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Ocean sailor Feature

Thunderbolts & lightning, very, very frightening

On our planet, there are 1.4 billion lightning strikes per year with certain geographical regions being more prone than others, such as within the Intertropical Convergence Zone (ITCZ). The global sailing locations most likely to be hit by lightning are ‘lightning alley’ in Florida and Singapore. According to BoatUS Marine Insurance, the odds of a boat being struck by lightning are 1 in 1000, increasing to 3.3 in high risk areas. Multihulls are two to three times more likely to be struck than monohulls due to their increased surface area and lack of a keel. Lightning can literally be a ‘bolt out of the blue’ far away from the bottom of the storm cloud and its destructive randomness causes much anxiety. I remember seeking cover in Telaga Harbour in Langkawi when a large Cumulonimbus tracked overhead. With maybe 100 yachts in the harbour the yacht that got struck was the only one with a wooden mast.

You may also be surprised to know that your boat doesn’t need a direct hit from lightning to suffer damage. Lightning has a very high voltage and extremely high current with a corresponding large magnetic field during an electromagnetic pulse or EMP which can pass over your boat. This can induce unwanted current in wires and components causing damage that may not be initially apparent.

What is lightning?

Lightning or ‘significant voltage events’, are naturally occurring electrostatic discharges caused by the friction of ice crystals colliding with snow pellets in clouds. The heavier snow pellets contain negatively charged electrons and sink to the bottom of the cloud whilst positively charged ice crystals and their protons rise with updrafts to the top. The actual discharge is the culmination of a very complex process where the formation of an electrically conducting plasma channel 5km tall forms between the cloud and the ground surface. A large bolt of positively charged lightning contains 400,000 amperes (400kA) of current and 1 gigajoule of energy, with a typical flash having 300 million volts at a temperature of 60,000 degrees Celsius. It’s enough energy to power the average house for a day.

What kind of damage can you expect?

Yachts today carry a lot more electronic devices than they did 10-20 years ago and are highly networked. If your vessel is unlucky enough to be hit directly it will usually be through the mast. The 1 gigajoule of energy travels down the mast and is desperately looking to escape and earth itself.

The big problem is that the electricity surge is trying to find a way out to ‘ground’ or ‘earth’ and if a route is not provided for it to do so, it will find its own way by blowing a hole in the hull. In some cases the chain plates have been blown right off and tragically people on deck can be hit. In 2012 a nine-year-old boy was killed on a 26ft sailing boat during a pleasure sail on Lake Superior.

All electronics and metal machinery are potential targets for this rogue electricity and in one such example the damage recorded included:

  • The entire B&G electronic system (all of which was destroyed)
  • All radios and the entire satellite communication system
  • The ship’s compass was offset
  • The battery charger and inverters
  • All captive winch and bow thruster sensors
  • PLC’s for alarms and monitoring, hydraulics and load shedding
  • Audiovisual and galley equipment
  • Damaged through-hull fittings

 

Tip from DB:

Keep a Garmin hand held GPS and batteries in a box lined with multiple layers of aluminium foil in case this event does happen.

What can you immediately do to avoid injury to yourself and your vessel?

  1. When you hear thunder get your crew inside
  2. Wear rubber boating shoes on deck
  3. Put PEB’s like your phone, laptop, portable VHF into the microwave or oven as it acts as a Faraday cage
  4. Unplug and turn off all non-essential equipment
  5. Turn on the engine as it may be impossible later if the batteries are damaged
  6. Turn off the batteries
  7. If not underway, clip thick gauge electrical cables to your rigging around the boat and place 2-3m in the water and lower your anchor into the water, creating your own Faraday cage. (See the chapter in the book ‘12V Doctor Practical Handbook.’)
  8. If in a marina, disconnect the shore power to avoid surges through the shore power

What can you do to help prevent damage to your vessel?

There are preventive measures you can take to help mitigate damage to your yacht:

  1. Fit surge protector devices (SPD’s). They can reduce the voltage spikes but for total protection, you may need several fitted in a cascade system 
  2. Have the means to disconnect the mast radar and aerial cables
  3. Consider fitting a permanent lightning strike protection device
  4. Fit a dedicated large grounding plate to your hull and bond it to the major metal objects on the boat
  5. Make sure your insurance covers you for lightning strikes and the value of your electronics

 

I’m just about to fit a new electronics suite to my yacht so these preventative measures are very much on my mind. My strategy is to try to isolate it as much as possible and I’ve been researching some of the lightning protection devices available on the market.

We have seen the traditional vertical wire-brush like static dischargers but in truth we are sceptical of their efficiency, and you will only know they don’t work when it’s happened. The fact you haven’t been hit while you’re using one may only mean you’re one of the vast majority of lucky sailors never to have been hit. Our concern is they don’t seem to have the capacity to dissipate the huge voltage and current. The earth can supply energy 4,000 times faster than the rate at which a static discharge brush can dissipate the energy.

Multiple electric field compensator from SERTEC

There is a high-tech solution which is sold by Sertec called their CMCE solution. It consists of two UFO looking devices mounted on a pole. The design claims to attract and ground excess negative charges from the atmosphere preventing ‘streamers’ for the plasma channel. Without streamers, there is no lightning. I contacted them recently and the price was 13,000 Euros for one antenna – they suggested I purchase two as I sail a ketch! Maybe if I owned a superyacht this could be an option but not as a recreational and charter sailor perhaps?

How does Kraken Yachts tackle lightning?

I must now choose what kind of sailor I am. Some are the type that are aware of the dangers, have a healthy concern but resigned to do nothing and play statistical roulette and others try to implement some kind of strategy and hope it does more good than harm. I’ll think I’ll try to isolate my systems as much as possible, keep my family safe and let the insurance company do the rest… if that fateful day ever comes.

You will find 3 grounding plates on the underside of a Kraken; AC, DC and Lighting. The last one is connected with a thick copper wire to the mast base and offers the shortest path for the lightning strike. Everything electrical or metal is grounded and isolated. Additionally, owners can choose to spec other protective circuits like dedicated condenser strips around the navigation instruments circuits to “fizzle out” the energy from the lighting.

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