Open water swimmers often wear transponders when competing in professional marathon races and other open water swimming competitions around the world.
The transponders are often worn on their wrists when there is an in-the-water finish and other times worn on their ankles when there is an on-the-shore finish.
The accuracy of these transponders are never in question by most athletes, coaches, media, and fans especially because similar types of timing devices are used in the marathon running and triathlon communities.
But because of limitations on the commercial usage of GPS technology, the accuracy of these transponders during in-the-water events is only +/- 60 cm (23.6 inches). Given the proximity of a pack of competitive open water swimmers in close races, 60 cm is not nearly accurate enough to correctly judge places among a fast-finishing pack.
This situation is often seen in many professional races when the eyes of the judges reviewing video tapes of the finish is how the race finishes are judged. That is, the transponders are not used to determine placing – it is the human eye.
Copyright © 2014 by World Open Water Swimming Association