In the past, when we have written about “Man Overboard”, and about whether you need a life-jacket or not, the main thrust was all about safety of life at sea. But there is a little-known fact that you can drown right at the marina – in the most shocking way! It is called “ESD” – Electric Shock Drowning.
Most mariners are not aware that such a danger even exists other than in the most blatant way. If there were an electrical cable thrashing about from a downed power wire, well, it is pretty obvious that whether that happens at the dock or in front of your house, this is a major danger. If it happens to knock you off the dock as it paralyzes you, you’re going to drown. But how about a charge as low 10 milliamps (.010 A)?
Sources of Stray Currents at the Dock
There are two sources of stray current at the marina – shore power transformers and a vessel’s shore power-derived electricity. This second aspect is the source of significant risk. At the dockside power source, if there is a non-functioning grounding system, or an improper grounding of the neutral-white power conductor or just unapproved wiring near the water, there can easily be a charge snaking through the waters of the marina. Although these are all violations of the National Fire Protection Association’s PFPA 303 Fire Protection Standard for Marinas and Boatyards, it will be cold comfort for you if you reach into the water to retrieve your cap and your muscular system is shocked into
paralysis. The amount of electricity entering the body can be so small that often the post-mortem doesn’t catch that stray current was the cause of death. “Poor Charlie reached in for his skipper’s cap and just kept going! He must have been dead when he hit the water because he never even tried to get back on the dock!”
The most unnerving aspect is that if muscles are exposed to charged water, they can become paralyzed, making it impossible to swim or even breathe. Drowning happens just that much faster since obviously you can’t do anything to aid yourself.
What Can I Do About It?
First, stay out of the water in a marina. Never, ever, go into the waters of a marina. If your cap blows off your head into the drink, get a boat hook with at least a rubber grip and snag it.
Secondly, check with your dock master to be sure that the marina itself is wired to ABYC and NFPA standards. A more sophisticated marina may have an inductive amp-clamp on hand. In the hands of someone who has been trained in its use, this can be used to identify potentially dangerous shore power leakage. Ask him check the waters periodically. No danger at the time of the test doesn’t mean no danger – it just means there’s no danger then and there. Again, never, ever, go into marina water. But if it does show a charge, the dock master can immediately address the issue. As you can see from the diagram below, testing will need to be conducted every few boat slips as these charges are not very powerful – just powerful enough to paralyze you.
You might even convince the dock master to stage an “Electrical Safety Day” at the marina. Inducing (pun intended) boat owners to have their boats checked for ABYC Standards is a good thing, even if the boat’s electrical system itself is not contributing to ESD risk.
He’ll thank you for it – as will everyone at the marina.