Hi Mark,
I’ve owned a 13′ Maravia self bailer since 2006 and I store it every winter. I’ve had good success making sure that the raft is clean and dry, rolling it up as tight as I can and then sticking it in a basement, shop or garage, basically anywhere out of the sun and dry. The only other tip I have is to store it on a warm day, my raft is hard enough to roll when warm, the couple of times that I’ve done it when cold out were much more difficult, especially if you’re doing it solo. If anyone has additional tips, I’d love to hear them!
Mike