The measurements we will now add for mast bend are just like those we added for draft - an extension at each chord measurement that will make our new luff curve even more convex (the small brown chunks on the drawing - next to the blue chunks and red chord lines). Unless the mast is a real noodle, I'll usually add about an inch for bend at the one-quarter height, two inches at the half height and maybe 1.25"-1.5" at the three-quarter height on a sail of this type and general size. There may well be times when the mast is bending more than that in use, but you have to consider what bend allowance does in light air, too. If it's not windy enough to bend the mast much and we wind-up with more allowance than we need, that extra fabric works just as if we had added more draft allowance and suddenly we have a very deep draft sail in conditions where deep draft doesn't work too well. See, I told you it would be a compromise.

So...we've drawn our chords and added small chunks for creating some draft and to allow for bend. We are now ready to tape out our actual luff curve on the floor.

Step #3 - Okay, we have five points to connect with a batten, and then we'll mark our new luff line on the floor with tape. We'll connect the three chord+draft+bend spots with the original tack and head corners. Note that just running a batten along them doesn't always create a fair curve. There is a certain amount of acceptable "fudge factor " here, when needed. The head needs to be at the head and the tack needs to be at the tack. It's a good idea to also leave the half-height (maximum bend and draft) alone as well. If you need to fudge a little on the ¼ & ¾ height positions to get a nice curve, that will still work fine. If you find yourself off by half-a-foot or some other big distance, go back and re-check your measurements and calculations. Once the new curve looks good, tape it out on the floor.