The present invention provides a wireless power-supply control assembly 100 for wirelessly controlling a boat's main power supply. The assembly 100 comprises an enclosure assembly 110, wherein a latching relay 600 and a wireless-receiver relay 300 are mounted. The wireless receiver relay 300 is controlled by commands from a wireless transmitter and causes the latching relay 600 to connect or disconnect the boat's main power. In other embodiments, an ignition-sense relay 400 is also mounted within the enclosure and disconnects power to the wireless-receiver relay 300 when the boats ignition is on. In yet another embodiment, a manual override switch 200 is provided within the enclosure for bypassing the latching relay 600 and manually connecting the boat's power.