I'm about to get new antifouling (Coppercoat) on my Bav40 and also want to address the (partially) rusty keel.
I'll grind and brush the keel as good as possible and then apply Hempel's Light 45551.
I suppose, when all rust is removed the keel won't be smooth as a baby's bottom. Should I worry and address this or is it just optics?
I wouldn't worry about it. You're not planning to do any serious racing, are you?
Suggest you have the keel blasted. Grinding is really not good enough to eliminate rust on an existing keel. Coppercoat needs the keel to be fully encapsulated in several coats of epoxy. Obviously costs more than grinding but will give a better chance of working. If you can't get it blasted properly then suggest you don't Coppercoat the keel and accept that rust will come through eventually - but is easier to patch with conventional antifoul compared with Coppercoat.
The keel on my new 33 in 2015 was ground to remove the factory coating before Coppercoating and rust started to appear after only 3 years. I then had it blasted, 5 coats of Hempel Hempadur and then new Coppercoat.
Quote from: Krumelur on August 06 2023, 09:13
I suppose, when all rust is removed the keel won't be smooth as a baby's bottom. Should I worry and address this or is it just optics?
I wouldn't bet on it, some cast iron keels can become 'slabby' over the years... where corrosion tracks under the surface causing thin layers to detach in patches..
This is obviously likely to occur during grit blasting and results in an uneven surface...
It's also worth noting that quite a lot of moisture can get trapped beneath these layers and the keel should be allowed to dry after grit blasting and before any treatment applied....
Although aesthetically poor, None of this affects the integrity or functionality of the keel and as suggested by others blasting is the way to go as apposed to grinding....
Bare metal will start to rust immediately. I would additionally recommend one or two coats of Zinga paint. I found it to be excellent against rusting.
If using epoxy best to get the first coat on immediately the blasting is finished or give it a sealing coat to stop flash rusting. I have done it both ways, but for Coppercoat based on my experience, epoxy on immediately is preferred.