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RFID Navigates South African Rivers in Kayak Marathon

The event's organizers could identify where participants were located throughout the 120-kilometer course, based on RFID technology that read the tags of kayaks passing checkpoints, thereby allowing friends and family to meet paddlers along the river and provide food and water.
By Claire Swedberg

The Natal Canoe Club, Eldridge says, does not provide any signage pointing in the direction that would keep participants on course. Instead, the racers are expected to make their own choices—which, in some cases, means leaving the river to hike along the shore, or taking a different tributary to return to the next required checkpoint. "Paddlers will be exposing themselves to risks by entering the event," the entry form warns.

For Dusi Marathons held in previous years, the club stationed an individual on the shore at each day's finish line, whose job it was to press a stopwatch as each participant arrived, and to manually record that kayak's ID number on a sheet of paper, along with the racer's finishing time. Since there is no cell phone coverage along the racecourse, participants' supporters had to predict where to meet them along the way for water handouts. At some of the more treacherous parts of the marathon, a kayak could remain completely out of sight from everyone for several hours, so if a racer were in trouble, it would be difficult for others to realize it. The marathon posts personnel along the route to serve as lookouts, and several staff members in kayaks serve as sweepers, bringing up the rear during the race, to ensure that no one falls behind.

To overcome the tendency of a kayak's Kevlar or carbon fibers to affect UHF RFID transmissions, Tadbik designed a tag that extended upright. Photographer: Anthony Grote.
With RFID, Eldridge says, the club believed it could better manage participants' safety, as well as automatically collect time-keeping information. So Finish Time began working with Tadbik to identify the best tags to use, and their best placement on the kayaks. The club wanted to keep the tag well above water to prevent any transmission interference, and found that the best location was at the front of the boat—which was also the highest point. Kayaks and paddle boards are composed of Kevlar or carbon fibers that have the ability to affect transmission, in the same way that metal would, so Tadbik built the tag to extend upright, above the surface of the kayak or paddle board, in an upside-down T. Although tags could theoretically be attached to participants' helmets, Eldridge says—which would position them higher above the water—no helmets are worn during this event. "This is South Africa," he points out, where athletes consider themselves too tough for such headgear.

When Eldridge approached Tadbik for an RFID tag, he told the company that he was aware of several methods of tracking canoe race times, but that he was unsatisfied with their results and reliability. Tadbik asked Eldridge about the environmental conditions to which the tags would be exposed, as well as the read range expected and the watercraft's surface material specifications. "We tested several constructions of labels that we had in mind," says Michal Yanuv Max, Tadbik's sales and marketing manager, "and came up with the T-shape label to avoid the proximity of the tag to the carbon fiber materials."

Tadbik piloted several versions of the tag internally before he was satisfied that it would provide the long read range required and survive the harsh conditions. The result is a custom-designed Tadbik tag featuring Smartrac Short Dipole tag with an Impinj Monza 5 chip that could be read from up to 14 meters (46 feet) away, using battery-powered RFID Race Timing Systems' Ultra Readers with built-in Impinj Speedway Revolution four-port readers and MTI Wireless Edge antennas. Each reader antenna was mounted on a pole, typically planted into the riverbed, at a total of about 12 sites, generally with one reader per location (two units were used at each day's finish line, for example, to ensure a more precise read time).

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