MariTech Swim Guard propeller guard. We took this photo when they were demonstrating how quickly the guard can be installed. They just grabbed some parts that were not yet painted for the demonstration.
Aspects of the Propeller Safety Debate chart
Houseboat Propeller Regulation Proposed and Withdrawn by USCG: Analysis by PGIC
History of Boat Propeller Safety
Mitigating Boat Propeller Injuries & Fatalities Chart