The so-colled “KIHANSEN”, a small wooden cargo ship whose length is about 20 meters or more, operates mainly on the Seto Inland Sea, a typical Archipelago in Japan. In the previous papers, the authors studied its safety with regards to its loading conditions, its particular ship form and construction, and complicated sea conditions under which the ship must navigate. And concluded that the causes of its casualties were 1) extraordinary length-breadth ratio ( L/B ), namely, about 3.8 2) undesirable loading conditions which are unsuitable with ship nature especially in case of carring heavy cargos, and 3) the unfavorable hold arrangements for seaworthiness, which allow shipping sea water easily. In this paper, to confirm above conclusions, with deta of 164 serious ship casualties, the situations of affairs are examined and studied severally, and furthermore some designing problems are discussed in connection with the safety of this sort of ship.