first make a template for the arches, Take a piece of cardboard and lay inside the front or back edge of the cockpit and mark a line following the top shape of the cockpit. You can adjust the height if you want.the cockpit on mine is wider in the middle so I used the same arch from the front just made the arches longer. The arches are then covered with luan or other type of plywood. make sure the luan overlaps the sides and the front or back of the cockpit, where they meet in the middle they should butt up against one another. Then you need a 3 or 4" strip overlapping the back cover. Make sure it overlaps from front to back keeps water out when travelling and also aerodynamics. the small metal tabs are what hold it on the hatch. The arches should be the same thickness as the gunnel lip at least on the ends where the metal tabs will be. The front and back tabs are stationary the ones on the sides spin so they can be installed.
Thanks. That is a great pictorial. I asume you fiberglass the top of the covers. Also, The locking mechanism looks to be in the middle of the two covers. One has an eyebold of sorts and the other a latch that goes over the eyebolt. Am I correct?