The tragedy is that sun penetrating the safeties can accentuate the buildup of humidity under the cover. Vents should be added after the wrap is in place. This licenses airflow into the boat and helps stop growth and density. If you want access to the boats interior, a zippered door is available. Most tarpaulins are made from sheet flexible with some kind of supporting network fused in place. Nautical stores have shrink-wrapping kits accessible. They contain the whole thing from the film, to the propane radiator and even a filmed of how to do the packaging. Often numerous boaters will group together and buying one kit and additional film, splitting the costs. Carpet scrapings or sprig protected in place work well. If you have movable antennas, place a length of PVC pipe over them when wrinkled. Often they are complicated structures, assembled and exposed year after year. With shrink-wrapping the boat is enclosed with plastic film that is impoverished in place and then shrunk with a propane burner.