If you see an A-class sweeping by on the downwind in speeds around 15-20 knots and you see that the hull is lifted clear from the normal waterline due to the lift from the hydrofoils I would file a protest immediately. Since the hydrofoil is a grey zone and there are no ways no measure if a device is a hydrofoil or not this must probably be handled on water. There are no "rule" that bans the tips from the foils to be closer than 1.5 meters at the ISAF or A-cat website.

/hakan