Half-breadth plan

The half-breadth plan, or waterlines plan, is the top-down (plan) view of the lines drawing, showing the waterlines, the half-breadths of the hull at a series of heights above the baseline, projected onto the horizontal plane. Because the hull is symmetric about the centerline, only one side (the half-breadth) is drawn. Each curve is the intersection of the hull with a horizontal plane at a fixed waterline height, so the design waterline, the upper and lower waterlines, and the deck-at-side line all appear here. The half-breadth plan is one of the three mutually consistent views of the lines plan, with the sheer (profile) plan and the body plan; a point faired in one must agree in the other two.