FRP was used partly for the hull construction of the OYASHIRO, the first submarine built in Japan after the World War II. Recently, we had an opportunity to investigate the effect of actual service on the property of FRP. Test pieces cut from the fairwater of submarine, which had been in service for over five years, were tested and their results were compared with the original data. It was shown that FRP degraded to some extent, but it was still met the specification requirements and was serviceable.
