yes - the lake freezes.

I should also clarify. The sailboats in particular need the bridges raised which is why they have a scheduled time to exit. Ordinary boats can be removed closer to the water or navigate the river without the bridge being raised. Those boats are also removed for the winter.

These particular sailboats are stored in the winter at either Chicago Yacht Works or the Canal Street Boat Yard.

Yes. The lake and river will typically freeze over for most of the winter. Any boat in the water would be smashed to bits by wind-blown ice.

Chicago in February is indistinguishable from Hoth.