It is true GPS fundamentally calculates location in x,y,z coordinate system. However, those calculations are so complex that all GPS units have sufficient calculation horsepower to derive speed and bearing information from successive positions and with quite high accuracy (typically better than compass, speedometer, knotmeter, etc). I didn't watch this weekend, but last year during trials, the network had excellent graphics (wind direction, tacking lines, etc) overlaid on their blimp shots of the boats. Really helped explain the course (to a sailor). The shots from water level are impressive closeups, but a little hard to interpret without the big picture from overhead.
________________________________ From: "mechtly, eugene a" <[email protected]> To: U.S. Metric Association <[email protected]> Cc: U.S. Metric Accociation <[email protected]>; "mechtly, eugene a" <[email protected]> Sent: Monday, September 9, 2013 11:28 AM Subject: [USMA:53233] RE: Americas Cup Sailing (by meters and seconds) m moon, I stand corrected. GPS does not give speeds directly in meters per second. However, both catamarans had onboard computers, so I *am certain* that they calculated speeds live during the races, but I can only speculate that wind, boat, and current speeds were calculated live in meters per second. Eugene Mechtly ________________________________ From: m. f. moon [[email protected]] Sent: Monday, September 09, 2013 10:14 AM To: mechtly, eugene a Subject: Re: [USMA:53232] Americas Cup Sailing (by meters and seconds) GPS, per se, does not provide speed data, only location in x, y, and z. Lat-long and other information such as speed has to be derived from these three factors. m moon ------ Original Message ------ Received: 08:11 AM PDT, 09/09/2013 From: "mechtly, eugene a" <[email protected]> To: "U.S. Metric Association" <[email protected]> Cc: "mechtly, eugene a" <[email protected]> Subject: [USMA:53232] Americas Cup Sailing (by meters and seconds) Did you watch the Americas Cup Sailing races in San Francisco Bay Saturday and Sunday? Spectacular technology! By GPS measurements, the on-screen displays superposed on live photographs numerical values of distances in meters and separation closing times in seconds. The two catamarans (one from New Zealand and "Oracle" from the US) reached speeds approaching 20 meters per second (about three times the wind speed) while arising above the water on their carbon-fiber plaining foils. Replays can be viewed on YouTube. The only flaws in the presentations were the digital displays of wind speeds in knots and commentary in miles per hour rather than in meters per second. I am virtually certain that the original GPS data provided speeds in meters per second! Eugene Mechtly
