Pretty much right in the centre of the main window behind the boom ... where you usually get a few creases from rigging. I am usually in a rush to get out on the water, so I dont take quite as much time as I should but I am happy to accept a few creases in my sails. Never been a problem in the past. However unfortunately in the newer North Sails, they seem to crease & create a hard opaque ridge - just an inch or two long. Which I guess kinda sounds normal except these feel harder, more brittle and a bigger ridge .... then an eventual crack or split!? It's just a bit worrying as I have a whole quiver of them!