WindStorm Semi Custom Boat covers are simply the most durable boat covers on the market. They are made of marine grade fabric that will withstand the harshest weather elements and will outperform all critical categories of protection. Check the chart below and see how Windstorm sands up to Carver Boat Covers and Westland Boat Covers.The WindStorm Superior Boat Covers are backed by a logo of excellence. The fabric has a Durapel marine rain finish and is sewn together with a marine cross grade stitching. An alpine shock cord is sewn into the hem with mildew resistant thread. They have 12 XT heavy duty straps that secure through rugged canvas tie down loops. These boat covers promise to be the best boat covers and you will rate them s in customer satisfaction. They come in 10 colors and are backed by a full 7 year warranty. Features. Outboard Motors. Size - 15 ft 6 in.. Beam Width - 76 in.