Hey
I had/have the same problem with some of the literature out there for Hobies. Never knew which condition was which. But Matt made a good point. It depends much on the experience of the sailor. When my girl friend and I started sailing, anything over 15kn was ‘heavy’. The problem is that we have strong continual trade winds which often blow 25kn (constant- never mind the gusts), the stronger days going over 30knots. Thus, our term for ‘heavy wind’ moved up very quickly as we gained experience. Medium down here is probably 12-20knots (we haven’t quite mastered the 25+ range and I start stressing when the weather man predicts in this region). It not nice when you’re the one standing on the beach because you think the wind is too strong while the others go out. But it just takes time, even my girl friend can sail happily at about 22knots now
The guys in Cape Town will probably be like the Ozies..
My two cents…

Clint