The Arc Crack starts on the south side of the Arc Crack Boulder. Start standing with both your hands in the fingercrack. Crank a few hard moves to get your feet established above the steep wall. Then follow the crack right as it traverses the whole east face of the boulder. Top out easily up and right.
This is a really unique problem because of its traversing nature and its length. The sit start is a project, and looks to include excellent 5.13+/14- crack moves to gain the stand start.
Start on the south face of the boulder and traverse right to the east face.