C-22 without shore power - will I regret it? Easy to add?

Interesting Sandy. Care to expand on that? I never thought of that before.
Click to expand...
As I'm sure you know, salt water is a fair conductor of electricity (due to the Na and Cl and other ions). OTOH, fresh water is a pretty good insulator. Intuitively, you might think that salt water would be the worse danger since it conducts, but in fact the opposite is true.

The reason? All electric currents represent a source of electrons that travel thru some medium seeking their way back to the source. So say a boat or a dock is "leaking" electricity into the water. At that point a voltage gradient is established between that point and all paths the electricity could and does take back to the source. The voltage gradient diminishes as the distance from that point increases. If you as a swimmer are near enough to that point where the voltage gradient is strong, since the electrons take any and all paths "down" the voltage gradient, one such path is through your body. Since the amps that flow (number of electrons) are equal to voltage divided by resistance, more amps (or more likely milliamps) flow in the paths of least resistance. In salt water there are lots of low resistance paths to take through the water since salt water presents a low resistance compared to the relatively high resistance path through you; so very little amps go through you. In fresh water you become a lower resistance path relative to the water paths since the fresh water conducts poorly, so more current will flow through you.

Note injury or death can happen in either fresh or salt water, but you have to be very near the source of the electricity leak in salt water for enough voltage potential to exist between one part of your body and another for enough amps to flow through you to hurt you. In fresh water the voltage gradient extends much further out from the source.
 
Thanks Sandy, and yes, we are nothing but a big old (well some of us) bag of salt water. Thanks for the enlightenment. I had never thought that one through.

Harvey
SleepyC :moon

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No problem.

BTW, one aspect perhaps some folks don't realize is that someone in the water doesn't have to be touching anything to get a shock (or electrocution). It is the voltage difference between one part of your body and another part that drives the electrons (amps) through your body. If you think about it, while you are in the water every part of your body is touching something (the water). Some folks get confused by this since we've all been told since we were kids that the danger is when you touch a metal fixture in the bathroom, or stand on the ground in bare feet while touching metal. But in water all of your body is in contact with a conductor (the water) and given the voltage gradient that extends out from the source of the electrical "leak", there will be a voltage difference between the part of your body that is closest to the source and the parts of your body that are farther away. If that voltage differential is strong enough to drive enough electrons through your heart, you're dead!
 
To expand slightly on Sandy's excellent discussion, I will add that it does not take heart damage to cause electro shock drowning. Only 15 milliamps will cause skeletal muscle paralysis-and this will lead to drowning, with out primary heart stoppage. Muscles depend on electrical potential difference between the inner and outer cellular fluids to cause contractions. Also there is an effect on nerve conduction.

This is why the most recent marina regulations have a much more sensitive ground fault interruption system. New construction must have "ground-fault protection set to open at trip level currents exceeding 30 mA”. There was some "confusion since the first code standards said "Less than 30 mA" leakage. The "old "standard was 100 mA. There are some marinas which have the GFP set at 4 to 6 mA. Those will be the safest. However many of our boats have "leaky" appliances, such as microwaves, where there may be 5 to 10 mA leakage--with a boat which is wired properly. If you experience this problem (tripping the ground fault at the power pedestal in the marina. Unplug appliances, and turn off the water heater and battery charger. If it trips still, there is most likely a problem in your boat's wiring.

Be safe--stay alive!
 
WOW Great information. Thank you Sandy and Bob.

Have always known not to swim in marinas and had one ambulance call to a marina in Portland years ago.

Harvey
SleepyC :moon

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