Rocker

A description of the amount of curvature in the bottom of the hull. Often measured in inches of height to bow or stern from the lowest point in the hull's bottom. Unfortunately, this can cause a lot of confusion because the bow and the stern are always even with the water surface and the lowest point of the boat is the draft which really does not change all that much between various boats, really all you are talking about is the draft. Rocker really tells you how quickly the keel of the boat approaches its full depth.

A boat with a lot of rocker will slope gradually down to its deepest point, where a boat with little rocker will slope down quickly and then it will have a relatively straight keel.