Safety
Kill switch
An engine cut-off lanyard or wireless device that stops the engine instantly, killing the propeller if the driver is displaced or a rider is endangered.
A kill switch (engine cut-off switch or ECOS) is a safety device that immediately shuts down the engine, and therefore the propeller. The classic version is a lanyard clipped to the driver that yanks the switch if the driver leaves the helm; wireless versions trigger if a person goes overboard. Federal law requires recreational boat operators to use engine cut-off devices in many situations.
In wakesurfing the ability to instantly stop the prop is vital given how close the rider operates to the stern; cutting the engine the moment a rider is down in the fall zone prevents prop strikes.