40 or 80 grit for grinding back keel

[shortjohnsilver]

Hauled the boat yesterday - cast keel and found that the bulb and it’s wings have taken a bit of a bashing over the last year with dinks and nicks out along both wings and rusting pushing through in areas of damage.
This year I’ll need to take a bit more of a robust approach and will be purchasing an angle grinder. Going to get some flap discs and at point of purchase wondered what’s best 40 or 80 grit?
Thinking I’ll grind back to bright metal and then coat with epoxy light primer 3 or 4 coats. Then fill and fare with epoxy marine filler, fare that smooth and then coat another couple of coats of the epoxy light primer. Then antifoul.
So, 40 or 80 or a couple of both?

 

[neilf39]

Tercoo wheel will probably be better.

 

[shortjohnsilver]

Thanks neilf39 I’m going with both grit flapper discs. It’s cosmetic really and not a full scrape back.

 

[MisterBaxter]

I found the twisted wire cup brush extremely good for cleaning steel back to bare metal with an angle grinder. Gets into the pits a little better that a flap disc.