The raw material... · Okay, we start with a piece of most any kind of wood, preferably something with a small grain. The dimensions will depend upon the size of the port cut into the hull side. A slot is created in the wood using whatever tool you wish. I used a router bit that was almost equal in diameter as the port opening is wide. In this case 10mm. Note that the wood is wider by about 3 mmm greater than the port opening size. This flange on each side of the slot will be glued behind the planking either side of the port opening.