Hi Paul,
My portholes are aluminimum with two dogs. And, yes they saw salt water service, and are pretty bad. There approximately 23.5" long by 9.5" wide, that would include the frame. I have been looking at Spartan Marine Hardware, Mariner's Hardware, and a couple of west coast shops but a like porthole is going to cost about $500/each. Any, leads to buy original portholes in good condition would be greatly appreciated.
Mike |