Definitions

An adequate lightning capable grounding point for a sailing vessel is specified by the ABYC as a conductor plate having a minimum surface area of 144 square inches.

Our research has shown, however, that it is not the plate surface that is important but the bulk of the plate and the amount of edges and points it has. Electrical energy will contact water more easily through edges and points than the surface. The ABYC standard should be considered as a very basic minimum requirement. Their standard E-4 also recommends a #4 conductor. We recommend nothing smaller than an AWG 1/0 and a well shielded wire as well.

The voltage from a lightning strike rises very fast, typically to its peak in a few millionths of a second. This energy must be returned to "earth" or in our case, to earth via the water that surrounds our vessels as quickly as possible, through a low impedance path, otherwise dangerous side-flashing may occur. The build-up of electrons on the ground system also must be dissipated to prevent dangerous voltages in the equipment. The ground system must therefore be adequately designed to permit the water to absorb the energy.

Necessity of a ground system

In order to neutralize the harmful transient energy, it must be returned to earth ground before the harmful energy can take another path through the sailboat. Therefore, it is absolutely imperative that a good grounding system be installed.

We have observed numerous boats which have been struck by lightning. It is apparent to us that boats following the traditional grounding theory successfully endure lightning strikes with only minimum damage to the boat. Damage to electronics is, however, very possible and is due mainly to the large electro-magnetic energy pulse which is produced when lightning strikes. This magnetic field can induce large destructive currents in electronic circuits and destroy them.

Lightning protection is not a black or white issue. Lightning cannot be observed under controlled conditions and is very difficult to understand and predict, but we need to be very cautious with it. Protection as specified by ABYC seems prudent. The Strikeshield system offers you a cost effective off-the shelf grounding system that meets and exceeds the required ABYC standards for your sailboat.