Please select your home edition
Edition
Newport Boat Show 728x90

Lightning at sea- Myth and Reality

by Des Ryan on 22 Oct 2012
Lightning - unavoidable if you are already at sea .. .
Lightning strikes, like collisions with whales or floating containers, cannot be planned against if you are already at sea, and thunderstorms are among the most violent forces of nature. Here Des Ryan separates fact from fiction.

At sea, it is possible to encounter squall line thunderstorms that have developed over land. Thunderstorms that form at sea occur most often in the early morning around dawn. However, tropical thunderstorms can occur at any time, often daily because of intense heating over land and an unlimited supply of moist tropical air from the ocean.

Thunder is the result of a lightning bolt. Lightning is a large current for a short period of time (milliseconds). This is a danger on an unprotected boat. Lightning can vaporize antennas, destroy electrical power, navigation systems, blow a hole in the hull or start a fire.

Cruising friends who have experienced a lightning strike aboard their boat have agreed on one thing - the strike was so severe that no normal lightning protection would have worked, as the electricity was so powerful that it jumped through the air to reach metal objects, sometimes as far as 20 cm.

However, this is anecdotal evidence, and who knows how much worse the strike would have been had these boats not had lightning protection. To equip your boat with lightning protection, the following system needs to be installed: A sharp pointed rod (lightning rod) at the top of the highest point of the boat has to be connected with a good conductor of electricity. On sailboats, the mast can be used if it is made of metal. From the rod or mast, run a heavy copper wire (#8AWG) to a metal keel. This wire should be run straight, without sharp bends. All connections need to be mechanically strong. The metal keel plate needs to be through-hull bolted and in good electrical contact with the water.

The theory is that the properly grounded mast (lightning rod) will provide a cone of protection. The point of the rod should extend at least 6 inches above everything it is to protect. The cone then makes roughly a 60-degree angle with the vertical, and the circle of protection at waterline has a radius of 1.5 to 2 times the height of the lightning rod. If all of the boat is within this cone, you are protected at least 99 percent of the possible strike. Within 45 degrees, the protection is 99.9 percent.

However, if you are caught in a thunderstorm, have everyone stay in the center of the boat. If you have a hand-held VHF or GPS, put it in a microwave if you have one. If not, separate it by a wide distance from anything metallic. Don’t let anyone go into the water. Stop fishing. Do not touch or go near anything metallic.




Here are some of the common myths attached to lightning:

Myth 1: Lightning does not strike the same spot twice:

It is a myth that lightning does not strike the same spot twice. In a typical lightning flash, several strokes may hit the same spot in rapid succession. This is proven by the fact that tall structures are sometimes hit many times a year.

Myth 2: There is no danger of being hit by lightning if it is not raining:
It is a myth that if it is not raining there is no danger of being struck by lightning. Lightning bolts can and often do strike as much as ten miles outside of the rain area of the main storm. Recent research on lightning deaths finds that most fatalities occur in the period when the storm appears to be ending.

During the height of most thunderstorms, sailors are below anyway, seeking protection from the rain. For the ten or more minute period after the rain ends, and even after the sun comes out, lightning is still a threat. Lightning can be a threat as the storm approaches as well. The storm may be a good distance away and may have blue sky overhead. A lightning strike would still be possible.

Myth 3: If you touch a lightning victim, you’ll be electrocuted:
The truth is that the human body does not store electricity. Therefore, it is safe to touch a lightning victim and give them first aid.

Myth 4: If you are on shore and lightning is about to strike, lie flat on the ground:
The best thing to do in that scenario is to crouch down, ie, put your feet together, squat low, and tuck your head. Lightning induces electric currents along the top of the ground that can spread out and be deadly over 100 feet away. While lying flat does get you low, your chances of getting hit by ground currents are increased. You want to be as low as possible but also touch as little ground area as possible. Obviously, getting inside to proper shelter would be even
better.

For a worthwhile technical description of the interaction between lightning and sailing boats by the University of Adelaide, http://l-36.com/read_html.php?file=lightning/LightningAndSailboats&title=Lightning%20And%20Sailboats!click_here.

Colligo Marine 660x82Barz Optics - San Juan Worlds Best EyewearT Clewring - Generic

Related Articles

Kids Polarised Sunglasses from Barz Optics
Barz Optics have developed a quality range of junior polarised sunglasses ideal for sailing and fishing. Barz Optics have developed a quality range of junior polarised sunglasses ideal for sailing and fishing. Each pair are supplied with a neoprene case and sunglass retainer.
Posted on 4 Aug
Reducing weight aloft with composite backstays
Reducing weight aloft is one of the most cost effective ways of increasing your boat speed and performance. Reducing weight aloft is one of the most cost effective ways of increasing your boat speed and performance. Every kilogram you take out of the rig is roughly equivalent to 4kg added to the bottom of your keel!
Posted on 26 Jul
Free $US3,000 Carbon Vang with SouthernFurl boom orders in July
Southern Spars is giving a free carbon vang - valued at US$3,000 - with SouthernFurl in-boom furlers ordered in July Southern Spars is giving away a free carbon vang - valued at US$3,000 - with all of their SouthernFurl in-boom furlers ordered in July. Carbon gas vangs make a great addition to the furling boom package, though if you’d prefer to keep your existing one, Southern Spars will offer you a 5% discount on the price of your boom instead.
Posted on 29 Jun
Newport Bermuda Race - High Noon takes honours
As the Newport Bermuda Race fleet rushed to the finish line on Monday in the wake of the first-to-finish boat, As the Newport Bermuda Race fleet rushed to the finish line on Monday in the wake of the first-to-finish boat, the powerful 100-foot grand prix Comanche, to the surprise of many they were led by an unusual boat and crew. High Noon, at 41 feet, is fully 59 feet shorter than Comanche and tens of feet shorter than many other entries.
Posted on 22 Jun
Platino recovery - Family confirms that tug has made rendezvous
Reports in social media say a salvage tug has made a rendezvous with the Platino earlier than expected. Reports in social media by family and friends of Nick Saull, the crew member killed during a catastrophic incident abroad the 66ft yacht Platino say the salvage tug which left on Tuesday night has made the rendezvous earlier than expected. The Facebook report says the tug, Sea Pelican, arrived on Friday morning, the weather in the area has eased and with a more favorable outlook.
Posted on 16 Jun
Royal Queensland Yacht Squadron to ban bottled water
Approval has been given to create a ban on bottled water that comes in plastic containers. The RQYS Management Committee has confirmed that approval has been given to create a ban on bottled water that comes in plastic containers. This will place the club as a leader in environmental impact management in Australia and around the world. The Royal Hong Kong Yacht Club earlier this year did likewise. Who’s next?
Posted on 16 Jun
SouthernFurl In-Boom furling systems withstand Sydney Hobart test
Southern Spars design team have developed the SouthernFurl Boom smaller budgets and yachts from 35-70 feet. Have you ever scared your family when you got stuck with too much sail up when you should be reefed? Southern Spars’ range of SouthernFurl booms are the answer – letting you reduce sail quickly and easily without leaving the safety of the cockpit.
Posted on 23 May
2016 Garda Trentino Olympic Week - Day 4
Garda Trentino Olympic Week 2016 draws near to the conclusion: the weather once again proves difficult. Garda Trentino Olympic Week 2016 draws near to the conclusion: the weather once again proves difficult. Tomorrow the medal race is scheduled for the Lasers and another two races for the three paralympic classes.
Posted on 13 May
CCA presents RCC Award to Scott and Mary Flanders
CCA has announced that Scott and Mary Flanders are the recipients of the organization’s 2015 Royal Cruising Club Trophy. The Cruising Club of America (CCA) has announced that Scott and Mary Flanders are the recipients of the organization’s 2015 Royal Cruising Club Trophy.
Posted on 22 Apr
Cyclone Winston Relief Fund – Help the people of Fiji
Sea Mercy is sending volunteer fleet of small and large vessels, loaded with shelter, food and medical supplies to Fiji. Sea Mercy is once again sending our volunteer fleet of small and large vessels, loaded with shelter, food, water and medical supplies and teams to Fiji.
Posted on 27 Feb