Swing keel refurb. (long)
Chris,I've reconditioned two cast iron swing keels so far. The first was for a Venture 22, the most recent my 1979 Catalina 25. Here's what I did to them: After removing the keel from the boat, I had it sandblasted to "bright" metal. Done right, this is so not fun that I cheerfully paid someone else to do it both times, even though I own a sandblaster and two compressors. As soon as I got the keel back from blasting, I etched it with hydrochloric acid (a.k.a. industrial strength toilet bowl cleaner - be carefull!) to remove the rust remaining in tiny pores, rinsed it with lots of water, and then treated it with two coats of phosphoric acid (a.k.a. "Ospho"). After that was thoroughly dry, I used a stiff nylon scrub brush to remove any dusty residue. Keep a garden hose handy when working with strong acids. Don't let acid spills remain on concrete that you care about. Don't wear clothes that you care about for any of this work. I believe it's very important to get rid of all existing rust before encapsulating the keel. I think we've all seen how even a small amount of rust expands and spreads over time, even under a waterproof coating such as paint. At this point, the surface of the keel looks like pitted moonscape. Next, I applied two coats of WEST epoxy. This is done to seal the iron from exposure to oxygen, including water. At this point, the surface of the keel still looks like moonscape, but with a glaze. Then I made up fairing putty from WEST with filler additives (407), and rough faired the keel. If one were to get lazy, and apply bottom paint before this step, and then at some later point in time decide to fair the keel, getting the paint off of the rough surface (glazed moonscape) would surely be an agrevating task (a.k.a. big pain in the ...). After rough fairing, I wrapped the keel in two layers of 14oz. fiberglass cloth and WEST epoxy. This was done to protect it from misc. abrasion in the future. This step also serves to assure atleast a minmum thickness of epoxy over any raw cast iron high spots that may have become exposed while sanding down the rough fairing. At this point I also added a bronze shoe where the keel runs aground, and piled on several more layers of cloth and epoxy in that area, and along the leading edge. On the first keel I did, I tried leaving off the bronze shoe. The fiberglass quickly wore away where the keel touched bottom in shallow water. If you're the kind of sailor who will never run aground, feel free to skip this step. (If you're the kind of sailor who will never run aground, you can probably walk on water too.) I then did another round of final fairing on top of the fiberglass (WEST with 410) before applying copolymer bottom paint and reinstalling the keel. The hardest part of all this by far was dealing with the weight of the keel. The 500# one could be wrestled around by three people. The 1,500# one was a bit more of a challenge. This has been discussed on the Trailer Sailor BBS many times in detail.If there can be a good side to all this work, it's that if you do it right, you don't have to do it again.Good luck with whatever method you decide to use. -- Leon Sisson