The Maretron WSO 100 delivers wind data without the cups and moving parts of a traditional masthead anemometer. Windspeed and direction are measure by sonic pulses passing between the sensors (explained in the diagram below).

When you have a delicate instrument with moving parts spinning around at the top of your rig, there are bound to be numerous trips aloft to replace bits and pieces of your wind direction/speed sensor in its lifetime.  Broken vanes, missing cups, and wands tweaked off centerline are the stuff we've long had to deal with to get the wind data we need. But two companies, Maretron and Airmar, have developed wind speed/direction sensors that use no moving parts. Using sonic technology, these units provide accurate information about wind direction and speed, as well as barometric and temperature information. Consider them as masthead weather stations.

Will this technology benefit racing sailors? "Absolutely", says Maretron's VP, Larry Anderson. "The information from our WSO 100 sensor feeds information directly to a NMEA 2000 backbone, which also has compass, GPS, and speed information. Those bring the corrections for the true component of the wind that you need and want." Any system that's capable of reading NMEA 2000 messaging, he tells us, can use this data.

Such compact systems are commonplace on powerboats and the major concern has always been whether the systems would work on a raceboat.

"This is even better than some mechanical units," says Anderson. "It's been designed aerodynamically to work on an angle of up to 30 degrees of heel with no degradation of accuracy whatsoever."

So how does this sonic technology work? The Maretron sensor consists of three ultrasonic transducers. One by one, the three sensors generate ultrasonic sound pulses, which are received by the unit's other two sensors.