According to Steve Falk (a Sunfish and 470 champion) "in a small boat as the wind strength increases, the heeling forces on the boat become more than you can control by hiking or putting weight on the rail. Here you want to increase twist to reduce the forces on the upper portions of the sail." That is where you want to start easing the vang to allow the top of the sail to twist off to leeward. The bottom portion of the sail still drives and keeps the boat pointing, but without the big heeling moment caused by the upper part of the sail. So the answer, it seems to me, is that you ease it enough so the top of the sail falls off enough so that you can control the heel of the boat with you weight.
the jib luff tension should always be less than the forestay tension , you want the forestay carrying load of the rig not the sail.
Ease your jib halyard , if your getting excessive forestay slack , adjust by tightening the shrouds.
I'm struggling with tuning my shrouds. I have them a bit loose because I read somewhere that the mast on the C-14 (and mine is actually an Omega 14) should be able to move back and forward for best performance beating and running, respectively. So here is my question. Before you put the sail, or even the boom on the mast: Should the mast be able to move fore and aft, or should the tension on the headstay and shrouds be enough to hold it from moving?
I have mine set-up to where you need a slight amount of pressure applied to the mast to to be able to insert the jibstay into the adjuster. on a close reach, in wind over 10 knots my leeward shroud slackens visibly.
That was about how the boat was set up when I got it. I had loosened up the shrouds one notch on each side and it is so loose there are times I hear the mast clunk as it moves back and forth in light wind when the boat rocks. So I'm going to look at either tightening the adjuster on the forestay or shortening the shrouds back a notch. Should there be any rake in the mast without vang or mainsheet tension? check the rake on the international 14 in the picture! Jim M