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

[Robert Wilson]

Three of four Ph.Bronze through-hull retaining bolts for seacock sheared within the hull then the nuts and end bit of bolts glued (sikaflex?) back in place on the internal flange - presumably to make the seacock LOOK normal for survey/inspection.
The seacock is for the port-side cockpit drain, located very awkwardly behind the engine in very cramped space.
Luckily, during total re-wiring, and hence fitting new bonding wire to the seacock we found that one of the nuts plus end of bolt just fell off. We checked the other three and only one was intact.

Who would be so cretinous? I have no idea how long ago the crime was perpetrated or who by, but a very full inspection of all the other through hull fittings is in progress........

P.S. Finding replacement Ph.Bronze coach bolts is a nightmare. Eventually found Classic Marine on the web. A very helpful and pleasant guy can supply (£9+ each.....). If anyone has an alternative supply I'd be pleased to have a note of it for future reference.
Ta

 

[Seajet]

Reminds me of the old practice of ' coffin ships ' where the copper nails / bolts just had ends showing but weren't joined in the middle, with the idea the over-insured ship would founder and the owners get the insurance...

 

[macd]

Isn't it ignoble to bond bronze seacocks?

 

[Lakesailor]

Reminds me of the old practice of ' coffin ships ' where the copper nails / bolts just had ends showing but weren't joined in the middle, with the idea the over-insured ship would founder and the owners get the insurance...

Gosh. You must be old.

 

[Tranona]

Luckily, during total re-wiring, and hence fitting new bonding wire to the seacock we found that one of the nuts plus end of bolt just fell off.

No need to bond seacocks. They sound like they are Blakes which if original are bronze, or more recent DZR. Nothing to be gained by bonding them to an anode. Alternatives for bolts are Blakes , Anglia Stainless or Seaware.

 

[vyv_cox]

Who would be so cretinous? I have no idea how long ago the crime was perpertrated or who by, but a very full inspection of all the other through hull fittings is in progress........

My ex-boss. He bought a new house and during a survey the inspector noticed that some heavy tie bolts that basically held his house to the one next door had not been fitted by the builder. It was a condition of the mortgage that this should be rectified as there was a risk of serious damage if they were not present. He looked into it and found that retro-fitting was going to be quite an expensive business, so he bought short bolts of the appropriate size, drilled holes for them himself and Araldited them in.

 

[SAMYL]

Why do they have to be Ph. Bronze? I always thought that was for bearings. Just wondering.

 

[vyv_cox]

Why do they have to be Ph. Bronze? I always thought that was for bearings. Just wondering.

Bronze in the form of Gunmetal or one of the modern versions, LG2 and LG4, can contain oxides that reduce its strength. The addition of phosphorus deoxidises the bronze, making it a lot stronger. For bolts this is a big advantage. Phosphor bronze bearings are used for heavy loadings, for the same reason, but they are not able to take high speeds. One of those trivia things you remember for your whole life - it is used for lathe carriage beds.

 

[rotrax]

No need to bond seacocks. They sound like they are Blakes which if original are bronze, or more recent DZR. Nothing to be gained by bonding them to an anode. Alternatives for bolts are Blakes , Anglia Stainless or Seaware.

Why are you assuming they are bonded to an anode?

My boat has high quality bronze skin fittings fitted as OE by the builder. All are bonded to the negative side of the battery, not to an anode.

Most modern American boats have this bonding to the battery negative.

European boats do it differently, but both systems have their champions.

 

[prv]

My boat has high quality bronze skin fittings fitted as OE by the builder. All are bonded to the negative side of the battery, not to an anode.

Most modern American boats have this bonding to the battery negative.

I've not come across that (not surprising, as I've only been on one American boat and I wasn't digging around in the bilges).

I can't really fathom what it's meant to achieve.

Do you know why they do it?

Pete

 

[Robert Wilson]

My ex-boss. He bought a new house and during a survey the inspector noticed that some heavy tie bolts that basically held his house to the one next door had not been fitted by the builder. It was a condition of the mortgage that this should be rectified as there was a risk of serious damage if they were not present. He looked into it and found that retro-fitting was going to be quite an expensive business, so he bought short bolts of the appropriate size, drilled holes for them himself and Araldited them in.

He didn't by any chance own a Javelin30 some years ago, did he?............


As for the "to bond or not to bond" seacocks, I have no idea why or why not. I have read on these fora arguments/discussions/rants both for and against - and I'm still none the wiser!
I reckon that if there's actually no harm to do it, and the man with the pliers and wire is down in the dark parts of the boat he might as well do it. When I put the conundrum to him he said it was better to bond.

So bonded they will be - unless anyone can give definitive proof against it.

 

[vyv_cox]

I've not come across that (not surprising, as I've only been on one American boat and I wasn't digging around in the bilges).

I can't really fathom what it's meant to achieve.

Do you know why they do it?

Pete

It's a mystery. Every American forum and technical website will tell you that bonding is essential, with pages of information on how to do it. Nigel Calder's book has a comprehensive section on it, although I have heard that he is beginning to question the need for it. Every explanation begins with words like 'metals in seawater corrode from the moment they are first immersed'.

Conversely, in Europe we know well that underwater fittings made from the correct material do not corrode and will last a lifetime. It is quite probable that no European made boats have bonded fittings from manufacture, yet they last as well as USA ones.

It seems to me that bonding as in rotrax' boat could cause more harm than it solves. Unless every fitting has identical metallurgy the more noble will be protected by the less noble in the absence of an anode. However, in boats with fittings that are bonded to an anode it seems most unlikely that they will be protected because it is virtually impossible for every fitting on a hull to be in line of sight of a single anode.

 

[rotrax]

Back in the sixties I was asked to take the Morris Minor pickup truck to Guildford-IIRC- to collect a pair of Oxy Acetylene bottles.

The BOC depot had several loading bays so that trucks could back up level and be loaded easily.

The management had decreed that in the interest of safety chains be strung across the brick piers either side of the loading bays, so the bottles could not fall to the yard floor.

The day I collected the pair of bottles this rule was very fresh.

At the bay I backed into the yard man lifted the chain clear one side, loaded my bottles, replaced the chain.

As I made the bottles secure I noticed the chain was loosely hung around the necks of the end bottles at each side of the loading bay.................................

 

[rotrax]

Back to bonding of skin fittings, I seem to remember something about electrical safety when on shore power.

Perhaps the 120v systems the American's use require it?

Our boat has three electrical systems-12v, 120v and 240v, via a 6KA transformer.

The battery charger, calorifier, air con, microwave use 120v, plus we have two double S/S 240v sockets for European stuff when on shore power.

It works well, and was an inexpensive way to use the 120v kit that was fitted.

 

[SAMYL]

Bronze in the form of Gunmetal or one of the modern versions, LG2 and LG4, can contain oxides that reduce its strength. The addition of phosphorus deoxidises the bronze, making it a lot stronger. For bolts this is a big advantage. Phosphor bronze bearings are used for heavy loadings, for the same reason, but they are not able to take high speeds. One of those trivia things you remember for your whole life - it is used for lathe carriage beds.

Thank you.

 

[vyv_cox]

Back to bonding of skin fittings, I seem to remember something about electrical safety when on shore power.

Perhaps the 120v systems the American's use require it?

Our boat has three electrical systems-12v, 120v and 240v, via a 6KA transformer.

The battery charger, calorifier, air con, microwave use 120v, plus we have two double S/S 240v sockets for European stuff when on shore power.

It works well, and was an inexpensive way to use the 120v kit that was fitted.

While trying to find more information about bonding from a US point of view I found vehement assertions that the 120 volt supply should be grounded to the battery negative and hence to the bonding system, and equally vehement statements that that was wrong and dangerous. I don't pretend to know the answer from the electrical side.

 

[prv]

While trying to find more information about bonding from a US point of view I found vehement assertions that the 120 volt supply should be grounded to the battery negative and hence to the bonding system, and equally vehement statements that that was wrong and dangerous. I don't pretend to know the answer from the electrical side.

It does seem somewhat beneficial to have the 12v system earthed from the mains point of view. That way a stray 240v (or 110v) wire coming into contact with the usually less-well-insulated 12v wiring should trip the protective device, rather than bringing all sorts of unexpected surfaces all over the boat up to 240v. Obviously the 240v could short to either positive or negative, and for obvious reasons you can't earth them both, so I guess you hope that a short to one will flash over to the other since 12v devices won't be up to blocking it.

I believe the UK shoreside rules solve the problem by physically keeping "Low Voltage" (240v) and "Extra Low Voltage" (12v) apart.

I would also expect an RCD to offer protection, without lots of current having to make its way to the shore power earth to trip an MCB.

Pete

 

[Paddingtonbear]

Apparently our colonial friends are fearful of electrocuting persons swimming near their boat, possibly when hooked up to shore power?

 

[ripvan1]

Interesting thread and now for possibly the daftest question ever posted - If fittings can be bonded to a battery anode, why are zinc anodes placed on the exterior where they can't be seen?

I'm expecting a really obvious answer - (it's an age thing)

 

[Tranona]

He didn't by any chance own a Javelin30 some years ago, did he?............


As for the "to bond or not to bond" seacocks, I have no idea why or why not. I have read on these fora arguments/discussions/rants both for and against - and I'm still none the wiser!
I reckon that if there's actually no harm to do it, and the man with the pliers and wire is down in the dark parts of the boat he might as well do it. When I put the conundrum to him he said it was better to bond.

So bonded they will be - unless anyone can give definitive proof against it.

Electrolysis is the fear. But this occurs where there are two dissimilar metals in contact in an electrolyte (seawater). This can either be two components (shaft and prop for example) or an alloy of two different metal (plain brass, which is copper and zinc). These conditions do not exists with bronze seacocks such as yours unless it is connected through other metal, for example with a copper pipe to the engine. The material is chosen specifically because it is resistant to corrosion in seawater. So why connect it to other metals or to the battery? As others have said there are thousands of boats using that type of seacock without any bonding and suffer no ill effects. Have a look on the MG Duff site. They are the experts and make money out of selling anodes and they do not recommend bonding skin fittings and seacocks.