Try to see how relatively 'round' or curved the foot is between tack and clew compared to the leech. If the foot seem's stretched flat and the leech is fluttering then it may only be lead car setting that's the issue.
As a starting point, drawing an imaginary line from the block through the clew it should intersect the luff at it's midpoint between tack and head.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"