Not long ago I attempted to design and build a single chine S&G kayak with the bottom panels somewhere in size between those a Point Bennett 18 and a Chesapeake 17 and using the same type of geometry. I did not understand developable surfaces as well as I thought I did, being extremely ignorant of conical development. I worked out my offsets for the bottom panels assuming that they would "twist" from a dead rise of about 10 degrees amidships to nearly vertical at the bow and stern. When I went to stitch the bottom panels to the side panels, they did not match as they approached the bow and stern. I was able to cut off the sections that did not match, join another piece on, adapt the keel offsets from the Point Bennett &/or Chesapeake 17 which are quite similar and scribe the outer offsets to fit the chine. I completed the kayak and have paddled it for some time. I have since realized that I needed to use conical development in the bottom panels. Can anyone tell me where I need to put the apex of the cones to produce bottom panels like those on the Point Bennett and Chesapeake 17?