The Edge 14.5 and the Edge 15 are very similar boats . Just think if you took the 14.5 and stretched it out a bit - very similar volume and carrying capacity. The longer tapered bow will slice through the water a bit more so will be a slightly faster ...
HI The cover will fit most common cockpit sizes between 80 to 100 cm in length and 40-52 cm in width. The Edge 11 has cockpit size of 97 cm x 52 So yes it will fit but snuggly which is good so it's not too loose. Hope this helps,
For an older Edge 14.5 seat back, we do sell the older style seat to fit your kayak: Seat Back: https://boutiqueborealdesign.com/collections/seat-back/products/touring-backrest-for-sea-kayaks?variant=28063920947284 Base Seat Cover: ...