Lighting Is Striking Again; Again

According to US insurance claims (from BoatUS Marine Insurance) the odds of a boat being struck past lightning in any year are about 1 per 1,000, increasing to 3.3 per 1,000 in lightning prone areas such as Florida. Pantaenius reports that while loftier-run a risk areas include the Caribbean, Florida and Mexican Gulf, the incidence in other areas is rising: "10-12% were in the Mediterranean, and that is coming from beneath 5% in the final decade," explained managing director Martin Baum.

Pantaenius handles more than 200 cases of lightning damage every yr. "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 twelvemonth is already ten% or more in some cruising areas such equally 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 2 to three times more than probable to be struck past lightning than monohulls, due to the increased surface surface area and the lack of a keel causing difficulties with adequate grounding. Besides increased likelihood of being hitting, the cost of a strike has also risen enormously every bit yachts carry more networked electronic devices and systems.

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

Fugitive lightning strikes

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

Unfortunately, many of the nearly popular cruising grounds are located in tropical waters. Advisedly monitoring the atmospheric condition and being flexible to changing plans is an essential role 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: y'all can cheque the CAPE index on windy.com (see in a higher place) every bit part of your lightning protection programme.

Protection against lightning strikes

Yachts that had no protection when lightning struck often feel all-encompassing 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 furnishings of their strike: "The extent of the damage was not immediately obvious. For days afterward 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 information technology 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 principal 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 most the engine have the highest chance 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 consequence of a strike, i temporary method to limit the impairment is to direct the current exterior the gunkhole using heavy electric 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 principal flaw in this plan is that an aluminium mast has much greater electrical electrical conductivity than stainless steel and is a more likely pathway to the ground. This system as well requires adequate copper to exist 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 alarm before a strike to drop the cables over the side and turn off/disconnect and unplug.

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

Posting an 'Emergency Lightning Procedures' card in a fundamental location of the boat showing where to stand up and what quick preparations to take is a uncomplicated outset step.

Permanent lightning strike protection

In a thunderstorm, molecular motility causes a massive build upwardly of potential energy. Once the voltage difference overcomes the resistance of the airspace in between, invisible 'channels' form betwixt the base of operations of the clouds and tall objects like masts, providing a path for a lightning strike to discharge some of the accumulated electric energy. In that location will exist less damage to a vessel if the discharge is contained in a well-designed lightning-protection organisation.

Grounding

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 cablevision can be used as a down conductor.

If non installed during production, a grounding plate can be retrofitted during a haul out. On monohulls a single plate virtually the base of the mast is acceptable. A ketch, yawl or schooner requires a vertical path for each mast and a long strip nether the hull between the masts, whereas catamarans usually require 2 grounding plates to complete the path to the h2o.

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 organisation designed past 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 continued to a copper grounding plate on the outside of the hull via ½in diameter bronze bolts."

The grounding plate was an viii pointed star shape. "Some liken it to a spider." Warwick says, "And the very minimal electrical damage nosotros experienced when struck was directly owing to this spider setup."

A copper '10' 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 exist routed abroad 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 exist routed on the opposite side."

Bonding

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

Morgan explains: "Equally modern boats are condign increasingly circuitous careful consideration is required to ensure the bonding system is designed correctly. At that place 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 exist 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 downwardly the electricity cable looking for ground. It tin 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 xx,000V surge tin be diminished to half-dozen,000V but the additional electric current tin still exist enough to impairment sensitive electronics. Therefore fitting 'cascaded' surge protection with several SPDs in line on disquisitional equipment is a practiced idea.

High-tech solutions

Theoretically, if a lightning dissipator bleeds off an electrical charge on the rigging at the same rate as it builds upwardly it can reduce or preclude a lightning strike. Lightning dissipators such as 'canteen brushes' are occasionally seen on cruising boats, though these are relatively old technology. Modern dissipators feature a 3⁄8in radius brawl 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'southward CMCE system, which claims to reduce the probability of a lightning strike past 99% inside the protected area. The system has been widely installed on airports, stadiums, hospitals and similar, only has at present been adapted for small marine use (and may reduce your insurance excess).

Arne Gründel of Sertec explains: "The CMCE system prevents a lightning strike past alluring 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 of measurement, designed to dissipate lightning

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Source: https://www.yachtingworld.com/special-reports/yacht-lightning-strikes-damage-protection-127469