Prop coating

solent clown said:
As we have powder coasting facilities I am going to epoxy powder coat our prop. Another experiment, but hopefully it will provide protection against both corrosion and fouling - If it fouls with naughty little barnacles, we can just pop the prop off, stick it in the oven until the coating burns off, and reapply - in theory.
Any reason this shouldnt work?
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Plascoat make a plastic coating which has been tried and tested for decades. http://www.plascoat.com/en-gb/coating-applications/marine-environments.html

They claim it reduces marine fouling. It's very smooth and remains flexible.

Work on anti-fouling has been done involving silicone coatings which are effective and long lasting.

http://www.gallois.be/ggmagazine_2006/gg_06_12_2006_267.pdf Newcastle university carried out the research on a propeller in conjunction with International Paints. The conclusion was that it worked.
 
I've used Plascoat many times. It is a very thick coating, but not so well adhered. It's my guess it would detach. (But that's not a criticism of the product, for what its designed to do its excellent)
 
How well it stays in place is presumably related to what the Plascoat is applied to. Galvanised steel is difficult. Dishwasher baskets are successfully coated and whereas at one time they would loose their coating as you describe it seems to be less of a problem now.

A Danish magazine tested Hempel's Silic One silicone coating on a propeller and seemingly it worked.http://www.marinesuperstore.com/cms/images/Forms/2017 03 Hempel Silic One Article 01.pdf
 
2Tizwoz said:
How well it stays in place is presumably related to what the Plascoat is applied to. Galvanised steel is difficult. Dishwasher baskets are successfully coated and whereas at one time they would loose their coating as you describe it seems to be less of a problem now.

A Danish magazine tested Hempel's Silic One silicone coating on a propeller and seemingly it worked.http://www.marinesuperstore.com/cms/images/Forms/2017 03 Hempel Silic One Article 01.pdf
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Yes it does depend on the material being coated, in two different ways.
One is adhesion in any spot, ie the actual adhesion of the coating to the metal. Achieved either by re-profiling such as shot blasting or sanding, or chemical, by growing some crystal on the surface to which the coating adheres.
The "adhesion" is by enveloping. In a diswasher basket for example its coating wire essentially. And the coating envelops the metal such that even if not adhered, it stays in place by enveloping the wire. The greater the surface area (like prop blades, and any other relatively flat surface (compared to wire), then the less useful this type of "adhesion" is.
 
solent clown said:
As we have powder coasting facilities I am going to epoxy powder coat our prop. Another experiment, but hopefully it will provide protection against both corrosion and fouling - If it fouls with naughty little barnacles, we can just pop the prop off, stick it in the oven until the coating burns off, and reapply - in theory.
Any reason this shouldnt work?
Click to expand...

Should be ok with a sail boat but i have a friend did something simular with a motor boat only to find in moved the rubber bush at the center and he had to scrap the prop!
 
Let us know how everything goes after putting the prop in in the oven long enough to burn the epoxy off. It might need to be a high temperature some epoxies can stand a temperature of 150 to 200C before burning, also bear in mind the smoke burning the epoxy will create and what it will do to the oven.
 
I would not put am epoxy coated prop in an oven to burn of the epoxy as you would need to clean it after anyway to remove the ash residue.

I would grit blast to prepare for recoating. This would also create a roughened surface as recommended for coating any metal to the greatest adhesion.

To me the maine problem with coating is the metal/coating interface adhesion. This is why plating any metal surface is better as there is more of a chemical bond than just a mechanical bond as with non metallic coating. Again this is why grit blasting is recommended as it increases the mechanical bond.

Vyv's test of copper plating is of great interest as copper has anti fouling properties and the chemical adhesion would resist the abrasion that any prop turning in water has to endure.
 
Rogershaw said:
I would not put am epoxy coated prop in an oven to burn of the epoxy as you would need to clean it after anyway to remove the ash residue.

I would grit blast to prepare for recoating. This would also create a roughened surface as recommended for coating any metal to the greatest adhesion.

To me the maine problem with coating is the metal/coating interface adhesion. This is why plating any metal surface is better as there is more of a chemical bond than just a mechanical bond as with non metallic coating. Again this is why grit blasting is recommended as it increases the mechanical bond.

Vyv's test of copper plating is of great interest as copper has anti fouling properties and the chemical adhesion would resist the abrasion that any prop turning in water has to endure.
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+1

I'd remove any epoxy with a really coarse grit, 40# - such that the final surface catches the skin on your fingers and feels 'nasty' (but after touching it you will leave grease from your fingers - so degrease afterwards). Anything more smooth and you may lose whatever you apply next.

But Vyv's test are the most interesting and intriguing option I have heard of to date. I wonder how this might work on any folding prop and whether the thickness of the electroplated components will impact its ability to fold. I guess its not an insurmountable issue - but something to think of.

An alternative to electro-plating with copper might be CopperCoat. It might be less effective, but better than anything else currently.

Jonathan
 
To me its all about getting what is put on the prop to stay.

This is an interesting article about the anti fouling proprietors of Cu-Ni

https://www.copper.org/applications/marine/cuni/applications/hulls/performance_corrosion.html

In the forward it states

Cu-Ni possesses the ideal requirements for a boat hull. With both good resistance to corrosion and macrofouling, coatings are unnecessary, providing both savings in fuel and hull maintenance time and cost. Over the last 30 years, experience has been gained in constructing hulls using different product forms of Cu-Ni.

Cladding a fibreglass, wood or steel hull with Cu-Ni alloy sheet or foil

With tight restrictions on the use of organo-tin copolymer coatings and the quest for alternative antifoulants underway, Cu-Ni as a boat hull material can offer many practical benefits.

https://www.copper.org/applications/marine/cuni/applications/hulls/fouling_free.html


When I looked into this some years ago the only downside was cost or the raw material for construction of a pleasure craft. Commercial vessels would have quite different economics.

In terms of props currently mainly some type of bronze (Cu-Ti) so not vastly interns of rew materials. So copper plating of Cu-Ni plating or construction may solve the fouling problem.

Now copper coat also seems to be effective for huls but again the problem is the adhesion properties of the copper coat on a fast rotating prop would be solved with a plating or metal spraying process.

I don't know if dipping in molten Cu-Ni if its possible may also be a solution. I fabricated my current prop in 316 stainless steel with the lasor cut blades tig welded to a turned boss so dipping could work and it it does what about dipping mild steel fabricated props and the Cu-Ni coating would protect it from corrosion and from fouling with a low cost basic manufacturing method.

Some interesting info here

https://www.copper.org/applications/marine/cuni/properties/DKI_booklet.html#3.1
 
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I don't get why copper plating would be a great idea. My prop and through hulls are bronze. Bronze is 85% copper roughly, much more copper than in anti foul paint, yet is fouled up as bad as anything.

Fouling is a mega problem for the world's ships and boats. You won't find a solution that hasn't been tried before unless you do something really clever and with a serious science basis.
 
down at the marina most of the yachts are out of the water now. Most obvious thing to see, barely any fouling on hull beyond mud staining, and no fouled props....
 
We know - when we raced - we dry sailed, no AF. Worked a treat.

But the deal we had was that our costs were no different to someone with a marina berth, we simply paid a fixed rate per month. The yard dropped us in whenever requested and lifted as soon as we got back, or next day. I don't think we would get the service today (or not at those costs).
 
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