I trashed five seacocks at sea!

[VicS]

VicS is yer man for this, but my guess is that your propeller would have been fizzing away happily in a cloud of, erm, hydrogen-I-think bubbles

Ive been working on the boat all day ..... well nattering to other owners and doing a bit on the boat and its now late.

I am going to re-read the thread and think about whats been going on here .. not sure I see why the prop anode was attacked rather than being surrounded by hydrogen bubbles. Connected to the anode by brushes on the shaft??

 

[G12]

I don't understand this (but there again I've demonstrated already how ignorant I've been!). How would the heat-exchanger, Jabsco/Johnson pump, copper-pipe have been effected? What part of the circuit would they have been in?

The heat exchanger has it's own zinc anode screwed into the side. I think they're about £7.

 

[misterg]

I'm still thinking through the enormity of this...

1. The engine is earthed (negative).
2. The anode and seacocks were bonded to the starter (positive).
3. When 16amps (positive) were being pumped to them, they reacted with the seawater and eroded.
4. I assumed that they eroded because the seawater has its own earth (negative) elsewhere.
5. But did they also erode because the seawater was in contact with raw-water side of the engine cooling system (negative)?
6. If this is the case, would the parts on the engine (negative) side of the circuit also have eroded?

I think (4) is wrong, (5) is right.

You would have had a circuit between battery +Ve (the seacocks / anode, etc.) and battery -Ve(sterngear ??) via the salt water.

On the face of it, the material that was lost from the seacocks & anode should be deposited on the sterngear, but I suspect it was mostly washed away, leaving the prop/sterngear fizzing a bit. (In effect you were using the battery to impose a protection voltage on these parts.) I assume that you checked the prop, and it was OK.

The possible risk I can see to the engine internals is that you had a circuit between the cooling water inlet (connected to +Ve) and the pump body (connected to -Ve) assuming that this was the first bit of metal that the cooling sea water comes into contact with. In theory (again) material lost from the inlet should be transfered to the pump spiggot. Maybe worth a check for peace of mind, though.

Kudos for sharing this - it'll certainly stick in my mind.

Don't beat youself up about it. What's happened has happened, and it now boils down to how you handle it. Pretty darn slick by the sound of it.

Andy

 

[Norman_E]

Look on the bright side of this, no lives or boats were lost, only a bit of cash. If you send the story to YBM for the "Confessional" you will receive a certificate to frame, and quite possibly an original cartoon to go go with it. You will be admiring that and laughing over the event long after the cost has been forgotten.

 

[Babylon]

...I am going to re-read the thread and think about whats been going on here .. not sure I see why the prop anode was attacked rather than being surrounded by hydrogen bubbles. Connected to the anode by brushes on the shaft??

No brushes on shaft, but a bridge across flexibile-coupling.

 

[greenalien]

Thanks for sharing this - they say that people mostly learn from their mistakes, and people who don't make mistakes never learn anything!

 

[Babylon]

I think (4) is wrong, (5) is right.

You would have had a circuit between battery +Ve (the seacocks / anode, etc.) and battery -Ve(sterngear ??) via the salt water.

On the face of it, the material that was lost from the seacocks & anode should be deposited on the sterngear, but I suspect it was mostly washed away, leaving the prop/sterngear fizzing a bit. (In effect you were using the battery to impose a protection voltage on these parts.) I assume that you checked the prop, and it was OK.

The possible risk I can see to the engine internals is that you had a circuit between the cooling water inlet (connected to +Ve) and the pump body (connected to -Ve) assuming that this was the first bit of metal that the cooling sea water comes into contact with. In theory (again) material lost from the inlet should be transfered to the pump spiggot. Maybe worth a check for peace of mind, though...

Andy

This makes complete sense to me. I'm due back down to the boat today to check things:

1. Quadruple-check all new seacocks
2. Disconnect seacocks from bonding wire (retain only hull-anode to engine block wire)
3. Check raw-water pump spigot
4. Check heat-exchanger and anode
5. Check insurance excess!

 

[Heckler]

as a general point, would insurance cover such an event ?

Just reading this months PBO about insurance, they dont cover the inevitable. Its the other one they cover (forget the word)
Stu

 

[Norman_E]

Just reading this months PBO about insurance, they dont cover the inevitable. Its the other one they cover (forget the word)
Stu

It is a quirk of English that "inevitable" is a common word, and that although it is an antonym of "evitable" the latter is rarely used.
Evitable is in fact a perfectly good word meaning avoidable or possible to avoid.

 

[Haven't-a-Clue]

Can anyone tell me just how important the annode in the end of my Beta BZ482 heat wxchanger is? I ask 'cos all it seems to do is fall apart over a period of about 6 months and block half the cooling channels, reulting in overheating, usually at the most inconvenient moment I'm attending to it this weekend and wondering if I could just leave the stub of anode in situ without trashing the engine in some way.
Ta in advance.
Ian

 

[chubby]

You are lucky that your insurance covers negligence: some years ago I left my loo flushing, dont ask how but sea cocks open, loo flushing and antisiphon loop didnt work?, anyway damage to starter motor etc mounted outside the engine, claim rejected despite appeal to the top, as damage to engine and electrics caused by negligence not covered in the small print, interesting speculation on difference between accident and negligence, as most accidents are avoidable etc, got me nowhere.

 

[vyv_cox]

Can anyone tell me just how important the annode in the end of my Beta BZ482 heat wxchanger is? I ask 'cos all it seems to do is fall apart over a period of about 6 months and block half the cooling channels, reulting in overheating, usually at the most inconvenient moment I'm attending to it this weekend and wondering if I could just leave the stub of anode in situ without trashing the engine in some way.
Ta in advance.
Ian

If Beta decided it was needed then it wouldn't be very wise to remove it. But you might well be able to improve it. When you say it falls apart, do you mean that it corrodes away or breaks due to mechanical causes? I have no idea of its shape or location, but would using alternatives be a more robust arrangement?

 

[Haven't-a-Clue]

If Beta decided it was needed then it wouldn't be very wise to remove it. But you might well be able to improve it. When you say it falls apart, do you mean that it corrodes away or breaks due to mechanical causes? I have no idea of its shape or location, but would using alternatives be a more robust arrangement?

Hi there, thanks for the quick reply. Sorry, what I implied (badly!!) was that the anode crumbles away into small pieces which are EXACTLY the right size to block the channels of the heat exchanger leading to the problem as described earlier. It's obviously doing SOMETHING, I just can't figure out what it's protecting.....and why it can't disolve into tinier bits, I just don't know, 'cos it would make life at hamble spring ebbs much LESS exciting!

 

[westernman]

In Germany there was the case of some one who had his Porsche stolen while on holiday in Italy while it was parked outside his hotel room.

The insurance company refused to pay on the grounds that taking a Porsche to Italy is grossly negiligent.

It went to court, and the court agreed with the insurance company. It went to appeal were the court ruling was reversed, I was not around long enough to know whether the insurance ever did pay out or whether the court battles are still going on.

 

[vyv_cox]

Hi there, thanks for the quick reply. Sorry, what I implied (badly!!) was that the anode crumbles away into small pieces which are EXACTLY the right size to block the channels of the heat exchanger leading to the problem as described earlier. It's obviously doing SOMETHING, I just can't figure out what it's protecting.....and why it can't disolve into tinier bits, I just don't know, 'cos it would make life at hamble spring ebbs much LESS exciting!

I don't know what it looks like, but here are some ideas:
Use one that is a different shape but fits the mountings
Change from zinc to aluminium
Tie a piece of plastic netting around it (securely!)

I assume it is protecting the heat exchanger. Is it made from more than one metal? Tubes and tube sheets and ends could all be different.

 

[Haven't-a-Clue]

I don't know what it looks like, but here are some ideas:
Use one that is a different shape but fits the mountings
Change from zinc to aluminium
Tie a piece of plastic netting around it (securely!)

I assume it is protecting the heat exchanger. Is it made from more than one metal? Tubes and tube sheets and ends could all be different.

What it looks like is a 17mm (? I think that's the spanner size) brass plug about 5/8 inch long with a 3/4 long, 3/16 dia grey metal rod that sits in the rear end cap of the heat exchanger. Shape wise, I think a cone shape would be better/longer lasting. I think it's zinc. Re the tube assembly, yes I think 2 different metals, can't remember exactly. And yes, I think it is protecting the heat exchanger.....I seem to recall copper tubes and brass? sheet and ends.
A potent combination for short life if unprotected, I suspect !!

Edit: just found a piccy of the anode

www.boatpartsandspares.co.uk/anodes-1-c.asp so I suspect my original description may be a little wide of the mark

 

[BabaYaga]

Photo showing the tube stack and end caps from my Beta 722, zink anode bolt on the right.


http://www.ybw.com/forums/attachment.php?attachmentid=11231&stc=1&d=1304168027

I have also noted how quickly the anode falls apart, more from mechanical wear from the water flow than from galvanic corrosion/protection, I suspect.
The end caps are bronze, the tube stack seems to be made of brass and copper tubes. Metals that should not be too problematic together, perhaps?
Maybe the anode is there to protect the heat exchanger shell, which seems to be made of some alloy, possibly alu? I theory there should not be any direct contact between stack/endcaps and shell due to the two rubber O-rings...

 

[vyv_cox]

I'd be tempted to get someone to make a copy in aluminium and see what happens.

 

[VicS]

I'd be tempted to get someone to make a copy in aluminium and see what happens.

Dont forget aluminium anodes are not made from any old aluminium alloy. They are a US military spec alloy, or similar, containing several % of zinc and crucially, it seems, a very small amount of indium.

they will then offer any aluminium componets in the system the same degree of protection as zinc anodes.

 

[Haven't-a-Clue]

Photo showing the tube stack and end caps from my Beta 722, zink anode bolt on the right.


http://www.ybw.com/forums/attachment.php?attachmentid=11231&stc=1&d=1304168027

I have also noted how quickly the anode falls apart, more from mechanical wear from the water flow than from galvanic corrosion/protection, I suspect.
The end caps are bronze, the tube stack seems to be made of brass and copper tubes. Metals that should not be too problematic together, perhaps?
Maybe the anode is there to protect the heat exchanger shell, which seems to be made of some alloy, possibly alu? I theory there should not be any direct contact between stack/endcaps and shell due to the two rubber O-rings...

Yup, that's what mine looks like. I wonder about the flow erosion, could that be it? I'm tempted to clean the stack out and leave the anode stub in situ and re-examine after a month to see the effects..... am I commiting mechanical hari-kari