Originally Posted by Weyalan
For those who have runners / checkstays, cranking on plenty of runner and backstay and easing checkstay can also help flatten your main which will help with your helm. Incidentally, added runner will flatten the headsail too.
Not sure tensioning the runners flattens the main in all cases. What flattens the main is bending the masthead aft with the backstay and the middle of the mast
forward by easing anything that moves the middle of the mast aft. Tensioning the runners would tend to reduce the mast bend IMO, and therefore reduce the flattening of the main. On the other hand, to the extent the runners are going more amidships than to the stern, tensioning them might actually pull the top of the mast down, and thus promote more mast bend. So I think it depends on the boat.
I say "not sure" because my actual experience is limited to racing
a fractional rig sloop
. I own a cutter
44 that I have not sailed much yet, but enough to know there is a weather
helm problem that I have to solve.