This, in my opinion, is the toughest trick in sailing: As you accelerate down a wave, the chute is overrun and starts to collapse so the crew sheets, sheets, sheets. Meanwhile the driver is steering down and across the wave trying to hang on to it as long as possible. The crew by now has caught up with the sail and starts to ease, ease, ease to keep it pulling and helping the driver stay with the wave. Once the wave passes, the driver quickly steers up and out of the trough before the boat stalls out, so the crew must again sheet, sheet, sheet to keep up with the higher angle, then ease, ease, ease as the boat gets out of the trough and the driver heads down. (Don't forget to breath.)
Watching the best teams pull this off is a beautiful thing and one of the biggest reasons these teams win so often. I know how to do it, but getting my body to respond in time with the driver (or crew if I'm driving) is a different matter. When it does happen properly, the feeling of speed and control is amazing; there is no greater thrill in sailing. If you're looking for a demonstration of this maneuver, watch Kenny Pierce. He is the master of wave sailing and one of the best front-of-the-boat technicians out there.