Coopercoat: what do you put on saildrives and FFOF propellers

[capnkev]

Have had Coppercoat on two boats over the years. It’s a great product. We used Trilux on the saildrives and props to be safe. Some people say not to Coppercoat drives, but the company says they have treated thousands of aluminum boats and out drives without incident.
It’s so much easier to coat the hulls once every 10-15 years than to repaint every 1-2 years.

[EWOL Props]

Some years ago we tried Coppercoat on our feathering propellers but it did not work well, bubbles were appearing on the surface (see picture https://ibb.co/T4bQbYZ), so we abandoned the idea.
We do recommend Prop Speed or Prop One since many years, but since a couple of years we have also added our own antifouling paint that we called FastBlades, this has been developed together with a manufacturer of marine paint with great experience on the market

[CaptainRivet]

Hi all,
Thank you all for your contributions so trilux or prop speed will it be. No need to haul out untill i have a repair to do so effectively all 3 years a haul out where i can reapply trilux or Propspeed.

I won't apply because my friend, a top notch surveyor advised not to. Reason is he discovered lately several corrosion damages on saildrives where coopercoat was properly applied. This he knows because he supervised the work on behalf of the owners.
Issue appear to be the joints of the saildrive as
stated here too when alu gets exposed, same happens in case of scratch down to the aluminium.

To understand why this is happening i will tell you what exactly Coopercoat is, what is the secret why it works and how it actually works. How do I know:a buddy of mine is a sailing manaic and chemistry professor and leads one off the biggest labs in the world, he took it appart, Reengineered it and even figured out their original suppliers and products they use.

So here we go:
Ingredient 1:99.9% atomized cooper powder
On 1kg Epoxy 2kg of 99.9% atomized Cooper is used. Its 2kg because that results in the maximum allow concentration of poison per sqm of treated surface with the coopercoat when(!) it is mixed and applied correctly.

Ingredient 2: water-based 2k Epoxy used to seal concrete floors of industrial building.
Coopercoat is 500g medium hardner, 500g waterbased Epoxy and 2kg of 99.9% atomized cooper powder mixed into the 1kg epoxy.

Thats all, well partly.
It needs an epoxy primer to isolate the conductive coopercoat product from the hull or wherever its applied. Its conductive because a small part of the cooper powder is not fully encapsulated by the epoxy in the first and last layer. How much this is dependents on the quality of constant mixing and the roller used during applying. Correctly applied the top layer is only lightly conductiv directly after applying and drying.
And this amount of exposed cooper is not enough, so short before you put into water you sand away so more cooper is exposed to the salt water and creates a poison barrier that works as antifouling. This top layer is now highly conductive too but isolated from the surface applied by the epoxy primer underneath but if this gets damaged in any way an electrical path between coopercoat and and the applied surface is likely created and corrosion issie may start...

The secret how coopercoat actually works is the timing as the top layer of the water-based epoxy changes over time and erodes. This is timed to standing time of the cooper exposed to the salt water as this wears down too. If the epoxy eroses it reveals a new layer of fresh 99.9% cooper. And this timing is important, if erosion is too small it stops working, if its too fast too much cooper gets exposed and you will have dead fish floating around your boat.
So no sanding down with the boat in water is needed. But if you haul out for longer then 3 days the cooper oxides and stops working as antifouling. So before haul in you need to sand away the oxidation surface from the cooper what they call reactivation.

[CaptainRivet]

The reason why you have to take away all old antifouling before applying coopercoat is also the water-based epoxy as it reacts when drying and transforms already with only small quantities of conventional antifouling.
Then the epoxy gets harder and looses his ability to change and eroding stops completely means cooper is not exposed so coopercoat doesn't work anymore after some time,2nd the epoxy reacts then with the cooper and neutralize around 30% of the surface area so whats left its less effective and 3rd surface gets rougher through this and more grim sticks and starts to grow. And you cannot cure that by sanding off one layer or 2.

So preparation, constant mixing during applying and apply during pot life is the key.
Minimum 4 people, 2 applying, 2 mixing

.what you do is roughly all 1 till 3 month depending on water temp and growing pressure take a black scotch pad or similar and clean in the water the grime and slime on the hull away. That also takes a bit of the surface oxidation of the exposed cooper and extends the life of this layer a bit.