The raft was lined up perfectly for the massive rapid. The Colorado-based team — eight accomplished paddlers on sliding seats atop a 48-foot custom raft designed to fly down the Grand Canyon — was on pace for a record. Suddenly the boat was vertical. Then it was broken. “It sounded like a gunshot,” said Ian Anderson. “Followed by the sound of a jet engine,” said Seth Mason. In the pitch black of night on the Colorado River’s burly Lava Falls rapid, an aluminum bar had snapped and punctured a 4-inch hole in the inflatable beam of the custom-built craft.