Major Harbour Danger – Shocking

Kids love to Swim. As responsible boaters and parents, we check to make sure it’s a safe area and supervise them so they can play and enjoy the water and their water toys.

tyler-swimmingSometimes, they fall off the boat like our grandson Tyler. He wanted to put his feet in the water, so we let him sit on the platform and kick up a storm with a big grin on his face. But, he kicked too hard and fell in. We were right there, and as he bobbed back to the surface, Doug reached out and picked him up.

Tyler was a little frightened by the whole episode at first, and then he started the tale of his adventure. The more he told his story; the deeper he went down; the imaginary fish he was face-to-face with grew bigger and bigger; the time he was under got longer and longer; the more we laughed and the more he loved being in the spotlight.

We all have our stories and most are hilarious and funny. Sometimes though, the ending is horrific.

Another major harbour danger you can’t see or smell is Electric Shock Drowning.

Electric Shock

There are many documented cases where adults and children have been shocked by electric current while in the water with a high percentage resulting in fatalities. Electric shock deaths are usually recorded as drowning because victims show no signs of burns, so it is difficult to determine just how many Electric Shock fatalities there have been.

Preventable Dockside Tragedy

Kevin Ritz, a boater in Oregon, shares his story about a preventable dockside tragedy. Kevin has given us permission to put his story on our site in hopes of preventing another tragedy.

12V and 110V

Your house has a 3-wire system using one wire to ground to the earth under your house to carry the energy away from you and allow it to discharge into the ground protecting you from electrocution.

Your boat doesn’t sit on the ground or earth–it floats, so you cannot run a ground wire to the earth under the boat.

The 12V system (2-wire) on the boat grounds back to the battery. The negative terminal on the battery is connected to a grounding cable connecting all the metal surfaces on the hull. This bonding system equalizes potential current between the fittings elliminating any potential difference in voltage between the fittings. This not only protects you from electric shock, it also helps reduce corrosion.

110V Shore Power or Generator Power is a totally separate, independent wiring system. It is a 3-wire system that is grounded back to shore, or the generator.

When Something Goes Wrong

When an uninsulated part of a 110V (hot) live wire comes in contact with an uninsulated part of a 12V wire, the uninsulated 110V then uses the 12V ground, making all the metal parts on the bottom of the boat live with 110V. Because fresh water is a poor conductor, it forms a gradient around the boat. If a person enters this gradient while swimming, the current will flow through the body causing paralysis or ventricular fibrillation and death because the the human body is a better conductor than fresh water.

A parallel we’ve all heard about is a car becoming electrified when live hydro wires fall and touch the metal of the car. The rubber tires insulate if from ground. When a person standing on the ground touches the vehicle, the current passes through the body to get to ground, electrocuting the person. The human body is a better conductor than rubber, air or water.

It’s no different on the boat. When a person enters the gradient around the boat, the current passes through the body to get to ground and the person dies from electric shock. The only difference is that there is no burn mark on the victim in the water and the death is usually labelled as drowning.

What Causes a Fault?

Faults causing this gradient can occur from frayed, corroded or faulty wiring, poorly installed or non-marine appliances (marine and onshore residential electrical standards and safety requirements have some very important differences). It could be caused by a current leak from electrical components such as pumps, refrigerators or battery chargers or a non-approved receptacle. It could also be caused by hull movement chaffing or rats or other animals chewing wires. Using automotive-type battery chargers or running appliances on domestic 2-wire extension cords could also cause a fault. It could also be caused by reverse polarity if the wiring on the dock or the wiring in the boat or an appliance has black and white wires reversed. If a domestic appliance with two prongs is used, there is no ground and it’s a 50% chance that it can get plugged in the wrong way.

You will read in Kevin Ritz’s story that a random sampling of 50 boats in three freshwater marinas in the Portland area found 26% had faulty wiring. So, even if you have had your boat checked, you have to be aware of all the other boats around you as well.

Stray Current is Destructive and Dangerous

I was alarmed that such a high percentage of boats had faulty wiring; but, I spoke with local marine technicians who agreed with the finding and shared some of their stories. There are too many to print, but I can share a few with you.

One technician told me of a boat that had its prop and outdrive eaten off by electrolysis (in just three weeks) from current leaking into the water. It took him some time to find the problem, but he found that the boat owner had put a screw into a bulkhead and unknowingly screwed through a 110V wire causing it to ground to the 12V system. The 110V went straight to the 12V grounding system into the water and destroyed his props and drives. If he had jumped into the water around his boat, he would probably have died from electric shock–all because of one misplaced screw.

Another case was a woman who complained about her legs and feet tingling when she put them into the water from the platform. The marine technician pulled the Shore Cord (laying in the water between the dock receptacle and the boat) and the tingling stopped. It turns out the shore cord was old and dried and cracked and there was leakage of the 110V current directly into the water.

Apparently, marine technicians are constantly finding wires improperly joined and uninsulated–just twisted together. The movement of the boat can shift the wires and cause a fault, resulting in current leakage into the water.

One boat owner had severely corroded props and drives and when the marine technician investigated, he found that the sailboat next to him had faulty wiring and there was a gradient around the sailboat from the 110V leakage that was enough to destroy the props and drives on the boats on both sides as well as damage to his underwater gear.

Capt. David Rifkin (USN, Ret.) participated in a USCG Safety Grant to study Electrical Shock Drowning. He has much more information on his site. You can see his findings and lots more technical information at Click on the “Electric Shock Drowning” button on the left.  A list of Electric Shock Drowning Incidents can be found at as well. They are listed under “Documents”.


Marinas and boaters must be aware of the dangers of Electric Shock and do all they can to prevent it. The investigators recommend, that marinas have an annual check of grounding system integrity and 24/7 monitoring for electrical ground faults in a marina system. Boat AC Electrical circuits and equipment, as well as floating docks, should be installed, maintained and inspected by qualified marine electrical personnel.

no-swimmingThey also recommend that boaters use only marine approved appliances and electronics, installed by marine technicians and most importantly,

No swimming should be allowed in the harbour.


As tragic and frightening as electric shock drownings are, they are preventable. Our hope is that this article will help bring an awareness to the danger and destructiveness of installing or maintaining all things electrical without the necessary knowledge and skills, so that boaters and marinas will pay more attention to their wiring systems and make sure they are installed and maintained by marine technicians.

We should all help Kevin Ritz bring awareness of this danger and work towards a solution. And as Kevin Ritz says “If you have any doubts about your boat, it should be inspected by an ABYC-certified technician. Do not depend on an electrician with experience only on land. Let’s boat safely and save lives”.

Brenda Dawson


2 thoughts on “Major Harbour Danger – Shocking”

  1. I read this article with great interest, because many people I’ve talked with have never heard of this danger. Would love to read the linked articles, but the links don’t seem to be active. Can this be fixed? Thank you.

    1. Cindy
      Thanks for your comment. I checked all the links in the above article and they all worked fine for me. Could you try again. If you are still having trouble, call me and we can work it out. Tks.

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