A boat loading guidance device including an array of indicator lamps which signals the boat operator when a boat has been maneuvered into correct longitudinal alignment with a submerged boat trailer. In the preferred embodiment a pair of actuating arms are angularly disposed to form a V-shape and adapted to engage the bow of a boat at the forward end of the boat trailer. Upon contact with the bow of a boat, the actuating arms close an associated switch passing electrical current by a plurality of circuits to either a port or starboard indicator lamp informing the boat operator of the direction in which the boat must be maneuvered into correct alignment with the trailer. In one embodiment, the boat loading guidance device is adapted to receive power from the battery of a towing vehicle by way of an existing trailer wiring harness. In an alternative embodiment, the device is self-powered by a plurality of dry cell batteries for supplying electric power to the lamp circuits. The boat loading guidance device is provided in kit form and adapted for attachment to an existing boat trailer with no modification or changes to the existing boat trailer wiring.