On my last assignment, a lightning protection device fitted above the ship’s mast caught my attention. I had experienced two lightning strikes at sea: one destroyed the forward anchor light including the spare, while another destroyed GMDSS equipment. Those incidents gave me a practical reason to examine what the installation could protect.
Navigation lights and GMDSS are essential to safe navigation and distress communications. Damage can delay departure until repairs are completed or temporary arrangements are accepted by the relevant authorities.
The commercial consequences can quickly exceed the replacement cost: emergency technical attendance, missed schedules, possible off-hire and, where serious deficiencies remain, detention. Lightning protection therefore deserves attention as part of the ship’s ability to remain operational. Its value depends on how effectively the complete installation protects the equipment the vessel needs to sail safely.
Why a steel hull does not protect every circuit
A steel ship provides a conducting path for lightning current to reach the sea. This can limit structural damage, but it does not guarantee the survival of the equipment connected to its masts and antennas.
There are two important routes for that damage. A surge can travel along an electrical connection into equipment, while the rapidly changing magnetic field around the lightning-current path can induce voltages in nearby wiring loops. This second mechanism, called inductive coupling, forms part of the lightning electromagnetic pulse, or LEMP. Equipment inside the accommodation can therefore remain vulnerable through its cables, despite the shielding provided by the surrounding steel.
IACS Recommendation 178 distinguishes structural protection from secondary electrical damage. The practical implication is that protection must address both the route taken by lightning current and the circuits serving essential equipment. That requires examining how conductors, bonding and surge protection work together across the installation.
These paths can occur together. The diagram illustrates possible mechanisms, not a reconstruction of either strike I experienced; nearby strikes can also induce surges.
Three protection approaches
Conventional conductors: controlling the current path
A conventional arrangement provides an intended attachment point and a suitable conducting path towards the water. Depending on construction, it may use the metal mast and hull or dedicated conductors. Bonding reduces dangerous potential differences between conductive parts, helping to limit uncontrolled sparking.
This approach manages the strike rather than preventing it. Its effectiveness depends on the complete route, including connections and nearby electrical installations. The US National Weather Service similarly distinguishes interception and conduction from the additional surge protection needed for connected equipment.
Dissipators: can a device prevent a strike?
Dissipators aim to change the electrical conditions around the mast so that lightning is less likely to strike the ship. Manufacturers claim that their devices interfere with the formation of the electrical path between the cloud and the vessel. This is the proposed operating principle; reliable prevention of strikes on ships has not been established by the research reviewed here.
Dinnteco’s DDCE Marine is one example. Its manufacturer claims that the device alters local electrical conditions to inhibit this process. Other designs use multiple discharge points to release charge into the surrounding air. Their intended benefit is to reduce the likelihood of a direct strike.
The research reviewed for this article does not establish that these devices reliably prevent lightning strikes on ships. A 2022 study of two land-based dissipation-array installations found that they had neither prevented strikes nor changed long-term lightning density. That study did not test every marine product, but it provides grounds for questioning broad prevention claims.
Owners should therefore require evidence relevant to the proposed installation and marine conditions, including salt exposure, corrosion and vessel movement. Until reliable performance is demonstrated, a dissipator should not be treated as a guarantee against lightning or a substitute for bonding and surge protection.
Surge protection: protecting equipment from voltage spikes
Lightning can send a sudden surge of electrical energy through cables connected to radios, navigation equipment and other electronics. Surge protective devices, or SPDs, limit the voltage reaching these circuits, reducing the risk of damage even when the equipment itself has not been struck.
Different devices provide protection at different points. Type 1 devices are designed to handle a share of the lightning current entering an electrical installation. Type 2 devices limit surges within the distribution system, while Type 3 devices provide additional protection close to sensitive equipment. They need to work together, with their selection matched to the ship’s electrical arrangement.
For communications equipment, the power cable is only one possible route for a damaging surge. Energy can also enter through the antenna feeder or other connections. Antenna protectors must therefore suit the radio and allow its signals to pass normally. Protecting the power supply while overlooking these connections can leave the same radio vulnerable.
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Redundancy can share a failure path
A second radio or GPS receiver provides backup when the first fails. However, both can remain vulnerable to the same lightning event if their cables follow a shared exposed route or their power supplies connect through an inadequately protected distribution point. A surge reaching both installations could disable the backup along with the primary equipment. Shared dependence also features in DeepDraft’s analysis of GNSS interference, where disruption of one position source can affect several bridge systems. The mechanism differs, but the need to examine what duplicated equipment shares remains relevant.
This is a common-cause failure: one event affecting systems intended to provide alternatives. Assessing redundancy therefore requires looking beyond the number of units fitted. Cable routing, power supplies, shielding, bonding and surge protection should be reviewed together to establish whether the backup is protected against the same event that could disable the primary system.
IMCA’s review of incidents reported in 2011 records a drilling vessel struck at least twice by lightning during a thunderstorm. It lost signals from two satellite-positioning systems, two gyros, two wind sensors and a hydroacoustic reference, followed by its remaining position references. The vessel disconnected and moved under joystick control to a safe handling zone. Several positioning inputs were available, yet the lightning event still forced the operation to stop.
Protection starts with the technical specification
Lightning protection should be assessed when a ship is designed or its electrical and communication systems are modified. The shore technical team, supported by designers and specialist contractors, should establish how exposed equipment, cable routes, bonding and surge protection work together. Required class review forms part of that process. Selecting a masthead device alone does not resolve the protection of equipment connected below it.
A fleet-wide specification can establish a consistent standard, but its application still needs to reflect each vessel’s arrangement. Differences in mast construction, antenna positions, power supplies and cable routing can leave ships with different vulnerabilities, even when they carry similar equipment. Retrofit proposals should identify the weakness being addressed and explain how the installation reduces it.
Once fitted, the arrangement must remain effective through maintenance and later modifications. Shipboard teams need clear inspection requirements, accessible maintenance records and a process for reporting damaged connections or protection-device faults. Changes to antennas, sensors or cable routes should return to the technical team for assessment. This places design decisions with those responsible for the installation while giving the crew a practical role in preserving it.
The DeepDraft view
The commercial exposure extends beyond replacing damaged equipment. Loss of essential communications or navigation capability can delay departure, require emergency technical attendance and lead to off-hire, depending on charter terms. Serious deficiencies may also prevent the vessel from proceeding until repairs or acceptable temporary arrangements are in place.
Owners should therefore assess lightning protection against the functions the ship needs to retain. That assessment should identify vulnerabilities in the existing installation and establish where conventional conductors, bonding or surge protection can reduce them. Devices claiming to prevent strikes require evidence relevant to their intended application before those claims become the basis of a fleet purchasing decision.
Having experienced the loss of an anchor light and GMDSS equipment in separate strikes, I see a practical case for this work. The responsibility lies with the shore technical team to specify suitable protection and ensure it remains effective through maintenance and modifications. For the Master, its value is straightforward: preserving the equipment needed to communicate, navigate and continue the voyage safely.
Media Section
Sources reviewed
- US National Weather Service: How conventional lightning conductors protect structures.
- Journal of Advanced Marine Engineering and Technology: Lightning damage mechanisms and protection of shipboard equipment.
- DDCE Marine manufacturer: The claimed operating principle of charge-compensation devices.
- Lightning Eliminators & Consultants: How dissipation-array systems are intended to work.
- Mata and Hill, ICLP 2022: Research examining strike-prevention claims at two land-based installations.
- DEHN technical presentation: Electromagnetic effects and how lightning induces damaging voltages in wiring.
- DEHN surge-protection guidance: The different functions of Type 1, Type 2 and Type 3 protective devices.
- DNV: Class review of vessel modifications.
- Paris MoU GMDSS guidelines: How serious radio deficiencies can affect permission to sail.
- IMCA M 227: Station keeping incidents reported for 2011, incident 1112. Lightning-related loss of positioning systems on a drilling vessel.
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