"It is almost incomprehensible that a sport like sailing, with its many financially strong participants, has long lacked something as critical as reliable speed measurement," writes the US technology magazine "Wired "The impeller measured the boat's speed, but not very precisely," Robert Hopkins is quoted as saying. Together with Puma Ocean Racing and the Norwegian company Nortek, he developed the Doppler Velocity Log (DVL), which is now set to change everything. The problem, according to Hopkins, lies in the turbulent water flow and the fact that the hull comes far out of the water at high speeds, which makes measurements inaccurate or even impossible. "You get a lot of bad data," says Hopkins.
GPS alone does not make you happy because it only measures the speed over ground. To sail really fast, you also need to know how fast you are travelling through the water. Conventional impellers, which are mounted on the underside of the hull, are not precise because they measure drift and are affected by algae growth after a short time. After one and a half years of development and several prototypes, DVL is now in racing use on the Puma. It is a small, circular device that is installed on the underside of the keel bomb and emits four beams in different directions, which are reflected by the plankton in the surrounding area. The deceleration effect of the "echo" is measured, from which the speed can be calculated.
Accurate speed measurement through the water is particularly important on the VO-70 racers, according to the report, because in addition to the tilt keel, they also have two centreboards that counteract drift, but also have braking friction in the water. "If we need less lateral force, we can minimise the frictional loss by catching up with the daggerboards," Puma skipper Ken Read is quoted as saying. In short in-port races, the advantages of the DVL are unlikely to be significant, but spread over several weeks, on an ocean leg thousands of miles long, a clearly noticeable gain could be achieved. In theory at least.
The DVL première is said to have already taken place in the summer at the Transat race, which Puma won on calculated time. Puma has an exclusive contract with Nortek for the duration of the Volvo Ocean Race, which means that no one else has access to the technology. "We can trust our data completely, while the others have to have doubts," says Hopkins. Whether there is any truth in the matter or whether it is part of psychological warfare remains to be seen. In the end, in every regatta, places sailed are still the deciding factor, not measured speed. Incidentally, Puma is almost 200 miles behind the leading Groupama according to the position report from 02:00 today. And they are sailing with the old Speedo.
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