[Aktungbby]

At seventy, the only cavitation I ponder is my teeth! https://wonderfulengineering.com/her...kept-a-secret/ & https://nationalinterest.org/blog/re...minance-164733 https://www.popsci.com/resizer/etaCx...GP5QWOYVC4.jpg

A rim-driven pumpjet has a ring-shaped electrical motor inside the pumpjet shroud, which turns the vane rotor (a vane rotor has the fan blades attached to a rotating band built on a cylinder interior, as opposed to a propeller shaft) inside the pumpjet cavity to create thrust. Previous submarine pumpjets are "shrouded propellers," which consist of a tubular nozzle covering the propeller. By removing the shaft of the propeller, the reduction in the number of moving parts decreases the noise made by the pumpjet, as well as saving hull space. Civilian manufacturers also claim that rim driven pumpjets are easier to maintain, and have less cavitation (bubbles that form during propeller movement), making them even more quiet.