Electric Shock Drowning:
Spread. The. Word.

Growing up we spent summers living on our boat at South Shore Yacht Club. We put on our life jackets on Memorial Day and didn’t take them off until Labor Day, going to our land home only on a rare occasion to do laundry. Days were spent taking sailing lessons, swimming off the back of the boat in the slip and occasionally throwing one another off the dock. Heck, we’d throw my little brother in just to see how cold the water was. If his lips turned blue, too cold to swim that day. Now swimming isn’t allowed in marinas or from any dock that has electricity supplied to it. Why? Electric shock drowning.

What is Electric Shock Drowning?

Electric shock drowning is two things. It is first and foremost an electrical injury. Electrical current traveling through the water shocks a swimmer, paralyzing their muscles. The swimmer, unable to use their arms and legs to keep their head above water, subsequently drowns. It happens lightning fast, invisibly, silently, before an onlooker may even realize there’s a problem. Because it looks like just drowning, bystanders often jump into the electrified water to save the victim, becoming victims themselves. Unless someone lives to tell the tale, these deaths are typically reported as common drownings. Even on investigation and autopsy, the true electrical cause of death shows no signs. As a result, there hasn’t been keen public awareness, so electrified water continues to kill. Until now. Let’s educate our children and one another. Spread. The. Word.

How ESD Works

In the typical electric shock drowning, the water becomes electrified from a fault in the wiring of a marina or private dock; or from boats that are connected to the dock’s power supply. Most commonly, electricity enters the water from an electrical fault aboard a boat. This is wiring that doesn’t meet current ABYC (American Boat and Yacht Council) and NFPA (National Fire Protection Association) standards. In most cases, the victim doesn’t feel the electricity immediately when they enter the water. The electrical fault is often intermittent such as when a light switch is flipped; or a battery charger, A/C unit, dehumidifier or other electrical appliance cycles on. In the blink of an eye, the water becomes deadly.

Why AC?

I love science and also I realize that it, like fractions, strikes fear in the hearts of many. Let’s see if we can’t make it understandable. There are two basic types of current, direct and alternating. In direct current (DC), electrons flow in one direction from a negative side to a positive side, such as in a battery. Boats away from the dock use DC battery power. Alternating current (AC) pushes the electrons back and forth, changing the direction of the flow rapidly. This is the type of electricity power plants produce for our homes. Boats hooked up to shore power are using AC power. This is important because it’s the AC power that causes ESD. The cycling nature of AC power disrupts our nerves and muscles far more that the straight flow of DC electricity.

Why Fresh Water?

Electric shock drownings occur almost exclusively in fresh water. Electricity is looking for the easiest, least resistant way back to it’s source. While salt water is 50 – 1,000 times more conductive than fresh water, the conductivity of the wet human body is much closer to salt water. In fresh water, the human body is much more conductive than the water itself. That means that in salt water, the body only slows down the electricity, unless the swimmer grabs hold of something electrified like a prop or swim ladder. The electricity slows down, but passes. In fresh water, the current gets stuck and creates a voltage gradient that can kill the swimmer who bridges it. It doesn’t take much current to cause a problem; 3 milliamperes is very painful, 6mA causes agonizing pain, 100mA, less than the amount needed to light a 40 watt bulb, is almost always fatal.

Prevention, as Always, is Key

  • Never swim within 100 yards of any dock powered by electricity.
  • Many of the problems occur because someone didn’t understand the differences between shore and boat electrical systems. Invest in an ABYC certified electrician to do any electric work on your boat.

    ESD either GFI or ELCI

    A dockside shore power pedestal.
    Photo courtesy Shelly Galligan.

  • Let’s have our boats tested once a year to see if they’re leaking electricity. DIYers can do it themselves with a clamp meter. If there are any issues, have an ABYC trained electrician come take a look.
  • Have a qualified ABYC electrician install an ELCI (equipment leakage current interrupter). ELCI protection on each shore power line, combined with protection of ground fault interrupters, will reduce the risk to those on the boat, the dock, and in the water surrounding the boat. These devices measure the current flow and switch off the electricity if they detect a potential leak.
  • GFIs protect against flaws in devices plugged into them, where ELCIs provides protection for the entire shore power system. ELCIs are required for new boat construction. Older boats will need to be retrofitted.
  • As an alternative to ELCIs, consider an isolation transformer. This baby makes your boat shockproof for swimmers, prevents galvanizing corrosion and protects your AC power from reversed shore power polarity. Read more about it here.
  • Never dive on a boat or hire someone to do so while it’s plugged into shore power, even in salt water.
  • If you feel a tingle, stay upright, swim out the way you came in and head for shore 100 yards or more from the dock.


If you see someone you suspect has encountered electrified water:

  • Call for help (911 or channel 16)
  • Turn off the shore power at the metered base
  • Reach, throw and row, but do not go! DO NOT ENTER THE WATER
  • If the victim is not breathing or does not have a pulse, start CPR

Fresh water mixed with alternating current equals danger. Please be aware, be careful out there, protect yourself and those you love and spread the word. Let’s make sure that no one else loses a child to ESD on our watch.

References for further reading:

  • ElectricShockDrowning.org. Their ESD Resource page has countless more resources.
  • This video was funded by the USCG and features Kevin Ritz, one of the founders of the Electric Shock Drowning Prevention Association, telling his personal story of losing his son to ESD.

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