Once the winter cover is on, it stays pretty dry under there, and when the sun comes out, even in the cold of winter, it stays warm! The cover is a very thick canvas that holds the warmth of the sun quite well. Think of what it was like way-back-when camping in a canvas tent and how warm those got in the sun! But the idea of covering a boat is not necessarily to keep it dry, but to keep rain and melting snow from freezing in areas that could cause eventual leaks such as between the fiberglass and window seals. If water got in there and then froze, the ice could cause it to expand and the window to leak. The cover also protects the boat from UV during the winter, thereby protecting the deck of the boat and its components. It also makes it nicer for working on projects under the cover while the snow is flying in the winter! I can plug the boat into outside electricity in order to keep the batteries charged as well as to use a portable heater and electric tools.
Here are some pics and a short video of what it looks like under the cover of Adventures Await. We use a ladder to get on the swim platform on the stern of the boat to climb inside. The video of inside the boat shows the cushions askew, doors open and looking like a mess, but we leave the cushions and doors that way to allow for air flow and to prevent mold.