Everything was going smoothly until I glued the first blocks across the ribs. Instead of marking my block locations on center, I marked to the top edge but ended up gluing and brad nailing them to the bottom...

I'm not sure how many of you install your blocks without any offset. I would think a small dado (maybe 1/8") to hold them on each side of the rib would work instead of nails, but I thought that might be overkill and went with the offset and nails instead. As far as strength goes I'm not sure there is any difference. The hatch is very rigid and has minimal amount of twisting if forced. I am a happy camper!