Another guest crew post by David Afternoon mid-Atlantic. Swells are the denizens of the open ocean. Lumbering mountains of water, they roam out of the center of distant gales, nudged by persistent breeze over vast reaches of ocean. Physics says that the rhythmic motion of a swell is just frictionless fluid dynamics on a large scale, but their power is impressive; these behemoths lift the 30 tons of Spirit as if she were a cork. A ride on the front of a steep swell is a helmsman’s treat. In the catalog of swells, every seventh or so, by some odd rule of nature, is the biggest. We encounter some in the ten-foot category, not large enough for us to surf for long, but big enough for some fun. It begins as the boat mushes down the back of a wave into the trough. Seconds later, the water behind begins to surge as the next wave lifts the stern up the steepening wave front, dropping the bow for the run. A quick look behind elicits a silent, “Whoa!” The helmsman feels the wave nudge the rudder, and Spirit accelerates. Which way will the bow be pushed as we drive ahead? Quick action at the wheel straightens the boat, and 30 tons begin to surf downward. Speed peaks, the boat relents and the wave moves on, Spirit riding up and over the crest, braking in a cushion of roaring foam into the next trough hoping to repeat the process. A ride on one in five is a good day. Such is the joy of a boat driver in an afternoon far at sea looking for the perfect wave.