Lightning Onboard

More thunderstorms to come this week! One tug captain, Joel Milton, recounts an event that occurred one summer afternoon:

“I had just gone below when a tremendous clap of thunder shook the tug and the clean smell of ozone filled the air. It turns out that we became part of the circuit for some of that dangerous, cloud-to-ground lightning. The lightning bolt struck the tallest point on the upper pilothouse — a six-foot radio antenna — leaving only a few inches of charred fiberglass sticking up. The radio attached to the antenna was fried, as was our navigation light panel, but that was it. All in all, we got off pretty easy. But I wondered what could have happened had I been up there when the lightning hit.

Our upper house is made of aluminum and the tug itself, including the mast, is steel. We were in saltwater. The boat did a great job of conducting the bolt into the bay with minimal damage, especially considering that lightning is generally not taken into consideration when vessels are designed. This may sound strange, but it’s true. In any case, I was just plain lucky that I was not in the upper pilothouse.”

Below, a summary of what he had written in WorkBoat magazine:

• Give the lightning a place to go rather than through you. “A mariner has more of a chance of being hit by a side flash from the main bolt. The body is an excellent conductor. If your body provides a lightning bolt with a better path to the ground than a part of the vessel does, then it will likely take it. So the better your vessel can conduct the charge, the safer you are.”

• “All-metal vessels conduct electricity quite well. This makes them less susceptible to damage from lightning and inherently safer for crews. Fiberglass and wooden vessels, however, are very poor conductors. Consequently, the likelihood of damage to the vessel and injury to the crew is much greater. ”

• “Salt water conducts electricity very well, while fresh water is a relatively poor conductor. Vessels in fresh water are much more likely to be damaged during a lightning strike.”

• “Everyone onboard should stay inside. Keep all doors, windows and portholes closed, and stay away from them. Avoid contact with any metal objects if possible, particularly with your hands. Do not hold metal steering wheels, jog levers, throttle controls, searchlight handles, etc., which gives the electricity a direct path through the heart and increases the odds of being killed. Donning a radio headset or holding a radio mike or cell phone is also very risky. And hold off on showers or washing the dishes.”

• “Turn off any electronic devices that are not immediately necessary for safe navigation or communications. Disconnecting radios and GPS receivers from their antennae and/or lowering the antennae may save them from damage, although this is seldom practical. You must also weigh the benefit against the risk to personnel by unnecessarily exposing them to a lightning strike. ”

• “Keep in mind, that lightning can easily strike in the same place again.”

“For those who wish to learn more, two excellent sources of information can be found at lightningsafety.com and marinelightning.com.”

Many thanks, Capt. Milton, for permission to use this article which is taken from Workboat Magazine, 2005.