Beckson PO512-DWC-20 Rain Drain Opening Port, 5" x 12", 2" Spigot Depth, White with Clear Lens. For ports mounted on a sloped surface. Rain Drain ports are designed for use where cabin sides are sloped, and other ports would collect rain and spray. The molded in Rain Drain? channels drain while tipped as much as 40?. They resist clogging and are easy to clean. No water enters the boat when you open the port after a rain.