Nortek Dopler Velocity Log Aids Volvo Ocean Race Entrant
Nortek collaborated with Puma Ocean Racing to fit a modified compact Doppler Velocity Log to PUMA’s 'Mar Mostro' Volvo Ocean Race competitor
“The collaboration between Nortek and the entire PUMA team has resulted in an tool that provides unique information to the sailing crew. They can now measure leeway, a first in sailing, and use it to measure ocean currents much more precisely than ever before,” said Atle Lohrmann, CTO of Nortek.
“This is the biggest advancement in sailing instrumentation since the invention of the GPS,” said Hopkins, who runs performance testing for PUMA and worked with Nortek on the project. “Nortek adapted their new DVL technology to our sailing performance needs, to measure very high speeds along the boat's track and very low speeds across it. With Nortek's history of deploying instruments on buoys in hostile Arctic conditions, we knew that we could trust the Nortek DVL in a race around the world.”
Leeway is the sideways skidding angle a boat makes as it sails forward. Leeway can be changed on a Volvo Open 70 yacht by adjusting the daggerboard immersion and canting the keel. The adjustable daggeboards and keel act like wings underwater to counteract the force of the sails. The crew relies on Nortek DVL leeway measurements to optimize PUMA's Mar Mostro performance at all times, providing the core data upon which every other performance measurement is based.
The Nortek DVL uses acoustic techniques to measure water velocity along each of the four beams. The sensor is mounted in the bottom of the lead bulb of the keel. The acoustic beams are oriented forward, aft and abeam. Data from each beam is streamed to the on board computer which also receives data from the inertial motion sensor and the keel cant angle sensor. Velocity and orientation measurements are then used to output true forward boat speed and leeway. Real time currents can be directly estimated by differencing the GPS boat speed over ground and the boat speed through the water.