[chumbucket]

Yeah, it can definately crack hulls. The ice flows can actually lift pilings right up and out of the bottom. When the tide drops and ice forms around the pilings, it takes hold, then when the tide comes back in, it'll lift it. Over an extended time, it'll take it's toll. Usually, most marinas, or at least boat owners will keep a circulator in the water next to their boat to keep the water moving therefore preventing freezup around the hull.