Once the keys are in and the Hatch is fitted to the companion way the top piece has to be marked and cut to match the curve on the sliding hatch. The sliding hatch has to drop over the drop hatch so it catches, this means leaving the drop hatch about 1/8″ higher than the bottom of the sliding hatch. I also have to bevel the top curve of the drop hatch till the sliding hatch can easily drop over and catch. The block plane makes this easy to do, just mark with pencil and plane down to the marks.
A latch is added so the boat can be locked up and then the pieces need to be sanded to remove any saw and plane marks. Using a piece of carpet to sand on keeps the hatch from sliding around. Be careful not to create cross grain scratches at the mitered corners.
Some oil will finish these up nicely.