The guy on the left who looks like he’s about to dive off the front of the boat just has the two-at-a-time arm paddle technique. Most of the team members use one hand to paddle at a time, with a leader counting off from 1 to 20. At the count of 20, the people either leap across the boat to switch sides, or twist around in place to be able to use their other hand. I was on a bridge about 3/4s of the way through the race, and by this point, some people were starting to just take a pause rather than keep up the pace, at the count of 20.