Up here in the northern climate, we all know what happens to roadways when water enters pavement cracks, freezes, expands and then thaws. The substrate is undermined, surface crumbles - resulting in potholes. This analogy can be associated to boats left exposed.
Most of the 500+ sailboats, in water or dry docked at my marina for the winter, are not shrinkwrapped or covered. They seem to survive the effects of ice, snow, freezing and thawing.
What is not immediately visible, is what expanding ice does to deck fittings and minute gel coat cracks. My boats have always been either shrinkwrapped or protected by custom fabric covers every winter. The risk of damage is just too high, especially with my current boat which has a forest of teak, including teak decks.
True Blue . . .
sold the Nauticat