Port rain shields by Beckson Marine help protect boat interiors from water while allowing fresh air to circulate to help prevent mildew and mold. Beckson offers internal and external models to fit a wide range of ports. Internal versions feature heat-repellent, smoked lenses and integrated bug screens. They can be adapted to fit some non-Beckson ports. Starting at $100 for internal models, $36.10 for the external/hood versions; amazon.com