modified cover
Like others, I hang my mast and boom in the garage over the winter, and I'm fortunate to be able to garage the boat over the winter. But for a summer cover, I bought a generic 17' cover from Wal-Mart. Out of the box it fit well except for the stern, where there was too much material. So I pulled the cover snug, gathered the excess and held it temporarily with clothes-pins, marked the location of the new border with bits of tape, and then took a pair of scissors to it, leaving a little extra material to fold over and glue. I used a length of the nylon tie-down cord that came with the cover, laid it along the new edge, folded the flaps over, and glued the flaps in place with clear Goop sealant/adhesive. I left the ends of the cord sticking out, as well as a knotted loop at the aft end centerline. I terminated the ends of the cord, as well as the trimmed ends of the elastic cord, with line stopper knobs from my local marine store. Now there's no excess material, no slack in the cover, and I can pull it tight enough to shed water without the support of battens or anything else underneath.