Electrolysis issue from survey

[talltales]

I have a recent survey from a boat I am interested in buying.

The survey states that the "Initial impressions where (that this 2007 narrowboat) was in above average condition. However, further investigation did find an electrolysis issue which will require remedial action." The recommendations: Re-black the lower hull (which has now been done) Replace the anodes (which has been done) Have the vessel checked by a qualified marine electrician (still awaiting) as the boat will not be for sale until three weeks time. 

The seller has been very helpful responding to my concern about this issue saying he rang the surveyor after receiving the survey late last year, he told him that he had to write it down but went on to say it was normal for steel to exhibit some degree of electrolysis if it has spent time in a marina. Asked if there was any concern and the seller was reassured there was not. This was November 2021.  Now when the seller put the boat in for blacking in April this year, he got a marine engineer to inspect the boat who said the hull was in very good condition for its age and the electrolysis was nothing to worry about and needed no further action.

This is the bit that I am unclear about, the seller told me that before he had bought it, it had been moored in a marina and for several years. But the boat has a galvanic isolator installed so either something must be wrong or perhaps the galvanic isolator was a late thought and possibly installed AFTER any damage had been done? Thoughts? My concern is that while the survey showed little to no pitting, corrosion it might still have weakened the hull structure? Its all a bit unclear to me. Any help of advice on this matter would be greatly appreciated. 

Thank you. 

 

 

[john.k]

If there is no metal wasting,the structure is not weakened....Obviously the concern about marina storage is  stray electric fields from other boats ...the question is whether the concern is actual or potential..............incidentally,the only agent I know of that can weaken apparently solid steel is halogen ion ......halogens can invade the grain boundaries of the solid metal and completely disintegrate the metal 

Edited September 14, 2022 by john.k

[LadyG]

My boat was in a marina for twenty years  , connected to shoreline with no GI and no Galvanic corrosion. I put a GI on it, and when I had it out there was one circle of surface corrosion the size of a new farthing. 

The hull was in great condition,  remarked upon by boatyard staff, unprompted. It had been epoxied from new.

PS have you ever found a marine qualified electrician, sounds like a bit of a cop out by the surveyor. I would ask him to recommend one!

So, don't worry about the hull.

Ask the surveyor to tell you his opinion of the electrics, without pulling a boat to bits a detailed electrical investigation would be impossible in my opinion, but a good impression can be gained from a look with a torch. A rat's nest of wires and lots of wires at battery terminals is always a bad sign, imho. Ask for an electrical diagram, from vendor, that's a start.

 

 

 

 

Edited September 14, 2022 by LadyG

[Arthur Marshall]

The only as advertised "marine qualified electrician" I ever used was the bloke who rewired the engine bay of my boat. Next safely test, the inspector made me do it all again.

[john.k]

Friend of mine was a marine qualified electrician .....apprenticed to the shipyard in South Brisbane ........there is a lot of heavy DC electrics in ships.,generators ,motors ,heavy conduits etc..............sadly ,they also threw asbestos around like snow ,and he died of lung cancer before he was 70.

[Tonka]

Galvanic isolator could have failed. Have you had it checked. Is it actually in circuit or being bypassed?

[Richard10002]

8 hours ago, talltales said:

 

The survey states that the "Initial impressions where (that this 2007 narrowboat) was in above average condition. However, further investigation did find an electrolysis issue which will require remedial action."

 

 

 

"an electrolysis issue" ???

 

Given that "the survey showed little to no pitting, corrosion", can you quote the part of the survey which shows what investigation found the electrolysis issue, and how it manifested itself?

 

 

[talltales]

4 hours ago, Richard10002 said:

 

"an electrolysis issue" ???

 

Given that "the survey showed little to no pitting, corrosion", can you quote the part of the survey which shows what investigation found the electrolysis issue, and how it manifested itself?

 

 

Hi Richard, reading through the survey several times it does not mention what investigation found the electrolysis issue, besides what I have already quoted, I have included a screen grab of the survey's conclusion. I think the way forward is for me to call out an electrical engineer, check that the isolator is working correctly.

10 hours ago, LadyG said:

My boat was in a marina for twenty years  , connected to shoreline with no GI and no Galvanic corrosion. I put a GI on it, and when I had it out there was one circle of surface corrosion the size of a new farthing. 

The hull was in great condition,  remarked upon by boatyard staff, unprompted. It had been epoxied from new.

PS have you ever found a marine qualified electrician, sounds like a bit of a cop out by the surveyor. I would ask him to recommend one!

So, don't worry about the hull.

Ask the surveyor to tell you his opinion of the electrics, without pulling a boat to bits a detailed electrical investigation would be impossible in my opinion, but a good impression can be gained from a look with a torch. A rat's nest of wires and lots of wires at battery terminals is always a bad sign, imho. Ask for an electrical diagram, from vendor, that's a start.

 

 

 

 

A cop out indeed, thanks for the advice, much appreciated. 

[pearley]

Canal Junction have a list but many of the names are no longer trading.

https://www.canaljunction.com/boat/electrics.htm

 

Where in the country are you or boat?

Edited September 14, 2022 by pearley

[David Mack]

3 hours ago, talltales said:

Hi Richard, reading through the survey several times it does not mention what investigation found the electrolysis issue, besides what I have already quoted, I have included a screen grab of the survey's conclusion. I think the way forward is for me to call out an electrical engineer, check that the isolator is working correctly.

It might make more sense to first go back to the surveyor and ask him what the "electrolysis problems" are that he refers to in his conclusion, but not in the main body of the report. Ideally he will clarify and amend the report. As it is currently written it may well raise more questions than it answers when your insurers see it.

[Richard10002]

1 hour ago, David Mack said:

It might make more sense to first go back to the surveyor and ask him what the "electrolysis problems" are that he refers to in his conclusion, but not in the main body of the report. Ideally he will clarify and amend the report. As it is currently written it may well raise more questions than it answers when your insurers see it.

 

I believe it is the sellers survey, so I dont think the surveyor would entertain queries etc. from a potential buyer..... having said that, it wouldnt be the survey that the OPs insurers would see.

[Richard10002]

6 hours ago, talltales said:

Hi Richard, reading through the survey several times it does not mention what investigation found the electrolysis issue, besides what I have already quoted, I have included a screen grab of the survey's conclusion. I think the way forward is for me to call out an electrical engineer, check that the isolator is working correctly.

 

 

It's hard to know what to suggest. The surveyor uses a word, but doesnt back it up with information. It looks to me like he has a bee in his bonnet about electrolysis, and feels the need to mention it, even if any damage is minimal, or non existent. Easy for me to say as you are the one who has to sleep comfortably, having bought the boat.

 

I'm not sure what an electrical engineer can tell you that a simple test with a meter couldn't.

 

I suppose, if I was going to suggest anything, I could suggest that you commission your own survey, perhaps explaining your concerns regarding the sellers survey.

[Slim]

6 hours ago, talltales said:

Hi Richard, reading through the survey several times it does not mention what investigation found the electrolysis issue, besides what I have already quoted, I have included a screen grab of the survey's conclusion. I think the way forward is for me to call out an electrical engineer, check that the isolator is working correctly.

A cop out indeed, thanks for the advice, much appreciated. 

Leaving everything else aside whether or no the galvanic isolator IS OR IS NOT working can be checked out in literally a couple of minutes with a multimeter. Any number of posts on this site as to how to do it.  

 

 

Beaten to the point by Richard 0002

Edited September 14, 2022 by Slim

[talltales]

3 hours ago, David Mack said:

It might make more sense to first go back to the surveyor and ask him what the "electrolysis problems" are that he refers to in his conclusion, but not in the main body of the report. Ideally he will clarify and amend the report. As it is currently written it may well raise more questions than it answers when your insurers see it.

The seller does seem very friendly and forthcoming to me, I don't think he'd have an issue contacting the surveyor he used back in Nov 2021, but as its been nearly 10 months would the surveyor still have any relevant info at hand to pass on, I mean anything might have happened in the ten months since? The other option that has been mentioned and considered by myself is taking out another survey paying particular attention to the waterline... and frustrating that this surveyor the seller used came with good credentials but just seems so vague! 

[MtB]

Look its a boat made of steel, and steel goes rusty in water. The boat has a limited life, unlike a house which surveys are for.

 

If it is still floating after 50 years it is living on borrowed time. At 15 years old this boat is probably doing ok. Survey report full of ol' twaddle about electrolysis notwithstanding, it will prolly still be floating in another 15 years. And then a further 15. Surveyors make their living out of looking at boats and coming up with scare stories like this. If you employ your own, he or she will prolly come up with a completely different list of scare stories. 

 

Don't buy it if you are risk averse. It WILL go rusty over the decades. Stick to houses.

 

 

The art is to use and enjoy the boat for slightly fewer decades, then sell it or scrap it. 

 

[MrsM]

Glad you have found a boat with enough headroom for you! Can you tell us more about it (builder etc)? The only way you are going to put your mind at ease is to commission your own survey (even better if you can attend the survey). I expect you had planned to do this with any boat you found and it just so happens that the boat you have settled on had a survey almost a year ago. I've no idea what the 'electrolysis' means - is it rusty and pitted? As the boat is generally in good order with a decent professional fit-out I expect it is costing £40-60k. In your shoes I would get my own survey booked asap and put these questions to him/her. Best of luck and let us know how things progress. 

[Alan de Enfield]

8 minutes ago, MrsM said:

I've no idea what the 'electrolysis' means - is it rusty and pitted?

 

No one knows anything until they are taught it, or, do their own investigation / reading.

 

A little light reading :

 

Electrolysis on Boats: What You Need to Know (boatsafe.com)

 

New boaters are often unaware that electrolysis is something they need to be on the lookout for. Let’s be honest, a lot of us don’t even know what electrolysis is. So let’s start with the basics.

Electrolysis happens when an electrical current passes through water. That in turn causes a chemical reaction. That’s the simple, bare bones version. In terms of boating, the electrolytic reaction occurs between two metals. The electrical current strips away one metal and deposits it on another. Remember, it happens between two dissimilar metals.

In order for electrolysis to occur, a current has to be forced into the reaction. That usually means bad wiring. It doesn’t have to be a high current, and not even one dangerous to living things.

 

This is very different to Galvanic corrosion which is caused by dissimilar metals in an electrolyte

 

Galvanic corrosion is pure chemistry. Two different metals in an electrolyte, which is salt water, will exchange electrons. Freshwater does not allow for this kind of corrosion. No current needs to be present to allow for this corrosion to occur. This is your boat essentially becoming a natural battery.

 

 

In a boat you may have any number of metal parts touching the water. Mild steel, stainless steel & bronze, are all commonly used. The process of electrolysis sees electrons being stripped from the anode. Then they head towards the cathode. So what does that mean?

• A cathode is a negatively charged electrode. The more noble metal in the reaction will always be the cathode.
• The anode is a positively charged electrode. The less noble metal in a reaction will be the anode.
• Electrons travel more easily through salt water from the anode to the cathode. This is why having something like zinc anodes is important. It allows those electrons to leave the unimportant anode. That saves the important parts of your boat, like the prop or the shaft.

In freshwater or brackish water, it’s best to use different anodes. Magnesium and aluminum are often used here.

 

The wires in your boat connect metal parts. That basically makes your boat a battery. Non-metal boats will have a copper bonding wire inside. This connects all metal parts so they can share anodes. This bonding connection also includes the metal frame of your boat’s hull which serves as the negative battery connection. And the engine and negative side of your boat battery. Stray current will damage this system.

If your anodes die quickly, your dock may have a faulty shore power ground lead. It should never be connected to the ground bonding system. If the shore power ground connects to the boat’s underwater bonding system, it can wear your anodes out. The shore power circuit is not typically something you can fix under normal circumstances. It can result in your boat being electrically connected to all the other boats. That stray current corrosion can be the most destructive form of electrolysis.

 

[MrsM]

20 minutes ago, Alan de Enfield said:

 

No one knows anything until they are taught it, or, do their own investigation / reading.

 

A little light reading :

 

Electrolysis on Boats: What You Need to Know (boatsafe.com)

 

New boaters are often unaware that electrolysis is something they need to be on the lookout for. Let’s be honest, a lot of us don’t even know what electrolysis is. So let’s start with the basics.

Electrolysis happens when an electrical current passes through water. That in turn causes a chemical reaction. That’s the simple, bare bones version. In terms of boating, the electrolytic reaction occurs between two metals. The electrical current strips away one metal and deposits it on another. Remember, it happens between two dissimilar metals.

In order for electrolysis to occur, a current has to be forced into the reaction. That usually means bad wiring. It doesn’t have to be a high current, and not even one dangerous to living things.

 

This is very different to Galvanic corrosion which is caused by dissimilar metals in an electrolyte

 

Galvanic corrosion is pure chemistry. Two different metals in an electrolyte, which is salt water, will exchange electrons. Freshwater does not allow for this kind of corrosion. No current needs to be present to allow for this corrosion to occur. This is your boat essentially becoming a natural battery.

 

 

In a boat you may have any number of metal parts touching the water. Mild steel, stainless steel & bronze, are all commonly used. The process of electrolysis sees electrons being stripped from the anode. Then they head towards the cathode. So what does that mean?

• A cathode is a negatively charged electrode. The more noble metal in the reaction will always be the cathode.
• The anode is a positively charged electrode. The less noble metal in a reaction will be the anode.
• Electrons travel more easily through salt water from the anode to the cathode. This is why having something like zinc anodes is important. It allows those electrons to leave the unimportant anode. That saves the important parts of your boat, like the prop or the shaft.

In freshwater or brackish water, it’s best to use different anodes. Magnesium and aluminum are often used here.

 

The wires in your boat connect metal parts. That basically makes your boat a battery. Non-metal boats will have a copper bonding wire inside. This connects all metal parts so they can share anodes. This bonding connection also includes the metal frame of your boat’s hull which serves as the negative battery connection. And the engine and negative side of your boat battery. Stray current will damage this system.

If your anodes die quickly, your dock may have a faulty shore power ground lead. It should never be connected to the ground bonding system. If the shore power ground connects to the boat’s underwater bonding system, it can wear your anodes out. The shore power circuit is not typically something you can fix under normal circumstances. It can result in your boat being electrically connected to all the other boats. That stray current corrosion can be the most destructive form of electrolysis.

 

Thank you Alan. I will try and find a little dusty corner in my brain to store this - it's feeling pretty full at the mo! 😀

[cuthound]

It is even possible that the reference to electrolysis in the conclusion but not in the main body of the report is due to "cut and pasteitis", where the surveyor used an earlier survey for another boat as the basis for this survey but accidentally left the reference to electrolysis in 

 

I would check with the surveyor to eliminate this possibility.

[Tacet]

43 minutes ago, cuthound said:

It is even possible that the reference to electrolysis in the conclusion but not in the main body of the report is due to "cut and pasteitis", where the surveyor used an earlier survey for another boat as the basis for this survey but accidentally left the reference to electrolysis in 

 

I would check with the surveyor to eliminate this possibility.

Just possibly the surveyor is using electrolysis to mean rusting.

 

Does not all rusting involve electolytic reaction - even if no purposeful power source is in the equation? 

 

 

[MtB]

9 hours ago, Tacet said:

Does not all rusting involve electolytic reaction - even if no purposeful power source is in the equation? 

 

I'd say no. Steel rusts perfectly willingly without the presence of electrical currents. 

 

Have you never owned a 1963 BMC Mini or Triumph Spitfire?! 

 

 

 

[john.k]

Steel structures in marine environment are protected by having a small but carefully modulated electric current applied.

[Tacet]

18 hours ago, Tacet said:

Just possibly the surveyor is using electrolysis to mean rusting.

 

Does not all rusting involve electolytic reaction - even if no purposeful power source is in the equation? 

 

 

 

9 hours ago, MtB said:

 

I'd say no. Steel rusts perfectly willingly without the presence of electrical currents. 

 

Have you never owned a 1963 BMC Mini or Triumph Spitfire?! 

 

 

 

My Triumph is rather older than a Spitfire.

 

But does not rusting require electrons to shift about in local cells? If so, would the chemist say tiny currents and electrolytic reaction is occurring?

[Tonka]

9 hours ago, MtB said:

 

I'd say no. Steel rusts perfectly willingly without the presence of electrical currents. 

 

Have you never owned a 1963 BMC Mini or Triumph Spitfire?! 

 

 

 

Is there not a battery and lights with an earth return through the body on those cars  ?

[MtB]

46 minutes ago, Tonka said:

Is there not a battery and lights with an earth return through the body on those cars  ?

 

 

Yes but if you have a look at where they rust, it's only the wet bits, not all the bits carrying electrical current. 

 

Therefore, Occam's Razor suggests it is water that causes the rust.