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Some time earlier Michigan State University was called to investigate
why cows at a certain farm kept falling over dead for no apparent
reason. It was found that stray currents through the ground from
faulty barn wiring produced a very small current through the ground
the cows were standing on and it only takes 2 Volts from the front
legs to the hind legs of a cow to interrupt it’s nervous system. It
becomes paralyzed, can’t breath or move, and it eventually falls over
dead. The farmer wearing rubber sole boots is unaffected.
The boys suffered a very similar fate, US Navy divers in a study found
that the same 2 Volts AC flowing from a healthy mans head to his legs
can paralyze him to the point where he can’t breathe, move, or swim,
and if not saved he’ll drown.
As we all know, a piece of marine equipment can work fine today and
fail tomorrow. Just because you’ve jumped in the marina before,
doesn’t mean you can survive it again. A different (and possibly
faulty) boat may be docked near you next time. The boys had done it
many times before. It should be noted, the battery charger in
question on the boy’s boat still worked well as a battery charger, it
just wasn’t safe.
In the following years, the USPS updated their Marine Electronics
course and test in the ‘92-’93 season. Many boat OEMs began
installing galvanic isolators and GFCIs as standard equipment, and the
issue faded into obscurity. Recent events however have brought it to
light again, and the following pages will describe in technical detail
the scenario I’ve just described in layman's terms for you.
The purpose of this article is to put a complex technical issue into a
format the non-technical reader will understand. Here’s the Take
Away:
If you must swim near a boat in the water; Make Sure You
UNPLUG IT, AND EVERY BOAT NEAR YOU!