Cavitation occurrence on the propeller blades may have severe effects, such as cavitation noise, vibrations in the aft ship, and material damage on propellers or rudder. While noise and vibrations affect comfort and stability, cavitation erosion might lead to a significant reduction of the propeller efficiency and structural integrity. Cavitation erosion prediction is therefore extremely important. However, it still remains a challenging issue, especially on marine propeller applications where computational time limit in a practical propeller design environment is imperative. This paper focuses on cavitation aggressiveness on the propeller blades of the KCD-193 model propeller. Cavitation intensity is assessed by the potential power density. Following the idea that the potential power is the basis of the cavitation aggressiveness, we found that by computing the potential power of the first layer of cells, in contact with the blade surface, it gives a useful first estimate of the regions that are exposed to a high erosion risk. The use of a mean field pressure, which is the time average of the local pressure, as the driving pressure behind the cavity collapse, was necessary to get a good match with experimental observations.