65+ is just a number, and it sounds better than heavyweight in my opinion. Most of the boats I'm refering to are probably more like 75-80kg in reality.

65+ is roughly half way between minimum class weight and the average weight of the heavier boats. Actually if it were 70+ I don't any of the era boats I'm referring to would be eliminated or forced in the lighter division. If I had to take a wild stab in the dark, I would say most boats pre sail number 1200-1300 would be a heavyweight.