Arne is right, the Reddish sail that Shirley adopted has positive batten stagger - a lot more in fact than the standard Hasler-McLeod sail plan, hence the need to extend the yard forward to avoid it coming off the mast as the sail is reefed.  I think if you add camber (Shirley did at one pint but then reverted to a flat-cut sail as she thought it looked untidy!), then the amount of batten stagger may be less.

I have long been attracted to the sailplan of Shirley Carter’s Sppedwell; with its increasingly angled battens and overall shape - but how do you reef it?

I can see that the lowest panels are parallel but the angle increases further up the sail. Does it have  adjustable lazy jacks or does the sail move forward when heavily reefed?

Paul