The total allowed area is 17m2, so if your sail is 16.6 that only leaves 30m of mast surface (For reference, a Tiger's mast surface is 150cm).
It must be a typo, although 15.6 would still be quite large The Tiger's mast perimeter is 33cm, the Infusion mast is wing shaped
to its perimeter must be at least the same if not more (The maximum allowed is 38.5cm).