Those bubbles do collapse, but the problem is that as they collapse they generate tiny little shockwaves. Apart from being noisy, these implosions can be quite

Those bubbles do collapse, but the problem is that as they collapse they generate tiny little shockwaves. Apart from being noisy, these implosions can be quite destructive—the constant bubble collapses are fairly energetic, and cause cyclic stresses on materials. Over time, these can actually eat away at the surface of the propeller [0]. [0]: https://en.wikipedia.org/wiki/Cavitation https://en.wikipedia.org/wiki/Cavitation