The fist step is to cut the hatch ribs. I used the wall template to create the first rib, then used that rib for the rest. Here I am lining up the pattern for the second hatch rib. Originally I thought I would use a router to cut each piece but the rib was a bit too flimsy so I traced it and used a jigsaw instead.
Here all 7 ribs (I had to make an extra one later). After the ribs were cut I clamped them together and used a rasp to make them as uniform as possible and smooth out the curves. It was important to get these smooth or else my plywood skin might be lumpy or uneven.
Using clamps to hold the ribs on with a piece of 1/4″ scrap to allow for the hatch movement.
Allowing space for the hatch and galley skins, each 1/8″.
I used double thick ribs on the outside for rigidity and allow space for the hatch struts to be installed. It will also help distribute the load of the hatch struts which will bolt directly to this section.
The ribs were secured with short deck screws for fitting and once the measurements are complete for the cross members, it will be reassembled with Titebond III wood glue.
Here you can see the 3/8″ gap for the hurricane hinge installation.
The cross members were installed with glue and brad nails to hold them while the glue dried.
Material from the outside rib was removed to allow space for the hatch struts to be installed. When fully closed the a large portion of the struts will rest inside this gap.
The larger blocks here are needed to back the lights and locking assembly which will be installed later.