If something comes adrift, it is no longer attached to an object that it should be part of. Three insulating panels had come adrift from the base of the vehicle. = loose
without direction, without purpose; (Nautical) drifting, not anchored (of a ship)
If a boat is adrift, it is floating on the water and is not tied to anything or controlled by anyone. They were spotted after three hours adrift in a dinghy