I tacked the stretched canvas up to the decks on my first canoe yesterday. It went smoothly by and large, but some of the tacks have noticeable sags between them. I tightened the canvas from end to end (longitudinally?) as I went along, and that helped, and also stretched it laterally with the canvassing tool, but still have a few that seem problematic. In "Jerry's Production Journal" in "The Wood and Canvas Canoe," Jerry Stelmok writes that "when the pliers release their grip, a tiny fold of canvas is formed directly over the fastenings," but he doesn't suggest it's the end of the world. In "This Old Canoe," Mike Elliott first says I need to remove all the tacks, retighten the canvas longitudinally, and then refasten everything. He also says that "small sags between the tacks will disappear when filler is applied to the canvas, so there is some leeway in the process." If I need to retighten the canvas longitudinally, I need to do it before I remove the stretching rig. It does seem to me that the outwale should flatten it out, but I don't want to take any chances with something I can't do over later. Any advice?