Coopercoat: what do you put on saildrives and FFOF propellers

[boatpoker]

Originally Posted by fstbttms

In a proper application on a saildrive the Coppercoat is not in direct contact with any aluminum. So how would the saildrive leg anode also be protecting the Coppercoat, assuming that's what you are inferring would happen?

The key word is "proper".

Paint the drive then install the anode on top of the Coppercoat and it becomes "improper".

Hit something in the water and scratch through the Coppercoat and epoxy to the aluminum S/D surface and it becomes "improper".

[Locquatious]

We have a reversing Paul Luke prop and have used PropPurr on it for years. PropPurr is a very thin silicone release coating that chemically bonds to the copper in any bronze prop. Since it's so thin it never binds up gearing or sliding surfaces. It's a snap to remove prior to next season's re-coat.

[Martkimwat]

Originally Posted by fstbttms

Not as long as the anode mounting area isn’t coated.

This is incorrect. The whole idea of the anode that it is sacrificial, that means it slowly corrodes away instead of your nice shiny propellor. Painting over it stop it from corroding and therefore doing what it is supposed to do, having a good electrical connection between the anode and the item it is protecting is only half the story. DO NOT paint anything over your anode, it will prevent it from doing its job.

[fstbttms]

Originally Posted by Martkimwat

This is incorrect. The whole idea of the anode that it is sacrificial, that means it slowly corrodes away instead of your nice shiny propellor. Painting over it stop it from corroding and therefore doing what it is supposed to do, having a good electrical connection between the anode and the item it is protecting is only half the story. DO NOT paint anything over your anode, it will prevent it from doing its job.

1.- You misunderstood my post. I said that as long as the metal where the anode is mounted isn't coated, the saildrive leg would still be protected. I didn't indicate that painting the anode was a good idea and I think we can all agree that is common knowledge.

2.- The saildrive leg anode protects the saildrive leg. It provides little (or no) protection for the prop.

[Martkimwat]

The leg anode will provide some protection to the propellor if there is an electrical path from the anode, through the leg to the propellor, because it is within the field of 'view' of the anode. In the same way a hull anode will protect skin fittings within its field of view. Interestingly there isa school of thought that says you do not need to bond various skin fittings to the anode, for it to work, though from my experience this is not the case. I had a hull anode within 18 inches of my propellor which never eroded in three years even though it was bonded to the engine. It was only when I fitted a bonding strap across the shaft coupling that it began to erode. Fortunately I had a nosecone anode fitted to the prop as well which did it's thing, eroding completely in a season. Now it lasts two seasons with the hull anode now working as well. I don't have any metal through hull fittings so it was only the prop and shaft I was concerned about.

[boatpoker]

Originally Posted by Martkimwat

Interestingly there isa school of thought that says you do not need to bond various skin fittings to the anode, for it to work, .

This field of thought did not come from anyone with education in marine corrosion. - Retired Certified Marine Corrosion Technician.

[Uncle Bob]

Originally Posted by boatpoker

This field of thought did not come from anyone with education in marine corrosion. - Retired Certified Marine Corrosion Technician.

Even more interesting is that where I am the only vessels that are bonded are those imported from the US. No one that I am aware of here bonds all the through hull fittings, and to date there is not a whole lot of problems.

[boatpoker]

Originally Posted by Uncle Bob

Even more interesting is that where I am the only vessels that are bonded are those imported from the US. No one that I am aware of here bonds all the through hull fittings, and to date there is not a whole lot of problems.

To bond or not to bond is a separate issue and involves more than corrosion i.e. The North American standards see it as just as much of a grounding safety issue as a corrosion issue.

Contrary to your "other school of thought", the science is clear, simple. and undisputed in the US, Europe or anywhere else ... An anode cannot function without an electrical connection.

[Uncle Bob]

Originally Posted by boatpoker

To bond or not to bond is a separate issue and involves more than corrosion i.e. The North American standards see it as just as much of a grounding safety issue as a corrosion issue.

Contrary to your "other school of thought", the science is clear, simple. and undisputed in the US, Europe or anywhere else ... An anode cannot function without and electrical connection.

Selective or "cherry picking" quotes and adjusting them to suit does your position no good at all.

[boatpoker]

Originally Posted by Uncle Bob

Selective or "cherry picking" quotes and adjusting them to suit does your position no good at all.

I haven't stated a position I'm simply stating the proven science that you appear to disagree with.

[David B]

Originally Posted by fstbttms

Not the point. The point is that the anti fouling product on your HULL is not keeping your PROP clean.

Next time I'm down there, I will ask the little buggers why they are on my neighbours boats props, and not on mine then

[boatpoker]

Originally Posted by David B

Next time I'm down there, I will ask the little buggers why they are on my neighbours boats props, and not on mine then

Obviously because you are smarter than everyone else

[David B]

Originally Posted by boatpoker

Yes, there is a reason, The S/D manufacturer determined the mass and surface area of the anode for cathodic protection. They did not calculate an extra 2.5sq.ft of what essentially becomes a copper cathode.

How much effect will this have ..... it depends on integrity of the epoxy coating, even a single scratch through the epoxy to the aluminum can complete the galvanic circuit. An anode affixed on top of a Coppercoat painted surface so that it is in contact with the Coppercoat will complete the galvanic circuit.

How serious is this ? Maybe not serious at all or may cause significant corrosion ... no way to tell without measuring with a silver silver chloride half cell

The thing is, Coppercoat is non-conductive. Check their website.

[fstbttms]

Originally Posted by David B

Next time I'm down there, I will ask the little buggers why they are on my neighbours boats props, and not on mine then

Then please describe for the assembled crowd the mechanism by which Coppercoat, a coating that leaches so little biocide that the manufacturer describes it as "non toxic", can prevent fouling on uncoated surfaces many inches or even feet away from it. Is it your contention that Coppercoat provides a "bubble" of anti fouling protection around it? Is this copper biocide (that does not leach out of the coating) somehow raining down on other surfaces, preventing them from becoming foul? Seriously, I'd like to know just how this miracle product can be so effective as to keep nearby unpainted metals clean.

[boatpoker]

Originally Posted by David B

The thing is, Coppercoat is non-conductive. Check their website.

If that is the case ... there is no copper in it.
Is their advertising "sales puffery" ?
Is their claim of 99% pure copper in the paint false ?
What is your house wiring made of ?
Do you know of anyone that has had it work for 10yrs as they claim ?

From Coppercoat ...
"With the resin carrier insulating each copper particle, the final coating is inert and non conductive. Consequently Coppercoat does not cause electroloysis problems or cathodic decay in steel or aluminium craft. Sacrificial anodes should be fitted in the usual manner."

If the copper is completely insulated by the resin how can it possible change to cuprous oxide from contact with salt water ?
This make no sense.

Check out this thread ... https://www.cruisersforum.com/forums...at-192093.html