The curve of the surfboard bottom from nose to tail viewed from the side. Probably the single most important factor in surfboard design, because it controls the general flow of water from its entry (where water first contacts the bottom) to its release (where water leaves the board). Generally, a surfboard with more tail rocker will turn easier but might be a little slower, while a surfboard with less tail rocker will turn harder but might be a little faster. The difficulty of hand shaping an evenly balanced rocker is legendary among shapers, but has largely been relieved by improved blank technology and the use of computer shaping machines.