Do you get snow? If you get snow it is imperative to cover. The condensation factor is HUGE. Picture a foot of snow on your decks! Now picture the sun coming up and the outside temperature climbing to 45 degrees but the inside boat temperature is still 20 degrees from the previous night. Drip, drip, drip.....
Hopefully that helps
paint the picture....
I once looked at an Ericson 38 that looked like an ice cave inside. It had cool looking icicles hanging from everywhere and the headliner had fallen away. It had over two feet of snow sitting on the decks and basically the boat was totaled from one season uncovered in Maine!
If you don't cover shovel or clear the snow after each storm..