Boat bottoms or hulls come in a variety of shapes and sizes. Each hull type is designed to either displace or plane through the water. Sailing vesselsa vessel under sail, provided that propelling machinery, even if present, is not being used. and large cruise ships use displacement hulls because the combination of their size (weight) and power will not allow them to plane. On the other hand, smaller powerboats are typically built with planing hulls that are designed to rise up and ride on top of the water at higher speeds than displacement hull boats.