A Grounding System for Reducing a Surge Current between Two Grounding Electrodes on FRP Boat

Abstract

When a small boat, which made of insulation material such as Fiber Reinforced Plastic (FRP) or wood, is struck by either direct or nearby lightning, a surge current flows in a power cable or a grounding wire on the boat. The current due to a direct lightning strike flows out from grounding electrodes for a radio or the other electrical equipment. On the other hand, if the boat is struck by nearby lightning, the current flowing in seawater invades into the equipment on the boat via the grounding electrodes. To reduce the current flowing in the circuit on the small boat, an installation of a ring electrode around the hull of the boat is proposed in this paper. For the direct lightning, the countermeasure can reduce the current flowing out from the grounding electrode for the radio and the other equipment by a connection of the electrodes with the appended ring electrode. The ring electrode bypassing the lightning current. Even if the lightning strikes a surface of seawater nearby the boat, a few percent of the lightning current invades into the boat. The proposed countermeasure also reduces the invading current by about 60%.