This report presents towing tests made in the N.A.C.A. tank of a parent form and five variations of a flying-boat hull. The beams of two of the dervied forms were made the same as that of the parent and the lengths changed by increasing and decreasing the spacing of stations. The lengths of two other of the derived forms were made the same as that of the parent while the beams were changed by increasing and decreasing the spacing of buttocks, all other widths being changed in proportion. The remaining derived form has the same length and beam as the parent, but the lines of the forebody were altered to give a planing bottom with no longitudinal curvature forward of the step.