Lightning Protection On Yachts: Thunderstruck
According to statistics, lightning strikes the world up to 44 times per second. The Maracaibo Lake in the northwest of Venezuela is the ultimate lightninghotspot, experiencing lightning strikes 300 days a year, on average.
In other regions, thunderstorms are at least a seasonal occurrence and Holger Flindt, Head of the Pantaenius Claims Department, explains why this can pose aparticular problem for yachts. Pantaenius handles between 200 and 250 claims of lightning damage to boats per year, and the trend is rising.
Although this figure is just a small percentage of the total amount of claims, the individual sums caused by lightning are usually twice as high as the average reference value in the Pantaenius damage statistics, as Holger Flindt (Manager of the claims department) reports: "As a rule, the electronics are the first victim on board.
In most cases, the complete electrical system has to be replaced after a lightning strike. But the yacht itself is also in danger: The lightning searches for the path with the least resistance to grounding potential. If it encounters resistance, rudder blades can be split, masts can burst and hull or keel casings can be blown away. In order to minimise these risks, use of a lightningprotection system is strongly recommended."
The lightning protection system does not prevent lightning strikes, but allows for the impact point and path of the lightning current to be better controlled. The enormous current of a lightning bolt, which can reach between 20,000 and 100,000 amperes, must be conducted into the water in the fastest and easiest way. While this is a relatively minor problem for aluminium and steel yachts due to Faraday's cage principle, itis more complicated for wooden and GRP yachts.
The higher the grounding potential, the more likely the impact. In recent years, Pantaenius has observed that lightning strikes catamarans more frequently than mono hulls of a similar length, as they have a larger surface area in the water.
Unfortunately, there is still no standardised regulation on lightning protection for yachts. Although large yachts built according to class regulations are often equipped with such systems, there is no obligation for the shipyard to do so, explains Holger Flindt:"Damage from a lightning strike does not usually result in a total loss, but the damage from loss of use can be enormous for an owner. The repairs are always complex and time-consuming, especially when the ship can no longer reach the shipyard on its own keel due to lightning damage. In areas such as the Pacific, the repair possibilities for large yachts are particularly limited."
It is a common misconception that motor yachts are less affected than sailing yachts. It is equally common to assume that lightning will strike at the highest point. Research has shown, however, that the direction a lightning strikes depends mainly on the distribution of electric charge in the clouds and the air. The surface structure on the sea or in the harbour still plays a certain role for the point of impact, as lightning will naturally be more likely to connect with high points rather than low on its last hundred or someters to earth. Not always, however, must it be a direct hit.
Lightning can strike the water, jumping over yachts or causing damage to yachts in the immediate surrounding area through induction: "We record damage in both the sailing and motor yacht areas, where by the vessels are usually in port when the lightning strikes. Most recently, we have been handling a claim for damage amounting to half a million euros aboard a 42m motor yacht."The owner did not have any lightning protection devices and in the end, was without his boat for half a year.
Since most shipyards do not proactively encourage people to invest in lightning protection, we often see this problem. In many cases, visual objections are decisive. With a sailing yacht, the generously dimensioned mast makes it easy to run an appropriate grounding cable and thus install a much more discreet lightning protection. But even here, such a precaution is sadly not a matter of course."In summary, there is no way to prevent the lightning strike itself.
However, an appropriate lightning protection system helps to prevent or minimise damage to the craft. The 147m superyacht TOPAZ, which survived a direct impact unscathed, is testament to the system’s affectivity.
OBJECTIVE: BRINGING LIGHTNING UNDERCONTROL
- Use a lightning arrester to pinpoint the point of impact on the mast or a suitably high point on board.
- The power is then conducted into the water via sufficiently dimensioned cables in the simplest, fastest and thus shortest way.
HOW DOES LIGHTNING OCCUR?
Lightning is caused by the fierce ups and downs of water and ice particles within a thundercloud. In this way, the natural electricity of the air is polarized. While the positive electrical charge increases in the upper part of the cloud, the negative charge accumulates on the bottom of the cloud. The ever-increasing electrical voltage field finally discharges in a flash - comparable to a short-circuit