The problems of using models in planing tests are addressed. If one passes from the model to a hull of linear dimensions n times greater, the speeds are connected by the law of mechanical similitude. The normal forces given by the hydrodynamic equations (perfect fluid) also follow the law of dynamic similitude (Reech's method) and are multiplied by n(exp 3). A series of tests were performed and the actual results were compared to theoretical results.

This study will be concerned with the critical examination of two main questions, mainly, susceptibility of centering and more generally, the conditions of static stability, longitudinal equilibrium, and the question of dynamic stability, or at least the damping of longitudinal vibrations about a position of equilibrium that may result from a small variation in the angle of attack.