survey report

[Jacq]

Hello,

Having just read the servey report on a boat i am hoping to buy, it shows that in 5 years the bottom plate has lost 0.4 mm in some areas , which isnt too bad .

But it mentions areas of pitting, Do you think this is a cause for concern or is it normal ?

Any other tips on specific areas to look at when checking condition prior to purchase would be most welcome.

Thanks for your help.

[allybsc]

Hello,

Having just read the servey report on a boat i am hoping to buy, it shows that in 5 years the bottom plate has lost 0.4 mm in some areas , which isnt too bad .

But it mentions areas of pitting, Do you think this is a cause for concern or is it normal ?

Any other tips on specific areas to look at when checking condition prior to purchase would be most welcome.

Thanks for your help.

 

Phone up your surveyor and ask him to explain.

[blackrose]

Pitting is both normal and a cause for concern.

 

Unfortunately an otherwise sound 6mm plate with 2mm deep pitts should for all intents and purposes be considered down to 4mm.

 

I say that pitting is normal and others here can probably explain in more detail how the process begins, but if the steel is properly painted and the hull is protected from galvanic corrosion while on shore power with a galvanic isolator or isolation transformer, then it shouldn't really happen.

[John Orentas]

The ex-owner of my local dry-dock had some ideas on all this, having studied hundreds of boats he was convinced that pitting a fairly new phenomena and began to appear on canal boats coincident with the fitting of sacrificial anodes, he advised everyone not to fit them.

 

I am inclined to agree with him though in my case the anodes fitted to my boat never seem to degrade at all so presumably they are doing nothing. The more experience I accumulate the more I am convinced that hull corrosion is 99.9% chemical. Yes there are plenty of people around who are trying to make a living out of all these magical isolators and other gizmo's but I have yet to see the slightest evidence for any of it. In fact these silly stories seem to escalate yearly, mooring next to steel piles ? Under power lines ? Rubbish I say, the whole lot of it.

[carlt]

The ex-owner of my local dry-dock had some ideas on all this, having studied hundreds of boats he was convinced that pitting a fairly new phenomena and began to appear on canal boats coincident with the fitting of sacrificial anodes, he advised everyone not to fit them.

 

I am inclined to agree with him though in my case the anodes fitted to my boat never seem to degrade at all so presumably they are doing nothing. The more experience I accumulate the more I am convinced that hull corrosion is 99.9% chemical. Yes there are plenty of people around who are trying to make a living out of all these magical isolators and other gizmo's but I have yet to see the slightest evidence for any of it. In fact these silly stories seem to escalate yearly, mooring next to steel piles ? Under power lines ? Rubbish I say, the whole lot of it.

Rewriting the laws of physics again John? I'd hazard a guess that, if your anodes are the only ones on the cut that have never suffered any degradation, they are incorrectly fitted, they're isolated from the hull and your hull is rusting nicely.

 

What's next? "That gravity malarkey? Load of rubbish dreamt up by parachute salesmen. I've never died by falling out of a plane so it can't be true!"

Edited August 6, 2007 by carlt

[Tootles]

The ex-owner of my local dry-dock had some ideas on all this, having studied hundreds of boats he was convinced that pitting a fairly new phenomena and began to appear on canal boats coincident with the fitting of sacrificial anodes, he advised everyone not to fit them.

 

I am inclined to agree with him though in my case the anodes fitted to my boat never seem to degrade at all so presumably they are doing nothing. The more experience I accumulate the more I am convinced that hull corrosion is 99.9% chemical. Yes there are plenty of people around who are trying to make a living out of all these magical isolators and other gizmo's but I have yet to see the slightest evidence for any of it. In fact these silly stories seem to escalate yearly, mooring next to steel piles ? Under power lines ? Rubbish I say, the whole lot of it.

 

Remember where I used to moor John, before I came up near you?? The pilings were galvanised girders, and after two years our boat, and the one at the other side of the walkway were docked. We both had large 'circles' of minor pits, identical and opposite to each other....Coincidence??? Dont think so, the pits were shiny. Never happened since we moved.

[John Orentas]

Remember where I used to moor John, before I came up near you?? The pilings were galvanised girders, and after two years our boat, and the one at the other side of the walkway were docked. We both had large 'circles' of minor pits, identical and opposite to each other....Coincidence??? Dont think so, the pits were shiny. Never happened since we moved.

 

 

But Dave, all the geeks will tell you that a 230 volt shoreline is is the vital element of all this, you never had a shoreline so it had to be the gremlins with their little angle grinders.

[Tootles]

But Dave, all the geeks will tell you that a 230 volt shoreline is is the vital element of all this, you never had a shoreline so it had to be the gremlins with their little angle grinders.

 

No, but I was running an on board genny, as was the guy next door, so dosent that count??????????

[mayalld]

The ex-owner of my local dry-dock had some ideas on all this, having studied hundreds of boats he was convinced that pitting a fairly new phenomena and began to appear on canal boats coincident with the fitting of sacrificial anodes, he advised everyone not to fit them.

 

I am inclined to agree with him though in my case the anodes fitted to my boat never seem to degrade at all so presumably they are doing nothing. The more experience I accumulate the more I am convinced that hull corrosion is 99.9% chemical. Yes there are plenty of people around who are trying to make a living out of all these magical isolators and other gizmo's but I have yet to see the slightest evidence for any of it. In fact these silly stories seem to escalate yearly, mooring next to steel piles ? Under power lines ? Rubbish I say, the whole lot of it.

 

John,

 

why is it that just about every post you make could be summarized thus;

 

"I know absolutely nothing about the physics/chemistry/mechanics of this, but I've seen several boats, and I have decided that all the experts are wrong about everything"

[carlt]

John,

 

why is it that just about every post you make could be summarized thus;

 

"I know absolutely nothing about the physics/chemistry/mechanics of this, but I've seen several boats, and I have decided that all the experts are wrong about everything"

Conspiracy theorist.

 

The lizard people are the true owners of all the electronic gadget companies in the world (and you thought Gibbo just had psoriasis) so they start these scare stories (which just happen to agree with conventional science) to finance their continuing control of our world.

[mayalld]

Conspiracy theorist.

 

The lizard people are the true owners of all the electronic gadget companies in the world (and you thought Gibbo just had psoriasis) so they start these scare stories (which just happen to agree with conventional science) to finance their continuing control of our world.

 

well, obviously, everybody knew that bit already!

[Gary Stacey]

The more experience I accumulate the more I am convinced that hull corrosion is 99.9% chemical.

 

 

Groan.....look up corrosion in a decent textbook or on the web and you'll find that it is primarily an electro-chemical process! yes indeed rewriting the laws of chemistry/physics.

 

A for the 'piiting only became a problem with the fitting of anodes' - corrolation between one event and another does not neccessarily mean the two are interelated.

[Machpoint005]

Groan.....look up corrosion in a decent textbook or on the web and you'll find that it is primarily an electro-chemical process! yes indeed rewriting the laws of chemistry/physics.

 

I thought it happened because the electrical fluid is insoluble in canal water...

 

Ian

[Lady Muck]

Remember where I used to moor John, before I came up near you?? The pilings were galvanised girders, and after two years our boat, and the one at the other side of the walkway were docked. We both had large 'circles' of minor pits, identical and opposite to each other....Coincidence??? Dont think so, the pits were shiny. Never happened since we moved.

 

Our survey revealed pitting (actually it was pretty obvious to the naked eye!) it was all down one side - the side which was moored against the piled bankside of the mooring.

 

As there was no mains eletricity at our mooring, we thought that must have been the cause of the pitting. Our surveyor said it could be too but we should also get an electrician to conduct a megatest on the boat eletrics and also to consider a galvanic isolator for when we get shore power.

[blackrose]

Galvanic action can occur between dissimilar metals which are electrically connected & submerged in an electrolyte (i.e. dirty canal water), or on a larger scale between boats connected to each other and to steel pilings by the earth in their shore power cables (where these have not been isolated by galvanic isolators or isolation transformers).

 

I think most of us have all witnessed this flow of electrons in our science classes at school when building a basic battery from dissimilar metals and a lemon, for example. Why these basic laws of physics are still not accepted by some people beats me. Perhaps they need to do some reading: http://en.wikipedia.org/wiki/Galvanic_cell

http://en.wikipedia.org/wiki/Galvanic_corrosion

 

As for anodes causing pitting, well it's news to me, but I have an open mind and if the person who came up with this theory would like to explain it in a bit more detail I'm sure we'd all be interested. Personally can't help thinking that if it were true we'd have heard it from a more reliable source.

Edited August 7, 2007 by blackrose

[DHutch]

The ex-owner of my local dry-dock had some ideas on all this, having studied hundreds of boats he was convinced that pitting a fairly new phenomena and began to appear on canal boats coincident with the fitting of sacrificial anodes...

Or a drop in the grade of steel used?

[Cris P]

I think Dhutch probably has it right. Steel quality has gone down.

[carlt]

I think Dhutch probably has it right. Steel quality has gone down.

That's exactly what they want us to think.

[blackrose]

That's exactly what they want us to think.

 

And who exactly are "they"?

[David Schweizer]

I think Dhutch probably has it right. Steel quality has gone down.

I remember the builder of my boat claiming that before the introduction of a British Standard for Steel, it was possible to buy steel of a much higher standard ( I asume he was referring to purity) than that required by the new British Standard, but after it's introductiion the mills all started to produce down to the minimum standard.

 

I don't know how true his claim was, but I have certainly observed a decline in the quality of many manufactured items since the introduction of British Standards for those items. So maybe he was correct.

[Big Steve]

If it's true that mooring next to steel piles causes hulls to corrode due to electro chemical action, then if you connect a big battery between the steel piling and your boats hull, assuming you get the polarity right, won't this cause your boats hull to get thicker? It would save an awful lot of trouble rebottoming boats wouldn't it? Could I patent the system and make a fortune?

 

Steve

[mayalld]

If it's true that mooring next to steel piles causes hulls to corrode due to electro chemical action, then if you connect a big battery between the steel piling and your boats hull, assuming you get the polarity right, won't this cause your boats hull to get thicker? It would save an awful lot of trouble rebottoming boats wouldn't it? Could I patent the system and make a fortune?

 

Steve

 

Active cathodic protection has been around for many years on oil rigs and the like.

[Tootles]

That's exactly what they want us to think.

 

I think I will blame the Lizard People, carlt. We all need someone to blame, and in this case, with electromagnetic fields and whatnots running around, unchecked and unlicensed by BW, then it must be the Lizard People who cop for it.

 

Anyway, they wet there nests!!

[carlt]

unchecked and unlicensed by BW, then it must be the Lizard People who cop for it.

 

Anyway, they wet there nests!!

 

BW are the lizard people (see chapter four of David Icke's book "Actually, it is rocket science" )

[ChrisPy]

consider this - there is an unseen 'electrical energy force' that would like to blow off iron molecules from your hull given half a chance.

so you coat your boat in the best quality coating that science can produce.

if there is a relative weakness in the coating at one point - all the potential for corrosion is concentrated at this one point - QED: localised pitting!

 

in the pipeline business we coat the buried pipes using hugely sophisticated coating sytems, and then protect them with extensive active electrical cathodic protection systems. we still get localised corrosion.

 

I have encountered UNCOATED steel pipelines that have been in the ground many years and have only suffered from slight general surface corrosion.