I have been experimenting over the past few months, deliberately going out with the "wrong" kite size. Riding with 4-5m kites in the mid teens and 10-12-15m kites in up to 25 knots. All kites have been 3 strut surf-style LEI kites on 24m lines.
It appears you can put up any kite you want and make it work. Obviously the "right" size kite is more fun for the conditions, and smaller kites are always a joy.
The limiting factor of small kites seems to be the ability to water start reasonably comfortably. If you can get going with a couple of swoops then you can ride ok. If the kite is too small then you're fine as long as you can keep up and riding. The apparent wind is ample for riding but you might not have enough power to get up on the board. The biggest risks are getting stuck in the water in a lull, or stalling the kite, mainly during a transition.
With a large kite, if the wind is too light the kite can be too slow to get a decent water start. At the upper end, riding along is fine, apparent wind upwind is scary but manageable. Transitions can be a but dodgey. The downwind legs of a transition can be extended and it can take a while to slow down.
Jumping seems to be compromised (well it is for me). If the kite is too big I find it hard to hold the edge to get a good boost. Smaller kites with more wind seem to jump better. That could be me.
The conclusions I am being drawn to are:
- foils are so efficient that you get a heap more bottom end out of a kite.
- that increase in the bottom end doesn't translate into a proportional loss in top end. The same skills and abilities that apply to TT and surfboards apply just as well to a foil. The same ability to edge and apply body weight and position in the window and managing apparent wind work just fine. The loss in top end is relatively small.