The study of the viscous drag of ships in model basins can be promoted in the following two steps : (1) First, to study turbulent, smooth, and rectangular plane surfaces with varying aspect : ratios, (2) Second, to investigate ship hull forms with varying particulars. With respect to the first of the above, quite recently an almost fully satisfactory solution has been found by Dr. G. Hughes (1952 ·1954). However, the second and consequently the final step still remains unsolved, and the need is emphasized of the adoptation of submerged double models by the Skin Friction Committee at the Seventh International Conference on Ship Hydrodynamics (1954). The first part of this report gives a short description of a resistance dynamometer to be used for a submerged body, which was designed at the Tokyo University Tank during the years 1952-1953. In the second part, form factors are directly deduced according to various hull forms through the use of the above-mentioned dynamometer. Further, a possibility is also suggested of indirect estimation of form factors by applying wave-making theory to ordinary resistance tests of surface models.