"hot" marina poll

[LakeSuperior]

Originally Posted by Panope

Does wearing a dry suit protect against electric shock?

Intriguing question. Having to inspect the hull of a friends boat in fresh water a couple years ago after hitting a log I had the marina trip the breaker for the power to the docks. This I double checked. I made sure the inverter on the friends boat was off. I was wearing a Viking dry suit which is a rubber layer bonded to a scrim. I was also wearing an attached rubber hood and rubber dry gloves.

I would suppose the resistance of the rubber improved my chances of not getting poked. However, it seems like a high gradient electric field across my unprotected face could be an issue.

Looking online it is stated that only pure rubber can protect you from a shock. Viking dry suits are not pure rubber as they contain dye. However, I would think the resistance is still way higher than a human pathway.

In the end, I think a safe assumption would be no as the stakes are pretty high for getting it wrong.

[donradcliffe]

Originally Posted by LakeSuperior

However, it seems like a high gradient electric field across my unprotected face could be an issue.

I would have assumed you were wearing a diving mask across most of your face, but shutting off dock power was a good call

[barnakiel]

Marina Las Palmas, the one where the ARC starts.


Local staff and electricians completely useless. First they refuse to take notice, then they refuse to take action. Then when they finally (two weeks' waiting) take action -the electricians come, go, but the problem remains.


On the second go the marina manager, she tells us we do not know. I look at my German neighbour, he looks back at me. For sure we are hallucinating.



Now we are waiting for the first casualty. We hope it will be a cat rather than a child. For you know WE DO NOT KNOW.


Ignorance and indifference in its purest form. Welcome to the South.


b.

[boatpoker]

Originally Posted by barnakiel

Marina Las Palmas, the one where the ARC starts.


Local staff and electricians completely useless. First they refuse to take notice, then they refuse to take action. Then when they finally (two weeks' waiting) take action -the electricians come, go, but the problem remains.


On the second go the marina manager, she tells us we do not know. I look at my German neighbour, he looks back at me. For sure we are hallucinating.



Now we are waiting for the first casualty. We hope it will be a cat rather than a child. For you know WE DO NOT KNOW.


Ignorance and indifference in its purest form. Welcome to the South.


b.

There are no recorded incidences of ESD in salt water.

[sailorboy1]

Originally Posted by boatpoker

There are no recorded incidences of ESD in salt water.

Almost impossible as the current would much prefer to through the water than a body. We used to do the math on nuclear submarine wit a 460V ungrounded system as to what it would take.

It is kind of like that unlike in movies if you toss the toaster into the bath tub it doesn't kill the person.

[GordMay]

Originally Posted by boatpoker

There are no recorded incidences of ESD in salt water.

Thanks for your patience!


Electric Shock Drowning [ESD] happens in fresh water, where minute* amounts of alternating current are present.
* Current -☞ Level Probable Effect On Human Body
1 mA [1 thousandth of an Amp] -☞ Perception level. Slight tingling sensation. Dangerous, under certain conditions.
5 mA -☞ Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions, to shocks in this range, may lead to injuries.
6-16 mA -☞ Painful shock, begin to lose muscular control. Commonly referred to as the freezing current, or let-go range.
17-99 mA -☞ Extreme pain, respiratory arrest, severe muscular contractions. Individual cannot let go of an electrified object. Death is possible.
100 - 2,000 mA [2 Amps] -☞ Ventricular fibrillation, muscular contraction, and nerve damage, begin to occur. Death is likely.
2,000+ mA [2A] -☞ Cardiac arrest, internal organ damage, and severe burns. Death is probable.

A rough value, for the internal resistance, of the human body, is roughly 300 Ohms [Ω].
Since men tend to have thicker arms and legs (more muscle), they usually have lower resistance. Naturally, the resistance also depends on the path that electricity takes, through the body. - If the electricity goes in the left hand, and out the right foot, then the resistance will be much higher, than if it goes in and out of adjacent fingers.

The approximate electrical resistance of:
sea water is 20 to 30 Ω/m
brackish river water is 200 Ω/m
unfiltered tap water 1,000 to 5,000 Ω/m

So, it’s apparent that the human body is a better electrical conductor, than freshwater, and a poorer conductor, than seawater.

[newhaul]

Originally Posted by sailorboy1

Almost impossible as the current would much prefer to through the water than a body. We used to do the math on nuclear submarine wit a 460V ungrounded system as to what it would take.

It is kind of like that unlike in movies if you toss the toaster into the bath tub it doesn't kill the person.

Just don't dead short the generator contacts . Doesn't end well . Vaporized a dogging pipe on the carrier

[GordMay]

I think the title is fairly self-explanatory:
“Conduction of Electrical Current to and Through the Human Body: A Review” ~ by Raymond M. Fish, and Leslie A. Geddes
➥ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/

[CharlieJ]

@ GarretW #26:

There is stray DC current in the shore power system of my marina pier. My hull potential is approx -980mV isolated. When plugged into shore power it drops below -500mV. So somebody has a problem and it ain’t me.

Your conclusion is incorrect. This is the text book test we use during corrosion surveys.

Your anodes are protecting metal components that are connected to the shore safety ground wire system. Remedy with either a galvanic isolator that meets ABYC A-28 or with a more expensive, and very effective, isolation xfmr.

[CharlieJ]

@donradcliffe #24

Just for fun, go down your dock and put a clamp on ammeter around each shore power cord--the whole cord. In a perfect world, it should stay at zero, but I usually measure close to an amp of AC leakage on about 30-40% of the boats.

This is the first of two tests that must be performed to test for AC leakage. In many cases amperage >30mAAC trip point for an RCD will be observed. The cause is a poor land based safety ground system, difference of potential between the shore safety ground system and the water column, etc. I have observed close to 1AAC flowing when the main panel circuit breaker for the boat is open!

Use this test as a go/no go test.

The real test for AC leakage into the water column is to use a meter with a sensitivity to at least 0.1mAAC, and install a temporary breakout adapter between the pedestal and the shore cord. The breakout adapter allows the tech to clamp each conductor in the shore cord individually. With the adapter installed and the pedestal breaker closed, clamp N and L (L1 & L2 in a 240VAC installation), bring power aboard and start turning on AC loads by closing the branch breakers. Operate all AC equipment while noting the leakage current.

I rarely see a boat with less than 5mAAC using this test.

[Boatwright]

Locally we had a teenager who ignored the signs and went swimming at our municipal marina. The electrical contractor, and inspectors had screwed up with a major wiring error during the installation of new equipment.

Tragically, the kid died. Major lawsuits followed.

I always use one of the idiot-light plug-in testers whenever at a marina, that at least tells me if there is a hot/neutral/ground mix-up or an open circuit. At least once a year (not as often as I should), I'll check between an AC ground and the engine ground buss both plugged in to shore power and running on the inverter. for anything funny going on. However in fresh water, accurately testing for stray current to "ground" (Lake Michigan fresh) requires a $500 Fluke Multimeter, which I don't happen to have kicking around in my tool box. We also have big seasonal difference in water conductivity due to winter road salt runoff.

Take care of one's own system and hope that your dock neighbors aren't idiots with poorly maintained boats is the best one can do I suppose.

[boatpoker]

Originally Posted by Boatwright

Locally we had a teenager who ignored the signs and went swimming at our municipal marina. The electrical contractor, and inspectors had screwed up with a major wiring error during the installation of new equipment.

If this "local" marina was in fresh water please provide official citations on this incident as there are no recorded incidents of ESD in fresh water according to my trainers on this issue.

PS. I took my ESD training from the discoverer of ESD (Kevin Ritz) and a consultant to the US Navy, USCG and BoatUS on ESD (Cmdr. David Rifkin).

[Boatwright]

My report of a freshwater marina electrocution has been questioned. this incident received extensive local news coverage:

http://https://www.northernexpress.c...rocution-case/

I think there may some confusion here about both the actual event and different scenarios for electrical shock in fresh water.

What is a bit unclear is whether this unfortunate kid was having a hard time with his swimming ability when he first jumped into the water, and then was electrocuted when he touched a metal ladder that was energized with full line voltage, or whether he was feeling the current when he was merely near the hot metal. Seems he was from the reports of his friends.

I also have to point out that you have the theory backwards. One is more likely to experience shock in fresh water because the salty human body is a better conductor, the path of least resistance, than fresh water.

I would also like to say, water -- salt or fresh, electricity, and the human body are not a good combination. Tell the truth now, would you be willing to sit on the dock with your feet in any water and grab onto a live wire?

[sealife2]

this thread has been a fascinating read!
initially my eyesight being not great I saw a poll on hot mamas??? 2 gin and tonics in im all about getting to the bottom of this! looking again realized the term is hot marina
i live out at the end of a very rural road in canada so hopefully you'll excuse my ignorance. ive heard of hot girls and have been paying close attention to that realm since i was about 13 but hot marinas??? i had to discover what this was about. and then a poll? ??? went on to read what seemed many very different views of what a hot marina is. and still i dont know what the term exactly refers to. boat poker may have a point in suggesting there are several possible meanings for the average reader.
so far it's like comparing apples oranges and totem poles, i won't vote yet as i still dont know what im voting for or really what im talking about. YET!!!! i have seen a lot of "hot" ground wires at marinas around here. one had over 200 volts in the gound but not a lot of amps. 2 separate110v legs on the dock wiring had leaks to the gound conducter one was a light dont recall the other source. the combined legs did manage put 200 plus volts into the ground and from what i could tell it went out through the ground of the boat 110 volt hot water heater and then to the shaft brush to the props and zincs into the water. AC or DC... dont know but
there was a lot of metal disappeared in short order from zincs props and heat exchangers thankfully i didn't stick my hand in the water and touch the dock ground at the same time. i might have become electrolysed. Will vote when i get the terminology straight. maybe tomorrow!
jake

[rslifkin]

I've always understood ESD to be a bigger risk in fresh water than salt, as a human is more conductive than the surrounding water. Is that incorrect?