Its hard to know where you might have gone wrong, but here is how I made the hatches for my CLC 17LT. I laid out the opening shape on a piece of drafting mylar and traced it out on the deck. I used this same pattern plus 3/4" all around for the hatch itself. I made a couple patterns for the deck curviture, noting as I did that the forward end of the forward hatch is different than the aft end of the fwd. hatch. I also noted that none of these curves matched the design radii very well. I attached the frames to the ply with epoxy using hand spring clamps on the ends.

My aft hatch came out twisted as well. I attribute this to twist in the ply. I clamped the upside down hatch to the workbench with a towel under it and racked it in the opposite direction plus some. I left it for a day and it straightened out fine.