Re: To cover or not...
My pontoon is kept in a boathouse without cover, however blowing rain has rotted my rear sundeck and the pads on each side of the motor. I replaced and painted the rear end plywood 6 years ago while installing all new carpet. The rest of my plywood is solid after 26 years usage. My vinyl is finally starting to crack--but would have lasted years longer if I had covered the boat.
If I purchased a new pontoon boat today, I would order the $800 factory snap on cover and a set of individual seat covers. As long as I used the boat weekly, I would use the seat covers. If I wasn't going to use the boat for 2 weeks or longer, I would put the snap on cover on it. If impending storms were coming, I would install the snap on cover. From October to May, I would use the snap on cover AND a secondary tarp--keeping the boat completely dry and out of direct sun--or inside.
A boat cover is a great investment, as it will make your carpet and seats last so long. Properly maintained pontoon boat can easily last 30 years+ with the same engine. No other personal asset has such value. My 3 1/2 year old grandson sits on my knee driving my pontoon--just like his momma did 20 years ago at the same age. It's almost like Deja Vu.