The first winter I covered "Rockhopper" with two tarps, one fore of the mast and one aft over the boom. Well, the one over the boom started to buckle in with the weight of snow. Water was the funnelled by the tarp (aka giant watercatcher) straight onto the cockpit from where it then made its way into the cabin, running into the aft berth. At the end I had a horrible stinky mess all over.
Not used a cover since. I might one day get a cover that properly fits the boat or better a proper shelter, but they are big bucks !
Boat Shelter Titanium 3,5 x 10 x 3,5 x 4,5. Strong boat shelter for sale. Boat shelters PVC. - Dancovershop UK