Anode bonding

[Calico Jack]

Apologies, my first inboard after two outboards... Have looked through the forum and am struggling to find definitive answers.

I have a beta 16, with a rigid shaft driven prop. At the moment the appears to be a wire from the anode bolt, at the end of the wire is a copper or brass ring, that sits loosely on the prop, no brushes or anything, just resting on the prop shaft, easily moved about. Doesn't seem sufficient to me in terms of bonding? or is this common place?

if not I would appreciate suggestions, with pics if possible please, how to bond this to the shaft properly.
TIA

 

[NormanS]

MG Duff sell a device with spring loaded brushes to do just that.

 

[VicS]

Apologies, my first inboard after two outboards... Have looked through the forum and am struggling to find definitive answers.

I have a beta 16, with a rigid shaft driven prop. At the moment the appears to be a wire from the anode bolt, at the end of the wire is a copper or brass ring, that sits loosely on the prop, no brushes or anything, just resting on the prop shaft, easily moved about. Doesn't seem sufficient to me in terms of bonding? or is this common place?

if not I would appreciate suggestions, with pics if possible please, how to bond this to the shaft properly.
TIA

As NormanS suggests one way is via a brush assembly such as the MG Duff "electro eliminator"

However common practice is to connect the anode to a convenient bolt on the engine or gearbox. If there is a flexible shaft coupling then that has to be bridged to complete the circuit to the prop shaft and prop.

Try the latter idea . If you get good continuity from the anode to the prop then problem solved. If you don't then look at the electro eliminator.

 

[Calico Jack]

As NormanS suggests one way is via a brush assembly such as the MG Duff "electro eliminator"



However common practice is to connect the anode to a convenient bolt on the engine or gearbox. If there is a flexible shaft coupling then that has to be bridged to complete the circuit to the prop shaft and prop.

Try the latter idea . If you get good continuity from the anode to the prop then problem solved. If you don't then look at the electro eliminator.

Thanks very much, I'll look to take it to a bolt on the gearbox or engine. I have a multimeter, I'm no whizz with it. Continuity should read near zero right? What would be considered 'good continuity'?

 

[VicS]

Thanks very much, I'll look to take it to a bolt on the gearbox or engine. I have a multimeter, I'm no whizz with it. Continuity should read near zero right? What would be considered 'good continuity'?

Ideally down to about 1 ohm but measuring low resistances with a multimeter is not easy. Getting good contact with the probes is the main difficulty.

 

[vyv_cox]

It may save you a lot of bother to check the resistance between the shaft and anode without the brass ring in place. With a rigid coupling you may well have continuity anyway. If you have a P-bracket and exposed shaft an anode on it is probably the best protection for your prop.

 

[VicS]

It may save you a lot of bother to check the resistance between the shaft and anode without the brass ring in place. With a rigid coupling you may well have continuity anyway. If you have a P-bracket and exposed shaft an anode on it is probably the best protection for your prop.

But ITYWF that he doesn't.

Hi
New member here. Just purchased a Cobra 750 with a Beta 16hp Indirect cooling inboard.

 

[vyv_cox]

But ITYWF that he doesn't.

That's why I wrote 'if'. I don't know the Cobra 750 and don't intend looking it up.

 

[Calico Jack]

I have no P-bracket on the Cobra.
It occurs to me that to test continuity with a meter will need quite an extension to one of the leads, if one tests it from the anode to the engine or pro shaft. Though I guest it be tested from the anode bolt to the shaft?
I think i will need to bond to the shaft as I seem to think there is a large nylon bush of some sort on the CV joint, probably to isolate the engine from the prop shaft no?

 

[sailorman]

I have no P-bracket on the Cobra.
It occurs to me that to test continuity with a meter will need quite an extension to one of the leads, if one tests it from the anode to the engine or pro shaft. Though I guest it be tested from the anode bolt to the shaft?
I think i will need to bond to the shaft as I seem to think there is a large nylon bush of some sort on the CV joint, probably to isolate the engine from the prop shaft no?

No, prol an R&D flexible shaft coupling http://www.randdmarine.com/flexiblesc.asp

 

[Calico Jack]

No, prol an R&D flexible shaft coupling http://www.randdmarine.com/flexiblesc.asp

not sure it looks like that tbh, maybe the same thing, different manufacturer, I'll take a few pics at the weekend, much more helpful than my inadequate descriptions.

 

[VicS]

I have no P-bracket on the Cobra.
It occurs to me that to test continuity with a meter will need quite an extension to one of the leads, if one tests it from the anode to the engine or pro shaft. Though I guest it be tested from the anode bolt to the shaft?
I think i will need to bond to the shaft as I seem to think there is a large nylon bush of some sort on the CV joint, probably to isolate the engine from the prop shaft no?

The continuity you need to test is from anode to the propellor . Hopefully the anode is close enough for the standard meter leads to reach, If it is much more it is too far away!

However a longer pair of leads is always handy to have ... I have made a pair with "extra flexible" wire.

If necessary you can locally check sections of the circuit . Anode to bolts., then internally bolts to engine block and engine block to shaft.

It does sound as though you do have some sort of flexible coupling that will have to be bridged. Does the Beta engine manual and installation guide not mention it?

EDIT The installation guide talks about the R&D coupling that sailorman mentions

 

[Calico Jack]

The continuity you need to test is from anode to the propellor . Hopefully the anode is close enough for the standard meter leads to reach, If it is much more it is too far away!

However a longer pair of leads is always handy to have ... I have made a pair with "extra flexible" wire.

If necessary you can locally check sections of the circuit . Anode to bolts., then internally bolts to engine block and engine block to shaft.

It does sound as though you do have some sort of flexible coupling that will have to be bridged. Does the Beta engine manual and installation guide not mention it?

EDIT The installation guide talks about the R&D coupling that sailorman mentions

ahh yes of course, prop to anode, not sure what i was thinking there. Pretty sure it's not flexible couple. On the invoices it mentions 'shaft coupling', there is no evidence of a flexible rubber flexible coupling. The shaft leaves the steel coupling and goes straight to the stern gland, and then through a tube to the prop

 

[VicS]

ahh yes of course, prop to anode, not sure what i was thinking there. Pretty sure it's not flexible couple. On the invoices it mentions 'shaft coupling', there is no evidence of a flexible rubber flexible coupling. The shaft leaves the steel coupling and goes straight to the stern gland, and then through a tube to the prop

The R&D one has a flexible moulded nylon or polyurethane disc, not rubber.

 

[Calico Jack]

The R&D one has a flexible moulded nylon or polyurethane disc, not rubber.

yes, it is the R+D steel coupling, with, as you say, poly' or nylon disc. Thanks for your patience VicS.

 

[VicS]

yes, it is the R+D steel coupling, with, as you say, poly' or nylon disc. Thanks for your patience VicS.

Then it will have to be bridged in order to complete the bonding ........ unless you fork out for the special conductive flexible insert they offer ... I bet that's not cheap!

 

[Calico Jack]

Then it will have to be bridged in order to complete the bonding ........ unless you fork out for the special conductive flexible insert they offer ... I bet that's not cheap!

By that you mean bridged from a convenient engine/gearbox bolt to the prop shaft? Which would take me back to how to bond to the prop shaft I guess. The electrical eliminators are pretty over priced in my view.

 

[VicS]

By that you mean bridged from a convenient engine/gearbox bolt to the prop shaft? Which would take me back to how to bond to the prop shaft I guess. The electrical eliminators are pretty over priced in my view.

No I mean a (braided) electrical connection between the two flanges that sandwich the plastics R&D thing

 

[Calico Jack]

No I mean a (braided) electrical connection between the two flanges that sandwich the plastics R&D thing

Excuse me VicS, having had only outboards before now. I'm not sure quite how to picture that and what to use. I can fabricate a clock movement from scratch, but these are new concepts. If and when you have moment to break it down a little I'd be very grateful. To sleep now though I think for me. Thanks again.

 

[VicS]

Excuse me VicS, having had only outboards before now. I'm not sure quite how to picture that and what to use. I can fabricate a clock movement from scratch, but these are new concepts. If and when you have moment to break it down a little I'd be very grateful. To sleep now though I think for me. Thanks again.

Your R&D unit is sandwiched between two flanges. One on the gearbox output shaft and one on the propshaft ?
Its purpose is to introduce a small amount of flexibility to the joint. However, it also electrically insulates the prop shaft from the gearbox and engine. If an anode is to be connected via the engine or gearbox to provide protection to the prop an electrical connection must be made between the two flanges. This can conveniently be done with tinned copper earthing braid.

If you follow the link given earlier and look at the R&D installation instructions you will see that they can provide a silver impregnated rubber tape which can be used sandwiched in the centre of the unit between the fail-safe straps. This is fine to do during the installation but perhaps not as a retrofit to an already installed coupling as basically you would have to uncouple it to fit the rubber tape.