Shock Hazard on boats in salt water

loren

Member
I can protect personal when they are on the boat from faults on the boat or the pier. But what happens when you have a boat next to you putting over 5 amps of AC current into the water.
Isolation transformers protect the boat and the people once they are on the boat but with no actual ground from the boat to the pier a person touching the boat while standing on the pier they can become a (deadly) path.
Any ideas on dealing with this?
 

donaldelectrician

Senior Member
Great Post , I've had 5 years on a Liveaboard Boat . The Best ever .

There have been Recorded Electrocutions in the way you posted . The other Boat has Wiring Problems . All too often this results in Electrocution !

If you can not get out of the Energized Water , you are done .

Many times when the person touches a Metal Ladder to boat or dock , when a boat wit a power problem is energizing the water , that is where the person gets electrocuted ... Then they find the boat responsible .

Using metal in boat or dock ladders is not too bright in my opinion . If you feel a shock , tingle while in the water , do not exit by way of metal ladder .



Don
 
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loren

Member
When a miss wired boat has no neutral or ground connected in his shore power cord. The boat is taking 6 amps of current AC. We are in the slip just to starboard. We have 3.3 amps of that current going to the shore power through the hull to the ground then thru the cord to the shore power box. The shore power box is bonded to the pier.
When the operator comes to leave he unplugs from the shore power box, then proceeds to step across from the pier to the boat. What do you think would happen if he was in bare or had wet feet when he did?
 

donaldelectrician

Senior Member
When a miss wired boat has no neutral or ground connected in his shore power cord. The boat is taking 6 amps of current AC. We are in the slip just to starboard. We have 3.3 amps of that current going to the shore power through the hull to the ground then thru the cord to the shore power box. The shore power box is bonded to the pier.
When the operator comes to leave he unplugs from the shore power box, then proceeds to step across from the pier to the boat. What do you think would happen if he was in bare or had wet feet when he did?


It is hard to think of a Boat powered from shore power and no N or G connection to shore power .

The boat is to your starboard side ... Load the Starboard Cannon and let fly ... Board the pirate vessel and raise your flag ... Scutel the boat .


http://www.westmarine.com/WestAdvisor/Marine-Grounding-Systems



Don
 
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dereckbc

Moderator
Staff member
Location
Plano, TX
Don , check this out . They say that salt water directs current around the body . I still will not take chances .

http://water.usgs.gov/edu/electrical-conductivity.html


http://www.boatus.com/seaworthy/magazine/2013/july/electric-shock-drowning-explained.asp



Don
I think what Don is trying to say is Salt Water is a better conductor than fresh water, thus will shunt more current then fresh water around the body much in the same way a Faraday Cage operates. Would I risk my life on it? Big Fat NOOOO. Although if I was forced to choose between say 5 amps of current flowing through earth vs Salt Water, I will choose Salt Water every time. 5 amps flowing through dirt say the distance between your feet can generate enough voltage to kill you, versus dipping your feet into water with 5 amps flowing. In salt water I doubt you would feel anything.
 

donaldelectrician

Senior Member
I think what Don is trying to say is Salt Water is a better conductor than fresh water, thus will shunt more current then fresh water around the body much in the same way a Faraday Cage operates. Would I risk my life on it? Big Fat NOOOO. Although if I was forced to choose between say 5 amps of current flowing through earth vs Salt Water, I will choose Salt Water every time. 5 amps flowing through dirt say the distance between your feet can generate enough voltage to kill you, versus dipping your feet into water with 5 amps flowing. In salt water I doubt you would feel anything.


Me neither !

Boat wiring is way to complicated for 1 cup of coffee . I am now starting my second cup .

The OP has a " Hot Marrina " .

http://www.westmarine.com/WestAdvisor/Marine-Grounding-Systems

I will read this on my 3 cup of coffee .


Don
 

loren

Member
I think what Don is trying to say is Salt Water is a better conductor than fresh water, thus will shunt more current then fresh water around the body much in the same way a Faraday Cage operates. Would I risk my life on it? Big Fat NOOOO. Although if I was forced to choose between say 5 amps of current flowing through earth vs Salt Water, I will choose Salt Water every time. 5 amps flowing through dirt say the distance between your feet can generate enough voltage to kill you, versus dipping your feet into water with 5 amps flowing. In salt water I doubt you would feel anything.
It is the part of being out of the water that is the issue. When you touch the boat and the pier where the current is attempting to get back to the source. In the water your body actuall offers more resistance than the water but out of the water when you touch a boat and the bonded pier you become a lease resistive path.

I am going to experiment with the resistance of the water where the boat is docked. There is plenty of fresh water entering this harbor only 70 ft away.
 

donaldelectrician

Senior Member
It is the part of being out of the water that is the issue. When you touch the boat and the pier where the current is attempting to get back to the source. In the water your body actuall offers more resistance than the water but out of the water when you touch a boat and the bonded pier you become a lease resistive path.

I am going to experiment with the resistance of the water where the boat is docked. There is plenty of fresh water entering this harbor only 70 ft away.


Loren ... Why will he not fix his Shore Power ?




Don
 

jstjohnz

Member
I would make the marina aware of the situation. Because of liability issues they should not allow any boat to attach to their shore power system if it produces an unsafe situation. Aside from the obvious electrocution risk, this type of issue will cause stray current corrosion of underwater metal parts.
 
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