I measured this stuff yesterday when I played around with retrimming my mainsail in order to catch our class chairman Hans in the next club race !

From fully untensioned after hoisting to flat sail all over and a tight downhaul/mainsheet I go from number 2 to number 8 on the magic marine stickers that have a spacing of one inch between the numbers (= 25 mm). So I do travel 6 inches = 150 mm. However when sailing I start at number 5 when having a slack downhaul and a modestly set mainsheet. so halve the travel length is caused by the mainsheet alone already and another 3 inches is pulled to flatten out the mainsail by pulling both tight.

In order to flatten my mainsail I have to play the mast rotation setting. I can't get it too flatten as in the pictures in Geerts post with playing the mainsheet and downhaul alone. But that maybe just my mainsail (and other Redhead mainsails)

Wouter