A little Physics...

That sucking sound sucks

Please let me stand up for the most abused word in hydrodynamics: Cavitation

Cavitation is not sucking air by a foil close to a free surface, cavitation is not sucking air by a redneck on a speedboat with flames on the side. Actually, there is no air involved in cavitation. Sucking air into the water and on the foil/propeller or whatever sucks, is ventilation.

Profiles (foils) in a fluid (water or air or whatever) have a suction side (low pressure side) and a pressure side (high pressure). When the suction side (for a profile in water) generates an extreme low pressure, the water can start to boil. Water (fluid) then becomes water vapour (steam, NO AIR but H2O) even at this low temperature. The profile/foil feels no longer a fluid but a gas and the lift dramatically decreases and the sh*t can hit the fan.

A pressure so low to create vapour can happen at high angles of attack (not well adjusted when accelerating) or at (very) high speeds (Vestas).

So: Air and cavitation never mix‼

– Anarchist John

From Sailing Anarchy