Aspect ratios
The aspect ratio refers to the rig dimentions. Boats with a tall "I" (foretriangle height) and a short "J" (from mast to jib tack) would have a high aspect ratio. (the same is true with the main, tall hoist, shorter boom) Example: I=42' J=12.2, the aspect ratio is 42/ 12.2 = 3.4426. This would be a high aspect rig, which is good for light air areas. In heavy air areas, a shorter aspect ratio is fine.
