Abstract: A boat plug apparatus is described comprising a boat having a circular drain hole at the exterior of the transom, and a ball which is pivotally attached to the transom exterior on both sides of the drain hole. The ball is positioned to be partially contained within the drain hole when acted upon by gravity. When the drain hole is not otherwise sealed, the exterior water pressure forces the ball into the hole and causes the ball to sealingly close the hole, preventing the water from entering the boat. When the boat is moving or is raised out of the water, the ball is free to swing away from the drain hole and water within the boat escapes through the drain hole.