A partial list of United Kingdom (UK) boat propeller accidents that MIGHT have been preventable with a boat kill cord / emergency engine kill switch, lanyard cord.
Houseboat Propeller Regulation Proposed and Withdrawn by USCG: Analysis by PGIC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