We used to motor a friend's J22 out by pushing it up on the ice, (Crew weight aft and full motor, then crew weight forward to break ice), for a New Year's Day sail. Another friend keeps his boat in all winter. It freezes around it, it squirts up, then it thaws and it settles back down. It has an outboard so no worries about thru hulls and all that. The hull is round so the ice doesn't really get a grip on it. Some years we have little or no ice. Some years the ice is more prevalent but in the twenty years he has wintered his boat this way there has been no damage. The greatest problem is trying to approach the boat on the dock when it is covered with snow and ice. He once ended up in the drink - a dangerous situation.
But we sail the boat at least once every month during the winter and they are some of the sweetest sails of the year. Everything about the experience is different than summer. The light is different. The clarity of the air (And water) is different. The density of the air is different causing the boat to react differently to the same wind velocities as summer. The sun angles make the water and sky look different. Instead of Osprey's there are sea ducks and seals. It's really a great time to go sailing. You just have to stay on the boat!