Take a look at just about ANY cruisers sails that are 'up', look at the main especially --- and watch to see inevitably that the boom is drooped so that the aft end of the boom is just about *always* lower than the gooseneck. This means that on boltroped dacron sails the 'preload' that the sailmaker designed into the sail to affect proper shape is hardly every stretched out. Such boltrope preload is what give a dacron sail stability in the design 15kt. wind range.
BTW - for almost all dacron sails with boltropes the amount of pre-load that should be stretched out (for sailing in 15kts.) is about 1" additional stretch out for every 10-11 ft. of luff length ,,,, all resulting in a sail whose tack angle (measured from the top of the boom to mast) is approx 90°. If one doesnt stretch out the boltrope preload (by additional halyard tension) you get 'baggy', draft aft shape and with a leech that is tight and hooked up to weather ... all resulting in a boat that aggressively heels, weather helm, has difficulty pointing and is SLOW. And what is worse, the boltrope get progressively shorter as its length shrinks over time and the boom droop can be 'bodacious'.

Im located on the Ches and each fall and my wife and I (racers and long distance cruisers) have a 'game' ....just for idle fun during late Sep/ early Oct, we purposely look for any southward bound cruising boat that doesnt have a drooping boom ... we hardly ever see one that isnt drooped. So, if your tack angle on your main when full raised (for 12-15kts) isnt at a 88-90 deg. angle .... that sail will never take on the shape that the sailmaker designed into it simply because the sail wasnt raised corredtly so it could take on its designed shape.