Cretin of the century award - runaway winner. Or can you beat this?

On canal narrowboats the steel hulls need to be protected from galvanic corrosion.

This is invariably done by arc or mig welding the tab of the-for freshwater-Magnesium anode directly to the hull.

In the mid seventies we purchased a simple narrowboat on the Grand Union Canal at Slapton-just a short distance from where the Great Train Robbery took place.

When it was hauled out, no anodes at all. The hull was pockmarked with 1/2 inch silver circles, some 2.5mm in depth. Hundreds of them.

Happily, it was a substantial hull, made from 3/8 steel plate.

I welded on anodes and no further corrosion.

That was the most graphic example I have personally experienced. It was not helped by the fact that the batteries were wired with positive ground, which I changed to negative after re-polarising the Yanmar dynostarter unit.
 
rotrax said:
I have selected this short bit of Vyv's post for a reason.

First Mate and I recently visited the Mary Rose Museum.

The bronze cannons recovered from the seabed where they had lay for almost 500 years show no significant corrosion.

Whatever the truth of it is, the skin fittings, sea cocks, prop and shaft show no corrosion or galvanic action on our American boat which are bonded to the battery.

The physical evidence shows that IF the theory is wrong, in practice it works OK.

That will do for me.
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Said bronze cannons have been subjected to extensive conservation work, though admittedly a lot less than the iron cannons needed (they had to be treated in a hydrogen reduction furnace). Although externally in good nick, I doubt the metallurgy is the same as it was the day she went down, and it would be a brave person who attempted to fire them! Further, they have (mostly) been sealed from seawater by a layer of impervious clay; that's why the Mary Rose artefacts have been so well preserved. They aren't at all representative of copper alloy items in the environment of a yacht's hull. I've read a few of the technical reports on the Mary Rose, and they make fascinating reading.
 
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ABYC isn't a regulatory body, entirely advisory, so there is no legal conflict.

There are differences - I believe the RCD insists on copper gas piping, the ABYC suggests flexible, for instance.
 
AntarcticPilot said:
Said bronze cannons have been subjected to extensive conservation work. Although externally in good nick, I doubt the metallurgy is the same as it was the day she went down! Further, they have (mostly) been sealed from seawater by a layer of impervious clay; that's why the Mary Rose artefacts have been so well preserved. I've read a few of the technical reports on the Mary Rose, and they make fascinating reading.
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Agreed-conservation, but not restoration.

I have no idea about the metallurgy but around the decorative and royal arms raised areas, the Bronze guns appeared to be fresh and clean-almost on one or two as fresh from the foundry.

The Iron guns were not so.
 
MYStargazer said:
And yet MG Duff also state that "Bronze and Stainless Steel Rudders, Rudder Hangings and Shaft Brackets should also be bonded to the main anodes" - http://www.mgduff.co.uk/pdfs/Fitting_Instructions.pdf.

If a rudder and its fittings are all bronze - why include them in the system...?

And while we're on that page, why include the engine and gearbox in the system - if the engine marinizing components also include their own zincs?
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Someone has already pointed out that the engine/gearbox is being used purely as a circuit for bonding the anode to the components to be protected, i.e. shaft and propellor. In answer to the other point, and Vyv can and indeed often has, filled in the correct details, not everything called "bronze" is equal. As different alloys are used to obtain the mechanical properties required for each component, or sadly to achieve the boatbuilder's profit margin, some are almost completely corrosion proof, but the types typically used for propellor manufacture and P brackets are really only an improved brass and won't last without an anode to protect them. Luckily the rudder and prop being in close proximity can share an anode!

Rob.
 
What a shame that a potentially amusing thread has degenerated into serious discussion on corrosion!

My experience is that it is the managerial classes that will accept and usually promote deceipt... This is promoted and promulgated by their incompetence and lack of understanding of the real world. I had a "manager" who insisted on planning the new workshop himself and he commisioned all the work before the plans had been checked... The p+++k had sketched all the drains running uphill. Every machine had to be mounted on plinths of increasing height to correct it. Deceipt? Yes, he put my name on the sketches to shift the blame.

Rob.
 
rob2 said:
My experience is that it is the managerial classes that will accept and usually promote deceipt... This is promoted and promulgated by their incompetence and lack of understanding of the real world. I had a "manager" who insisted on planning the new workshop himself and he commisioned all the work before the plans had been checked... The p+++k had sketched all the drains running uphill. Every machine had to be mounted on plinths of increasing height to correct it. Deceipt? Yes, he put my name on the sketches to shift the blame.
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An acquaintance of mine was hired to investigated quality problems at a very famous car company. It took him very little time to discover that the night shift, in order to save time, were keeping one bodyshell aside after it had passed quality control measurements and then putting it through the measurement system every time another body shell was ready. Management were far too grand to work nights, so had no idea what was going on.
 
JumbleDuck said:
An acquaintance of mine was hired to investigated quality problems at a very famous car company. It took him very little time to discover that the night shift, in order to save time, were keeping one bodyshell aside after it had passed quality control measurements and then putting it through the measurement system every time another body shell was ready. Management were far too grand to work nights, so had no idea what was going on.
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Many years ago I worked on shift at a company manufacturing steel sheeting for factory buildings. One day the police were called to the canal behind the plant, where they found some enterprising folk who had built a raft of oil drums, floated it down the canal and had removed a length of copper cable, around 10 metres long and 5 cm diameter from a disused railway bridge. Police asked our management to store it while prosecution was pending, which they agreed, putting it in the small warehouse used in my section of the plant. That night there was tremendous banging on the still-room floor above my lab, which on investigation proved to be my shift men cutting the cable up with an axe, the whole lot leaving the plant in short lengths down trousers and in snack bags.
 
vyv_cox said:
Many years ago I worked on shift at a company manufacturing steel sheeting for factory buildings. One day the police were called to the canal behind the plant, where they found some enterprising folk who had built a raft of oil drums, floated it down the canal and had removed a length of copper cable, around 10 metres long and 5 cm diameter from a disused railway bridge. Police asked our management to store it while prosecution was pending, which they agreed, putting it in the small warehouse used in my section of the plant. That night there was tremendous banging on the still-room floor above my lab, which on investigation proved to be my shift men cutting the cable up with an axe, the whole lot leaving the plant in short lengths down trousers and in snack bags.
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Did you know that the standard method of stealing whisky from bonded warehouses is to hammer a razor blade between two barrel staves and tie a thread around it. leading to a suitable container? The gaps formed at the ends of the blade allow whisky to come out a drop at a time and the drops run down the thread and into the container. Once the desired amount has been removed the razor blade is removed, leaving no visible trace, and as long as you're not greedy, the evaporative loss in storage is far more than the theft.

Metal theft? A chap I know worked in the Harwell Lab when mercury started going missing in huge quantities. Despite the best efforts of security, they couldn't work out how the theft was being done, let alone who was doing it. Until the day when one of the technicians let his bike fall over as he was wheeling it out of the gate ... and couldn't pick it up.
 
My first job was in the parts department at a tractor factory. Got overtime for taking part in the annual stock take at the end of the first year in a new warehouse. Big discrepancy in items like fuel injectors and spark plugs. Solution was to create a secure area right in the middle of the warehouse. Over the next few weeks, stocks of these items gradually increased inside the secure area until the numbers almost reconciled with the original computer stock figure!

Expect the same would happen with your bronze bolts - similar characteristics of high value, low density and anonymous nature.
 
JumbleDuck said:
Metal theft? A chap I know worked in the Harwell Lab when mercury started going missing in huge quantities. Despite the best efforts of security, they couldn't work out how the theft was being done, let alone who was doing it. Until the day when one of the technicians let his bike fall over as he was wheeling it out of the gate ... and couldn't pick it up.
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It's funny you mention that, as a colleague at my plant was involved in the investigation of that theft. Apparently a scam was being worked in which the mercury was being double-ordered but the paperwork only showed a single amount. We used to buy some mercury and my colleague was quizzed over the ordering procedure, which was how he heard the story.
 
When Vauxhall Motors first opened in Ellesmere Port it was possible for employees to purchase a car at very advantageous rates. Instead of the later scheme in which they took a voucher to a dealer and acquired a discount, they were issued with the build number before the car was made. When it was due to be built the prospective owner would follow the car right through the plant, telling each operator that he would be the owner. This resulted in a vehicle with extra coats of paint, spare alternator, spark plugs, belts etc in the door pockets, SE add-ons on a basic car, and so on. Took management several years to cotton on.
 
vyv_cox said:
When Vauxhall Motors first opened in Ellesmere Port it was possible for employees to purchase a car at very advantageous rates. Instead of the later scheme in which they took a voucher to a dealer and acquired a discount, they were issued with the build number before the car was made. When it was due to be built the prospective owner would follow the car right through the plant, telling each operator that he would be the owner. This resulted in a vehicle with extra coats of paint, spare alternator, spark plugs, belts etc in the door pockets, SE add-ons on a basic car, and so on. Took management several years to cotton on.
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I went round Halewood a few years ago. The tour guide told us that in Ford days, car radios were kept in a locked area next to the factory exit and only fitted as the cars were leaving - otherwise they disappeared en route.

On a slightly more boating theme, the Chairman of Cunard is reputed to have said of the workers at John Brown's that they were stealing her as fast as they were building her. It's said that a thousand mattresses went missing, for example. That, as well as the problems with her engines, probably explains why large shipbuilding on the Clyde died.

Mind you, does any of this come close to the Titans of Finance who destroyed our economy, ruined thousands of businesses and in return got trillions in state subsidy for fear that their finely honed talents would be lured abroad?
 
One of my old Racing mates is a senior Customs Officer. Some time ago he had to go and listen to an EU expert banging on about how the job was going to change with the EU rules.

On the same gig was a Republic of Ireland senior guy, also a Petrolhead.

They got to chewing the fat one night and the Irish guy related about the old building worker who crossed into Ulster every morning to go to work, and returned in the evening through the Republic's border post with three new bricks in the saddlebag of his bicycle.

Some years later the Irish customs guy met the building worker in a bar, and asked if he had ever built a house with the stolen bricks.

"It was not the bricks you should have been worried about" said the old boy "Every night I came across it was with a new bike................"

At that time the republic had draconian import duties and very high VAT- and no bicycle industry!
 
vyv_cox said:
Not sure I understand your question. What is a battery anode? Where bonding is used it is normal to ground everything to either the engine or the battery negative (which are normally in electrical contact anyway) to prevent the possibility of different potentials between them. Exterior zinc anodes are then supposed to protect the skin fittings and maybe other things such as rudder fittings, P-bracket, etc. but need to be in line of sight with all of them to do so. An exterior anode cannot protect an engine.
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Sorry Vyv, I meant battery terminal. My main question tho' is why are anodes placed on outside the hull?
 
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