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Thunderstorm on a boat: what to do on board
Short answer
Staying safe in a thunderstorm on a boat starts early: watch the forecast,
head for harbour at the first warning, reef, go below and keep clear of the mast and rigging.
The squall arrives before the lightning, and afterwards the boat needs a survey.
Summer thunderstorms build quickly over the land and then march out over the water, on the Solent as much as on the Dutch lakes or along the coast of Mallorca. The first thing to arrive is usually not lightning but the gust front: a sudden squall from a new direction that knocks boats flat and drags anchors before the first strike. Watch the inshore waters forecast and Met Office warnings in the UK, Navtex further out and the sky to windward, and make for harbour at the first sign rather than the last.
If you cannot get in, prepare the boat: reef hard or drop sail, put on lifejackets, stow anything loose and steer away from the shore and shallows. The safest place is below deck, near the middle of the boat, keeping clear of the mast, shrouds, guardrails and anything metal connected to the rig. Swimmers, paddleboarders and anyone in the tender come out of the water straight away. Switch off electronics you do not need and isolate them from the boat's supply where you can, but keep the engine running if you need it to manoeuvre.
After a strike, check the crew first and then the hull: lightning can blow out through-hull fittings or leave damage around the keel, and electronics, VHF and engine management often fail days later. Have the boat lifted or surveyed even if everything seems to work, and photograph scorch marks. When reading a policy, look at whether lightning is a named peril on every level of cover and whether surge, overcurrent and short-circuit damage to equipment counts when lightning caused it. That clause decides a claim for the electronics. With us lightning is named in every tier; only the Basis wording adds expressly that surge and short circuit damage can count as lightning damage.
Worth remembering
Gust front
arrives before the first strike
Lightning
check the wording for surge damage
The best lightning protection is an early start for harbour.
Questions
What owners ask us about this
Where is the safest place on a sailing boat in a thunderstorm?
Below deck, near the middle of the boat, away from the mast, shrouds and metal fittings. Do not touch anything connected to the rig, and keep everyone out of the water.
Should I keep the engine running in a thunderstorm?
Yes, if you need it to manoeuvre. Switch off electronics you can do without and isolate them from the boat's supply where possible, so a nearby strike does less harm.
What should I check after a lightning strike?
Injuries first, then whether the boat is taking on water, especially at the through-hulls. Then have a surveyor look at hull, rig and electronics, since faults often appear later.
Related
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