The classic division preserves the long legacy of the class before the foiling revolution. They remain the world's fastest single-hander in light conditions.
Classics have more conventional rudder blades but do have winglets, which make the boat easier to sail especially on bear-aways.
Daggerboards are allowed a small degree of curve, but not enough to make foiling possible.
The square-top and straight boom still provide performance advantages over foiling setups in sub-foiling wind strengths.
Most A Class classics in NZ are homebuilt and come in many shapes.