Anode to prop connection - how to complete?

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mattonthesea

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I have just fitted an anode (first one the boat has ever had - commissioned in 1979!) to my Rival 32 and was wondering how I make the connection across the shaft alignment correct thingy (the widget with two plates bolted though a wadge of rubber). If I use a couple of spade connectors under a nut on each side then will this upset the balance? And are the nuts set to specific tightness when the widget is set up?

Will 4mm flex be ok?

thanks
 
Why are you adding an anode if the boat has not had one for nearly 40 years? What have you changed or experienced that makes you think you need one?

Anyway, to bridge the gap you need a heavy gauge wire or braided copper with large eye terminals - the bolts will be at least 6mm, probably 8mm so a spade connector is not suitable.

An anode is not a good thing in itself. Only needed if you are experiencing dezincification of the prop. Many boats of that vintage had better quality alloy props than today, which is why your boat never had an anode. so, unless you have fitted a new manganese bronze prop think again. even then i would try it for a year without.
 
PaulRainbow said:
With a flexy coupling ?

If it's electrically attached it won't need a bridge wire.
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Already covered in post#2. You are making it too complicated. It is a perfectly standard setup. The problem is connecting the anode to the shaft because the shaft is not connected to the gearbox with a reliable path. so he has to bridge the coupling with wires.

Nothing to do really with whether he needs an anode or not as that depends on the interaction between the metals of the shaft and prop. My guess is that if they are the same as have been on the boat for near 40 years and no dezincification, there is no need for an anode at all. If the prop has been changed this may result in it suffering from dezincification as mot cheap props now are inferior alloys. However it may make no difference or a cone anode on the locknut may be enough.
 
Tranona said:
Highly unlikely on a shaft drive Rival. The prop will on a keyed taper so very firmly attached both physically and electrically.
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Tranona said:
Already covered in post#2. You are making it too complicated. It is a perfectly standard setup. The problem is connecting the anode to the shaft because the shaft is not connected to the gearbox with a reliable path. so he has to bridge the coupling with wires.
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Which is it ?
 
PaulRainbow said:
Which is it ?
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Both, as i understand it

The prop is almost certainly keyed directly to the shaft and therefore electrically connected to it, not isolated from it as you suggested in #3

The electrical path from prop to gear box is broken by a flexible coupling.
 
Tranona said:
Both - they are two completely different connections. Surely you can see that?
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Seriously ?

FFS i didn't mean the prop and shaft isolated from each other, that would be plain retarded. I meant the prop and the shaft (as an assembly) isolated from the rest of the metal bits that might be connected in such a way as to allow galvanic corrosion.

I'll say it again so it's clear, if the prop and/or the shaft, along with anything else metal, such as through hulls, are not electrically connected to form a circuit then there is no chance of them suffering from galvanic corrosion and an annode is pointless.

But, you already know that.
 
Good points but it has a three-bladed prop and a rope cutter so I imagine it must have been changed. On the other hand, the previous owner had things done properly so it is quite likely that the prop is of high quality. The anode is in place now so I could just wait until out of the water next as I won't be able to check the integrity of connection until then anyway.

Thanks

Matt
 
The rope cutter will have no effect as it is 316 stainless (if it is a Stripper). How long has this arrangement been in place? Is there any sign of dezincification on the prop? If you have a problem with a replacement prop it will show up pretty quickly.
 
Why not just fit a shaft anode ahead of the prop instead?

Oops, just looked at some pics of a rival 32 and there isn't space.
May be worth looking at fitting a set of shaft brushes in addition to bridging the flexi coupling with a bonding strap if you're really worried.
As others have said though, if your boat hasn't suffered corrosion of the prop in the last 40 years unless something has changed.
 
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PaulRainbow said:
I'll say it again so it's clear, if the prop and/or the shaft, along with anything else metal, such as through hulls, are not electrically connected to form a circuit then there is no chance of them suffering from galvanic corrosion and an annode is pointless.

But, you already know that.
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You seem to be labouring under the same misconception in two simultaneous threads. Try telling the owner of an aluminium boat that he does not need zinc anodes. No galvanic couple involved, just a 6000 series aluminium alloy.
 
vyv_cox said:
You seem to be labouring under the same misconception in two simultaneous threads. Try telling the owner of an aluminium boat that he does not need zinc anodes. No galvanic couple involved, just a 6000 series aluminium alloy.
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I wasn't aware that the OP had an ally boat.

The question relates to a 40 year old plastic boat that has never had a bonding circuit. I see no point creating one now and introducing even the vaguest possibility of creating situations where galvanic corrosion could occur. If it transpires that there is an issue with the prop, something which is entirely unclear, surely a local anode would be a better solution.
 
PaulRainbow said:
I wasn't aware that the OP had an ally boat.

The question relates to a 40 year old plastic boat that has never had a bonding circuit. I see no point creating one now and introducing even the vaguest possibility of creating situations where galvanic corrosion could occur. If it transpires that there is an issue with the prop, something which is entirely unclear, surely a local anode would be a better solution.
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That is a totally different argument. I was responding to your statement "I'll say it again so it's clear, if the prop and/or the shaft, along with anything else metal, such as through hulls, are not electrically connected to form a circuit then there is no chance of them suffering from galvanic corrosion and an annode is pointless." This is incorrect.

Also, the prop and shaft are always connected to form a galvanic couple, other than in very special cases.
 
vyv_cox said:
Also, the prop and shaft are always connected to form a galvanic couple, other than in very special cases.
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It looked clear to me that i was referring to the prop and shaft collectively, rather than saying they were not connected to each other. Obviously i was mistaken.

I was also answering the OPs specific question, related to his specific boat and circumstances. I wasn't talking about deep sea oil rigs, underwater pipes or ally boats.

I see in future i shall have to carefully word my replies to allow for every situation that might arise anywhere with anything. Or not bother to reply.
 
PaulRainbow said:
It looked clear to me that i was referring to the prop and shaft collectively, rather than saying they were not connected to each other. Obviously i was mistaken.

I was also answering the OPs specific question, related to his specific boat and circumstances. I wasn't talking about deep sea oil rigs, underwater pipes or ally boats.

I see in future i shall have to carefully word my replies to allow for every situation that might arise anywhere with anything. Or not bother to reply.
Click to expand...

The OP says:
I have just fitted an anode (first one the boat has ever had - commissioned in 1979!) to my Rival 32 and was wondering how I make the connection across the shaft alignment correct thingy (the widget with two plates bolted though a wadge of rubber).
Click to expand...

He asks:
If I use a couple of spade connectors under a nut on each side then will this upset the balance?
Click to expand...
And are the nuts set to specific tightness when the widget is set up?
Click to expand...

Will 4mm flex be ok?
Click to expand...


You dont appear to have answered any of those three questions

The first has been answered by Tranona

The second has not been answered yet AFAICS and I dont know the answer.

The third I can answer: ............. YES 4mm is the wire size MG Duff recommend!
 
VicS said:
The OP says:


He asks:




You dont appear to have answered any of those three questions

The first has been answered by Tranona

The second has not been answered yet AFAICS and I dont know the answer.

The third I can answer: ............. YES 4mm is the wire size MG Duff recommend!
Click to expand...

Typical pedantic, nit picking post from you.

For your information, the answer to question two is "yes".
 
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