Look at the telltales on the jib--if you haven't got them installed, install some yarn about a third down from the top and about 18" behind the forestay/luff on both sides of the sail; one on top of the other so you can see both. If both yarns fly nearly straight back, you are good. If not, play with the sheet tension until they do flow back together or change course until they flow back together. The manual actually has a pretty good description of what to do.
Formerly raced F24 Mk II