Help! Aluminium saildrive - wrong antifoul used!

[emsworthy]

Oh dear!!

My mate has painted our saildrive leg and prop with what I thought was a tin of Trilux. On checking the tin yesterday it turns out to be Interspeed Ultra, which I assume has a degree of copper content as the International website says not suitable for aluminium.

What should I do? Both the leg and the prop have several coats of Primocon followed by Prop-O-Drev underneath the Interspeed. Should I cut my losses and strip the lot off now or just hold my breath through the next year that the new anode on the leg will take the brunt of any galvanic reaction.

I really don't fancy having to strip the whole lot off and start again but what do the panel think?

 

[sailorman]

Oh dear!!

My mate has painted our saildrive leg and prop with what I thought was a tin of Trilux. On checking the tin yesterday it turns out to be Interspeed Ultra, which I assume has a degree of copper content as the International website says not suitable for aluminium.

What should I do? Both the leg and the prop have several coats of Primocon followed by Prop-O-Drev underneath the Interspeed. Should I cut my losses and strip the lot off now or just hold my breath through the next year that the new anode on the leg will take the brunt of any galvanic reaction.

I really don't fancy having to strip the whole lot off and start again but what do the panel think?

the cheapest remedy is strip the a/f & start over

 

[VicS]

Oh dear!!

My mate has painted our saildrive leg and prop with what I thought was a tin of Trilux. On checking the tin yesterday it turns out to be Interspeed Ultra, which I assume has a degree of copper content as the International website says not suitable for aluminium.

What should I do? Both the leg and the prop have several coats of Primocon followed by Prop-O-Drev underneath the Interspeed. Should I cut my losses and strip the lot off now or just hold my breath through the next year that the new anode on the leg will take the brunt of any galvanic reaction.

I really don't fancy having to strip the whole lot off and start again but what do the panel think?

Yes, like most antifouling paints, it contains cuprous oxide. (Trilux contains cuprous thiocyanate)

I think the wisest thing to do might be to contact International Yachtpaint's technical department.
With luck they may say that if the original coating on the leg was in good condition it'll not be a problem. OTOH they may say make him strip it all off!

Not painted over the anodes as well I hope.

Why the Prop O drev and the antifouling? Is that recommended

 

[Bosun Higgs]

The only really safe way is to strip it. But if the boat were mine and being by nature both mean and lazy I would probably cover the antifoul (after a quick sand down) with an impervious paint ( which hopefully would insulate) such as a vinyl primer like Primacon. Then antifoul with the proper stuff.

In theory the original coat of primacon should prevent the copper antifoul doing anything nasty anyway since there should be no electrical path between the ally of the leg and the copper antifoul. But I wouldn't want to rely on that since I could not inspect the coverage of the original primacon to reassure myself.

That a bit of a bodge TBH - better remove the lot then you can paint the ally leg with a proper underwater epoxy paint.

 

[emsworthy]

Why the Prop O drev and the antifouling? Is that recommended

The Prop O Drev is last year's which after a good jet wash was in pretty good nick but starting to get a few clingons. I figured a quick coat of Trilux would see us through the season.

Not to worry now though, the yard have just called to say they want to put her back in the 'oggin as she's in the way and will strip and repaint it for me for free!!

 

[wklein]

Not sure how big a problem this will be, definitely check with the supplier of the antifoul. I was recently assured by coppercoat that their products were absolutely fine on aluminium hulls and used on huge amounts of aluminium fishing boats so you never know

 

[billmacfarlane]

Funnily enough I asked a Volvo engineer recently what would happen if you used a copper based antifoul on a Saildrive. His reply was that it would be OK as long as you didn't scratch the Saildrive down to the aluminium as the Saildrive has a protective coating over it. That said I'd still be uneasy about leaving it on.