Lightning Strikes

June 07, 2019

Not quite the light you hope to take you out of darkness.

The flash and crack of a lightning strike become a very vivid memory for anyone unfortunate enough to be hit whilst at sea. Although lightniung strikes can be fatal, they are also posses great concern due to the potential immense damage. While a lightning strike can be very hard to avoid, there are some things you can do to protect your vessel.

In order to protect yourself and your asset from a lightning strike, it it necessary to first understand how the flash across the sky functions. We all like to take shortcuts, commonly choosing the path of least resistance, which in many cases is reflected in our structural engineering. For example, a crack will always follow a fault line and, equally, nature tends to do the same thing. Water will always ingress through the easiest or weakest point and lightning similarly follows this trend. As you can imagine, neither are terribly great issues to have with your boat.

The open seas are one of the least convenient places to be during a thunderstorm. On a yacht, the mast is the tallest object, and a lightning strike will seek the highest point in its environment in which to touch down. “Although the probability that a yacht will be struck by lightning is quite low, the potential for damage is large enough to deal with the issue in more detail”, notes Axel zu Putlitz-Lürmann, a claims expert from Pantaenius.

“Whilst the application of lightning protection systems for buildings is widespread, in the recreational marine environment it is still in its infancy. Unlike mega yachts, which are usually built with an appropriate protection system, sailing yachts usually have no special equipment installed. Mandatory standards and guidelines for lightning protection systems on yachts do not exist. It is up to the owner to take care of this area, and this is not an easy task for the layman.”

"Lightning protection is a very complex issue on a yacht, requiring a certain expertise. There is some literature on the subject from different areas, but an effective retrofit on yachts is always difficult, costly and potentially even very costly. Yachts today are equipped with more extensive navigation electronics and on-board technology than ever before, so the investment could end up being worthwhile.“

“Looking back, even as little as 20 years ago, many owners only installed electronic equipment such as VHF and HF radio, log, echo sounder, weather fax and wind gear as stand-alone instruments. Today, yachts are crammed with high-tech devices like GPS, chartplotter, AIS, autopilot, satellite communications, radar, fish finder and complex entertainment systems. The outcome of a lightning strike could be devastating, especially when you consider that many or indeed all of the devices are interconnected via a bus system. When lightning strikes the current can rush through the entire network and damage each and every one of the devices."


However, it is not only all your electronic equipment that could be at risk. Structural damage to the boat or even a total loss is possible, though these outcomes are very rare! In most cases damage to masts and rigging is minor as these components are simply conductors that facilitate the passage of the strike from the top of the mast to the water via the keel or alternate ground! There is almost always damage done to electrical components that are linked to the boats electrical system and pathways. "The strike seeks the path of least resistance to ground. Where the strike finds any form of resistance, then you can expect additional damage to occur", reported zu Putlitz-Lürmann, who has examined numerous examples of lightning damage.

A lightning protection system cannot deter a strike, however, it can control the point of impact and then the path on which it will follow through selective dissipation and grounding. Lightning is usually 20,000 to 50,000 amperes, but in exceptional cases can up to 100,000 amps! Remember, 0.3 amps can be fatal to humans. So, this huge current must be passed through a sufficiently sized ‘ladder’, which provides the simplest, quickest and shortest way to the water. On aluminium and steel yachts it is not a big problem, but with wood, fibreglass and carbon boats it is more difficult.

“A simple, if rather makeshift solution, is a system that consists of copper conductors and terminal devices that can be attached to the mast, the shrouds and stays. The free ends of the cables are dropped about 1.50 metres deep into the water, so as to conduct the lightning there. In theory, this sounds logical, but full protection cannot be guaranteed with certainty, because the behaviour of lightning is very complex. It splits, kicks over and may even come out of the water and back on board” (zu Pulitz- Lurmann).

“Then there is the danger of lightning from elsewhere. Typically, this is where the shore power is damaged and the spike hits directly into your system. So whether you’re building a new craft or retrofitting to a used boat, to create and implement an effective, peripheral lightning protection for your yacht, you should really seek the advice of a professional” (zu Putlitz-Lürmann).

However, no matter what other lightning strike prevention items you have on board, safety remains paramount. It is important to heed the following measures if you find yourself in or near a thunderstorm.

  • If possible, make for port or a protected cove.
  • Do not allow any persons on board to be in the water
  • Do not have any items, such as fishing rods, going into the water
  • If possible, go below deck and do not stand on deck. Wear rubber soled shoes
  • Avoid contact with metal parts (shrouds, railings, pulpit, etc.) and do not tamper with the anchor chain if it is down
  • If tied to the quay, disconnect your shore power
  • Turn off all electrical and electronic devices and where possible, remove power and antenna plugs or leads etc, especially where these devices have connections leading to items affixed to the top of the mast.  A total dissconnect of cables – connections for electronics, lights etc at the base of the mast will protect cabin mounted electronics in most cases!

Water and oil do not mix and we’re constantly reminded of this because it is very visible. Equally important, but far less visible is that water and electricity are. Common sense at sea is paramount, so in the case of electricity, keep reminding yourself that a regular, water based fire extinguisher is not the type to be used on an electrical fire for a very good reason. The charge or current can run back up the water to the holder of the extinguisher, which is of course almost always metal.

You can do a lot of things to protect your craft from lightning and more importantly protect yourself, your family and your friends. If you would like more information, assistance or just a chat then check in with the team that know boats. Go to or call +61 2 9936 1670 today.