My porthole liners seem to be very popular, so I though they deserved a page of there own! I have lots of liner examples in my Recent Work (Porthole Liners section), but below are a selection of different ones and a little about how they are made.
Each liner is different, and some times even the same size portholes have different size liners! They can be made as thick or as thin as you like, some time ago I even turned some 15” ones that were only 3mm in thickness. They are made usually from 6 segments and with at least 2 layers. The joins are staggered for strength and glued together with a waterproof high performance glue. The section can be whatever you prefer and in the wood type that suits your boat. They are all turned by hand on my old Harrison lathe, and I use self made jigs and fixtures to ensure perfectly flat and square faces are achieved.