The wind limits put in place are more general and not specific to any design parameters. It was originally 33 knots. After a couple of incidents and reviewing the boat capabilities and feedback with the teams, it was reduced to what it is now to keep things safe.

The rules create several limitations on the designs that affect the stability of the boats on foils. In particular, the rule about having no foils extend beyond the perimeter of the boat means the teams all have an asymmetric rudder foil that is longer on the inside and shorter on the outside. This rule makes sense...you don't want an overboard crew member to be struck with the foil. In order to maintain stability, the boats need a certain amount of rudder foil surface area but there isn't enough room to put it without making it uneven. Because they are uneven, it induces additional bending stresses on the rudder and rudder mounting systems. The rudder foil is a key element to keep the bows from going under and actually pulls the sterns down to keep the bows up when they are turning downwind. I haven't researched it but I've been wondering if the rules also dictate that the rudders must be on the centerline of the hulls - because they ~could~ otherwise mount the rudders more inboard.

Foil cavitation is where the pressure of the water flowing around the foil drops so low that the water flashes into vapor/steam. It's a technical limit to any submerged foil and these guys are probably pretty close to that at full speed. When a foil cavitates, it suffers an ever quickening loss of lift. On these boats, the rudder foils are much more fine than the daggerboard foils so it's more likely that the daggerboards would suffer the loss of lift before the rudders...we would probably just see the boats settle down toward the water and as their speed drops off from the loss of altitude, the cavitation will stop and they will accelerate again. It's more of a speed limiter than a crash and flip issue.