Polyester Boat Cover for the Corsair 28 Trimaran. The Corsair 28 Winter Cover is designed to protect and cover the boat’s three hulls when stored on its trailer. Collars are utilized to secure the cover where cut-outs are necessary for each beam. Cover includes: Vents, Secure Tie-Downs and an entryway door. Fabric Selection- 12.5 Ounce Harbortime. ( Acrylic Impregnated Polyester).