Screens for Man Ship Round Portlights Aluminum Framing Fiberglass screens Rubber gaskets to ensure a tight fit Most boat owners prefer to have screens on their portlights. Man Ship manufactures a high quality aluminum frame screen that fits snugly in place which lets the fresh air in and the insects stay out. Ventilation is very important in keeping your boat from smelling musty and stale. Regularly opening your portlights allows fresh air to enter and circulate throughout the cabin, which greatly improves the freshness, comfort, and interior temperature of each cabin.