Don, those photos are great, and very encouraging to a first time builder of a SOF boat. Mine is a SOF version of John Winters' 15' Osprey solo canoe, plans for the strip version from Green Valley Boat Works. I also had about 3/8" hogging in the middle of the keel and solved it by a similar filling strip left over from ripping the stringers. Had to fill in two of the bottom notches with filler pieces of ply on the two middle frames for the stringers next to the keel as they sat a bit out of the notches. A lot easier to correct than a wrongly cut plank of plywood for a S&G boat. I'm now painting the bare hull, and looking forward to skinning it next week. Peter Lord