An experimental study of the bearing strength, failure modes, geometrical parameters of prepreg composite blanks with clearance is presented in this paper. The main aim of the study is to evaluate the effect of seawater on the structural properties of prepreg composite materials. Two different geometrical parameters are investigated during analysis. The ratio of edge-distance-to-hole diameter (B/D) and the ratio of the specimen width-to-hole-diameter (W/D) are systematically varied. The specimens are kept into seawater having 3.8% of salt in a closed plastic container indoor for 1 and 2 months at room temperature. The experimental results obtained from the specimens kept into seawater are compared of control specimens that are not immersed in seawater. Corresponding failure modes and loads are defined. The results show that while the value of bearing strength decreases with the increase of immersing period, the failure modes for all configurations' are the same. Also, it is observed that the unimmersed specimens had higher failure loads than the immersed specimens.