In order to study the fundamental problems on the strength of life boat made of Fiberglass Reinforced Plastic, Statical strength test and drop test were carried out on a 7.5 meter life boat constructed with longitudinal frames of “open hat section”. In the statical test, 5 tons distributed load was applied to the life boat and were measured longitudinal bending stresses, transverse stresses, local stresses as well as the deflections of the boat. In the drop test, on the other hand, the boat carried with loads of about 4 tons was dropped from a height of 0.5 m to 3 m above the surface of the water, and the stresses and hydraulic pressures on the bottom shell plate due to the impact were measured. As a result of these tests, it was found that the maximum longitudinal stress was 0.5 kg/mm², corresponding to about one-eighth of the proportional limit of the material, but the local deflections of the bottom shell plate was considerably large due to its transverse floor less construction. It was also found that the stresses in the bottom shell plate caused by impact force at the dropping reached two-third of the tensile strength of the material. It was confirmed from these tests that, if a careful consideration is paid to the increase of the local deflection, the FRP life boat with soft construction has the sufficient strength for both the statical load and the impact force.