Gone Outdoors

How to Hook Up a Kill Switch on a Boat

by Nathan Fisher

Kill switches are designed to quickly disable an engine by interrupting current flow. When hooking a kill switch up on a boat, the switch should be designed to automatically shut the down engine in an emergency. A popular kill switch for marine applications has a "key" with two contact points that completes the ignition circuit when inserted into a housing. The operator attaches the key to his belt or wrist with a lanyard so it can be quickly detached if needed; if the operator is thrown overboard the key will automatically disengage.

Disconnect the negative battery cable with a wrench.

Locate a spot for the kill switch near the control console. Look under the console panel and locate the positive (red) wire leading to the ignition switch from the battery. If there is a covering on the bottom (or side) of the console remove the cover by removing the attachment screws with a screwdriver and pull the cover off. Consult a repair manual for your boat if needed.

Cut the red ignition wire six inches from the ignition switch with the electrical pliers. Move all wires aside and secure them out of the way with the duct tape and cut a hole in the console, in the selected spot, with the drill and spade bit.

Insert one of the wires from the kill switch and one of the cut ends of the ignition wire into opposite ends of a quick-connector and crimp the connector closed with the pliers. The wire does not have to be stripped as the metal tabs inside the "quick-connector" are designed to pierce the insulation when the connector is crimped onto the wire with the pliers, establishing the connection.

Apply silicone sealant over the ends of the connector to seal out moisture.

Repeat the quick connector attachment process with the remaining (cut) end of the ignition wire and the remaining wire from the kill switch.

Apply silicone sealant over the ends of the second connector to seal out moisture.

Insert the kill switch into the hole in the console, from the back side, and secure in place by screwing the attachment ring onto the threads of the kill switch bracket. Tighten the attachment ring in place with the pliers.

Secure the spliced wires with the wire ties and reconnect the negative battery cable.

Insert the key into the switch and start the engine. Test the kill switch by puling the key from the switch. If the engine does not shut off check the connections.

Items you will need
  • Wrench
  • Key-type kill switch
  • Electric drill
  • Spade drill bit (same size as the diameter of the kill switch)
  • Electrical pliers
  • Electrical quick-connectors
  • Marine silicone sealant

Tip

  • If you cannot find a convenient location for the kill switch near the boat's console, install it at the closest feasible location and add a length of cord to the lanyard of the key.

References

  • Heavy Weather Boating Emergencies: What to Do When Everything Goes Wrong: Chuck Luttrell and Jean Luttrell: 1999
  • Boatowner's Wiring Manual; Charles Wing: 2004

Photo Credits