Keel Problem

[defazfam]

I recently purchased a 1981 Catalina 27 standard rig. The keel has a noticable bulge about one foot square on the port side of the keel. It is toward the bottom of the keel and well away from the hull-keel joint. There is a fine crack in the bulge surrounded by a rust stain. If you tap the bulge with a hammer, it sounds hollow as though it has separated from the keel. I thought the Catalina 27 had a lead keel so I can't figure out what causes the rust stain. The boat yard where the boat is currently hauled is a little reluctant to tear into the keel, remove the bulge and fill the resulting depression with epoxy. They are concerned that the epoxy won't hold to the keel and might eventually fall off. Anyone know what might have caused this bulge and what is the best way to repair it? Or, should it be repaired at all?

[pigslo]

It sounds like an encapsulated keel that has crack that let water in that rusted the iron inside the keel. Have you been to the Catalina site to find out the specifics on whether your keel is bolt on or encapsulated?
pigslo

[sailingfool]

Your C27 does have an external lead keel, sounds like it must have a fiberglass skin over the lead or has been coated by a PO, and the skin has delaminated in a spot. Lead will show some rust.
I am surprised the yard is leery to open up the side of a solid lead keel - do they have mostly powerboats there?

This should be a simple DIY repair.
- Buy a supply of West Expoxy and microballoon filler.
- Use a putty knife or chisel to cut off the skin
- Grind the lead bright with a wire wheel or abrasive disk
- Clean and immediately brush on a coat of epoxy.
- Apply and sand additional coats of epoxy/microballoon paste
until the reapir is faired to your satisfaction, then paint. Read product directions as to time, temp, solvents to use, etc.
Anytime year you hit something hard and put a divot in the keel, you will need to go through this process to properly repair. This type of repair is strictly routine BAU.

Good luck.

[defazfam]

Thanks to pigslo and sailing fool for replies. As I understand, keel is bolt-on (threaded studs with nuts show in the bilge above the keel) and encapsulated with epoxy and fiberglass fairing it into the hull. I have read that it is just about impossible to remove. I thought that all Catalina keels were lead but lately I have heard that some were iron. (I haven't had a chance recently to drive out to the boat to test the keel with a strong magnet). Interesting that lead can result in rust stains. Will the epoxy hold just as good on iron as on lead? (Boat yard where boat is hauled is about 50-50 power and sail but I think they do mostly mechanical work there).

[Sailormon6]

I had a 1981 Catalina 25. Early Catalina 25s were made with cast iron keels, and they changed to fiberglass encapsulated lead keels in about 1983-4. I think the same is true of the C27. If so, I'd suggest that you take 2-3 hours to strip all the old antifouling paint off the keel using a paint stripper designed for fiberglass. It's made for glass bodied cars, and you can get it at a store that specializes in auto paints. (About $15-20. a gal.) Once the old peeling paint is stripped away, you can see what you're dealing with underneath.

Cast iron keels were generally pretty crude castings, and Catalina coated them with coal tar epoxy to seal the iron. Then they used fairing compound to fill all the depressions and smooth them out. If you strip all the old paint from the keel so that all that's left is the fairing material, coal tar epoxy and bare iron, and clean the bare iron with a wire brush in a drill, and then re-seal it with coal tar epoxy, replace any loose fairing material and then paint it with antifouling paint, that will give a good, reasonably long lasting result for most purposes.

I do think every boat with a cast iron keel should have a sacrificial zinc or magnesium attached, depending on whether it's in salt or fresh water, because it'll prevent any reaction that might cause damage to the fairing compound. As you noted, those bulges are hollow, and I suspect they're caused by an electrolytic reaction that causes gas to form and lift the fairing compound. I had them happen almost every year until I installed a sacrificial anode.