Boat Engine Kill Switches: Things to Know

Whether you boat requires a kill switch or not, you should still get one. Laws are calling for new boats of 26 ft and under with motors capable of 115 lbs of thrust or more to be fitted with an engine cut-off switch.

However, boats that fall outside that category should have one installed anyway just in case. It’s just a common sense boating safety accessory, and a basic kill switch will only set you back a handful of dollars. Here are things to know about boat engine kill switches. 

What the Boat Engine Cutoff Switch Does

Commonly known as kill switches, engine cut-off switches are safety devices that immediately shut off the outboard or sterndrive if the helmsman becomes separated from the boat’s controls. 

The kill switch is a simple ON/OFF switch that completes an electrical circuit to the motor when it’s on, allowing it to run. When the switch is off, it breaks the electrical circuit to the motor, preventing the engine from running. It's attached to the helmsman, either physically or electronically. If the helmsman is thrown from the boat’s controls, the connection is severed and the switch automatically turns the engine off, thereby immobilizing the boat.

Types of Boat Engine Kill Switches

Boat cut-off switches are either tethered or electronic, with the differences being mobility and price. With the tethered system, the kill switch is a push-pull switch that’s held open by a clip or collar. This clip is physically attached to a lanyard or cord tethered to the helmsman. If the helmsman moves too far from the switch, the cord pulls the clip from the switch, allowing it to shut off.

With the electronic system, the kill switch is a transducer operated by a small transponder housed in a tag or fob worn by the helmsman. When the transducer and transponder are in close proximity, the switch is on. If the helmsman moves too far from the switch, the transponder no longer communicates with the transducer and the switch turns off.

Tethered or Electronic?

Tethered cut-off switches are very inexpensive, with a typical kill switch costing under $25 (as of this writing). The drawback is that you must be physically connected to the kill switch, so the tethered system can restrict movement around the boat. Plus if you’re not careful, you can inadvertently pull the clip from the switch and unexpectedly kill the motor.

Electronic cut-off switches offer more freedom. With no lanyard or cord between you and the killswitch, you can move freely on board without deactivating the switch. An electronic system can also be used simultaneously by multiple people. So if the helmsman is thrown overboard, another person can still maneuver the boat. The only downside to electronic kill switches is that they’re more expensive. 

Boat Engine Cut-Off Switch Tips

Make sure you’re tethered to your kill switch cord or have the kill switch transponder fob whenever your boat’s outboard or sterndrive is running.

Also, keep in mind that kill switches are typically made of plastics that eventually deteriorate due to sun exposure and age. They’re relatively delicate and can fail, so you should regularly test and replace your killswitch.