Cast Iron Keel Repair

[Bay Sailor]

Hello,
I'm getting ready to repair rust on my Mac 25 keel, I went ahead and purchased Pettit "Rustlok" and "Tie Coat" for the prepping which after some research looks like a good choice. But I have a fairly large pit to fill and fair about 10" x 5" and 3/16" deep. My question is how should I deal with that? My plan was to first hit it with two or three coats of the Rustlok, then use epoxy/filler over that - fairing and sanding smooth then proceed with coating the entire keel with Rustlok (two or three coats) - hit it with tie coat (two or three or four times) then top coat with Pettit ablative bottom paint. My fear is the epoxy won't adhere to the Rustlok as well as bare metal so should I do that first? I don't have the option of sandblasting and will be coating over some rust.

Bay Sailor

[wannago]

Sounds like you are spending an awful lot of time and money trying to avoid having it sandblasted. Maybe take a little extra time and find out what it would really take to get that done? Try an auto body shop or two?

You sounds like your putting forth a lot of effort to get a really good job done without just doing it right from the start.

[Bay Sailor]

...getting a 600 lb keel to and from a shop plus the expense of sandblasting is quite a task and much more expensive then doing a good encapsulating job I think. remember its a Mac 25 and easy to haul out (trailer) for any rust spots that bleed through (usually about every two years) plus its actually going to be berthed in fresh water most of the time. But yes you're right if it was a fixed keel and a more expensive boat I'd have second thoughts...

[SabreKai]

Hey, if you really want to go nutzo, you can get welding rod for your arc welder that will do cast iron. Fill the dish and grind it flush again. 3/16 deep is nothing. I had pits upwards of 3 inches deep on my last Grampian. That was done with epoxy and sawdust. Lasted 5 years between jobs, through very cold winters.

Sabre

[Bay Sailor]

Thanks, that's really not so nutzo... I've started already with the Rustlok first (after much wire brushing) and epoxy etc..
I've read a lot of testimonies about Rustlok and they've all been good. Anyway, we'll see and thanks!