Cheeky
The only one to go for is CuNigard. This is a fine mix of copper (Cu) and nickel (Ni) I think charged particles (least ways, the guy applying it got several mahusive static belts )
The difference is that the old copper coat was copper set in apoxy and although didn't need topping up or replacing for many years it does become progressively ineffective and needs abrading back every three years or so. Still better than most conventional antifoul.
With CuNigard, the epoxy is applied then the CuNi zapped into / onto it. This needs no abrading and they claim 10+ years but in the full knowledge that there are some oil installations out there for just over 20 years now
If it gets scratched you just top up at minimal cost.
Mine has been in for months and remains bright copper and nowt else -- pukka
CuNi is reletively newly released, to the general marine leisure market. CuNigard must be conforming well, as it would be a completely futile financial exercise if it wasn't so much better than the old stuff.
Treat her - you know it makes sense to keep a low maintenance bitch!