抄録
A boat made of fiber reinforced plastic (FRP) is heavily damaged by a lightning strike. When the boat without any protection is struck by a lightning, not only the boat but also the crew on the boat may be damaged. Although it has been known that the importance of the lightning protection, information on the lightning damage is insufficient. It is necessary to clarify the invasion route of the lightning for an effective lightning protection, at first.
Insurances had been paid on 94 cases for the lightning damages in FY 2011. Its total amount is about 84 million yen. The survey in this paper clarified that the small FRP boats are likely to be damaged by a lightning compared with ships. In many cases, a conductor located at a high position, such as an antenna or a rib of a tent of a fishing boat, was struck by a lightning. As a result, onboard electronic instruments were damaged.
A reproductive experiment is carried out to reproduce a destruction of an antenna. From the result, it is cleared that a high voltage is generated across a loading coil of a radio antenna by a steep lightning current. The high voltage is determined by the inductance of the coil and the slope of the lightning current. The destruction mechanism of antenna that mounted on boat in the report was clarified by this experimental result.
