fstbttms

Rapid Disintegration of Saildrive Leg

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It didn't look like this three months ago.
 

 

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They were still under warranty 3 months ago.

 

Seriously, any boat electrical work done in the meantime? Is the galvanic isolator still working? New slip neighbors?

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1 minute ago, IStream said:

Seriously, any boat electrical work done in the meantime? Is the galvanic isolator still working? New slip neighbors?

Unknown, although the customer says he contacted a marine electrician about it and was advised that a neighboring boat was a likely source of stray current. I personally would have thought it was a 12-volt DC issue aboard the boat in question, but what do I know? :rolleyes:

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New coat of paint and it'll be fine. 

I wonder that there isn't an aftermarket for bronze or SS saildrive legs. Not all that hard to produce, probably could be retailed for less than a Volvo or Yanmar replacement. The aluminum ones seem to be disposable. 

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Stray current from a neighbor boat if nothing was changed on the Lagoon.

  Or an internal issue on Lagoon -  like a battery charger with an internal DC short that is getting into a bonding circuit. 

Was the Lagoon hauled out and drive painted with copper based  paint in last 3 months? 

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1 minute ago, Zonker said:

Was the Lagoon hauled out and drive painted with copper based  paint in last 3 months? 

Boat was painted 4/2019.

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My saildrives are original from 1992.

The props look bad, too. There is a serious electrical issue and I’m betting it’s on the boat itself. 
 

whose mfg are those drives? They do not look like Volvo

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2 minutes ago, Max Rockatansky said:

whose mfg are those drives? They do not look like Volvo

Yanmar

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I can only speak from my own experience. Volvo have carefully designed electrical isolation from their drives. I check for continuity and there should be none.  I also have my drives barrier coated, and am careful not to paint with copper.

FB, if you didn’t get a shock, then the problem almost has to be on the boat itself.

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1 minute ago, Max Rockatansky said:

FB, if you didn’t get a shock, then the problem almost has to be on the boat itself.

The owner has already contacted a marine electrician who apparently is of the opinion that a neighboring boat is the culprit. That said, as of yesterday nobody had been aboard looking for the cause.

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With that kind of disintegration, it won't be long before the boat sinks. Seriously. The drive leg holds the rubber gaiter that keeps the water out. Once the leg is gone the boat will sink in minutes.

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That is big-time scary!!  Based on the difference in drive conditions they are nuts not to have someone tearing the inside of the boat apart ASAP.  Wonder if it's a dead short on a alternator or starter.  Probably  dont have block heaters there but maybe a common loop with hot water tank just on the one engine and a bad element.  In any case that's pretty scary stuff.

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Impressive and unfortunate.  If that happened in 3 months it seems like the cause ought to be pretty able to sort out with a multi-meter or maybe even a volt-tic!  Some serious cash there.. warrants calling in whatever expert corrosion/surveyor folks are willing and available including second opinions.  

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The boat won't sink. Those cats have engine rooms with waterproof bulkheads just forward of the engines and then there's the whole other hull. The engine rooms will fill a bit, but you might not even notice the boat off its lines.

Not clear from the video whether it's just one leg. If so, it's certainly a problem at the engine, not at a neighboring boat. If both legs are shot, it's harder to say.

 

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4 hours ago, Moonduster said:

 

Not clear from the video whether it's just one leg. 

 

I thought the captions “Port saildrive” and “Starboard saildrive” made it quite clear.

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I just watched again - it's not like those captions really stand out if one is watching the images. That said - this is pretty likely a problem in that one engine room.

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13 hours ago, fstbttms said:

The owner has already contacted a marine electrician who apparently is of the opinion that a neighboring boat is the culprit. That said, as of yesterday nobody had been aboard looking for the cause.

So I am to understand this ‘electrician’ has not been aboard, yet has pronounced the cause?

 

On another note, do I recall correctly that Yanmar s’drives are not electrically isolated?

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3 minutes ago, Max Rockatansky said:

So I am to understand this ‘electrician’ has not been aboard, yet has pronounced the cause?

 

On another note, do I recall correctly that Yanmar s’drives are not electrically isolated?

Apparently so to the former and I have no clue to the latter.

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FTA: “The design of the Yanmar SD20/SD40/SD50 range of sail drives is very different to the Volvo 'isolated' drives. The owner's manuals documentation is also very different with Volvo. The Volvo documents you can pull from the web go in to quite some detail on sail drive preparation and coating as well as the need for ensuring electrical isolation of the components. No such documents exist from Yanmar nor will they provide any details upon request in recent months. If anyone did get detailed written instructions during the last 4 years on how they should coat the drive with anti-foul from Yanmar Marine or any of their distributors (Mastry, Laborde or Mack Boring Parts Company), please email via PM with what you received in writing. Thanks, it would be much appreciated.”

 

thread link:

http://forums.sailinganarchy.com/index.php?/topic/71951-sail-drive-corrosion/

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If you don't know your way around a multimeter, get an electrician to check the integrity of your negative cables, especially if each engine has a separate battery / bank.

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BITD I had a OMC saildrive.  The OMC saildrive engine was a complete POS but the saildrive itself never had any corrosion issues.  I attached a large block of zinc to a stainless cable with the other end of the cable attached to the saildrive mounting bolt.  Everything on the boat was grounded to the engine block.

I think anyone in a marina with a saildrive should use a precaution like this.  It will be almost impossible to prove that a neighboring boat was the cause, and even if insurance covers the repair anyway it will be a big headache.  

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8 hours ago, Max Rockatansky said:

It appears to me that in the above video, the zincs are not particularly chewed up?

Saw the same thing, definitely points at a possible onboard issue.  When wierd metal bits are involved definitely a good idea to get someone who knows what they are doing involved.  We had our local marine electrician do a whole survey of our boat and thru hulls with a half cell.  You can over zinc a boat or use the wrong zinc etc.  He had us put a isolation transformer on and it was a big load off on the stray marina voltage worry.

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no details about the boat itself, is it plugged into shore power?

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23 hours ago, Max Rockatansky said:

It appears to me that in the above video, the zincs are not particularly chewed up?

The port anode had not been replaced. The starboard anode was replaced at the time the video was made.

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15 hours ago, Sailabout said:

no details about the boat itself, is it plugged into shore power?

Yes.

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14 hours ago, fstbttms said:

Yes.

isolation transformer, earth leakage breaker, residual current breaker?

common ground and bonding on the boat and next door has a problem....

Does that engine model have provision for an isolated earth install?

its all part of the grid now.

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The Yanmar saildrive legs on my St Francis were very severely pitted when I bought the boat.

Rather than buying new alloy legs I very aggressively sand blasted the surface with coarse, sharp, media. There were some spots where the wall was pitted all of 50% but by the time I was done the surface would skin your fingers - like a “badgers ass”!

I applied many coats of Interprotect 2000, spot filling the pits, allowing the recommended time frame between coats, flatting the surface a few times with 40 grit, until the leg was literally plastic coated with this excellent water barrier paint - in my opinion probably Internationals best product.

When reassembled and installed with new anodes throughout the engine and drive AND always isolating the engines batteries AND not frequenting marinas AND not applying bottom paint I have not seen ANY electrolysis on those legs in six seasons. The boat winters in the water. The props are stainless steel, two blade folding. I carefully scrub the legs and polish the props with a scotchbrite pad in the spring and a couple or three times during the sailing season.

Apparently that heavy coat of well adhered epoxy based paint is insulating the metal sufficiently to prevent electrical degradation.

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On 2/16/2020 at 4:05 PM, Sailabout said:

no details about the boat itself, is it plugged into shore power?

 

On 2/17/2020 at 7:31 AM, fstbttms said:

Yes.

 

I've found that keeping my boat unplugged as much as possible and charging with the solar panels has made a huge difference in zinc consumption and underwater corrosion - it's  the ultimate isolation transformer!  

It's also a good ongoing test to ensure that your off-the-grid systems actually work when you're off the grid.

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Just lose the on the grid systems - mostly unnecessary anyway!

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On 2/17/2020 at 4:31 PM, fstbttms said:

Yes.

any news on this?

any chance that the anode is for the wrong type of water.. since it looks intact - almost new?

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12 minutes ago, Kaptajnen said:

any news on this?

any chance that the anode is for the wrong type of water.. since it looks intact - almost new?

The anodes are aluminum and are designed to be used in saltwater, which is what this boat lives in. The one anode looks new because it is. It was replaced just prior to the video being made.

The owner had an electrician aboard whose only answer was apparently a lack of an isolation transformer caused this. The boat remains unplugged from the shorepower until one can be installed. The owner of course suspects a "hot marina" which in my experience, is almost never the case. In any event, the boat came out, had a new saildrive leg installed and we will go back and inspect it in a couple of weeks.

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16 minutes ago, fstbttms said:

The one anode looks new because it is. It was replaced just prior to the video being made.
 

How prior? just to get an idea about how fast this disintegration occured.

but something has been up then.. since the need to replace the one anode.
And what did the new aluminium anode replace? a zinc one?

I know aluminium anodes are the talk of the town.. but maybe not clever on an aluminium saildrive leg.. in saltwater

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16 minutes ago, Kaptajnen said:

How prior? just to get an idea about how fast this disintegration occured.

but something has been up then.. since the need to replace the one anode.
And what did the new aluminium anode replace? a zinc one?

I know aluminium anodes are the talk of the town.. but maybe not clever on an aluminium saildrive leg.. in saltwater

Like the day of. Look chief, I get that you think you're some kind of expert but I'm fairly sure you don't understand that we're talking about two different saildrives on the same boat. The new anode in the video was installed on the saildrive that hadn't begun corroding.

BTW- aluminium anodes are installed at the factory. Most engine manufacturers require them these days.  

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2 minutes ago, fstbttms said:

Like the day of. Look chief, I get that you think you're some kind of expert but I'm fairly sure you don't understand that we're talking about two different saildrives on the same boat. The new anode in the video was installed on the saildrive that hadn't begun corroding.

BTW- aluminium anodes are installed at the factory. Most engine manufacturers require them these days.  

Look you condescending prick - i'm not trying to be an expert, i'm asking questions... And i'm fairly sure that you failed to comprehend that I was referring to the anode on the corroded leg, showing no sign of wear.. Thats what I think is weird..

I get that aluminium is to be used in brackish and freshwater - right? And I've also read that its supposed to work (even better than zinc) in salt..
I have a yanmar saildrive, so of course i'm interested in finding out what went wrong.

I'll write yanmar and ask for my self. 

With the disintegration of the drive, I would have expected the anode to be gone..

sejldrev.png

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Then you and I have a different definition of "wear." That anode looks nothing like new. And I can tell you what Yanmar's response will be: They don't even sell zinc anodes for aluminum saildrive legs anymore.

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12 minutes ago, fstbttms said:

Then you and I have a different definition of "wear." That anode looks nothing like new. And I can tell you what Yanmar's response will be: They don't even sell zinc anodes for aluminum saildrive legs anymore.

Maybe so, and maybe its worse than what i can see from the video.. but it looks rather intact, even around the screw ports, where it, in my experience, tends to show wear first.

I've reached out to yanmar - thx

found this in a yanmar manual

Use only zinc or aluminum anodes in brackish and saltwater applications. In freshwater applications, use aluminum or magnesium anodes for best results.

and this too, which concurs with the engineer - as you mentioned


Vessels that are connected to shore power require additional protection to prevent destructive low voltage galvanic currents from passing through the shore power ground wire. Galvanic isolators are available from the aftermarket (not supplied by Yanmar) to block these currents while still providing a path to ground for dangerous shock currents. NOTICE: If the AC shore power ground is not isolated from the boat ground, sacrificial anodes may be unable to neutralize the increased galvanic potential. Corrosion damage that results from the improper system design or application is not covered by the Yanmar Limited Warranty.

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On 3/3/2020 at 5:05 PM, fstbttms said:

Then you and I have a different definition of "wear." That anode looks nothing like new. And I can tell you what Yanmar's response will be: They don't even sell zinc anodes for aluminum saildrive legs anymore.

Surely the point is that, however slow or sudden the corrosion, the anode should be long gone before corrosion even starts on the leg?

Wouldn't this point to the wrong type of anode?

[Just ordered my Zinc anodes for my Yanmars today]

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8 minutes ago, teamvmg said:

 

Wouldn't this point to the wrong type of anode?

What makes you think that aluminum anodes are the wrong type of anode for an aluminum saildrive leg?

From the Yanmar saildrive manual:

cKhJzN.jpg

https://www.yanmar.com/media/global/com/product/marinepleasure/sailBoatPropulsion/operationmanualgears/SD_OM_27MAR09.pdf

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36 minutes ago, teamvmg said:

Surely the point is that, however slow or sudden the corrosion, the anode should be long gone before corrosion even starts on the leg?

Wouldn't this point to the wrong type of anode?

[Just ordered my Zinc anodes for my Yanmars today]

Not nessesarilly, I don't have the metalurgy science or engineering behind it, but I have seen on ships and small boats.  If it is a severe electrical issue it can eat away at the closest thing depending on alloy and leave the zinc alone.

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Aluminium anodes are getting more common. In the US, for commercial vessels, you _have_ to use them unless its not practical.

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I converted over a year ago at the encouragement of my diver. No apparent difference in effectiveness, half the weight, same cost. I'm sold.

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8 minutes ago, Max Rockatansky said:

Here is a link to a galvanic table. Please note that Mg and Zn are well above Al. Given the instant discussion is about Al saildrives, please read and think really hard whether you want a more, equal, or less noble anode...

https://www.corrosion-doctors.org/Definitions/galvanic-series.htm

Yep. From a scientific perspective this whole thing stinks of the marketing department. While they might be good fun at the end of a night out they're fuck all use for anything else.

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 A little knowledge can be a dangerous thing. Aluminum anodes are not 6061 alloy or anything commonly listed on such a galvanic chart. Look up the actual galvanic potential of the actual aluminum used on an actual anode. Compared to silver/silver-chloride electrode in seawater, aluminum (Mil-A-24799) is more protective (-1100 mV) than zinc (Mil-A-18001) at -1040 mV. Despite today's political climate, there is actually such a thing as objective, testable fact. 

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Wow. That looks bad, wonder how the neighbors are doing?

I'm thinking about going from zinc to aluminium on my Volvo SD as the boat is now in brackish, almost fresh water (Baltic Sea). Which would you guys choose for brackish water?

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46 minutes ago, Itsabimmerthing said:

Which would you guys choose for brackish water?

Aluminum 

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Follow up inspection of the saildrives:
 

 

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On 3/13/2020 at 8:06 PM, DDW said:

Despite today's political climate, there is actually such a thing as objective, testable fact. 

Oh, hush yo' mouth!

(That "...testable fact" was a perfect comment.)

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On 2/8/2020 at 11:33 PM, Moonduster said:

The boat won't sink. Those cats have engine rooms with waterproof bulkheads just forward of the engines and then there's the whole other hull. The engine rooms will fill a bit, but you might not even notice the boat off its lines.

Not clear from the video whether it's just one leg. If so, it's certainly a problem at the engine, not at a neighboring boat. If both legs are shot, it's harder to say.

 

Lol. Watertight bulkheads? I know of a brand new lagoon hat sunk because the watertight bulkhead had holes cut in it. And the new owner lost the lawsuit over the watertight bulkhead not actually being water tight.

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My money is on a copper antifouled leg. Internal current wander, possibly via a negative/earth bond onto that saildrive in engine compartment. Led to advanced corrosion from inside out.

But really without being there with test gear......?... 

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2 hours ago, FixinGit said:

My money is on a copper antifouled leg...

Well, you would be wrong. 

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10 hours ago, fstbttms said:

Well, you would be wrong. 

Hence my comment of: “But really without being there with test gear....?...”

From what i can gather from your thread the saildrive leg has been replaced yet no exact cause for the original degradation has be found or identified.
But there is good online video footage of the problem....

Thats Quality service and fault finding.

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1 hour ago, FixinGit said:

Thats Quality service and fault finding.

I run a hull cleaning service. We are not electricians. Maybe you don't understand the difference. But part of my job is to notify clients of existing and potential problems, which I did in this case. In addition, I informed him of what I suspected the cause of the issue might be, based on my 25+ years experience in the industry. Anything beyond that is outside of my purview.

But hey, you're obviously an expert, Mr. Copper-Antifouling-On-An-Aliminum-Saildrive-Leg  :lol:

 

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Your a bit fragile and defensive about it all considering you posted it in a Fixit forum. 
Perhaps the same thing that attacked that saildrive is contagious? Or perhaps you are just hung like a hamster? 
 
But without being there with the testing gear whos to know.:D

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Was the cause of the failure ever identified?  Quite interested in knowing how it ended up.  The drastic difference in damage on a common hull.

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1 hour ago, FixinGit said:

Your a bit fragile and defensive about it all considering you posted it in a Fixit forum. 

Yeah, you're right. Why should I get my back up just because some douchebag noob know-it-all (who clearly doesn't know his ass from a hole in the ground) infers to the world that my work is sloppy and unprofessional?

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26 minutes ago, SASSAFRASS said:

Was the cause of the failure ever identified?  

If it was, that information has not been imparted to me.

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1 hour ago, fstbttms said:

Yeah, you're right. Why should I get my back up just because some douchebag noob know-it-all (who clearly doesn't know his ass from a hole in the ground) infers to the world that my work is sloppy and unprofessional?

“Infers” what you nutter? 
I clearly state that there is good online footage. Which from what i read in all the other posts is all you have done.
I feel social isolation or your gas mixture is fucking with your insecurity complex mate. 
Have a beer or horse tranquilliser and chill, smile at the world and live safe in the knowledge that your always right.... Coz clearly you are... :D
 

 

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On 4/23/2020 at 8:20 PM, SASSAFRASS said:

Was the cause of the failure ever identified?  Quite interested in knowing how it ended up.  The drastic difference in damage on a common hull.

I just spoke with the owner. His electrician tells him the cause is stray current from the shorepower system or a neighboring boat. He has just moved to another dock in the marina and we'll continue to monitor the situation.

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I had my saildrive leg corrode like this two years ago.  Totally user error on my part.  After many years of not having the mast grounded, I decided I wanted to ground it and ran a heavy wire from the base of the mast to one of my keel bolts.  Problem was that the vhf antenna mounted at the top of the mast is metal, and the outer shield on the antenna cable connects to the mount.  This meant that by grounding the mast to the keel bolt I basically connected the mast (and my keel) to the ground circuit in the boat.  The saildrive lasted the summer but when I hauled out I couldn't believe it was actually still running just before the haul out as there were a ridiculous number of worm holes in it.

Fixed the electrical issue by building a new antenna mount out of some old G10 that I had laying around so as to isolate the metal part of the vhf mount from the mast.  Also installed a DC block on the vhf antenna cable while I was at it, but I think this just covers the inner wire and not the shield, so okay for protecting electronics from a lightning strike but not for solving the grounding problem (hence the G10 mount).

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7 hours ago, Max Rockatansky said:

@Plumbean

was your saildrive Yanmar or Volvo? If Volvo, did you figure why the saildrive was grounded?

Yanmar SD20 paired with a 3YM30

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2 hours ago, Plumbean said:

Yanmar SD20 paired with a 3YM30

Oh, and the boat lives on a mooring, so not an issue with shore power and very likely not from a neighboring boat too.

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