Help!I bought my Hunter 35.5 4 yrs ago, had a survey and all was well. We hit a rock motoring at 6 knots and "hopped" over it with a pretty good impact. This was 20 months ago. We had a diver check for a "smile" line at the time and he didn't see anything. We pulled it for bottom paint last month and it's been the boatyard blues since then. We had the typical "smile" crack, and water seeping out from it. When we pulled the keel, the yard found keel bolt corrosion. My insurance is telling me they'll cover the re-bedding and fairing of the keel due to the impact, but the corrosion is a long-term issue and not due to the impact -could this be true? I don't see how. It was out for 3 weeks before the keel got detached, and the water was still seeping out of the crack. How else could corrosion occur other than at the point where water comes in contact? I'll rule out dissimilar metals as I would hope Hunter would pay attention to that. Crevice corrosion through the bilge maybe? I'm at a loss. Any comments are appreciated. I've surfed the archives and only a couple of references to this condition, but no causes are discussed. THANKS for your time!