The short answer: no system makes a boat immune to lightning, but a well designed protection path can give a strike a lower-resistance route to the water and reduce the risk to crew and hull. Electronics are much harder to protect and are often damaged even on protected boats.
Lightning strikes on the South Coast are uncommon, which is exactly why decisions about protection are often made on myths rather than facts.
The aim is to give a strike a direct, heavy conductive path from the highest point, usually the masthead, down to a ground plate or keel in contact with the water. Without that path, the current finds its own way, sometimes through rigging, wiring, crew or a through-hull fitting.
On many sailing boats, an aluminium mast stepped on a keel-stepped base with an external lead or iron keel already provides much of the route. Deck-stepped masts, encapsulated keels and GRP hulls change the picture. The connections between mast, rigging and keel need heavy conductors and sound joints to be effective.
Large metal objects near the main conductor, such as engines, tanks and shroud chainplates, can develop dangerous voltage differences during a strike. Bonding them to the protection system reduces the risk of side flashes. This lightning bonding is related to, but not the same as, the corrosion bonding covered in our earthing and bonding guide.
Poorly planned bonding can make galvanic corrosion worse, so the two need to be considered together.
Even a direct strike that the protection path handles well can induce surges that destroy electronics throughout the boat. Surge protection devices help a little, and disconnecting antennas and power leads during a nearby storm helps more. Many owners rely on insurance for electronics rather than expecting protection to save them.
If you are near a thunderstorm, stay below if you can, keep away from the mast and rigging, and avoid touching metal fittings. On a mooring, disconnecting shore power and antenna leads is sensible when storms are forecast.
Have the boat inspected even if nothing looks damaged. Strikes can burn out through-hull fittings, damage wiring insulation inside the boat and leave compass deviation. An electrical inspection and a hull check below the waterline are both wise.
Safety note: lightning protection design and bonding involve heavy conductors and interaction with the boat's corrosion protection. This is specialist work for a qualified marine electrician.
Motorboats without masts are less likely to be the tallest object nearby, but tall arches, radar masts and outriggers can still attract a strike. The same principles apply: a heavy conductive path from the highest point down to the water and bonding of large metal masses near that path. On many motorboats the practical options are more limited, and the focus shifts to protecting crew and knowing what to check afterwards.
If your boat has a tall arch carrying antennas and radar, consider how a strike would travel from it to the water, and whether any existing wiring would end up carrying that current instead.
A full protection system can be a significant job, particularly on a boat not designed for one. For many South Coast owners, the sensible approach is to understand what the existing mast and keel already provide, improve obvious weak points and accept that electronics may still be at risk. For boats cruising further afield or in stormier regions, a more complete system may be justified.
We will explain what is realistic on your particular boat and what it would involve, without overselling protection that cannot deliver what it promises.
A few ideas circulate on pontoons that do not stand up well. Dissipater brushes at the masthead are not proven to prevent strikes. Hanging a jump lead from the shrouds into the water is too light to carry strike current safely and may do little beyond reassure. A carbon mast does not simply behave like an aluminium one. And a boat struck once is not somehow protected from being struck again. Good decisions come from understanding the conductive path your particular boat offers, not from folklore or quick fixes bought at a chandlery.
Strikes are relatively rare, but they do happen, particularly to masted boats in exposed positions.
Not reliably. It mainly protects crew and hull. Electronics often suffer surge damage even on protected boats.
Yes. Damage to wiring and through-hulls is not always visible, so an inspection is worthwhile.
We can assess your boat's current conductive path and bonding and advise on what is realistic. Free assessment, written quote.