10% of the fatalities encountered by yachtsmen occurred as a result of lightning strikes. Boats waiting in the harbor are also at risk of lightning, but this risk is much higher for a boat offshore. The degree of this threat is directly related to the material from which the boat is made. In boats with a metal keel (steel or aluminum), a natural "Faraday Cage" is formed to provide protection against lightning. On wooden boats, there are thoughts that lightning will discharge from the shaft towards the sea by following the metal and electrically charged parts. It is known that wet sails conduct electric current well, but this does not mean that the electricity will be completely transmitted to the sea. The impact directed towards the water from the conductive metal parts of the sail hull equipment (wires, ropes that hold the sails), called rigging, can explode the covering boards, causing the keel of the boat to be punctured, burned, and as a result, the boat to sink.
In fiberglass boats, just like in wooden boats, the prevailing idea is that "lightning will discharge from the shaft towards the sea, following the metal and electrically charged parts". As for risks, there is the possibility of lightning causing the hull to explode on the metal parts to which the cross legs on fiber boats are attached, the possibility of melting electrical cables igniting the fiberglass, and the possibility of burning fiberglass emitting poisonous gases. Lightning is thought to rarely flow through wire ropes. It is assumed that it will generally pass over a wide-section and low-resistance aluminum pole, be directed to the electrical installation of the boat, and be discharged through the engine and engine shaft. In this case, the starter motor, dynamo and shaft bearings are likely to be damaged.
It is thought that metal rods placed at the highest position on some boats as a protection measure can transmit lightning to the water through a conductor connected to it. It is known that in some boats, an attempt is made to protect against lightning by creating a continuous electric current from an anode suspended in the water at the bow to the anode oscillated at the stern. However, it is thought that the most effective protection against lightning in water is the "Faraday Cage", as it is on land, and boats with this cage are safer. However, since many boats do not have this natural defense mechanism due to their structure, the need for an active lightning protection system at sea, as well as on land, has emerged. Because a boat without any protection measures will be constantly at risk of lightning.
Figure 1: “AMPER” Active Lightning Rod specially developed for boats
Grounding Precautions
When grounding marine vehicles, you first start with grounding the devices inside. The ground lines of the devices are connected to the ground busbar on the sub-panels, and the ground busbars on the sub-panels are connected to the ground bar of the main distribution panel. From there, it is connected to the ground plate mounted below the waterline of the boat. This plate must be resistant to salt water and must never be painted. Even if the hull of some boats is metal, it cannot conduct properly because it is painted.
Another type of grounding is grounding against "static electricity". Tanks, machine shafts, rudders, etc. The parts are connected to the same grounding plate. Navigation etc. A second plate can be used to ground electronic devices. This is important in order to eliminate any interference that may occur in devices.
Figure 2: “LICON” low impedance grounding conductor specially developed to prevent interference from cables on boats
Figure 3: “GR-MARINE” grounding specially developed for boats
Overvoltage Protection Measures
The parts most frequently affected by lightning on boats are communication antenna systems. For this purpose, surge arrester products that have technical values compatible with the boat electrical-electronics and are expected to be capable of protecting the equipment to which they are connected should be used. Voltage reducers used specifically for marine vehicles are produced by the Australian antenna manufacturer “Moonraker”.
Figure 4: Surge protection products specially developed for boats
Experienced Examples
·İsmail Korkut – Polyester (Beneteau) sailboat captain
· Year: 2006
· Location: Marmaris/Türkiye
"The ground is Marmaris, the air is a tornado, I can't see my surroundings. Everywhere is a column of water. I'm trying to take possession of the boat. I don't have 1 meter visibility. I went to the bow. I swung the anchor. My aim is to claim the boat. I had barely run to the back and took the helm, when a yellow light flashed across the entire mast. It surrounded the interior of the cabin. A noise. Lightning struck and reached the sea through the mast, inner mast, arbor and keel connection. All electronic and electrical equipment was reset. The alternator was broken from its stud. Both opposite parts in the bathroom were shattered as if they had been hit by a bullet, the engine continues to run. I "I was thrown from the steering wheel to the ground. Women and children inside the boat started crying in panic. There was no loss of life or injury. However, the entire equipment was replaced."
· Henk de Velde – Famous Dutch sailor with his 17-meter sheet metal boat named "Campina"...
· Year: 2002
· Location: Off the coast of Hawaii-Alaska
''As I moved north, meteorological forecasts said that storms were waiting for me. I was about 700 miles from Hawaii when I ran into a strong storm. The wind wasn't too strong, but the air was very electric. At one point I heard a big thump. The entire boat seemed to be surrounded by a fireball. My body stiffened under shock and I felt pain. I was lucky that this only lasted a few seconds and I came to my senses. When I was able to take care of the boat, I saw that all the fuses were blown. When I changed the fuses, the electrical system worked. However, my computer was not working. When I tried to start the engine, I realized that the dynamo was not charging the batteries. Thereupon, I started my generator, but it did not work properly and did not produce current. Even though I spent a night trying to repair the electrical system, I could not manage to charge the batteries. When I saw that the wind generator was also damaged, I decided to return. I believe that it would not be good seamanship to continue sailing without the opportunity to charge the batteries, because all navigation, autopilot and the systems that ensure the safety of the boat were powered by the batteries...''