I happened to have this picture in my files. (my apologies for the dirt! this was the first year I bought the boat, it is certainly cleaner in the bilge now!) It appears from this photo that the engine mount is a separate mold that has an approx. 2" flange all around the engine mount ribs. The engine mount U shaped component with that flange all around the "U" is laid down in position on the interior of the hull and the flange is overlayed with substantial piece of wetted out fiberglass mat and adhered to the flange as well as the hull itself between the flanges. That is what it looks like to me from the photo. This is my guess.
Regards,
Andre
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