Flash and Crack is not a new pop band

by John Curnow on 15 Nov 2015 To anyone who has been on an airliner hit by lightning, the flash and crack of the strike are vivid memories. It certainly gets your attention and when you land, all the technicians definitely run to the aircraft and give it a very close inspection. So now that we have heightened your senses, let us all remind ourselves that a lightning strike is not always fatal, but what can you do to protect your craft against it?

Don’t think it will happen to you at sea? Please think again. During a delivery down the Straits of Malacca, a large thunderstorm gathered quickly and unleashed its venom even faster. Sure it was not cold, but the sting from the huge droplets being delivered like serves from Nick Kyrgios was very acute and almost left you with bruises. All the crew had gone below and the lone helmer had directly in front of him a massive stainless steel wheel as the method for guiding the vessel under his command. The water in the cockpit was ankle deep, and as it had all happened so quickly, he was praying that the lack of rubber soles of his non-existent shoes would not become a major issue.

As he watched the flashes and heard the cracks, he reminded himself of the lesson to count one, two, three etc between the two to see if the storm was coming or going. Each time they occurred his lands leapt of the 316 wheel as quickly as those being raised at an evangelical sermon. Soon it was apparent that the storm was approaching and indeed atop of them. Something that was very evident from not even being able to get the “w” part of the word “one” out between the flash and the crack. That sailor is still here on this planet, but now with an even larger dose of respect for the elements.

Now most of us usually take the path of least resistance where we can and it is the same with structural engineering too. A crack will always follow a fault line, for instance. Equally, nature tends to do the same thing. Water will always ingress through the easiest or weakest point and lightning also follows suit. As you can imagine, neither are terribly great issues to have with your boat.

The open seas are also not a convenient place in which to be caught 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”, said Axel zu Putlitz-Lürmann, a damage expert from the leisure marine insurance specialists, 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”, said zu Putlitz-Lürmann.

“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 can be caused by a lightning strike. 'The strike seeks the path of least resistance to ground potential. But if it strikes any form of resistance, then the charge may rupture poles, split rudder blades and hull or keel cladding can literally be blown away', reported zu Putlitz-Lürmann, who has examined numerous examples of lightning damage.

A lightning protection system cannot deter a strike of and by itself. However, they 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.”

“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 said.

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

Water and oil do not mix and we’re constantly reminded of this because it is very visible. Equally and just as importantly, but far less front of mind, is that water and electricity are not good bedfellows, either. We always strive for common sense at sea, but 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 thereby keep the latest tunes from Flash and Crack blasting out from your entertainment system.

There are experts to provide you with assistance in this area. If cannot locate one, contact your Pantaenius representative who will draw on their large database of qualified and respected experts to help you get the result you need. Check in with the team that know boats. Go to www.pantaenius.com.au or call +61 2 9936 1670 today.

www.pantaenius.com.au/