Questions about corrosion and and what looks like a crack on my lead keel

[aDemilich]

Hey all,

I bought an old C&C 27 a few months ago as a first boat and have been working on slowly restoring it. This weekend I was working on scraping all the old paint off of the keel so that I can a fill a gap in the front of the keel-hull joint with epoxy filler, then cover everything with an epoxy barrier coat and paint it. The keel is in pretty rough shape, and I'm seeing two things that are pretty concerning. First, what is this rust(?!)-like corrosion all over the keel?

https://imgur.com/a/oukZHyG

The boat has a problem with stray DC current which ruined the prop shaft, so I'm guessing that was also the cause of this- but I'm a bit bewildered by how much this looks like rust, considering that the keel is supposed to be lead. Any information I can get about what's going on here and what I should do before priming over it would be greatly helpful. This is all over both sides of the keel, and is basically impossible to get off with a sander due to how pitted the whole surface is.

Also, there looks to be a thin crack in the lead itself right below the hull, which you can see someone previously filled in partially (as well as a bunch more of the rust-like stuff):

http://prntscr.com/1046xyj

I'm also aware of the sizable gap in the keel-hull joint shown here (which appears to be the result of a hard grounding) and am working to remedy that, but I'm wondering if I should also be worried about this. It only appears on one side of the keel.

[Rob_P]

I can't see your pics (old OS on this computer that HATES imgr) but I'd say to check your keel bolts for corrosion and proper torque. Ask a knowledgeable someone to verify what you find either way (good or bad).

Fix what's busted, putty/paint, and go sailing.

FWIW, rust on the keel usually means iron not lead despite what you've been told.

[rbk]

Sounds like you may shave a cast iron keel and the start of a ‘smile’. Check your keel bolts or drop the keel if you feel it’s warranted even just enough to properly inspect them. Re-bed the keel and tighten the bolts, continue fairing and prepping the bottom as planned. Look up ‘Catalina smile’ for more info (there is also a lesser known C&C smile which is the same thing).

[aDemilich]

Here's the second image re-hosted, since the forum didnt like my previous link: https://imgur.com/a/0bKCpZ7

It's hard to believe that the keel isn't at least mostly lead, as it's soft like lead and quickly oxidized white after sanding, plus all documentation I've seen about the C&C 27 states that it has a lead keel- could it be an amalgam?

[rbk]

Looking like the rust is from your keel bolts weeping out between the stub and keel. Might be worthwhile to separate and inspect.

[roverhi]

If the boat has the raked/swept back keel that was typical on C&C's, the gap may be normal and will close up when the boat is back in the water. The forces on a raked/swept keel when it is supporting the boat in the yard are the opposite of when the hull is supporting the keel in the water. Out of the water the weight of the boat pushes the aft end of the keel up and forward end of the keel down and the opposite in the water.

Filling the gap with epoxy or other hard filler won't allow the keel to assume its natural position when launched. I'd use flexible caulking to fill the gap unless it's way large.

Keel castings don't tend to be the best metallurgy. Those rough spots are possibly just imperfections in the metal from the casting process. Would be nice if you could have the keel soda blasted to clean out the bad stuff and coat the keel with epoxy scratched into the metal with a wire brush. Lead forms an oxide very quickly after it has been sanded bright that paint won't stick to. Using a wire brush on the wet epoxy scratches the epoxy into unoxidized lead.