Lightning damage on a boat is mostly invisible.
The dramatic version — a blown-out through-hull, a scorched mast step, a hole in the laminate where the current exited below the waterline — is real, and we repair it. But it is not the common case. The common case is a vessel that looks entirely normal, runs when you turn the key, and has a chartplotter that will not hold a fix, an ECU that has thrown a code nobody has read yet, and a bilge pump whose float switch quietly stopped working three weeks ago.
Fiberglass Solutions performs a comprehensive lightning damage inspection at no cost to the owner, anywhere in Florida, within 48 hours of your call.
Schedule a Free Lightning Damage Inspection24-Hour Storm Line — 866-950-3888
Direct Strike, Side Flash, or Nearby Strike — All Three Cause Damage
Boat owners tend to think of lightning as binary. Either the boat was hit or it was not. The technical reality is more graduated, and understanding it is the difference between a claim that gets documented and one that never gets filed.
Practical Sailor, drawing on ABYC-aligned technical standards, identifies five distinct mechanisms by which lightning damages a vessel:
A direct strike to the mast or the highest point on the vessel, with the current seeking ground through the boat.
Side flash, where different conductive components of the boat sit at significantly different voltage levels and the charge jumps from one to another. ABYC TE-4 defines side flash as a discharge between the lightning protection system and metallic objects, or between onboard conductors and the water.
A side strike that exits from interior components through the hull to the water — the mechanism responsible for through-hull and transducer failures, and for boats that sink after a strike. One documented case involved a trimaran with no bonding system and non-metallic seacocks that sank after lightning exited through a transducer and the hull.
Electromagnetic-pulse-induced surge currents in circuits that were not part of any primary or side strike at all. This is how a boat that was never touched loses its electronics.
Ground strike radiance from a nearby strike, with a risk radius that has been quoted as far as 100 to 300 feet.
The last two are the reason this page exists. ABYC TE-4, the marine lightning protection standard, states plainly that even on a vessel with a properly designed lightning protection system, complete protection from equipment damage or personal injury is not implied. A boat can do everything right and still take damage.
The full explanation — Hidden Lightning Damage →
What We Test
Our lightning damage inspection is a diagnostic process, not a walkthrough. Depending on the vessel and what the initial findings indicate, it may include the following.
Engines and engine control systems
Complete inboard or outboard electrical and impedance diagnostic checks. Engine computer and diagnostic scanning, including ECU and ECM fault retrieval. Inspection and testing of sensitive engine electronics and components. Sensor checks throughout the engine and the vessel. Lightning damage to an engine control module frequently does not prevent the engine from starting; it shows up later as intermittent faults, derates, and sensor readings that drift.
Wiring and electrical circuits
Wire and electrical circuit impedance and resistance diagnostic testing. Inspection of wiring, terminations, and connections. Identification of potential electrical discharge pathways and evidence of arcing. High-current events degrade conductors and connections in ways that a continuity check will not always reveal, which is why impedance testing matters.
Onboard electronics
Diagnostic evaluation of sensitive onboard electronics. GPS, radar, sonar and transducers, VHF, autopilot, multifunction displays, and network cabling including NMEA 2000 backbones and drops. Network cabling is a frequently overlooked casualty — the cable itself can be damaged while every device on it appears healthy.
Batteries, charging, and AC systems
Battery and charging system evaluation. Inverters, chargers, and isolation transformers. Shore power and onboard AC and DC system evaluation. Isolation transformers and chargers are among the most commonly damaged components in an indirect strike because of their construction.
Pumps
Inspection and testing of onboard pumps, including bilge pumps, livewell, washdown, and macerator pumps, along with their float switches and control circuits. We treat bilge pumps as a safety item, not a convenience item. A boat with an undetected bilge pump failure after a storm is a boat that can sink at the dock.
Bonding, grounding, and underwater fittings
Bonding and grounding system inspection consistent with ABYC E-2. Through-hull, transducer, and underwater fitting inspection. Research indicates vessels equipped with bonding systems — even substandard ones — are less likely to suffer damage in a strike, which makes the condition of the bonding system both a damage indicator and a forward-looking safety concern.
Fiberglass and structure
Inspection for burned, heat-damaged, or electrically affected fiberglass. Evaluation for potential delamination and hidden laminate damage. Inspection for evidence of electrical arcing or discharge damage. Lightning exit points below the waterline are a structural issue as well as a leak, and they are our core competency.
Why We Test One System at a Time
This is worth stating plainly because it is the most common way owners make their own situation worse.
After a strike, the instinct is to go through the boat turning everything on to find out what still works. The problem is that a damaged circuit board can short a healthy one. Powering up an entire system at once, when part of it has been compromised, can propagate the damage into components that survived the strike intact.
We test sequentially and in isolation, and we isolate before we energize. It takes longer. It also means the inspection does not add to the claim.
Florida’s Lightning Exposure Is Not Hypothetical
Vaisala Xweather’s 2025 annual lightning report ranks Florida first in the United States for lightning density at 305 lightning events per square mile. Polk County recorded 1,057,635 lightning events in 2025 — more than any other county in the country — and Seminole County recorded the highest lightning density of any US county.
BoatUS Marine Insurance claim data puts Florida’s lightning claim rate at 3.3 boats per 1,000 against a national rate of roughly 0.9. Risk scales sharply with size and rig: boats between 40 and 65 feet run about 6.0 per 1,000, monohull sailboats about 3.8, and multihulls roughly twice the monohull rate. Raising mast height from 35 feet to 45 feet nearly triples the odds. Small powerboats sit near 0.1 per 1,000.
If you own a larger vessel or a sailboat in Florida, you are not in the general population for this peril.
Free Lightning Damage Inspection — Anywhere in Florida
If there was lightning near your boat, we will tell you what it did. At no cost, within 48 hours.
Schedule My Free InspectionCall the 24-Hour Storm Line
Frequently Asked Questions
How do I know if my boat was struck by lightning?
Often you do not, and that is the problem. Obvious indicators include scorching at the masthead or antenna, a blown-out through-hull or transducer, pitting on metal fittings, a burnt smell, and multiple electronics failing at once. But a large share of lightning damage produces none of those. If there was significant lightning activity near your vessel, the only reliable way to know is to test.
Can lightning damage my boat if it wasn’t hit?
Yes. Practical Sailor documents electromagnetic-pulse-induced surge currents in circuits that were not part of any primary or side strike, and ground strike radiance from nearby strikes with a risk radius quoted as far as 100 to 300 feet.
How long does the inspection take?
It depends on the vessel’s size and complexity. A comprehensive diagnostic inspection on a mid-size vessel with a full electronics package typically takes several hours. We would rather take the time than miss something that becomes a supplement fight later.
What does the inspection cost?
The initial storm damage inspection is free.
My electronics worked after the storm. Am I in the clear?
Not necessarily. Damage frequently surfaces late — owners commonly report that components with semiconductors in them worked initially and failed the first time they were powered up days or weeks afterward. Insurance carriers often leave lightning claims open for exactly this reason.
Do you inspect sailboats?
Yes. Sailboats carry a meaningfully higher lightning claim rate than powerboats — BoatUS puts monohull sailboats at 3.8 per 1,000 against a 0.9 national average — and they bring their own considerations, including standing rigging and mast step condition.
Is a lightning damage inspection the same as a marine survey?
No. A marine survey is a broad condition and valuation assessment usually performed by a SAMS- or NAMS-credentialed surveyor, and your insurer may require one. Our inspection is a targeted diagnostic evaluation of storm-related damage, and it complements a survey rather than replacing it.