Bram van der Vlist propeller safety student project. Eindhoven University of Technology. Netherlands. 2005. His system sensed people in the propeller danger zone wearing a tag and took action.
Houseboat Propeller Regulation Proposed and Withdrawn by USCG: Analysis by PGIC
History of Boat Propeller Safety
Mitigating Boat Propeller Injuries & Fatalities Chart
Four Volume Review of the Boating Industry’s Boat Propeller Guard Product Liability Defense