I began making the hatches today. I made a template for half of each hatch with paper and transferred the shape to the deck on masking tape. I masked both inside and out to prevent scratches and de-lamination of the fiber-glass. I used a Japanese Bonsai saw which is very sharp and flexible and cuts on the pull stroke. Once the cut was about half done, I taped off the finished half to prevent too much vibration while finishing the cut. See the video below.
Once cut out, I smoothed all the edges with sandpaper and then sealed them with epoxy. I also put a one inch strip of ‘glass around the perimeter of the inside of each hatch to provide extra strength and a smooth surface that the seal will fit against.