Boat hulls or assemblies have sequences of groups of downward-facing sections such as planing sections. A sequence includes a lowermost group and supplemental groups above it. Each group could, for example, be a pair, and the pairs could be port-starboard symmetrical. The lower surface is shaped so that the boat hull, in a series of speed ranges, planes on successively lower groups, planing on the lowermost group in the highest range. The trim angle can be between 3.0.degree. and 6.0.degree. in a speed range. The boat hull can be structured so that, when planing on one of the groups, the next higher group dries out. For example, each pair of sections can have an outward angle not smaller than the next inward pair's. The lowermost group can have a maximum width approximately equal to an ideal beam width for a set of displacement characteristics and its target maximum speed.