sailboat lightning ground plate

Yachting Monthly

• Digital edition

Sailing in lightning: how to keep your yacht safe

• In partnership with Katy Stickland
• July 22, 2022

How much of a concern is a lightning strike to a yacht and what can we do about it? Nigel Calder looks at what makes a full ‘belt and braces’ lightning protection system

Storm clouds gather at Cowes, but what lightning protection system, if any, does your boat have for anchoring or sailing in lightning? Credit: Patrick Eden/Alamy Stock Photo

Most sailors worry about sailing in lightning to some extent, writes Nigel Calder .

After all, going around with a tall metal pole on a flat sea when storm clouds threaten doesn’t seem like the best idea to most of us.

In reality, thunder storms need plenty of energy, driven by the sun, and are much less frequent in northern Europe than in the tropics.

However, high currents passing through resistive conductors generate heat.

Small diameter conductors melt; wooden masts explode; and air gaps that are bridged by an arc start fires.

Sailing in lightning: Lightning is 10 times more likely over land than sea, as the land heats up more than water, providing the stronger convection currents needed to create a charge. Credit: BAE Inc/Alamy Stock Photo

On boats, radio antennas may be vaporised, and metal thru-hulls blown out of the hull, or the surrounding fiberglass melted, with areas of gelcoat blown off.

Wherever you sail, lightning needs to be taken seriously.

Understanding how lightning works, will help you evaluate the risks and make an informed decision about the level of protection you want on your boat and what precautions to take.

Most lightning is what’s called negative lightning, between the lower levels of clouds and the earth. Intermittent pre-discharges occur, ionising the air.

Whereas air is normally a poor electrical conductor, ionised air is an excellent conductor.

These pre-discharges (stepped leaders) are countered by a so-called attachment spark (streamer), which emanates from pointed objects (towers, masts, or lightning rods) that stand out from their surroundings due to their height.

Summer is the season for lightning storms in the UK. Here, one finds early at Instow, Devon. Credit: Terry Matthews/Alamy Stock Photo

This process continues until an attachment spark connects with a stepped leader, creating a lightning channel of ionised air molecules from the cloud to ground.

The main discharge, typically a series of discharges, now takes place through the lightning channel.

Negative lightning bolts are 1 to 2km (0.6 to 1.2 miles) long and have an average current of 20,000A.

Positive lightning bolts are much rarer and they can have currents of up to 300,000A.

Preventing damage when sailing in lightning

A lightning protection system (LPS) is designed to divert lightning energy to ground (in this case the sea), in such a way that no damage occurs to the boat or to people.

Ideally, this also includes protecting a boat’s electrical and electronic systems, but marine electronics are sensitive and this level of protection is hard to achieve.

Lightning protection systems have two key components: First, a mechanism to provide a path with as little resistance as possible that conducts a lightning strike to the water.

This is established with a substantial conductor from an air-terminal to the water.

Components of an external and internal lightning protection system. Credit: Maxine Heath

This part of the LPS is sometimes called external lightning protection.

Second, a mechanism to prevent the development of high voltages on, and voltage differences between, conductive objects on the boat.

This is achieved by connecting all major metal objects on and below deck to the water by an equipotential bonding system.

Without this bonding system high enough voltage differences can arise on a boat to develop dangerous side flashes.

The bonding system can be thought of as internal lightning protection.

Rolling ball concept

Lightning standards, which apply ashore and afloat, define five lightning protection ‘classes’, ranging from Class V (no protection) to Class I.

There are two core parameters: the maximum current the system must be able to withstand, which determines the sizing of various components in the system, and the arrangement and number of the air terminals, aka lightning rods.

Let’s look at the arrangement of the air terminals first. It is best explained by the rolling ball concept.

A lightning strike is initiated by the stepped leaders and attachment sparks connecting to form the lightning channel.

The distance between the stepped leader and the attachment sparks is known as the breakdown distance or striking distance.

If we imagine a ball with a radius equal to the striking distance, and we roll this ball around an object to be protected, the upper points of contact define the possible lightning impact points that need to be protected by air terminals.

Lightning protection theories and classifications rely on a ‘rolling ball’ concept to define requirements, areas of risk and protected areas. Credit: Maxine Heath

The air terminal will theoretically provide a zone of protection from the point at which the terminal connects with the circumference of the rolling ball down to the point at which that circumference touches the water.

The shorter the striking distance, the less the radius of the rolling ball and the smaller the area within the protection zone defined by the circumference of the rolling ball.

The smaller the protection zone, the more air terminals we need. So, we use the shortest striking distance to determine the minimum number and location of air terminals.

Class I protection assumes a rolling ball radius of 20m; Class II assumes a rolling ball radius of 30m.

Continues below…

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A personal investigation into how and why a catamaran was hit by lightning

‘Lightning destroyed the boat’s electronics’

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Boat building standards are based on a striking distance/rolling ball radius of 30m (Class II).

For masts up to 30m above the waterline, the circumference of the ball from the point at which it contacts the top of the mast down to the water will define the zone of protection.

For masts higher than 30m above the waterline, the ball will contact the mast at 30m and this will define the limit of the zone of protection.

If Class I protection is wanted, the radius of the ball is reduced to 20m, which significantly reduces the zone of protection and, on many larger recreational boats, may theoretically necessitate more than one air terminal.

Protection classes

With most single-masted monohull yachts, an air terminal at the top of the mast is sufficient to protect the entire boat to Class I standards.

The circumference of the rolling ball from the tip of the mast down to the surface of the water does not intercept any part of the hull or rig.

However, someone standing on the fore or aft deck might have the upper part of their body contact the rolling ball, which tells us this is no place to be in a lightning storm.

Some boats have relatively high equipment or platforms over and behind the cockpit.

Protection classes to protect your boat while anchored or sailing in lightning

These fittings and structures may or may not be outside the circumference of the rolling ball.

Once again, this tells us to avoid contact with these structures during a lightning storm.

Ketch, yawl, and schooner rigged boats generally require air terminals on all masts, except when the mizzen is significantly shorter than the main mast.

The external LPS

The external LPS consists of the air terminal, a down conductor, and an earthing system – a lightning grounding terminal.

The down conductor is also known as a primary lightning protection conductor.

All components must be sized to carry the highest lightning peak current corresponding to the protection class chosen.

In particular, the material and cross-sectional area of the air terminal and down conductor must be such that the lightning current does not cause excessive heating.

The air terminal needs to extend a minimum of 150mm above the mast to which it is attached.

A graph depicting NASA’s record of yearly global lightning events. The Congo once recorded more than 450 strikes per km2

It can be a minimum 10mm diameter copper rod, or 13mm diameter aluminum solid rod.

It should have a rounded, rather than a pointed, top end.

VHF antennas are commonly destroyed in a lightning strike.

If an antenna is hit and is not protected by a lightning arrestor at its base, the lightning may enter the boat via the antenna’s coax cable.

A lightning arrestor is inserted in the line between the coax cable and the base of the antenna.

It has a substantial connection to the boat’s grounding system, which, on an aluminum mast, is created by its connection to the mast.

In normal circumstances, the lightning arrestor is nonconductive to ground.

When hit by very high voltages it shorts to ground, in theory causing a lightning strike to bypass the coax – although the effectiveness of such devices is a matter of some dispute.

Down conductors

A down conductor is the electrically conductive connection between an air terminal and the grounding terminal.

For many years, this conductor was required to have a resistance no more than that of a 16mm² copper conductor, but following further research, the down conductor is now required to have a resistance not greater than that of a 20mm² copper conductor.

For Class I protection, 25mm² is needed. This is to minimise heating effects.

Let’s say instead we use a copper conductor with a cross-sectional area of 16mm² and it is hit by a lightning strike with a peak current corresponding to Protection Class IV.

Sailing in lightning: This catamaran relies upon cabling to ground from the shrouds but stainless steel wire is not a good enough conductor. Credit: Wietze van der Laan

The conductor will experience a temperature increase of 56°C. A 16mm² conductor made of stainless steel (for example, rigging ) will reach well over 1,000°C and melt or evaporate.

Shrouds and stays on sailboats should be connected into a LPS only to prevent side flashes.

The cross-sectional area of the metal in aluminum masts on even small sailboats is such that it provides a low enough resistance path to be the down conductor.

Whether deck- or keel-mounted, the mast will require a low resistance path, equivalent to a 25mm² copper conductor, from the base of the mast to the grounding terminal.

Grounding terminal

Metal hulled boats can use the hull as the grounding terminal. All other boats need an adequate mass of underwater metal.

In salt water this needs a minimum area of 0.1m². In fresh water, European standards call for the grounding terminal to be up to 0.25m².

A grounding terminal must be submerged under all operating conditions.

An external lead or iron keel on monohull sailing boats can serve as a grounding terminal.

This owner of this Florida-based yacht decided to keep the keel out of the equation when is came to a grounding plate. High electrical currents don’t like sharp corners, so a grounding plate directly beneath the mast makes for an easier route to ground. Credit: Malcolm Morgan

In the absence of a keel , the cumulative surface area of various underwater components – propellers, metal thru-hulls, rudders – is often more than sufficient to meet the area requirements for a grounding terminal.

However, these can only be considered adequate if they are situated below the air terminal and down conductor and individually have the requisite surface area.

Metal through-hulls do not meet this requirement.

If underwater hardware, such as a keel, is adequate to be used as the grounding terminal, the interconnecting conductor is part of the primary down conductor system and needs to be sized accordingly at 25mm².

Propellers and radio ground plates

Regardless of its size, a propeller is not suitable as a grounding terminal for two reasons.

First, it is very difficult to make the necessary low-resistance electrical connection to the propeller shaft, and second, the primary conductor now runs horizontally through the boat.

The risk of side flashes within the boat, and through the hull to the water is increased.

Sailing in lightning: GRP hull, fairing filler and iron keel will have carried different voltages during the strike – hence this damage

An engine should never be included in the main (primary) conducting path to a grounding terminal.

On modern engines, sensitive electronic controls will be destroyed in a lightning strike, and on all engines, oil in bearings and between gears will create resistance and therefore considerable heat which is likely to result in internal damage.

However, as it is a large conductive object, the engine should be connected to the internal lightning protection system.

Internal lightning protection

On its way to ground, lightning causes considerable voltage differences in adjacent objects – up to hundreds of thousands of volts.

This applies to boats with a functioning external lightning protection system but without internal protection.

Although the lightning has been given a path to ground along which it will cause as little damage as possible, dangerous voltages can be generated elsewhere, resulting in arcing and side flashes, threatening the boat and crew, and destroying electronic equipment.

We prevent these damaging voltage differences from arising by connecting all substantial metal objects on the boat to a common grounding point.

One of the holy grails of marine photography – a direct lightning strike on a yacht’s mast. Credit: Apex

The grounding terminal is also wired to the common grounding point.

By tying all these circuits and objects together we hold them at a common voltage, preventing the build-up of voltage differences between them.

All conductive surfaces that might be touched at the same time, such as a backstay and a steering wheel, need to be held to the same voltage.

If the voltages are the same, there will be no arcing and no side flashes.

The bonding conductors in this internal LPS need to be stranded copper with a minimum size of 16mm².

Note that there can be bonding of the same object for corrosion prevention, lightning protection, and sometimes DC grounding.

We do not need three separate conductors.

Electronic Device Protection

With lightning protection systems, we need to distinguish electric circuit and people protection from device protection.

Even with an internal LPS, high induced voltages may occur on ungrounded conductors (such as DC positive) which will destroy any attached electronics.

A mechanism is needed to short high transient voltages to ground.

This is done with surge protection devices (SPD), also known as transient voltage surge suppressors (TVSS) or lightning arrestors.

Marine-specific SPDs are few in number and domestic models are not suitable for boats

In normal circumstances these devices are non-conductive, but if a specified voltage – the clamping voltage – is exceeded they divert the spike to ground.

There are levels of protection defined in various standards depending on the voltages and currents that can be handled, the speed with which this occurs, and other factors.

This is a highly technical subject for which it is advisable to seek professional support.

Most SPDs are designed for AC circuits.

When it comes to DC circuits there are far fewer choices available to boat owners although there are an increasing number for solar installations that may be appropriate.

There is no such thing as a lightning-proof boat, only a lightning-protected boat, and for this there needs to be a properly installed LPS.

Nigel Calder is a lifelong sailor and author of Boatowner’s Mechanical and Electrical Manual. He is involved in setting standards for leisure boats in the USA

Even so, in a major strike the forces involved are so colossal that no practical measures can be guaranteed to protect sensitive electronic equipment.

For this, protection can be provided with specialised surge protection devices (SPDs).

The chances of a direct lightning strike on a yacht are very small, and the further we are north or south of the equator, the smaller this chance becomes.

It’s likely your chances of receiving a direct lightning strike are very much higher on a golf course than at sea.

‘Bottle brush’-type lightning dissipators are claimed by sellers to make a boat invisible to lightning by bleeding off static electrical charge as it builds up.

The theory rests upon the concept that charged electrons from the surface of the earth can be made to congregate on a metal point, where the physical constraints caused by the geometry of the point will result in electrons being pushed off into the surrounding atmosphere via a ‘lightning dissipator’ that has not just one point, but many points.

It is worth noting that the concept has met with a storm of derision from many leading academics who have argued that the magnitude of the charge that can be dissipated by such a device is insignificant compared to that of both a cloud and individual lightning strikes.

It seems that the viable choices for lightning protection remain the LPS detailed above, your boatbuilder’s chosen system (if any), or taking one’s chances with nothing and the (reasonable) confidence that it’s possible to sail many times round the world with no protection and suffer no direct strikes.

Whichever way you go, it pays to stay off the golf course!

Enjoyed reading Sailing in lightning: how to keep your yacht safe?

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Getting the Charge Out of Lightning

No matter how well protected the boat may be, few manage to escape unscathed..

Miraculously, relatively few people are injured in lightning strikes. Frequently, of course, no one is aboard the boat when it is struck, and it is only by after-the-fact detective work that the extent of damage is discovered.

There are, however, two attendant bits of unpleasantness water, and contaminates like dirt, dust, rust, scale, bugs, and bones.

Most boat owners have only the vaguest idea of what is involved in protecting their boats from lightning damage. Many believe that their boats are already protected by the boat’s grounding system. Most are wrong.

Just because your boat may be bonded with heavy cop-per conductors connecting the masses of metal in the boat doesn’t mean that it is protected against lightning. A bon-ding system may be a part of a lightning protection system, but bonding itself offers no protection to the boat unless a good, direct path to ground is part of the system.

The purpose of bonding is to tie underwater metal masses in the boat together to reduce the possibility of galvanic corrosion caused by dissimilar metals immersed in an electrolyte. The purpose of lightning grounding is to get the massive electrical charge of a lightning strikethrough the boat to ground with the least possible amount of resistance.

Most lightning never reaches the earth: it is dispersed between clouds of different electrical potential. The lightning that concerns sailors is the discharge of electricity between a cloud and the surface of the earth, or an object on the surface of the earth, namely, your boat. The amount of electricity involved in lightning can be, well, astronomical. We’re talking about millions of volts.

Granted, the duration of a lightning strike is extremely short. But in the fraction of a second it takes for lightning to pass through your boat to ground, a great deal of damage can be done. And here’s the kicker. No matter how elaborate your lightning protection system, there is no guarantee that a lightning strike will not damage your boat.

Certainly you can reduce the potential damage from a lightning strike. That’s what protection is all about. But to think you can eliminate the possibility of damage is folly. There are too many recorded instances of so-called properly lightning-protected boats suffering damage to believe in the infallibility of lightning protection systems.

The goal of lightning protection is to offer a low resistance path to ground, in this case, the water. On a sailboat equipped with an aluminum mast and stainless steel standing rigging, the basic components of the lightning protection system are in place.

While neither aluminum nor stainless steel is an outstanding electrical conductor, the large cross-sectional area of both the mast and the rigging provide adequate conductivity for lightning protection. The trick, however, is get-ting the electricity from the mast and rigging to the water.

The straighter the path is from conductor (mast and rigging) to ground, the less likely are potentially dangerous side flashes. Put simply, side flashes are miniature lightning bolts which leap from the surface of the conductor to adjacent metal masses due to the difference in electrical potential between the charged conductor and the near by mass of metal. Ideally, therefore, the path from the bottom of the mast and rigging to ground would be absolutely vertical. In practice, this is rarely achieved.

If the boat has an external metal keel, the mast and standing rigging is frequently grounded to a keelbolt. There are pitfalls to this method. First, the connection between the bottom of the mast and rigging to the keelbolt must be highly conductive. ABYC (American Boat and Yacht Council) standards say that each primary conductor for lightning protection systems should have a resistance equal to or less than a #4 AWG copper conductor. (Secondary conductors should have resistance not greater than a #6 AWG copper conductor.)There is no drawback to using an even larger conductor.

Connecting the short conductor to the mast and keelbolt presents some problems. A crimp eye can be used on the end that is to be attached to the mast, but you may have to fabricate a larger eye for attachment to the keelbolt. This can be made from sheet copper. Soldering the connections is not recommended, since the heat generated in a lightning strike could melt the solder.

Then you have to face up to a basic problem. Your mast is aluminum, yet you’re connecting it to ground with a copper cable. Everyone knows that aluminum and copper are not galvanically compatible, so what’s the solution? While it will not eliminate corrosion, a stainless steel washer placed between the copper cable’s end fitting and the aluminum mast will at least retard it. But this connection is going to require yearly examination to make sure that a hole isn’t being eaten through the mast. In addition, of course, the process of corrosion creates wonderful aluminum oxide byproducts, which have very low conductivity. The aluminum oxide may reduce conductivity to the point where your theoretical attachment to ground is in fact non-existent. Once again, disassembling the connection and cleaning it yearly are essential to maintain conductivity. Constant attention to all the conductor connections is essential in any grounding system, whether it’s for lightning protection or grounding of the electrical system.

Even if all the connections in the system are flawless, you’re faced with getting the electrical charge out of the boat and into the water. Keels are always coated with bottom paint. Depending on the type of bottom paint used, the keel itself may be a fairly poor ground. An iron keel properly primed with epoxy mastic before bottom paint is applied is fairly well isolated from the water. If it weren’t, it would rust. The same goes for lead keels prepared in the same way. In practice, the electrical charge will probably be powerful enough to get to ground through the protection system on the keel. The same problem exists, of course, on painted metal boats with their systems of barrier coats. The barrier coats reduce conductivity, but do not eliminate it.

Do not under any circumstances ground the rigging or mast to ballast located inside a fiberglass hull shell. The electrical charge tends to travel on the surface of the conductor. Finding no path to ground from the isolated inside ballast, you may literally blow a line of holes through the hull along the top of the ballast line. Surveyors have reported occurrences of this type of damage to us, as strange as it may sound.

For boats with inside ballasting, or for powerboats, some type of external grounding plate is required. These are usually made from sintered bronze: tiny particles of bronze fused into a porous block. The effect is to give a much larger surface area than defined by the dimensions of the block itself. It is very important to use as large aground plate as necessary, and to position it as close to vertically in line with the primary lightning conductor (the mast) as possible.

Racing boats are not going to be willing to do this, since a ground plate creates a fair amount of drag in light air. Cruisers would be advised to trade off the drag for the protection offered.

A grounding plate installation is not a nail-it-in-place-and-forget-it installation. As with any bare metal underwater, oxides build up in the grounding plate, reducing its efficiency. The manufacturer of the plate can tell you the proper remedies, which may include removing the plate yearly and treating it in an acid bath to restore proper conductivity.

It is probably a poor practice to use the same grounding plate for lightning grounding and grounding of electronics such as Loran. If the lightning charge is too great for the plate to instantaneously transmit to ground, the charge may travel back through the ground wire to your electronics, with disastrous results.

For this article in its entirety please click the below link…

Getting the Charge Out of Lightning   

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An approach to a modern sailboat lightning protection system

We were lucky when we were struck by lightning on our small 35’ GRP cruising sailing boat in Turkey in 2013, but without an LPS. All the plastic and some of the metal gear at the top of the mast exploded (see photo below) and simultaneously the headlining in the saloon exploded downwards with a loud bang. So much smoke that we initially thought we were on fire; but my wife and I survived unscathed to tell the tale.

The most likely discharge exit was through the propeller shaft, but practically all electronics were violently destroyed and, as an electrical and electronic engineer, my assessment for our insurance claim afterwards showed that most devices had experienced severe arcing with small electronic components having exploded internally (see photo below).

An lightning protection system is a bonding, grounding and shielding arrangement made of four distinct parts: Air terminals, down conductors, a low-impedance ground system and sideflash protection.

The best lightning protection system cannot guarantee personal protection, or protection from damage to sensitive electronic equipment. Also it is not a lightning prevention system. I knew the private owner of one large blue water catamaran which has been struck three times in its life and it is not an old boat. Fortunately no one was hurt on any occasion, but many electronic systems on that complex boat were effected and had to be replaced on each occasion. Unfortunately catamarans are many times more likely to be struck than mono-hulls and records in the USA, where certain locations are particularly prone to electrical storms (e.g. Florida where boat ownership is high), show that mono-hull sailing boats are about 25 times more likely to be struck than motoryachts.

Lightning is very hard to study and to accurately predict its behaviour is almost impossible, but it is driven by the simple fact that a massive potential difference (voltage) exists between the highly charged clouds of a brewing thunderstorm and the surface of the Mother Earth. Eventually, a path is found through the atmosphere down to ground for some of the accumulated charge to discharge and the creation of a discharge path first requires the creation of so called ‘streamers’ [1],[2]. Bear in mind that air breaks down at 3 million Volts per metre, and you get some inkling of the enormous voltage differences involved.

In the middle of a large body of water, with your sailing yacht in it, the top of the mast, being the highest point around, looks like a handy point to discharge through. So the LPS is designed to control the first point of discharge and then make the onward path to ‘ground’ – in this case the sea – as direct as possible and capable of conducting very high currents for a very short time during the discharge.

In 2006, the American Boat and Yacht Council (ABYC) technical information report TE-4 [3], [4] recommended the following:-

• lightning protection system conductors must be straight and direct and capable of handling high currents. The main ‘down’ conductor is recommended to be 4AWG, or 25mm2 in European sizing; see diagram.

• A large enough area ground must be provided between the vessel and the water to offer an adequately low resistance path (ABYC recommends 1sq.ft. {0.1m2} in salt water; much larger in fresh water. NB this is not adequate for acting as the SSB counterpoise). Metal-hulled vessels naturally offer a large ground contact area with the sea, but the connection between the hull and all other electrical systems needs careful consideration.

• Heavy metal objects such as fuel tanks and engines must be bonded to the ground bonding arrangement to reduce the risk of ‘side flashing’ where the lightning literally can jump from one conductor to another, seemingly better path. Similarly, it can jump out of corners in cabling, so if bends must be made, then they should not be more than 90° and with as large a bend radius as possible.

The basic arrangement is as depicted in the diagram, where the ‘air terminal’ is a rounded end (circled in photo) metal wand mounted at the top of the mast to ‘attract’ lightning to it and, most importantly, to stand at least 6” (15cm) higher than anything else e.g. above the VHF or other antenna. Providing the air terminal is securely electrically bonded, presenting a high surface contact area, low resistance path to an aluminium mast, the mast itself can be used as the down conductor at least to the deck or keel, depending on where the mast is stepped. In the case of wooden, or carbon composite masts they present too high electrical resistance and a 4AWG cable must be run straight down the mast as the main down conductor. From the bottom of the aluminium mast or down conductor, the 4AWG onward path needs to be as direct and short as possible to the ground plate, or the metal hull.

It is actually better to leave through-hull metal fittings electrically isolated if they are already insulated from the rest of the boat by dint of their attached rubber or plastic hoses and their insulating mounting plates – decent quality bronze alloy seacocks and engine intake strainers will not unduly corrode if left submerged for extended periods of time without needing connecting to the vessel’s earth bonding. However, in the US it is more normal to bond everything metal below the waterline, use a tinned copper bus bar running the necessary length of the vessel, above any bilge water level, to connect each through-hull fitting to, which is then connected at one point only to the main grounding route out of the boat. This bonding arrangement is gaining in popularity outside the US with consideration of a lightning protection system.

Note in the diagram that all tie-ins, including fore- and back-stay (unless insulated) must use at least 6AWG (16mm2 European) cable. All large metal objects within 6ft (2m) of the lightning down path also need tying in with 6AWG (16mm2) cable. Examples are metal fuel tanks, main engines (despite them usually already being connected to the water via their prop shaft) and generators; this is to minimize the risk of ‘side flashing’ where lighting can literally jump from conductor to metal object, looking for a better path to ground, even if one does not exist.

In considering of the creation of a ground plate of sufficient size, a metal hulled vessel is ideal, but nevertheless only one electrical connection point to the hull should be made from the main 4AWG down conductor. This same point should have all the other earth bonding made to it alone. The DC main negative bus in turn should be connected to the earth bonding in only one place, though European boats generally have their DC system isolated from any bonding system to discourage DC earth faults, the US differs in this respect, preferring direct bonding. One solution to this dilemma is to use a suitably rated surge capacitor between the DC negative busbars and the bonding system for the LPS. In the case of a non-metal hulled sailing vessel, the attraction of using the keel as a discharge point should be resisted as it is in contact with the water some distance below the surface where already a lot is going on with respect to charge balancing, so an alternative point is likely to be sought out by the discharge, nearer the surface. It seemed clear to our very experienced (and ancient) marine insurance surveyor that, during our own strike in Turkey, the discharge was out through the propeller shaft.

So far, so good, but recent thinking and good practice [5],[6] has modified the above ideas to take into consideration the danger of side flashing much more. A side flash is an uncontrolled spark that carries current to the water and can do extensive damage to hulls and equipment. The good practice and standards for a lightning protection system relating to marine situations, such as they exist (see NFPA 780, latest version, especially chapter 8, ‘Protection for Watercraft’, [7]) are tending to treat a boat more and more like a building to exploit those well tried and tested techniques used in a land based situation. Rather than a ‘cone’ below the air terminal, the ‘zone of protection’ is now more reliably envisaged to be formed from a ‘rolling sphere’ of 30m radius, as shown below for a larger yacht [7],[8]:-

Diagram of Boat with Masts in Excess of 15 m (50 ft) Above the Water; Protection Based on Lightning Strike Distance of 30 m (100 ft).

With a large building, the down conductors from the various air terminals run down the outside of the building to a number of grounding stakes; not so with a yacht where, as we have described, we’ve now concentrated the discharge right in the middle of the boat, where the danger of side flashing into other metal parts is very real; if these parts are not bonded and protected by a properly designed, low impedance path there’s are very real further danger of the side flash finding its way onwards and out through the side of the boat to the surrounding water surface. This has indeed been experienced by an American friend of mine on a high-tech, all carbon racing sailing boat on its way back to Newport, which after being unavoidably struck several times in a violent storm, put in to New York and immediately hauled to find literally a thousand or more tiny holes around the waterline when the discharge had exited! Apparently lightning does not always take the straightest path to the water, but rather has an affinity for the waterline.

The latest version of this NFPA 780 standard recognises this danger and, in a departure from the older versions, provides for multiple grounding terminals to provide the shortest path to the surrounding water surface. These ‘supplemental grounding electrodes’ conduct lightning current into the water in addition to that conducted by a main ground plate. The new standard provides for a continuous conducting loop outboard of crewed areas, wiring and electronics. Placing the loop conductor well above the waterline, outboard, and with grounding terminals below it retains the advantages of an equalization bus, whilst correcting for its weakness with side flashes having nowhere else otherwise to go.

Protection of electronic equipment by a hermetic system on larger yachts

So much electronic equipment on board a yacht struck by lightning is very susceptible to permanent damage. The only safe way to fully protect electronic equipment is to have it completely disconnected from all other circuits when thunder and lightning are nearby, and I still to this day do that as much as possible, but how practical is complete protection really?

A recent idea I had whilst discussing the problem with a 30m ketch owner may have some merit, and I call it a ‘hermetic system’, so suggesting that it is sealed from the outside world: If the most critical and/or sensitive electronic equipment can be enclosed within its own quite separate power and cabling set, separate from the rest of the boat’s electrical and electronic wiring, then it is possible that it could be saved in the event of a lightning strike. One way to do this would be to run all those systems required to be protected effectively off an Uninterruptable Power Supply (UPS), powered from the AC bus (via the generator), then down converted to the necessary 24/12VDC electronics supply. In the event of a lightning storm, all AC connections to the UPS and any signals, power or ground returns outside the hermetic system must be open circuited by large clearance contactors. The electronics contained within the hermetic system can still continue to operate, for a limited time (depending on the capacity of the UPS batteries) and further choices can be made about what to shut down within the hermetic system to extend the battery life, leaving for example just the absolute minimum electronics to continue to safely navigate e.g. Depth, GPS, Chartplotter. Very careful consideration must be given to cable runs.

The VHF antenna on the main mast may be protected by a surge arrestor from one of several suppliers e.g. www.nexteklightning.com. No guarantee is likely to the effectiveness of this as a protection device in all cases of lightning strike and the manufacturers should be consulted for further information.

I certainly now resort to the marvel of a GPS chart plotter on my mobile phone when there’s a nasty electrical storm about and I’m out at sea! References: –

1. Top 10 best lightning strikes (USA) by Pecos Hank, with rare photo of an upward streamer. 2. http://marinelightning.com/index_files/SFMechanism.gif for a graphic showing the formation of negative streamers 3. ABYC (US) technical report TP-4 “Lightning Protection”. 4. Nigel Calder – “Boatowner’s Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat’s Essential Systems” 5. “Complexities of Marine Lightning Protection”, By Ron Brewer, EMC/ESD Consultant, April 2011 6. “A New Concept for Lightning Protection of Boats – Protect a Boat like a Building” Ewen M. Thomson, Ph.D.; published in the October 2007 edition of Exchange 7. National Fire Protection Association (US) document NFPA 780-2014 “Standard for the Installation of Lightning Protection Systems” – see especially chapter 8 ‘Protection for Water craft’. 8. “Evaluation of Rolling Sphere Method Using Leader Potential Concept – A Case Study” P.Y. Okyere, Ph.D & *George Eduful – Proceedings of The 2006 IJME – INTERTECH Conference

Feature article written by Andy Ridyard. Andy Ridyard has been a professional electrical and electronics engineer for more than 35 years and started SeaSystems in 2008. His business is dedicated to providing troubleshooting, repair and installation services to superyachts internationally, specialising in controls and instrumentation. He lives with his wife in Falmouth, UK, but works mostly in the Mediterranean. SeaSystems has fixed countless intractable problems with marine control systems, marine electronics, Programmable Logic Controllers (PLCs) and marine electrical systems. For more information visit SeaSystems.biz .

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• Practical Boat Owner
• Digital edition

Make a grounding system to protect your boat from lightning strikes

• March 5, 2021

Metallurgist Vyv Cox explains how a heavy conductor can keep you safe at sea during lightning storms

A surprising amount of research has been carried out into lightning strikes on yachts and boats , much of it in Florida but some in New Zealand, Australia and other countries. The findings are somewhat confusing when it comes to the layout of protection.

To summarise, the optimum protection according to all authorities is provided by a heavy conductor, preferably copper of at least 21 sq.mm. running from 15cm above the masthead and all antennae in as straight a line as possible to an underwater plate beneath the mast foot (see Fig 1 ). This should be copper, bronze or Monel, not sintered and not embedded into the yacht’s hull, as electricity prefers to exit via an edge.

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This arrangement creates what is known as a ‘cone of protection’ within which people are relatively safe provided they are below deck, sitting as high above the waterline as possible and well away from the mast (see Fig 2).

The American approach is similar but greater attention is paid to the possibility of side flashes, which may be particularly damaging to electronics and may even blow holes in the hull. This is the reason for the USA preference for electrically bonding all underwater components, such as seacocks, engine, drive and rudder. The cable used is of considerably heavier gauge than is needed for purely galvanic purposes. It is believed that this practice forms a cage-like network of conductors, helping to protect anything within it.

Further problems arise in the case of secondary paths from the main, vertical, path of the current, where the electricity can follow unpredictable routes to the sea, resulting in serious damage and risk to life. Again, bonding helps to reduce the likelihood of secondary paths but may have an adverse effect on corrosion.

Grounding system to protect against lightning

A grounding system is designed to provide a very low resistance path to the ground. The air terminal should be made of copper rod of between 10mm and 19mm diameter, installed at least 150mm above all other objects on the boat. On a yacht, this is typically at the top of the mast. On a powerboat, a mast structure of some sort is required.

The down conductor cable provides a low-impedance path between the air terminal and the external grounding plate. An aluminium mast is usually sufficient to facilitate the necessary lightning flow, but should be connected by the cable at its base to an external grounding plate in order to complete the circuit. Non-aluminium masts (eg. carbon fibre and wood) need a conductor.

The external grounding plate should be located where it’s never out of direct contact with the water, and should be made of either copper, bronze or Monel (a predominantly nickel and copper alloy). A long strip is more effective than a square plate.

• Find out what marine surveyor Ben-Sutcliffe Davies has to say about lightning strikes

Some more useful websites on lightning

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• Digital Edition

Yacht lightning strikes: Why they cause so much damage and how to protect against them

• August 27, 2020

A lightning strike may sound vanishingly unlikely, but their incidence is increasing, and a hit can cause severe damage costing thousands of pounds, as well as putting an end to a sailing season, writes Suzy Carmody

Lightning strikes of boats are still fairly rare – but are on the increase. Photo: Image Reality / Alamy

Pantaenius handles more than 200 cases of lightning damage every year. “Over the past 15 years, the total number of such loss events has tripled in our statistics. The relative share of lightning damage in the total amount of losses recorded by us each year is already 10% or more in some cruising areas such as the Med, parts of the Pacific or the Caribbean,” added Pantaenius’s Jonas Ball.

Both UK and US-based insurers also report that multihulls are two to three times more likely to be struck by lightning than monohulls, due to the increased surface area and the lack of a keel causing difficulties with adequate grounding. Besides increased likelihood of being hit, the cost of a strike has also risen enormously as yachts carry more networked electronic devices and systems.

The CAPE index measures atmospheric instability and can be overlaid on windy.com forecasts

Avoiding lightning strikes

The only really preventative measure to avoid lightning is to stay away from lightning prone areas. Global maps of lightning flash rates based on data provided by NASA are useful to indicate areas of more intense lightning activity. They show that lightning is much more common in the tropics and highlight hotspots such as Florida, Cuba and Colombia in the Caribbean, tropical West Africa, and Malaysia and Singapore in south-east Asia.

Unfortunately, many of the most popular cruising grounds are located in tropical waters. Carefully monitoring the weather and being flexible to changing plans is an essential part of daily passage planning during the lightning season in high-risk areas. CAPE (Convective Available Potential Energy) is a useful tool for indicating atmospheric instability: you can check the CAPE index on windy.com (see above) as part of your lightning protection plan.

Protection against lightning strikes

Yachts that had no protection when lightning struck often experience extensive damage. The skipper of S/V Sassafras , a 1964 carvel schooner, reports: “Most of the electronics were toast. Any shielded wiring or items capable of capacitance took the most damage: isolation transformer; SSB tuner; autopilot and N2K network Cat 5 cables.”

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The owner of Matador of Hamble , a Rival 41, recalls the effects of their strike: “The extent of the damage was not immediately obvious. For days afterwards anything with a semi-conductor went bang when we turned it on.”

The crew of Madeleine , a Catana 42S catamaran, had a similar experience. “We were struck in Tobago but only discovered the electrical damage to the port engine when we reached St Lucia and it was in the Azores that we found out the rudder post was broken and we had lost half our rudder.”

It therefore seems prudent that in lightning prone areas a protection system should be implemented where possible to protect the boat, equipment and crew. As a first step analysing the boat and the relative position of all the main metallic fittings can often reveal a few safe places to hide and places to avoid. Areas such as the base of the mast, below the steering pedestal and near the engine have the highest risk of injury.

Stays on a steel boat are attached directly to the steel hull. Photo: Wietze van der Laan / Janneke Kuysters

In terms of minimising the effect of a strike, one temporary method to limit the damage is to direct the current outside the boat using heavy electrical cables attached to the stainless steel rigging. With the other end of the cable immersed in the ocean, this provides a conductive path from the masthead to the ground.

The main flaw in this plan is that an aluminium mast has much greater electrical conductivity than stainless steel and is a more likely pathway to the ground. This system also requires adequate copper to be in contact with the seawater to discharge the current.

Other temporary measures include disconnecting radar and radio aerial cables, putting portable electronic items in the oven or microwave as a Faraday cage, turning off all the batteries or nonessential electronic equipment if at sea, or in a marina unplugging the shore power cord. All these procedures rely on someone being on board with several minutes warning before a strike to drop the cables over the side and turn off/disconnect and unplug.

Cable used as a down conductor from the shrouds on a catamaran. Photo: Wietze van der Laan / Janneke Kuysters

Posting an ‘Emergency Lightning Procedures’ card in a central location of the boat showing where to stand and what quick preparations to take is a simple first step.

Permanent lightning strike protection

In a thunderstorm, molecular movement causes a massive build up of potential energy. Once the voltage difference overcomes the resistance of the airspace in between, invisible ‘channels’ form between the base of the clouds and tall objects like masts, providing a path for a lightning strike to discharge some of the accumulated electrical energy. There will be less damage to a vessel if the discharge is contained in a well-designed lightning-protection system.

Lightning rods or air terminals installed at the top of the mast connected to an external grounding plate on the hull, via an aluminium mast, provide a permanent low impedance path for the current to enter the water. On boats with timber or carbon masts a heavy electrical cable can be used as a down conductor.

If not installed during production, a grounding plate can be retrofitted during a haul out. On monohulls a single plate near the base of the mast is adequate. A ketch, yawl or schooner requires a vertical path for each mast and a long strip under the hull between the masts, whereas catamarans usually require two grounding plates to complete the path to the water.

The current from a lightning strike is dissipated primarily from the edges of the plate, so the longer the outline the better. Warwick Tompkins installed a lightning protection system designed by Malcolm Morgan Marine in California on his Wylie 38 Flashgirl :  “Two heavy copper cables run from the foot of the mast to the aluminium mast step, which was connected to a copper grounding plate on the outside of the hull via ½in diameter bronze bolts.”

The grounding plate was an eight pointed star shape. “Some liken it to a spider.” Warwick says, “And the very minimal electrical damage we experienced when struck was directly attributable to this spider setup.”

A copper ‘X’ grounding plate, used on boats that have a fin keel some distance aft of the mast. Photo: Malcolm Morgan Marine

Morgan adds: “Any cables associated with lightning protection should be routed away from other ship’s wiring wherever possible. For example, if the navstation electronics and main switchboards are on one side of the vessel, the lightning protection cables should be routed on the opposite side.”

An internal bonding circuit connects the major metal objects on a boat to the grounding plate via bonding cables. This can help prevent internal side strikes where the current jumps between objects in order to reach ground.

Morgan explains: “As modern boats are becoming increasingly complex careful consideration is required to ensure the bonding system is designed correctly. There are five possible grounding systems on a vessel (lightning protection, SSB radio ground plate, bonding for corrosion, AC safety ground, and DC negative) and all need to be joined at one common point and connected to the external grounding plate.”

This strike exited through the keel, blowing off the fairing and bottom paint. Photo: GEICO / BoatUS Marine Insurance

Surge protection

Yachts anchored close to shore or on shore power in a marina are susceptible to voltage surges during a thunderstorm. If lightning strikes a utility pole the current travels down the electricity cable looking for ground. It can enter a vessel through the shore power line or can pass through the water and flashover to a yacht at anchor.

Surge-protective devices (SPD) are self-sacrificial devices that ‘shunt’ the voltage to ground. They reduce the voltage spikes eg a 20,000V surge can be diminished to 6,000V but the additional current can still be enough to damage sensitive electronics. Therefore fitting ‘cascaded’ surge protection with several SPDs in line on critical equipment is a good idea.

High-tech solutions

Theoretically, if a lightning dissipator bleeds off an electrical charge on the rigging at the same rate as it builds up it can reduce or prevent a lightning strike. Lightning dissipators such as ‘bottle brushes’ are occasionally seen on cruising boats, though these are relatively old technology. Modern dissipators feature a 3⁄8in radius ball tip at the end of a tapered section of a copper or aluminium rod. The jury is out on their effectiveness.

A more high-tech solution is Sertec’s CMCE system, which claims to reduce the probability of a lightning strike by 99% within the protected area. The system has been widely installed on airports, stadiums, hospitals and similar, but has now been adapted for small marine use (and may reduce your insurance excess).

Arne Gründel of Sertec explains: “The CMCE system prevents a lightning strike by attracting and grounding excess negative charges from the atmosphere within the cover radius of the device. This prevents the formation of ‘streamers’, and without streamers there is no lightning strike.”

A Sertec CMCE marine unit, designed to dissipate lightning

• 1. Avoiding lightning strikes
• 2. ‘A lightning strike caused £95,000 of damage to my yacht’

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How to Prepare for Lightning Strikes

• By Ken Englert
• Updated: January 24, 2012

Lightning will always take the most direct conductive path to earth by striking the highest object in the area. Unfortunately, on the water, the highest and most attractive object to a lightning bolt just might be your boat. Be advised that when lightning strikes your boat or even near your boat, your electronics are vulnerable to damage. Here’s how to be prepared.

Create a Short Circuit There is no absolute protection against lightning aboard a boat. But there are steps you can take to avoid or minimize damage. The most likely targets are antennas, fishing rods, towers, T-tops or any elevated electrically conductive surface. You can’t prevent a lightning strike, but you can create a safe path for lightning to travel.

To conduct a strike safely to “ground” (on a boat this means to the water), create a low-resistance path from the highest point on your boat to a metal grounding plate in contact with the water. Start with a solid half-inch-diameter steel or bronze rod elevated six to 12 inches above every other object on the boat. The tip of that rod should be pointed, not blunt. Run a conductor made of at least a No. 8 gauge wire from the rod in as straight a path as possible to the water-grounding point.

The recommended water ground is a metal ground plate mounted outside of the hull. It can be copper, monel, naval bronze or other noncorrosive metal and should be solid, not the porous type used for radio antenna grounds, and be at least one square foot in area. Check with the manufacturer to see if this already exists. Also know that factory-installed lightning rods and grounding conductors are sometimes unwisely removed or disconnected by boat dealers or unknowing buyers.

Ground, Ground, Ground Ground all electronics and large metal objects on board, including metal cases or grounding studs on electronics and electrical equipment. Not to be overlooked are the engine(s), stove, sink, tanks, refrigerator, air-conditioner, metal railings, tower, arch and Bimini top. When running grounding conductors, don’t attempt to neatly bundle grounding cables together with the rest of the electrical wiring. Keep them separate from all other conductors, including antenna wires. Also, do not run the ground conductors in close proximity to or parallel to existing wire runs to prevent arcing.

More Detailed Lightning Protection Tips and Strategies

Storm Safety Tips – Lower all antennas and downriggers.

– Disconnect all power, antenna and interconnection cables to the electronics and electrical gear.

– Do not touch two metal surfaces at the same time (engine controls, a railing, helm, etc.) or you may become a convenient conducting path yourself.

– Do get out of the area and head for shore, and send the crew belowdecks.

Check out more tips on how to protect yourself and your boat during a lightning storm: 3 Crucial Tips to Avoid Lightning Strikes

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MARINE LIGHTNING PROTECTION: Getting Z-Z-Z-Zapped on a Sailboat

I have to admit I don’t normally think about this too much. As is true of many sailors I suspect, I have subscribed to the philosophy that lightning and its effects are so random and poorly understood that you can get royally screwed no matter what you try to do about it. Which is a great predicate, of course, to going into denial and doing nothing at all. But the death in Florida last summer of Noah Cullen , a most promising young man who presumably was killed in a lightning strike while out singlehanding on his pocket cruiser, got me pondering this in a more deliberate manner. On doing some research, I found there are some hard facts out there that are well worth knowing.

Much of what we tend to learn about lightning is anecdotal, which mostly serves to make it seem more mysterious. I, for example, have never been struck by lightning, but I did once cut through some severe thunder squalls in the Gulf Stream in a grounded fiberglass boat and saw a bolt of lightning the size of a large tree trunk flash straight into the water just a few yards behind us. I can’t begin to tell you why it didn’t hit our nice 55-foot aluminum mast, and ever since then I’ve believed a strike is pretty much an act of God. It’s either going to get you, or not, and there’s nothing you can really do about it.

I have met a number of sailors who have been struck by lightning, mostly in grounded boats, and in every case they told me they lost all their electronics. So I have also always assumed there is nothing you can really do to protect installed electronics from a lightning strike.

But you should forget all the anecdotes you ever heard, at least temporarily, and think about the following:

Likelihood of a strike: It’s probably much higher than you like to think. One source states that a sailboat with a 50-foot mast will on average be struck once every 11.2 years. According to insurance data, the general average for all boats is about 1.2 strikes per 1,000 boats each year.  The average bill for damage is around $20,000. Most strikes are on sailboats (4 strikes per 1,000 sailboats each year). And these are likely lowball numbers, as it seems many lightning-strike victims are not insured or do not report the strikes to their insurers. According to one independent survey, unreported strikes could be as high as 50 percent of the total.

Location is also a big factor. Some areas, including very popular cruising grounds like Florida or Chesapeake Bay, are much more lightning-prone than others, and you are obviously much more likely to get struck when sailing within them. The overall average for reported lightning strikes on boats in Florida, for example, is 3.3 strikes per 1,000 boats each year, nearly three times the national average.

Map showing lightning strike probabilities around the world. The higher the number, the higher the probability

Interestingly, catamarans overall apparently are struck twice as often as monohulls. Could this be because they are effectively twice as much boat???

Preventing a strike: It really isn’t possible. There is no technology that can positively keep your boat from being hit. There’s seems to be little evidence, for example, that those silly little masthead bottle brushes some people put up are good for anything.

Spectacular image of a sailboat getting hit in Rushcutter’s Bay in Sydney Harbor, Australia, with inset images showing damage to the mast. Lots of other targets with masts around, so why did the bolt hit this one boat?

Limiting damage: This is where the action is. To paraphrase one writer: it is a fallacy to think in terms of “lightning protection.” What you want is “lightning control.” Which definitely means grounding your boat! An ungrounded boat is much more likely to suffer potentially disastrous damage when struck (i.e., holes in the hull, dead crew, etc.). A boat in fresh water is also much more vulnerable, because fresh water doesn’t conduct electricity as well as salt water. An ungrounded boat in fresh water is most vulnerable of all. If you’re on one of these during a strike, you may as well just forget about it and put a cap in your head.

Typical exit damage around an anchor well drain on a fiberglass boat. Hull damage just above the waterline is not at all unusual

Grounding your boat: The old school notion of leading a big copper strip from the base of your mast in a straight line to a single grounding plate on your hull is the process of being discarded in favor of a more sophisticated technique that connects the mast as primary conductor to a network of dissipating electrodes installed just above a boat’s waterline, the idea being in effect to make all of the boat’s hull something like a Faraday cage, so that the equipment and people within will be safer.

Example of a more modern grounding system

Note (I was particularly gratified to learn this): a metal hull is indeed a great ground, and the fact that it is painted, or coated in epoxy, or whatever, doesn’t change this. But you can still suffer significant damage on a metal boat!

Bonding: You and the gear on your boat are more likely to survive a strike without damage if the major bits of metal on your boat are bonded to the grounding system. This reduces the likelihood of dangerous side flashes. (It does, however, create complications with respect to the potential for galvanic corrosion on a boat.)

Saving electronics: First of all, stowing handheld electronics (or any disconnected electronics) in your oven will protect them during a strike. Just remember to take them out again before using the oven!

More importantly, you can protect installed electronics using various individual surge protectors, fancy spiral wiring, and other techniques I’m not going to pretend to understand, much less explain. See the sources below for more details.

Your personal safety: This should be most important, right? You want to stay off the helm if possible, stay below, stay dry, and don’t touch any big pieces of metal. All of which are easier said than done when you’re in the middle of a big squall! It would seem the most prudent tactic is severely reduce sail, or take it all down, pop the boat on autopilot, and get below well in advance of and after a thunderstorm.

Lightning and Sailboats : Academic paper published by Ewen M. Thomson, currently recognized as the most well-informed go-to guy on this subject.

Marine Lightning Protection : Website for a business run by Ewen Thomson (see above), who is a pioneer in modern cage-style boat-grounding techniques. Thomson will ground and bond your boat for you, if you like, but there’s also lots of useful raw info in here.

Lightning Survey Results : Discussion re results of a small independent online lightning-strike survey conducted by a cruiser who owns a power-cat named Domino . Very informative.

Considerations for Lightning Protection : Conclusions reached post-survey by the owner of Domino , referenced above.

Lessons in Lightning : Ocean Navigator article by a cruiser in an aluminum boat who was struck by lightning in the Baltic. Of particular interest to those (like myself) who own aluminum boats.

There are lots of other resources out there, but these four links are a very good place to start. You’ll find many other valuable sources just by reading through these articles and following the links within.

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We were hit by lightning in a fast moving front off Newfoundland many years ago (before gps). All the electronics were fried! The binnacle must have been demagnetized as it hopelessly spun in circles, giving us only a hand sighting compass to steer by. The smell of burned wire insulation in boat was overpowering. Luckily this is a rare occurrence and for the most part just bad luck!

@Robert: Interesting. In Bermuda once I met a tall ship, steel hull, that had been struck by lightning, and as a result the whole ship was magnetized. Which also kept their compasses from working properly. They were on their way to Norfolk, Virginia, to get degaussed.

I feel obligated to take issue with a fair bit of what’s been said above. Without writing a textbook, the following is best seen as “almost correct”. If you consider that the sky has a positive electrical charge and the sea a negative charge, grounding the boat and the mast gives them a negative charge. Hence as far as the lightning is concerned, the bonded mast raised the local sea level to mast top height. Lightning will tend to bridge the narrowest gap with the greatest electrical charge difference – so by grounding boat and mast, you have made them MORE vulnerable to lightning strikes, not less. In other words, NOT grounding the boat and mast will REDUCE your chances of being struck.

Tying an earth system into the keel bolts is not likely to result in loss of the keel, but it sure does constitute trying your best to do so. If the bolts are electrically weak they may act as a fuse and “blow” during a strike.

Making a Faraday shield form shown above does help mitigate the effects of the strike compared to a simple bonding of the mast to the keel in many situations, but it’s over-rated. In a big strike, lightning will try to follow a straight path and the energy contained in such a strike is often too great for a simple system to be effective. And it needs to be understood that either method makes the strike a whole lot more likely to occur.

A grounded mast does offer a degree of protection to a non-bonded electrical system in the boat underneath. There is what’s termed a “cone of protection” extending downwards at 30 degrees from the top of the mast. This is the standard system used in telecommunications.

The best protection you can have is to park your ungrounded wooden boat with a wooden mast and an electrical system isolated from the sea, right next to a grounded metal boat with a big aluminium mast. In the photo above depicting the Sydney harbour yacht being struck, the question was posed “why did the bolt hit this one?” The answer is that it was best grounded boat in that area.

@Bryan Tuffnell while part of what you say is true that a grounded boat is more likely to be struck the catch is that it will do less damage if struck where as a boat not grounded is less likely to be struck if it ever is you will have significantly more damage

Maybe, but quite likely not. The only way to offer lightning protection is to place a grounded lightning target above the mast, but electrically isolated from the mast and every other part of the boat. The grounding is completely independent of the mast, rigging, interior, electrical system, and above waterline areas of the hull. The idea is that this attracts the lightning and provides a low impedance path to ground, without drawing the charge into any part of the boat or its contents. Using this strategy one does not ground the mast, hull, rigging, etc. This is the only strategy to apply if one insists on lightning protection.

the sky has a positive electrical charge and the sea a negative charge

Its the other way round. When polarity builds up the negative charge is at the cloud base, and the positive at the sea surface. [quote=Bryan TuffnellNOT grounding the boat and mast will REDUCE your chances of being struck[/quote] Wrong – the enormous voltage actually doesn’t care if you’re grounded or not. Given the fact that the boats surface will always be wet or moist in some way it is “grounding” enough to raise the sea level polarity up to the mast top. The only thing proper grounding does is trying to guide the current of a charge in a way that does the least harm.

Not necessarily in the first case, and generally not true in the second… the polarity of lightning is variable, and there are countless examples of nearby strikes to ungrounded boats. Obviously if lightning didn’t care of you were grounded or not, lightning conductors wouldn’t work.

As far as doing the least harm goes, grounding the mast is about the worst thing you can do, particularly if you have grounded electrical items onboard.

Our boat (20′ cruiser) has no grounding system. Is it foolish to think that the method where a set of jumper cables is attached to mast and other end dropped overboard, might be a good emergency strategy if caught in elec storm?

what a topic indeed. to protect or not to protect, that is the question. simply do you use a brush type or spike type diffuser on your mast, do you protect for side strikes, or stay central with mast bonding.. im trying to find an answer like us all and so far , the answers all differ..

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Sailboat Grounding Systems

• By Steve D'Antonio
• Updated: September 1, 2021

Recently I met with a client to review and critique his vessel’s systems. One item I saw related to the bonding or grounding system. These systems serve similar purposes: to carry stray, galvanic or fault current back to its source.

Let me clarify two related matters. First, electricity does not “seek ground” as so many dockside sages insist. No, whether from a battery or shore power, it seeks to return to its source. One example of the return-to-source concept is all-too-often tragic; it relates to electric-shock drowning, or in-water electrocution. When AC current, which originates from shore power, “leaks” into the water in which the vessel floats, it attempts to return to its origin, which in most cases is a transformer located on the dock or in the marina parking lot. Once power passes through a transformer, that transformer becomes a power source. So if a shore-power transformer is installed aboard a vessel, fault current will seek to return to that transformer—rather than through the water—and on to the one supplying the marina, making it a safer option.

RELATED: The Dos and Don’ts of Boat Wiring

Second, while the terms are frequently and understandably used interchangeably, “bonding” is often used in conjunction with underwater metals and corrosion prevention, while “grounding” often refers to the connection of equipment chassis and hardware to the DC-negative terminal. The two systems are, however, almost always connected (along with the AC safety and lightning ground systems), so for the purposes of this discussion, they are one in the same.

In the case of my client’s boat, I noticed a 14-gauge wire connected to the engine block. It appeared rather new, and when I asked about it, the owner confirmed that an electrician had installed it in the not-too-distant past. A poor block ground can cause oil-pressure and coolant-temperature-gauge issues, which may have been the impetus for adding it. While this “fix” may have solved one problem, it created a fire risk.

Another electrical myth is “electricity takes the path of least resistance.” In fact, electricity takes all paths, with the current flow being proportionate to the resistance. Thus, more current flows through lower-resistance, larger-wire paths; when both are present, larger wires carry more current than smaller wires. But what happens if the larger wire breaks, or is inadvertently disconnected, or the connection loosens or corrodes? In that case, a small-gauge wire connected to an engine block will be called upon to carry high current, such as from a starter or alternator.

A few years ago, I was inspecting the engine room on a 60-footer. A mechanic had recently replaced the batteries, then started the engine to test his work. However, when removing the old batteries, he’d dropped one cable behind a battery box and then failed to reconnect it when installing the new batteries. When he turned the key, instead of flowing through a cigar-size 2/0 cable, the starter current instead took an alternate path through a 12-gauge bonding wire connected to the engine block. A few feet away, I recall feeling the heat on my face as it almost instantly glowed white-hot, and the insulation melted and then burned away. Fortunately, the wire melted before anything caught fire.

It doesn’t take a miss-wire scenario for an event like this to occur. If the starter’s or alternator’s positive cable chafes against the engine block (ABYC standards prohibit starter positive cables from touching the block in any way), current will attempt to return to the battery via all paths, including small bonding wires.

The simple moral? Every grounding/bonding wire connected to the block of an engine or generator, or to any other piece of DC equipment, must be capable of carrying full starting or fault/short-­circuit current, which means it can be no less than one size smaller than the largest DC-positive cable. Furthermore, bonding wires should not be connected to current-carrying parts. If the chassis of the block, thruster, etc., is common with the DC-negative, then it should not be bonded. Engine blocks and gensets that utilize isolated ground starters and alternators may, on the other hand, be bonded.

Steve D’Antonio offers services for boat owners and buyers through Steve D’Antonio Marine Consulting .

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what to use for a Lightning grounding plate?

• Add to quote

Amazon bought out smallparts.com a while back, they often carry metals. And there's onlinemetals.com and a few other places, if you can't turn up a local source. The Dynaplate should only be used as a radio ground, not part of the lightning ground circuit. Dynaplate is sintered bronze, literally full of air holes that give it great surface contact to make a great ground. But, all seawater in those holes flashes into steam and the plate can explode if it conducts a lightning strike. Not good.  

hellosailor said: The Dynaplate should only be used as a radio ground, not part of the lightning ground circuit. Dynaplate is sintered bronze, literally full of air holes that give it great surface contact to make a great ground. But, all seawater in those holes flashes into steam and the plate can explode if it conducts a lightning strike. Not good. Click to expand...

thanks Gary and hellosailor! Turns out that a big hunk of copper, even a fairly thin sheet, is pretty pricey. Looking at the ABYC standards, they recommend: Boats with internal ballast should have a copper ground plate of at least one square foot in size installed externally on the hull bottom. The grounding wire should then be connected to the ground plate. I think I'm good with what is left on the boat. The remaining piece of copper at the keel is at least 5 sq ft (prob more) so I think I'll clean it up, and re-glass the edges to secure it.  

The electric charge is dissipated by the edges so I do not think you want to glass them in! Bronze bolts to attach to hull and for cable attachment inside. Sent from my Pixel C using Tapatalk  

If you are stuck for material,check out roofers for suppliers of copper flashing and drains ,,,Re cycle Silicon bronze water tanks can supply sheets of good stuff if you can cut and roll but its tough material for amateurs  

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Should I ground my mast to the keel?

• Thread starter msmalter
• Start date Mar 8, 2014
• Featured Contributors
• Musings With Maine Sail

I have a Catalina 28 that is not bonded. I've read the ABYC recommendation as well as many other articles, and believe that bonding "may" increase the chance of getting hit by lightning, but will reduce the damage to the hull if it does get hit. I was planning to ground the mast to a keel bolt this spring using at least #4 wire (I've seen recommendation for up to 2/0). Some on the Catalina Forum suggest that I should not do this. Others say if I do it I need to ground all the chainplates also using #6 wire. I'm concerned that the #6 wire willl be next to the hull and could cause a sideflash through the hull. What do you recommend? (Do nothing, just mast, or everything)? What size wire? Does it make a difference if the boat is in fresh or salt water? (I'm in fresh) Mike Smalter  

There is lots of new thought on lightning grounding. MY opinion is lightning clouds induce a charge on the SURFACE of the water (<1/4" deep). The keel is deeper (and at a higher potential )than that so grounding the mast to the keel just brings lightning into the boat with nowhere to go except out the side of the hull. The electrical potential of the mast to keel wire has a very odd (for a wire) voltage distribution in this situation. High at the mast end, zero at the level of the water surface and higher (not as high as the mast but higher then the water surface) so the lightning has not reason to continue to the keel and tries to find the shortest route to the water surface, in this case it is (as the insurance folks will tell you) through some metal part near the hull and at the water surface level. Better to leave the keel disconnected and ground the shrouds and stays over the gunnel and down to the water surface and not bring the stuff into the cabin at all. You are going to find there is NO consensus on this topic so I'd take my info from the building industry which NEVER runs the lightning arresting wires into an occupied space and has not had much of a problem with frying stuff in the last 100 years or so. The only (IMHO) difference between a boat and a building is the actual "grounding rod" and the fact that earth is not as good a conductor as sea water.  

Stu Jackson

Read this and then make up your own mind. http://www.westmarine.com/WestAdvisor/Marine-Grounding-Systems Good luck.  

Ask the boat manufacturer the reason for which they do not bond the boats at the factory. If their answer is, as per recommendations of their attorneys you may take that to the Bank. The reality is that no one knows and opinions keep changing. Some seem to think that bonding not only increases the odds of getting a strike but also the severity of the strike. The awesome power in a lightning strike means it will go where it will go and not necessarily where we may try to steer it to. There is actual data that indicates that more strikes are recorded in boats near land than those at sea. Is that due to some interaction with land or just because there may be more boats docked than at sea at any given time. The legendary cone of protection afforded by the mast seems to work but then it could be just so by mere accident. I guess it just boils down to those that feel the need to be proactive will be happier if the bond and the rest of us will spare the time and effort for something else. There are two positive observations ; the risk to life and limb is minimal based actual count of casualties and a good insurance coverage will help mitigate equipment losses.  

If side flashes are the threat that Bill suggests (and it makes sense), it would seem pretty easy when at anchor or dock to clamp a piece of lifeline wire to a shroud and drop it in the water. Even better, attach a large copper bolt to the wire at the water surface. I've seen a short length of chain used but copper with sharp edges would seem a better dissipator Why not?  

Everything you ever wanted to know about sailboats and lightning can be found here: http://edis.ifas.ufl.edu/sg071 Produced by the University of Florida as part of NOAA's Sea Grant program. Great read for those wanting to know more about how lightning strikes form and move through a sailboat and what can be done to prevent substantial damage and injury to crew. Cheers, Brad PS: My H23 has, from the factory, a ground wire running from the base of the mast, down through the cabin and attached to a keel bolt.  

I just use car jumper cables. One end clamped to each side shroud, and then toss in the water. Nothing yet, knock on wood. When not being sailed, my boat sits on an elevated lift, on wooden slats covered with old carpet, so this would be the only contact with the water and hopefully give any lightening strike the "Path of least resistance". 1.21 gigawatts, Holy Crap Batman!  

SailingHarry

Every time the issue comes up, you hear the "some sort of wire over the side" argument. Seriously? You folks are sailing along, a thunder storm is coming up, you are working in a reef, and you have somebody clipping jumper cables onto a shroud and throwing it overboard? Or tie a chain around the mast and drag that over the waterway into the water? While making 6+ knots in a heavy sea? I just can't get my mind around that. Or, worse yet, you're going to make a connection with a giant alligator clip on a high resistance stainless steel shroud? While the commercial building industry does use a perimeter lightning grid with outside down-comers, they have no issues with how to get that to "ground" and it is as much a matter of convenience than anything. ABYC recommends a heavy grounding system (rig and mast) with a clear set of rules on how to do it. Most if not all boat builders follow that guidance. I'd be really leery about coming up with my own (or some other non-study based idea from someone else who has no engineering/electrical/study/lab basis). But as someone else mentioned, this is a contentious issue with about 1000 different opinions. So anything you do will meet with at least one approval! Back to the OP. I'd get the biggest wire I could, bond it to the mast as best I could, run as nearly vertical as I can, to the biggest keel bolt I can find. I'm about to upgrade my Sabre 34 mast ground from #10 (factory in 1979) to #1 (it's what I happened to have on hand) and I think that's a big improvement. The shrouds will still be #10 bonding -- hey, you can't do everything! Harry  

Thanks, Maine. There's just no substitute for real-world data and experience. I was toying with the idea of removing the bonding on my boat because it can make things worse in an electrically hot marina but now you've given me something to think about. We don't get much lightning here in the great PNW, but hopefully we'll someday be taking the boat to where it's more of a threat ;o).  

So MS Why do you think the lightning has a propensity for leaving the hull in some location other than the well bonded keel? I've been paying attention to this for years and it seems that lightning generally exits near the water line more often than not.  

Maine Sail said: I personally go well beyond ABYC standards. Our spar is bonded to the keel via 2/0 wire and these connections are kept clean and coated with terminal grease.. Click to expand

What have been you experience with encapsulated keels? Does the glass around the keel just blow off? Click to expand

Bill Roosa said: So MS Why do you think the lightning has a propensity for leaving the hull in some location other than the well bonded keel? I've been paying attention to this for years and it seems that lightning generally exits near the water line more often than not. Click to expand

Lightning Plate Material? MS, What would be the best material to make a ground plate for my encapsulated ballast full keel boat (Cabo Rico 38)? I've read that silicon bronze would be best, but I can't find a supplier of flat stock. Onlinemetals.com has aluminum bronze in stock and in the right sizes, but I'm not sure about saltwater corrosion with that material. They also have copper plate and flat bar stock, but again would the corrosion be a problem. Plan is to make 2 of 3/8" x 6" x 18" plates and install them on either side of the the keel just above the ballast cap. Connect to mast step with #2AWG. Also connect forstays and shrouds to the same plates with #4AWG. As a side note, I've looked at all the boats on the hard at my marina and two others, and I have never seen a boat with a ground plate attached to the hull of an encapsulated ballast boat. I wonder why? I have seen sintered bronze plates, but not sure if they are for lightning or a counterpoise. Another question: Should the Lightning ground be electrically seperate / isolated from the bonding circuits and DC ground? My bronze thru-hulls are bonded to DC ground and to 2 hull zinc anodes.  

SaltyHog said: MS, What would be the best material to make a ground plate for my encapsulated ballast full keel boat (Cabo Rico 38)? I've read that silicon bronze would be best, but I can't find a supplier of flat stock. Onlinemetals.com has aluminum bronze in stock and in the right sizes, but I'm not sure about saltwater corrosion with that material. They also have copper plate and flat bar stock, but again would the corrosion be a problem. Plan is to make 2 of 3/8" x 6" x 18" plates and install them on either side of the the keel just above the ballast cap. Connect to mast step with #2AWG. Also connect forstays and shrouds to the same plates with #4AWG. As a side note, I've looked at all the boats on the hard at my marina and two others, and I have never seen a boat with a ground plate attached to the hull of an encapsulated ballast boat. I wonder why? I have seen sintered bronze plates, but not sure if they are for lightning or a counterpoise. Another question: Should the Lightning ground be electrically seperate / isolated from the bonding circuits and DC ground? My bronze thru-hulls are bonded to DC ground and to 2 hull zinc anodes. Click to expand

brazenarticle

Hello MaineSail - If I may get back the the original question ( I also have a Catalina 28) what is best bet to get some level of protection? The mast is deck stepped on a stainless plate, I'm assuming fiberglass between that and the top plate of the compression post, and guessing there is no clean electrical connection other than wires in the mast. Would a #2 wire from keel bolt to compression post also need a jumper between post and mast? Attaching a longer directly will have to wait until I pull the mast for maintenance. How about the chainplates? Do they need to be connected to the keel bolts too? One last thing - what happens, what should I do if I am on the boat in a severe electric storm (common enough scenario on the Chesapeake). Is it just a numbers game that many more boats get hit but I have yet to hear of sailors struck? How long can we count on lightning bolts going for golfers more often than sailors?  

I think I'm going to stir this stew a bit more to get some clarification. Below is a plan I came up with after reading Calder's book and several lightning/bonding threads and I'd like some input/feedback. Page 233 of Calders book has a diagram where all the negatives/grounds/bonds (incl. lightning) go to a grounding bus, which is then connected to an "immersed ground plate or strip". However, another paragraph describes a separate lightning grounding system with external plate and no connection to common ground bus A. separate grounding system for lightning ground; cables straight/short as possible B. AC ground, DC negative, & bonding terminate at common ground, which has its own immersed plate External lightning ground strip (1/4" x 1.5" x ~120", I'm in brackish water) Through bolted about every 2 or 3 feet, wherever I can reach and get to if hole forms I have an isolation transformer 1. mast (2/0 wire), shrouds, stays connected (biggest I can manage up to 2/0) as straight as possible to external grounding strip through bolts. 2. Aluminum fuel tank (and deck fill) & all underwater metal fitting (including prop strut) daisy chained to each other, then connected to common ground with 8 awg 3. Large on-deck metal fittings, pulpits, stanchions, anchor roller daisy chained, then connected to lightning ground strip with 4 awg 4. No other connections to the lightning grounding strip, which begins fwd of mast, ends about 10' aft under galley. 5. DC negative terminates at negative bus 6. AC ground (not neutral) terminates at AC ground bus 7. Common ground point, engine or its own immersed copper plate? -- Questions -- What do I use for common ground for AC ground and DC negative: engine or separate, external copper bar, like with the lightning ground, but smaller? Engine has transmission, v drive, then out to prop The engine is freshwater cooled with raw water heat exhanger. Is there enough electrical contact in the cooling water system and the gears of the transmission and V drive use it for the common ground? Is the engine raw water intake metal thruhull electrically connected to the engine because the hoses are filled with seawater? What if water gets brackish? There would be no connection, if it was marginal to begin with. the water here can be salt, brackish, and sometimes sweet, if we've had a long run of rainfall. It seems that the more I reread Calder's book, the more I think using the engine/propshaft is not as good as a grounding plate outside the hull, esp. if I install a flexible coupling/drive saver. Is there any reason to connect the common ground to the lightning ground strip instead of its own ground plate (or engine/prop shaft)? Do I install a zinc to the external lightning ground strip? Thanks for the input.  

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The Musings of a Hopeless Wanderer

Engaging in the eternal search for the meaning of life...or a good time.

• Netherlands

Monday, September 3, 2018

Tackling moscow by train and boat.

Our first full day in Moscow started fairly late since we were still catching up on sleep.  Around 1, we finally were able to get our act together and get out the door. 

We stopped by a cafe to get some breakfast and headed over to the Red Square.  Since the festival is going on, we had to go through metal detectors.  Once we cleared security, we reached the State Historical Museum which provided an entrance to the Red Square.

We walked the length of the Red Square, passing by the Kazan cathedral.

Under normal conditions, the Red Square is a large walking area with the State Historical Museum on one end and St. Basil's on the other end.  On the sides is the Kremlin wall on one side and then the GUM shopping mall and the Kazan cathedral on the other side.  Presently, the walking area has been considerably narrowed and the fesitval grounds occupying a large space between the Kremlin and the mall.

We even asked a stranger to take our picture!

After walking around the Red Square, we had to leave to meet up with our Metro Tour.  

Moscow has famously pretty metro stations so metro tours are quite popular.  We booked a relatively inexpensive tour through a tour group which met outside of the Red Square.

On our way, we passed by the Kremlin gardens and the tomb to the unknown soldier and the eternal flame.

We soon met up with our group which, fortunately, was only 5 people.  Our guide told us that we were going to visit 8 stations during the 1.5 hour tour.  

Honestly, a lot of the stations blended in to me so I won't be able to give you a detailed description of all of them.  However, I did learn that there are 222 metro stations and the trains come every 2-3 minutes reliably.  For that reason, Moscow > DC. 

One of the first metro stations we visited had bronze statues all over of various depictions.  Many of the statues had superstitions tied to them.  For example, for a statue of the dog, it's held that if you rub the nose of the dog, you'll have good luck.  Consequently, most of the statue is tarnished - except for the nose.  I joked to Tomas that they probably rotate the "good luck" portion of the statue to ensure the entire statue gets polished.

However, I do remember some of the stations.

Novoslobodskaya is a station adorned with stained glass on the walls.

There was also Belarusskaya, which paid tribute to Belarus.

Another station which name I cannot remember but had pretty mosaics in the ceilings.

My favorite station was Komsomolskaya.  It's the busiest station and a hub for other connecting trains.  It was built during Statlin times and he wanted the station to embody beauty to set a good first impression to Russia.

I'd seen pictures of it beforehand since it's the most famous but it's so much more impressive in person.

Look at these ceilings!

Overall it was a very interesting tour.  Not sure of any other city which could offer a metro tour.  DC certainly can't...

After the tour, we headed back of the hotel to rest for a bit.  We had purchased tickets to a tour hour boat down the Moscow river.  The tickets were good for any time on any day and the boats left every 20min.  We decided to knock the tour out that day and headed over to the pier.  

We arrived at the pier and saw a boat by the company we had purchased from boarding.  We approached and they shook their head and said it wasn't the right boat. 

So we waited for another boat.

Another boat came along by the same company we had purchased from so weapproached them.  Again - we were told it wasn't the right boat and the boat we were looking for was coming.  

A third boat came along which was NOT by the company we had purchased from.  By this point, it had been longer than 20min waiting and I was starting to suspect that the correct boat was actually one of the ones which turned us away.   We approached the 3rd boat to ask if they knew which boat we should be on.  However, when we approached,  they waved us aboard without scanning our tickets.

So, we boarded the 3rd boat....which was definitely not ours.

We settled into an upper deck, open air table to take in the views.

We passed by pretty buildings.

The somewhat impressive cathedral of Christ the Savior.

This random statue.

After about hour on the cruise, Tomas remarked that it had been about an hour so we should be turning around soon.  I reminded him that we actually had no idea how long this cruise was or where we would be dropped off.  Since we were on the wrong boat.

Fortunately, it did turn around and took us back to the pier.  

For dinner, we decided to go to this burger place, Black Star Burger, which our guide told us about.  Tomas really liked his - I thought mine was OK.  It was a decent size patty with a mountain of Cole slaw on top.  We've realized that apparently Russians dislike getting their hands dirty while eating so some restaurants will give out gloves to use.  This particular restaurant gave out black gloves.

Tomas modeling our dinner.

Since little mum has been asking about pictures which show my feet, I assume she wanted to see my new shoes.  I recently bought Allbirds which are suppose to be super comfortable walking shoes which you wear without socks and can be washed.  I didn't wear them too extensively beforehand, so that was probably my first error.  I also didn't bring another pair of good walking shoes,  which was likely my second error.  The Allbirds were great the first two days without socks.  Midway through the third day, my right foot was quite unhappy. Left foot was a trooper. So, now I have a bandaid on the heel of my right foot and wear socks.  

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Lightning Probably Caused SSJ100 Crash in Moscow

Other factors under consideration by aeroflot accident investigators include pilot response to technical problems..

Following a daily brief at Moscow-Sheremetyevo airport May 6 during which investigators looked into causes that led to the crash-landing of an Aeroflot SSJ100 a day earlier, officials from The Investigative Committee of Russia (RIC) told journalists that the agency considers a lightning strike the most likely primary cause.

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An official published RIC report claimed that the airplane caught fire after touchdown on one of the airport’s two parallel runways. It further said that of 78 people on board, including five crew members and three children, only 33 passengers and four crew members survived. Forensic investigators have found and evacuated 41 dead bodies from the wreckage and have begun studying passenger documents and belongings for vital information before releasing them to their owners or relatives.

Other investigators have inspected the airplane’s wreckage, including pieces of avionics and radio equipment, as well as flight recorders, fuel specimens, and photo-video files from the airport’s monitoring system. 

Meanwhile, Russian media sources published what they describe as a brief interview with the captain, Denis Evdokimov, who survived the crash. In his view, the troubles began when lightning struck the Superjet as it climbed. Radios ceased to function and some avionics developed failures and malfunctions. The crew did not have a radio link with the ground upon landing. For a short while, however, the pilots managed to employ a backup radio using an emergency frequency. Although it did allow the crew to inform the air traffic controllers of what happened and request and receive clearance for an immediate landing, an “unsteady” connection with a flow of interruptions made communication difficult. Still, controllers helped the crew of the stricken Superjet with a bearing toward the runway and information on other airplanes in the air and preparing for takeoff. 

Reportedly, the final approach went smoothly, but because of a hard touchdown, the airplane bounced three times as it decelerated along the runway. It caught fire shortly after touchdown, when the damaged fuel system developed leaks and the leaking fuel ignited.

Evdokimov has logged 6,800 flight hours, including 1,400 in the Superjet; he became a captain two years ago.

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