Most lightning strikes occur in the afternoon - 70 percent between noon and 6:00 p.m. 

How thunderstorm clouds are created

As the air temperatures warm, evaporation increases. This warm, moisture-laden air rises and evaporates, forming fluffy cumulus clouds. As more moisture accumulates, the clouds darken and change into cumulus nimbus clouds - thunderstorm clouds - frequently, with a flattened top or anvil shape, reaching to 40,000 feet or more. Positive charges accumulate as a thundercloud passes overhead, a concentration of positive charges accumulates in and on all objects below the cloud. Since these positive charges are attempting to reach the negative charge of the cloud, they tend to accumulate at the top of the highest object around. 
On a boat that may be the radio antenna, the mast, a fishing rod, or even you! The better the contact an object has with the water, the more easily these positive charges can enter the object and race upward toward the negative charge in the bottom of the cloud. When ightning occurs when the difference between the positive and negative charges, the electrical potential, becomes great enough to overcome the resistance of the insulating air and to force a conductive path between the positive and negative charges. This potential may be as much as 100 million volts. To help you understand the magnitude of this voltage, the voltage needed in an automobile to cause a spark plug to fire is only 15 to 200 volts! And the spark plug gap is only a fraction of an inch! 
On water, boats are the highest objects in lightning's immediate area
When lightning does strike, it will most often strike the highest object in the immediate area. On a body of water, that highest object is a boat. Once it strikes the boat, the electrical charge is going to take the most direct route to the water where the electrical charge will dissipate in all directions. 

Consider a few possibilities:

1.	Lightning strikes the ungrounded radio antenna on your boat. The metal antenna carries the electrical charge to the radio, which does not have a good conductor to the water. Your hand is on the radio, or on metal connected to the radio. Your feet are on a wet surface, which is in contact with metal that extends through the hull of the boat to the water. Your body may then become the best conductor for the electrical charge. 
2.	On sailboats, lightning strikes the mast. The electrical current follows the mast or wire rope to your hands, through your body to the wet surface, and then through the hull to the water. 
3.	While you are operating a motor boat, the lightning strikes you, passes through your body to the motor, and then to the water. 
4.	Sitting in your aluminum or fiberglass rowboat, you are holding a graphite (a good electrical conductor) fishing rod. The rod is struck by lightning. The electrical charge passes through the rod, your body, then to the boat to the water. 
Worst-case scenarios
In all four examples you could be seriously injured. You could be killed. You need not even be in contact with the components of the boat struck by lightning. Unless the components of the boat that could conduct electricity are bonded together and are adequately grounded, there could be side flashes. A side flash occurs when the electrical charge jumps from one component to another seeking a better path to ground. You might be that "better path." 
Looks like rain
The best way to avoid a lightning strike is to avoid becoming a lightning target. Stay off or get off the water whenever weather conditions are threatening. Keep an eye on the weather. Watch for the development of large well-defined rising cumulus clouds. Once they reach 30,000 feet, the thunderstorm is generally developing. 
Now is the time to head for shore. As the clouds become darker and more anvil-shaped, the thunderstorm is already in progress. 

Distant lightning

Watch for distant lighting. Listen for distant thunder. You may hear the thunder before you can see the lightning on a bright day. You are two miles from shore. The thunderstorm, which is now five miles away, is traveling in your direction at 20 miles per hour, which means it could be overhead within 15 minutes. Can you reach shore - two miles away - and seek shelter within that time? You better move!

The scoop on lightning protection

There is no such thing as lightning-proof boats, only lightning-protected boats. All-metal ships are rarely damaged and injuries or deaths are uncommon. These ships are frequently struck, but the high conductivity of the large quantities of metal, with hundreds of square yards of hull in direct contact with the water, causes rapid dissipation of the electrical charge. 
But small boats are seldom made of metal. Their wood and fiberglass construction do not provide the automatic grounding protection offered by metal-hulled craft. 
Therefore, when lightning strikes a small boat, the electrical current is searching for any route to ground and the human body is an excellent conductor of electricity! 

At risk: small boats

Today's small fiberglass boats, especially sailboats, are particularly vulnerable to lightning strikes since any projection above the flat surface of the water acts as a potential lightning rod. In many cases, the small boat operator or casual weekend sailor is not aware of this vulnerability to the hazards of lightning. These boats can be protected from lightning strikes by properly designed and connected systems of lightning protection. However, the majority of these boats are not equipped with these systems. 
About lightning protection systems lightning protection systems do not prevent lightning strikes. They may, in fact, increase the possibility of the boat being struck. The purpose of lightning protection is to reduce the damage to the boat and the possibility of injuries or death to the passengers from a lightning strike. 
If you are considering the purchase of a new or used boat, determine if it is equipped with a properly designed and installed lightning protection system. This type of system is generally more effective and less costly than a system installed on a boat after it has been constructed. 
In the event of an emergency thunderstorms over coastal waters are frequently unpredictable. Even with the best weather reports plus constant and accurate observations of climatic conditions, boaters can still be caught in open waters in a thunderstorm. Then, with or without a lightning protection system, it is critical to take additional safety precautions to protect the people on the boat. 
•	Stay in the center of the cabin if possible. If no enclosure (cabin) is available, stay low in the boat. Don't be a "stand-up human" lightning mast! 
•	Keep arms and legs in the boat. Do not dangle them in the water. 
•	Stop fishing, water skiing, scuba diving, swimming or other water activities when there is lightning or even when weather conditions look threatening. The first lightning strike can be a mile or more in front of an approaching thunderstorm cloud. 
•	Disconnect and do not use or touch the major electronic equipment, including the radio, throughout the duration of the storm. 
•	Lower, remove or tie down the radio antenna and other protruding devices if they are not part of the lightning protection system. 
•	Avoid making contact with any portion of the boat connected to the lightning protection system. Never be in contact with two components connected to the system at the same time. Example: The gear levers and spotlight handle are both connected to the system. Should you have a hand on both when lightning strikes, the possibility of electrical current passing through your body from hand to hand is great. The path of the electrical current would be directly through your heart - a very deadly path! 

The importance of CPR

Make sure you are trained in cardiopulmonary resuscitation (CPR) and first aid. Many individuals struck by lightning or exposed to excessive electrical current can be saved with prompt and proper artificial respiration and/or CPR. There is no danger in touching a person after being struck by lightning. 
If a boat has been, or is suspected of having been struck by lightning, check out the electrical system and the compasses to insure that no damage has occurred.

Keep a clear head and consistently practice good boating habits to avoid thousands of dollars in repairs and, more importantly, the potentially deadly dangers of lightning.

