Dear all nacra 18 owners , i have just bought new nacra 18
when i pull the sail up , i find the sail when it reach top and get hooked on the sharp edge , the main sail stay with a gap of say ...10 cm , although i add a shakle to hook it , still the boom not in line with sail , it allow the air go in between , any body can advise , or this the way it is suppose to be [color:"red"] [/color]

I am not sure what you are asking. Are you referring to the gap between the bottom of the sail and the boom?

If the gap is at the top of the mast, thats a problem with either your hook, you knot on the ring being too big, or too many shackels in there. If it is between the foot of the mainsail and the boom, then there may not be enough to room there to down haul properly which will also be a problem.
Please explain a little more, or better yet, show us some pictures.

David Mosley
NACRA F18 Rigging Tips