What Is a Kill Switch (Safety Lanyard)?
A pull-cord that stops the engine instantly if the helm leaves the driver - the cheapest, most neglected life insurance on a small boat or tender.
A kill switch (safety lanyard) is a breakaway device with one end clipped to the ignition switch on the control panel and the other to the skipper’s wrist or lifejacket: if the helmsman falls overboard or is thrown clear, the cord pulls the switch and the engine stops at once. There are also modern wireless versions.
The scenario it prevents is one of the most frightening in boating: the boat turns in circles and comes back towards the person who has fallen into the water after the helm has gone overboard. On outboard tenders and fast boats, the one-second habit of clipping it on completely removes that risk.
Rules and maintenance
Clip-on habit: This is the only real failure mode; the fix is behavioural. The ignition key and the lanyard must live in the same place, and one should not be used without the other.
Worn cord: The stiffened coiled cord that goes brittle in the sun and any slack clips are checked once a year, and a spare lanyard is kept on board.
No bypass: If the switch fails, it is repaired, not disabled.
One sentence for anyone using a tender: if the engine is running, the cord is on your wrist. For anyone who goes off alone in a fast boat, a wireless system is a serious upgrade; if you fall, it not only stops the boat, some models also trigger a MOB alarm.