I had a look at that website. the 5" round port, in bronze, looks about right.
I take it that the 5" is the hole in the middle.
In a big sea, with the washboards in, we ask the helmsman on watch to sing. You can't see him, so we have to hear him so we know he hasn't fallen in the drink.
Although I sing absloutely beautifully... Bryan Ferry would not get a look-in.... the first mate's singing is shocking, and a portlight would be much cheaper than a shrink.