Special Order
David, I've had to replace the entire port. Mine are elliptical. I contacted Boat/US Special Orders desk to order the ports. They may have just the gasket. Try them.You may also try the distributor. Pompanette (www.pompenette.com) may also have replacement parts, but be prepared to pay extra. The entire port will cost about $100 from Pompanette ($75 from Boat/US) and you may consider replacing the whole thing. It takes about an hour and a whole 4 oz. tube of LifeCaulk. Check the dogs carefully where they attach/pivot in the port frame. They eventually pull out and the whole port needs to be replaced. I've had to replace all three elliptical ports on my L37. The problem with the gasket, though, is that it compresses over time and the sun also dries and cracks the gasket. My boat was 10 years old before I needed to replace the first one. With new gaskets, you also don't have to tighten them down so hard.