Antifoul on Saildrive Leg? (Coppercoat)

[RichardTaylor]

Our new boat is coppercoated, however the saildrive leg is as it left the factory.

The supplier suggested coating the leg with Trilux or similar (an annual chore I could do without - which was the whole idea of coppercoat from new).

I had sort of expected the leg to be AF with Coppercoat and reading their website it does suggest this is possible. What are peoples thoughts and experience on this?

 

[Twister_Ken]

Me too.

Reason - the SD leg is metal, Coppercoat is 'metal'. Possible dissimilar metals corrosion if one is in contact with the other. Thus, Trilux or some other metal friendly a/f. Don't worry, it's only 30 minutes work.

 

[haydude]

Use International Trilux-Prop-O-Drev antifouling.

ABSOLUTELY NOT COPPERCOAT!!!

Why: the saildrive is alluminium, which will corrode through electrolysis if joined with Copper.

Please read the VP Saildrive manual, it is paramount that the saildrive is always isolated from other metals. There is even electrical isolation with the propeller and the engine.

 

[Slipperman]

Antifoul on Saildrive Leg (Coppercoat)

I had the same problem when my boat was new. When first launched there was no antifoul on the leg or prop, and I had half a season like that. At the first winter pullout I used Trilux on the leg and prop (a Kiwi prop) and this seems to have worked well with just one annual top up coat for the last 5 years. In fact, the leg/prop has stayed cleaner than the hull!

 

[VicS]

Coppercoat is claimed to be a non conducting coating which causes no galvanic corrosion and can therefore be applied to metal structures including aluminium after a suitable epoxy primer.

Since not copper coated suitable antifouling include International Trilux 33, International Trilux Prop-O-Drev and Hempel Mille Drive.

Prop-O-Drev and Mille Drive are supplied in aerosol spray cans which make application to small awkward areas easy.

The boat will have to be lifted regularly for drive and prop anode replacement even if not for oil changes and it will not be a huge task to clean off and respray the leg at the same time.

Consult the manufacturers literature for the chosen product for details of the priming which is required

 

[Laurie]

As "Haydude" says. Absolutely not coppercoat. Make sure saildrive leg is properly primed prior to antifouling. Do not put propodrev or trilux onto bare metal.

 

[RichardTaylor]

Thanks for the replies, looks like spray cans are the way forward.

R

 

[njsail]

You can use the spray on trilux if you want but I found keeping a small can of trilux is easier to brush on each spring when I give it the once over quick coat on the sail leg. Make sure the leg is primed properly before adding trilux. Make sure you don't paint the zinc or the part of the leg the zinc connects to. Good luck. It's a quick job.

 

[Nostrodamus]

When we bought our boat the surveyor said that the leg and prop had so much corrosion they would need changing.
Sail drive legs are pretty bad at eating through anodes so you will need it lifting each season to check. It does not take long to re paint it although depending on which leg you have the anode change can take longer. It will also give you chance to check for blockages and crustation in the raw water in take and clean the prop. Some people also anti foul their prop where others don't.
I believe, as has been mentioned, you can epoxy the leg several times making it able to take the normal anti foul.
As they are aluminium the last thing you want on it is copper coat without protection.

 

[Quandary]

The leg on our boat is not antifouled, however it is coated with Propshield (lanolin wax) which is renewed every second year, it is expensive and fiddly to apply evenly at first but a tub does two applications. So far, after four seasons I am pleased with the result, the leg still looks as it did when new.
I tried it on the folding prop but decided it was a waste of time as it was long gone on lift out so I just polish that well which works as long as the engine is used occasionally.

 

[VicS]

Use International Trilux-Prop-O-Drev antifouling.
ABSOLUTELY NOT COPPERCOAT!!!
Why: the saildrive is alluminium, which will corrode through electrolysis if joined with Copper.

As "Haydude" says. Absolutely not coppercoat.

As they are aluminium the last thing you want on it is copper coat without protection.

From Coppercoat's website:

Does Coppercoat cause any problems with regards to electrolytic/galvanic action?

No. With the resin carrier insulating each copper sphere, the final coating is inert and non-conductive. A current can not pass through Coppercoat and this coating does not cause or promote electrolysis or cathodic decay. Consequently Coppercoat can be safely applied to metal structures such as iron keels and steel or aluminium craft (after the application of an appropriate epoxy primer).​

Although they do not specifically say that coppercoat is suitable for application to sail drives, if the above is true why should it not be ... They say it is suitable for aluminium craft.

 

[Twister_Ken]

Mmm. Let's see.

Price of new saildrive leg, enough to hurt.

Price of a tin of gloop, a few quid.

Nope, not a gamble I want to take.

 

[Laurie]

I agree with Ken...but note also, they still recommend (?) a primer....epoxy at that..

 

[VicS]

Mmm. Let's see.
Price of new saildrive leg, enough to hurt.
Price of a tin of gloop, a few quid.
Nope, not a gamble I want to take.

I agree with Ken.


Applying an antifouling paint may well be the most sensible way forward but I'd like to know why 3 people say do not use Coppercoat on the grounds that it will cause galvanic corrosion when Coppercoat themselves say it does not.

 

[vyv_cox]

I agree with Ken...but note also, they still recommend (?) a primer....epoxy at that..

They recommend a primer regardless of the substrate. It's to ensure good adhesion, not as some sort of galvanic isolator. The primer would have to be epoxy to match the Coppercoat. Anything else would fail.

 

[pvb]

....I'd like to know why 3 people say do not use Coppercoat on the grounds that it will cause galvanic corrosion when Coppercoat themselves say it does not.

You know the reason already, Vic! Lots of the "advice" posted on these forums is based on hearsay, ignorance or guesswork.

 

[Laurie]

or experience.....?

But I don't have that with coppercoat, but do have a lot with saildrives, and as Twister Ken says, a saildrive is an expensive thing to risk, for the sake of an aerosol or two...?
With ref. to the epoxy...of course it's for adhesion, but it'll certainly help with isolation too.....

 

[Nostrodamus]

I will put my hands up and say I don't know a lot about copper coat.
If someone can explain the difference (apart from price) between that and normal anti foul I would be obliged.

I do know that my surveyor advised going anywhere near it with a sail drive, that the boat yard advised me never to paint the sail drive leg with anything with copper in it, that boats I see out the water with sail drives have different anti fouling on the leg and that products are specially sold for legs as they are copper free. I also believe that Volvo say something similar.

I should imagine "copper coat" by it's name alone is not made up of aluminium.

I did once read something about using normal anti foul on a leg but that was only after several coats of epoxy and a good primer as I said before.

I may have been misinformed by many people so if anyone can put me right I will tug my forelock to them.

 

[Twister_Ken]

If someone can explain the difference (apart from price) between that and normal anti foul I would be obliged.

A coating of CC should last ten years with minimal maintenance. A coating of AF will last a season, then needs to be redone every year (or two if you're lucky). The sums tip in favour of CC after a few years - even less if you normally leave your boat in, and don't need lifts ashore to re-AF. Plus, with CC the boat always has a 'clean*' hull, so performance is better and for a mobo fuel burn is reduced.

*actually it does get a thin layer of easily removed slime, but nothing else grows.

 

[VicS]

I will put my hands up and say I don't know a lot about copper coat.
If someone can explain the difference (apart from price) between that and normal anti foul I would be obliged.

Normal antifoulings are paint coatings containing one or more of a variety of biocides and most prominently cuprous oxide. It's the copper oxide that causes the problem with aluminium structures.

Coppercoat is an epoxy coating containing metallic copper. ( see Coppercoat's website for all the info)

Mille Drive antifouling contains no copper compounds

Trilux, interestingly, contains cuprous thiocyanate but this does not appear to cause a problem with aluminium susbstrates