The race was a test of endurance and a test of hydrodynamics. Riding atop giant paddleboards, two teams of six battled resistance from the Chatfield Reservoir water below them and opposing paddlers on the board next door Monday. During the final charge back to the beach one team faltered. It was left paddling in the wake of opponents who had more energy and more evenly distributed weight on their vessel. On the beach, Ryan Avila, paddling since the beginning of the relay-style contest, celebrated victory as best he could while trying to catch his breath “It was tough, man,” said Avila, an events and marketing specialist for the outdoor industry.