yes you need a LOT more tension on your jib halyard. the forestay should have NO tension while you are sailing hard to windward. or on any other point of sail. ALL the load should be on the jib luff wire. the purpose of the forestay is to hold the mast up when the jib is not being used. you need the extra forestay adjuster to let the mast lean back enough to achieve block to block sheeting. and a little slack in the sidestays is good because the mast wont rotate freely if they are too tight. but the forestay should carry no load while sailing. when i set up on the beach i have about 8-12" of slack in the forestay, that means if i pull the slack out of the forestay toward the mast, as high as i can reach,there is about a foot of distance between the slack forestay and the jib luff wire. depending on how hard its blowing. when you are block to block sailing hard into 18 kn, your forestay still needs to have a little slack in it so that the jib luff wire is carrying ALL the load of the mast and mainsheet sheeted to the max- so that the jib luff wire is as straight as possible upwind. a curved jib luff creates a fuller sail which is slow upwind. especially when its blowing. when winds are lighter you dont need as much halyard tension because you shouldn't be sheeting as hard. the goal is to be ALMOST block to block with ALL the load on the jib luff wire and NO tension on the forestay. the forestay should be bowed, the jib wire should be as straight as possible : )