Someone touched on it here before but there are two types of issues that lead to a submerged foil losing lift and they are often confused. Cavitation is a violent action on a small scale and is tiny bits of water flashing into vapor bubbles and collapsing with a tiny explosive force. If something cavitates for a prolonged length of time (like a boat prop) it can damage the material surface. On these boats, cavitation wouldn't be some big dramatic loss of lift but would act like a gradual stall on the foil. The cavitating situation would only be a very intermittent issue and would be limited to small areas of the foil and would result in an drop in speed so it probably wouldn't cause a crash. It would be just like hitting a speed ceiling that you can't exceed.

Ventilation is a different animal that is often confused with cavitation - it's where the foil sucks in air from the surface and it very quickly loses lift. This happens quickly and envelops the entire foil leading to a surprising situation. This probably had some affect on NZ's nose dive as their rudder foil got really close to the surface. Vertical foils (like rudders) can have this issue at high speeds and start to lose lift/stability at the top of the foil if it is configured in such a way that it sucks air down from the top of the foil...our boats don't get near this kind of speed for this to be an issue.

As shown by the design of the Vestas Speed Rocket, foils were a big part of their ability to beat the sailing speed record. Foils (mostly steering foils) are designed like a wedge for higher speed craft to help reduce the amount of cavitation on the areas that are needed for directional control. Where they labeled "air" in this image is a bit mis-leading...it should really say "vapor" as this is the point that the pressure in the flowing water drops so low that it turns to water vapor.



Reducing the number of foils is part of the thing that helped the Vestas Sail Rocket get the record.