Both the A class and the F18 class are great success stories and deserve a lot of credit for promoting their class. However, I think the H16 probably has them beat for international envolvement.
Not that I am an authority.. but in all the years H16s have been made- has there ever been any significant changes? If one were to produce the same boat for 30 years then I would guess they would be worldwide.
Minor changes along the way - downhaul, main/jib travellers, integrated beams, better blocks etc however the sail plan, rig & hulls are all the same. Anybody who raced one in the 70's would immediatly be at home in a current boat.
Tiger Mike