I just bought a columbia 22. The diver who came down and did my first hull cleaning and inspection said the keel has rust and the boat should be hauled and the keel tended to. I have heard a couple of people suggest sand blasting, filling, fairing and then painting. The guys at the yard I'm going to said the mess was an issue. They suggested using a hot torch to heat the steel and "close the poors and remove any moisture" and then use a chemical to neutralize the rust, then fill, fair and seal. Anybody tried any of this? How did it work out?