Wow! I cannot imagine not covering the whole boat here in Michigan. I've done without and inevitably ended up with damage due to my negligence. The freeze thaw cycle will find any deficiencies in watertight integrity and make them into a more serious problem. I really don't want to get into the bone headed decision that led to my leaving the boat uncovered last year for a good portion of the winter. The money spent this spring was nothing as compared to the amount of time I spent for such laziness and stupidity. "Just a little rain" has a way of changing into "aw shucks" or maybe something a bit stronger. My hair hurts thinking about it.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.