The first task is to get everyone below decks and located as follows:
- Up as high in the cabin as possible (i.e. away from the waterline)
- Away from the sides of the vessel
- Well away from the mast
- As far as possible from the lightning protection system
- Away from all electrical cabling and electronic instruments
Avoid all contact with, or proximity to, any large metal objects, such as an engine or the helm (especially if it’s made of stainless steel). Also, remember the steering system is usually made of many metal components installed behind a bulkhead.
People should sit with their legs up to minimise their frontal surface area, thus minimising the risk of conducting a side flash. This position also affords some additional protection to the heart.
If a person is wet, they should dry off and change as soon as possible. In the case of a power boat, it’s also imperative that everyone remains well within the zone of protection (see Figure 4).
If a person must remain outside (for example, at the helm), he should avoid touching large metal objects and also stay well away from any likely secondary paths, such as standing rigging.
Anyone who is caught in an open boat should sit in the bottom of the boat (but not in any water), with legs folded up against the chest. It’s also imperative to remain as still as possible, as there is some evidence to suggest that moving objects may increase the chance of a lighting strike. While maintaining this position may become uncomfortable, it could well save your life.
Side flashes occur wherever the electrical flow incurs high impedance. This includes many types of electrical connections, rapid changes in direction of the electrical path, poor or loose connections or corrosion in the lightning protection system.
Side flashes can do substantial damage to a vessel. They can blow a hole through the side or bottom of the boat anywhere from 2mm to 100mm in diameter, depending on the location and the impedance to the electrical flow. Side flashes are also often the cause of damage to onboard electronics.