Over the side extra anode?

[jmnapier]

Hi Folks
I’d like to loop wires round my propshafts and hang them over the side with an anode on the end to increase my catholic protection. Would old stainless halyards be best? Any other thoughts?
thanks Jonathan

 

[Tranona]

They are of limited value as the normal anode will be the one that wastes first because it is closer to the shaft and prop. only becomes really useful when the main anodes are gone. If you are going to do it then best to wire from the gearbox to a plug on deck and plug your hanging anode into that. The other use is if you spend some time in fesh water when it might be useful to hang a magnesium anode, although now with ready availability of aluminium based anodes even that is doubtful.

 

[jmnapier]

I don’t know the state of the anodes on the bottom having had issues over the last two years with them. I can’t keep lifting the boat to check at £300 a pop. It’s simply for peace of mind when I leave the boat for a few weeks at a time. I don’t want anything permanent or ‘fitted’.
I’ve applied logic and assumed that stainless is the only acceptable wire to use simply for corrosion reasons. Will it conduct enough to safely connect the shaft and prop to the extra anode? Is there another option that will conduct better but also not corrode?
Thanks

 

[Tranona]

No, stainless is OK. That is what MG Duff use for their hanging anode kit.

 

[jmnapier]

That’s great, many thanks

 

[ari]

I saw someone do this once, dangling the anode off the side on the end of a piece of string...

 

[kashurst]

Your stainless safety rails around the sides of the boat should all be bonded electrically to the boat anodes.
You should be OK attaching your extra anode to one of the rails or uprights with a jubilee clip if its a temporary thing.

 

[Portofino]

I saw someone do this once, dangling the anode off the side on the end of a piece of string...

Interestingly don‘t mock the guy .I read somewhere in cases where’s a neighbours leak and / or nearby metal piles etc …..and you feel your normal anodes are eroding too fast doing all the work for the neighbours boat , the piles and your boats 3 rd inline .……then any zinc the sheer mass how ever connected nearby is better than the status quo.

Obviously better bonded , but if it’s pretty near on a piece of string it partially helps .
Bit like fishing acts as bait for the dodgy neighbours boat(s)

 

[jfm]

"I read somewhere..." The internet? It's just not correct.

@jmnapier - nothing to add - Tranona has covered it all

I'll happily stand corrected but I'd be surprised if safety rails are generally bonded to the boat's grounding system. Pretty sure they weren't on my last few boats.

 

[PaulRainbow]

"I read somewhere..." The internet? It's just not correct.

@jmnapier - nothing to add - Tranona has covered it all

I'll happily stand corrected but I'd be surprised if safety rails are generally bonded to the boat's grounding system. Pretty sure they weren't on my last few boats.

I have never had a boat with safety rails bonded and never worked on one. It would be pointless.

 

[Croftie]

I'll happily stand corrected but I'd be surprised if safety rails are generally bonded to the boat's grounding system. Pretty sure they weren't on my last few boats.

Previous boat did, but not the present one. Having said that previous was a Dutch Steel

 

[jmnapier]

Solved! I have no safety rails! Old working boat. Will go with plan A. Many thanks all.

 

[Tranona]

Your stainless safety rails around the sides of the boat should all be bonded electrically to the boat anodes.
You should be OK attaching your extra anode to one of the rails or uprights with a jubilee clip if its a temporary thing.

No, No a thousand times NO. Never seen that it it makes absolutely no sense. Anodes are needed where there are 2 dissimilar metals in contact underwater. an anode is introduced into the circuit to prevent the lower potential metal from being the anode and eroding away. The most common situations are propellers and shafts, rudders and stocks, drive housings and drive shafts as in outdrives and saildrives, trim tabs and actuators.

Stainless steel guard rails bolted to GRP decks do not fall into this category.

 

[kashurst]

No, No a thousand times NO. Never seen that it it makes absolutely no sense. Anodes are needed where there are 2 dissimilar metals in contact underwater. an anode is introduced into the circuit to prevent the lower potential metal from being the anode and eroding away. The most common situations are propellers and shafts, rudders and stocks, drive housings and drive shafts as in outdrives and saildrives, trim tabs and actuators.

Stainless steel guard rails bolted to GRP decks do not fall into this category.

apologies my post wasnt sufficiently clear - I meant attach the other end of the stainless cable that has the anode dangling in the water.

The purpose of bonding the safety rails is for lightening protection, not corrosion. I was under the impression all boats had bonded rails. It's an ABYC recommendation - clearly not.

 

[Portofino]

The classic view Tranona preaches is correct and oversimplified.But it works in practice should be followed .

The flooding of the electrolyte solution with zinc , all relative mass wise needs to be large reduces the decay of your boats important anodes . But it has to be larger and close .

What you are doing is changing the electrolyte sol concentration locally .
Not recommended hanging zinc off a piece of string but saying depending on its mass , relative to the other zincs , the other activities of nearby stuff , metals , leaky boats ( from a electrical pov ) it might in certain circumstances act as a “bait “and reduce depletion of yours .

Ideally it needs bonding that’s not in dispute .

So hanging a 1 oz off is useless .Hanging 16 kg off near your stern gear with string between the gear and the piles , when your anode weight is say 4 kg all up , is gonna get involved release more zinc ions and other stuff .It’s surface will create micro cells as when it cooled after casting ,its not completely uniform throughout + it’s sitting in a active solution, local to your boat with the piles and other leaky boats .Act as bait and take some wear off your own .Wether it’s enough is debatable. But it ain’t passive .

Point is it has to have some beneficial effect as it dissolves away albeit slowly .But it all depends on what’s around it how much stray currents are swimming around the jetty .Relative potentials and relative electrolyte concentration , the relative mass of the things

Works a hell of a lot better if directly connected which it should be . That’s a given .


Remember the neighbours leakage or / and near by unprotected metal piles nearby as an example, they aren’t connected to your boat .Let’s agree mooring lines don’t count with this . But are effecting it via the electrolyte sol , the sea . Hang more zinc between them and your are changing that localised solution . Don’t summarily dismiss the solution .It takes 3 to tango here .



Similarity there’s no metal connection in thin air clouds but they manage to create huge amounts of lightening ,electricity through different charge potentials of thin air .

 

[PaulRainbow]

The classic view Tranona preaches is correct and oversimplified.But it works in practice should be followed .

The flooding of the electrolyte solution with zinc , all relative mass wise needs to be large reduces the decay of your boats important anodes . But it has to be larger and close .

What you are doing is changing the electrolyte sol concentration locally .
Not recommended hanging zinc off a piece of string but saying depending on its mass , relative to the other zincs , the other activities of nearby stuff , metals , leaky boats ( from a electrical pov ) it might in certain circumstances act as a “bait “and reduce depletion of yours .

Ideally it needs bonding that’s not in dispute .

So hanging a 1 oz off is useless .Hanging 16 kg off near your stern gear with string between the gear and the piles , when your anode weight is say 4 kg all up , is gonna get involved release more zinc ions and other stuff .It’s surface will create micro cells as when it cooled after casting ,its not completely uniform throughout + it’s sitting in a active solution, local to your boat with the piles and other leaky boats .Act as bait and take some wear off your own .Wether it’s enough is debatable. But it ain’t passive .

Point is it has to have some beneficial effect as it dissolves away albeit slowly .But it all depends on what’s around it how much stray currents are swimming around the jetty .Relative potentials and relative electrolyte concentration , the relative mass of the things

Works a hell of a lot better if directly connected which it should be . That’s a given .


Remember the neighbours leakage or / and near by unprotected metal piles nearby as an example, they aren’t connected to your boat .Let’s agree mooring lines don’t count with this . But are effecting it via the electrolyte sol , the sea . Hang more zinc between them and your are changing that localised solution . Don’t summarily dismiss the solution .It takes 3 to tango here .



Similarity there’s no metal connection in thin air clouds but they manage to create huge amounts of lightening ,electricity through different charge potentials of thin air .

What a load of gibberish garbage, where on Earth do you get this nonsense from ?

 

[Tranona]

apologies my post wasnt sufficiently clear - I meant attach the other end of the stainless cable that has the anode dangling in the water.

The purpose of bonding the safety rails is for lightening protection, not corrosion. I was under the impression all boats had bonded rails. It's an ABYC recommendation - clearly not.

Again, never seen that. Anyway if it was bonded it would be to the keel as masts are, although i guess if no keel to an anode as a path to water.. The purpose of the anode is to protect the propeller from the shaft so would have absolutely no connection to the guard rails.

 

[Tranona]

What a load of gibberish garbage, where on Earth do you get this nonsense from ?

Probably in a shoe box under the bed which is full of gibberish on all sorts of subjects.

 

[kashurst]

Again, never seen that. Anyway if it was bonded it would be to the keel as masts are, although i guess if no keel to an anode as a path to water.. The purpose of the anode is to protect the propeller from the shaft so would have absolutely no connection to the guard rails.

I have seen people hanging anodes over the side and clamping them to the guard rails. It was regularly done on a big 80 foot sailing yacht moored near me. So I guess that boats rails were bonded or he was wasting his time.

I think this is what reinforced my belief that all boat rails were bonded to the anode and/or the keel. I used to have an old Princess 37 that had steel radar arch and steel rails and I think they were bonded. Having read the ABYC recommendations on boat wiring I then assumed all boats were the same. Every days a school day.
On a similar vein, why do we bond fuel fillers and fuel tanks? I always assumed to it was to ground any possible sparks, but a spark will only happen if there is a circuit to complete. Not bonding them would surely be safer, as the fuel filler is connected to the tank via a non conducting rubber pipe and the tanks are usually connected via again non conducting rubber pipes either all the way or part way. Or is there another reason?

 

[Hurricane]

I think you have to look at how all this stuff actually works.
AFAIK galvanic protection is all about corrosion.
And all corrosion is caused by the the flow of electricity.
By wiring two dissimilar metals together, you create a flow of electricity between the dissimilar metals.
One having a higher "noble value" than the other.
The idea of galvanic protection is to "corrode" one of the metals to protect the other.
In this case, we want the anode to corrode to protect the expensive propellers.

By default, the boat has an "earth/bonding" system that connects everything together (the wire).

So, if you can't afford to replace the anodes annually, adding extra ones would possibly be an option.
However, just looping wires over the prop shaft would, IMO, be a silly idea.
So @Tranona s suggestion of connecting a wire to the gearbox would be a better solution.
However you would need to keep the resistance of the wire down to as little as possible so use a thick wire.

But all this is pointless IMO.
£300 once a year isn't much to pay to protect your propellers and other underwater metalwork.
And if your anodes aren't lasting a year, - get bigger ones.