U.S. Patent 8,257,121 – 3PO Propeller Shield. Guy Taylor’s hexagonal boat propeller guard with the swing up / flip up rear screen to reduce drag when underway.
Houseboat Propeller Regulation Proposed and Withdrawn by USCG: Analysis by PGIC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