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Old 08-01-2012, 08:45 AM   #21
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I don't think divers unplug the boat. There could be too many issues with loss of refrigeration, battery charging, air conditioing, etc. when current is restored. Specifically, breakers on the boat tripping because of the surge of everything coming back on at once.

{quote]To say that swimming in a (saltwater) marina is foolish or even particularly dangerous is simply ignorant.[/quote]

You haven't been paying attention. That's ignorant.
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Old 08-01-2012, 09:59 AM   #22
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I don't think divers unplug the boat.
Of course they do. I'm a hull cleaner, have been for 18 years and have unplugged almost every one of the 20,000+ boats I have ever cleaned. Any diver using an electric hookah is likely to unplug the boat he's working on, if not for safety reasons then at the very least so he can plug his air compressor in.

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There could be too many issues with loss of refrigeration, battery charging, air conditioing, etc. when current is restored. Specifically, breakers on the boat tripping because of the surge of everything coming back on at once.
I'm not going to speak for anybody else, but if it's a choice between my safety in the water or your air conditioning, I'm choosing my safety. I don't have any clients who have a problem with that. And if they do, they're free to find another diver.
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Old 08-01-2012, 10:19 AM   #23
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We're probably not talking days on end to clean the hull. The food in the fridge is going to be ok. And you can sweat while your hull is cleaned, or go do something on shore. And if your batteries are that weak that they can't go a little while without a charge, then you have more problems than a dirty hull.
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Old 08-01-2012, 10:22 AM   #24
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We're probably not talking days on end to clean the hull. The food in the fridge is going to be ok. And you can sweat while your hull is cleaned, or go do something on shore. And if your batteries are that weak that they can't go a little while without a charge, then you have more problems than a dirty hull.
+1

A large power boat could typically be cleaned in 1-1.5 hours, at the most.
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Old 08-01-2012, 10:30 AM   #25
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Shocking news...

As one who has been shocked in the water while removing a crab trap line from a prop shaft on a commercial ferry... it does happen. If you do work on your boat keep in mind that simply turning of the breakers at the dock end does nothing to lessen the shock hazard from OTHER boats to the ground path through YOUR boat. Disconnect the cord, remove the path to ground.

Our hull cleaners have always disconnected the shore power cord prior to getting in the water
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Old 08-01-2012, 10:41 AM   #26
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As one who has been shocked in the water while removing a crab trap line from a prop shaft on a commercial ferry... it does happen.
Yes, but getting shocked and electric shock drowning are not the same thing. I know a diver who tells the story of how, as he swam towards a boat he was about to clean, his eyeballs started vibrating. He got out of the water in a hurry on that one!

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If you do work on your boat keep in mind that simply turning of the breakers at the dock end does nothing to lessen the shock hazard from OTHER boats
Unfortunately, you can't unplug all the boats. So you pays your money and you takes your chances. But again, I've been in this business a long time and to my knowledge, no hull cleaner around here has ever been killed or seriously injured due to electric shock while in the water. But it only has to happen once to ruin your day. That's why we unplug 'em.
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Old 08-01-2012, 12:13 PM   #27
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This is what I do and understand as I have had several marine electrician check/do work on the Eagle. It does not mean its 100% correct, so donít go postal.


You can check for stray electricity through the AC ground, green wire and the neutral wire with a volt meter at a plug in. I would leave the power cord plugged in as the AC ground wire is usually the best to ground. You can also measure the water by dropping one end in the water and connecting to the metal support of the dock power, which should be grounded. However itís not the volts that kill you itís the amps. Most marinas/boats have stray electricity at a low level, and in marinas that have maintenance crew they can tell you the level and/or they can do some checking for you. Every time a new boat moors close to us, I check for stray electricity, and if concerned have the marina check also. The down side, if it our boat they will turn off the AC power until fixed. IF higher than normal/acceptable level best to hire a marine electrician.


Most high amp demand items like battery chargers, heater, water heaters, stoves/oven produce some stray electricity, so when testing with them on and off. Our battery charger is the highest producer. Make sure all the high amp items are connected to the AC ground. The biggest cause is AC wired back words as most people think the black wire is HOT like DC. The easiest way to check is a AC electrical plug tester sold at hard ward stores. When away from the dock the zinc loop becomes the ground path to earth, so itís a bigger chance of being electrocuted in fresh water as fresh does not conduct electricity, and salt does.

So you can do some simple testing. Like I said don't go POSTAL if you don't agree.
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Old 08-01-2012, 09:37 PM   #28
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Of course they do. I'm a hull cleaner, have been for 18 years and have unplugged almost every one of the 20,000+ boats I have ever cleaned. Any diver using an electric hookah is likely to unplug the boat he's working on, if not for safety reasons then at the very least so he can plug his air compressor in.


I'm not going to speak for anybody else, but if it's a choice between my safety in the water or your air conditioning, I'm choosing my safety. I don't have any clients who have a problem with that. And if they do, they're free to find another diver.
I have never seen it done at my marina. If my diver unplugged the boat and the main breaker tripped and the batteries ran down because the refrigerator was on DC power without a charger and the food spoiled, I would be finding a new diver. I suspect my friends would do the same.

There's no shortage of people willing to dive boats for a living in my area.

edit: re: "you can't unplug all the boats", of course you can't. If you try, you are apt to find someone who seriously objects to you unplugging their boat. At best, he will plug it back in and say nothing. At worst, you might find yourself in a physical confrontation over the issue.

And for the poster who commented that the food wouldn't spoil in the time it takes to clean a boat, read my post before you respond to it.
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Old 08-01-2012, 09:49 PM   #29
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Can't speak for other marinas or dive services but the one in our marina doesn't unplug ground power cables before diving. I know this because we've been on the boat a few times when our twice-yearly scheduled dives occured. I have no idea if they perform any sort of inspection of the ground power cables on the boat they're diving on and the surrounding boats before they go into the water.
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Old 08-02-2012, 06:00 AM   #30
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I don't do enough corrosion work to get too much in detail on this subject but one quick easy test to do without disturbing anything can be done to your shore cord using a clamp on multi-test meter. Clamp your whole shore cord using AC amps scale and note your reading. Turn off the pedestal breaker and note your reading again then subtract the pedestal off figure from the other. <100 ma freshwater and <500 ma saltwater is OK. This lets you know if you have AC current leakage. A clamp on meter would typically read zero when you clamp a whole cord but if some of the current is leaking it will pick up the difference.
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Old 08-03-2012, 12:33 PM   #31
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Stray Current

I think some of this discussion would have sounded different if all of you would have take the time to view the video. After viewing the video one of the first things I did is walk down my dock and check shore power cords with my clamp style VDO as described in the video. Just as I suspected the house boat next to me was leaking 1.7 amps from each of it's shore power cords. That's 340 mil amps enough to kill in fresh water. The saving grace is this is a 50' steel house boat and the length and shape of it's hull radiates the current in a safer way than as if it was originating from a small metal part like a prop or zinc. I still would not touch the steel hull and the grounded metal dock. Also the alga and silt in our water may make it a better conductor out of the water as well. Because our bodies have approximately the same salt content sea water sea water electrocution is not a danger from stray current. Take the time to view the video all the way through it covers the danger of stray current thoroughly. My house boat neighbor who lives full time on his boat doesn't believe he has a problem because his grand-kids swim around the boat all the time. I'm going to make up a device to measure voltage in the water. Surprising of the 30 boats I checked only two showed stray current. The other next to the house boat was leaking 70 milamps from each shore cord. The other boats checked may have not had any ac current in use so the readings may not mean anything. My own boat which is a ac power hog"50amp 240v" uses isolating transformers and showed no leakage. The video highly recommended the use of isolating transformers.
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Old 08-03-2012, 01:29 PM   #32
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I think some of this discussion would have sounded different if all of you would have take the time to view the video.
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Old 08-04-2012, 08:39 AM   #33
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Scary, My corrosion worksheet says that if there are two cords you clamp them together to check for stray current. If you clamp them separately you take the difference. In the case you mention the difference may be zero which would mean no stray current.

The metal boat can be a hazard on another basis also. If the hull, DC negative and AC green ground are not connected then it becomes a hazard. The AC system needs to have a way to tell stray current reaches the hull and can do so if it is connected to the AC green ground. If a wire chaffs or equipment has an internal short that finds its way to the hull the breaker will trip (if it is a serious enough fault). Therefore, even though the metal boat may have no fault current today in the absence of proper grounding it could change with the next problem. Another way to think of this is to view the boat hull as the frame of an appliance. To protect users appliance frames and boat hulls should be grounded.

This guy: Quality Marine Services, LLC is out in front of this and has a good number of articles on the subject.

You are right to be concerned. With a little more information you may be able to help the guy be certain he doesn't run into trouble down the road...
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Old 08-04-2012, 11:19 AM   #34
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the video say's to add the amperage together

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Scary, My corrosion worksheet says that if there are two cords you clamp them together to check for stray current. If you clamp them separately you take the difference. In the case you mention the difference may be zero which would mean no stray current.

The metal boat can be a hazard on another basis also. If the hull, DC negative and AC green ground are not connected then it becomes a hazard. The AC system needs to have a way to tell stray current reaches the hull and can do so if it is connected to the AC green ground. If a wire chaffs or equipment has an internal short that finds its way to the hull the breaker will trip (if it is a serious enough fault). Therefore, even though the metal boat may have no fault current today in the absence of proper grounding it could change with the next problem. Another way to think of this is to view the boat hull as the frame of an appliance. To protect users appliance frames and boat hulls should be grounded.

This guy: Quality Marine Services, LLC is out in front of this and has a good number of articles on the subject.

You are right to be concerned. With a little more information you may be able to help the guy be certain he doesn't run into trouble down the road...
I may have misunderstood the video I'll look at it again. I thought it said to add them together. I seriously doubt his hulls are bonded to his shore power green. The professional house electrician that wired his boat may have bonded the neutral and green ground like you would do at the service of a home. I don't know how to approach him to check as he seems very defensive. He built his house boat and did a very nice job on the interior as he is a professional cabinet builder. The inside is gorgeous, but he's a trial and error guy and the engineering side of things are hit or miss. He had to add a larger outer hulls to float it as the original pontoons didn't have enough floatation, fuel, water, and holding capacities are meager and its underpowered and hard to handle. It works nicely as a dock queen and they live full time aboard. As for now I don't seem to be having any trouble with zincs and nobody is dead. I just won't be swimming near his boat.
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Old 08-04-2012, 11:52 AM   #35
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I just reviewed the video and you are correct

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I may have misunderstood the video I'll look at it again. I thought it said to add them together. I seriously doubt his hulls are bonded to his shore power green. The professional house electrician that wired his boat may have bonded the neutral and green ground like you would do at the service of a home. I don't know how to approach him to check as he seems very defensive. He built his house boat and did a very nice job on the interior as he is a professional cabinet builder. The inside is gorgeous, but he's a trial and error guy and the engineering side of things are hit or miss. He had to add a larger outer hulls to float it as the original pontoons didn't have enough floatation, fuel, water, and holding capacities are meager and its underpowered and hard to handle. It works nicely as a dock queen and they live full time aboard. As for now I don't seem to be having any trouble with zincs and nobody is dead. I just won't be swimming near his boat.
Apparently you do subtract the to amperage reading when measuring two shore power cords independently. According to the video this shows a shared neutral which would make sense given he is using a house style electrical panel. Thanks for pointing that out. This makes me feel a little better about being in the water near his boat.
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Old 08-04-2012, 12:32 PM   #36
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............. I don't know how to approach him to check as he seems very defensive.............
That's understandable. I think we all are to some extent. Just read postings in this forum and you'll see evidence of people being "defensive".

Just imagine your reaction if a slip neighbor came up to you and said "Hey buddy, I think your boat is wired wrong and I want to inspect it and tell you how it should be wired".

It's probably best to let it go unless it's actually damaging your boat or shocking you. Even if it is, it might be easier to move to a slip further away.
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Old 08-04-2012, 04:01 PM   #37
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If nothing else maybe you can pass along the link and let him do some reading on his own. I have had some spirited discussions with very knowledgeable folks who needed gentle persistent prodding to wrap their head around the topic. It is not an issue one wants to experience to gain understanding when others have already paid the price:/
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Old 08-05-2012, 02:47 AM   #38
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It would be in his, your and the marina's interest if any electrical problem was resolved. Maybe a discussion with the marina management would help bring it to a peaceful resolution.
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Old 08-05-2012, 06:34 PM   #39
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Since he seems to have a combined neutral for both shore power cords and that doesn't create a shock hazard for swimmers I think I'm just going to drop it and not worry about it.
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