They say if you haven't hit granite you haven't cruised the North Channel of Lake Huron. We had been through this very narrow and shallow passage three times within the last week, but the fourth time we discovered something hard. Up there it isn't something as soft as mud, or sand, or even coral. Weed was growing up nearly to the surface, making sight and the depth sounder useless. I was idling and coasting down from 4 knots (should have been going slower), boat came to an instant stop, almost dumped the wife up on the bowsprit overboard. Its a solid lead keel, and it is times like this that I am happy I insisted on 16 keel bolts made from K500 Monel, lab certified to 130Kpsi tensile! Damage wasn't as bad as I thought it might be considering the violence of the collision (the keel already has a flattened bulb foot similar to a Scheel shape - I didn't do that!).