... Without this feature, trapped moisture cannot escape. This leads to all kinds of moisture related problems such as mold and mildew. That’s why most boat covers are made of cotton. Cotton is made waterproof by using a very tight weave. This allows the material to swell when exposed to moisture and this swelling causes pores to close and prevent water from entering. When dry, the material shrinks and opens the pores to allow trapped moisture to escape. Uncoated cotton is also nonabrasive and this allows the boat cover to be installed down to the waterline without scuffing and damaging the surface. Extending the cover down to the waterline is better for securing it because wind can’t get under the fabric and pull the cover loose. You also need a frame to support the cover so it can shed snow and ice. These frames (and usually the covers) can be custom built for each boat. You can also find ready-made systems for popular boat designs and these do a good job of protecting your boat. Make sure you purchase a system that’s easy to install and remove. Storage is also a consideration and the system you purchase should be designed to take up very little space when not being used. Boat covers, especially custom built units, cost a lot of money. But the price is worth it when compared to fixing damage caused by weather. Ordering custom covers in the offseason will usually get you a good discount. ... Boat covers help to protect against damage from snow, rain, wind, and sun ...