airfields to give wind data. However when used horizontally, they can be used as a powerful weapon to predict the wind on the race course.

A lidar is similar to the more familiar radar, and can be thought of as laser radar. In radar, radio waves are transmitted into the atmosphere, which scatters some of the power back to the radar's receiver. A lidar also transmits and receives electromagnetic radiation, but at a higher frequency. Lidar operates in the ultraviolet, visible and infrared region of the electromagnetic spectrum and is received using an optical telescope. Choosing different types of scattering processes allows atmospheric composition, temperature and wind to be measured.

Lidar is still in the development phase for horizontal use and is extremely expensive at around US$300 000 each. Ideally one would need more than one transmitter to cover the race course making the whole proposal a scary thought. After the successful defence in 2000, Team New Zealand admitted that roughly 20% of their total spend was directed towards ‘picking the shifts’ and were the pioneers of the big weather team.

To harness such sophisticated wizardry takes a hugely powerful meso-scale computer model and Alinghi have harnessed the help of the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) and significantly have signed an exclusive deal with them to help with their ‘weather modeling’. Inputs include ‘runs’ or GRIB files, from the worldwide weather super computer models as well as satellite images and shore side observation points around the Hauraki Gulf.

The development of high resolution weather radar can also help predict wind shifts as well as the rain. The New Zealand MetService’s local radar for the Auckland area is extremely useful and is a terrific tool for tracking rain clouds as they approach the race course and is updated every fifteen minutes on the MetService intranet.

Despite all the ‘high tech’ weapons, it is still the original ‘mark one eyeball’ that is the best sensor of picking wind shifts. In light conditions we regularly see Murray Jones onboard Alinghi scaling the mast to give him better a view and call the wind further up the race course. Even the ‘mark one eyeball’ gets expensive assistance in the America’s Cup.

Oracle BMW’s well publicised ‘Formula One sun glasses’ developed for Ralph Schumacher, allowed crewman Eric Doyle to have wind data projected onto his lenses like a fighter pilots ‘heads up’ display. At a higher altitude, OneWorld’s multiple 49er dinghy champion; Morgan Larson would get airborne in a helicopter for two hours and fly over the Hauraki Gulf to spot wind before the race started.

Weather wise, the Hauraki Gulf must be the most highly monitored race course in history. Despite the multi million dollar budgets, it is still that mark one eyeball that is the most potent weather weapon, carefully honed and trained in tiny Optimists and P Class sailing dinghies.