A rig unit for a fishing line includes a float body and a ballast mass removably coupled to the float body. The ballast mass and the float body are configured to remain coupled together during a launch phase and a flight, and to separate from each other upon impact with the water at the end of a flight path. During flight, when the float body and the ballast mass are connected together, the rig unit is orientated with the float body arranged in front, and the ballast mass arranged behind it. After separation upon impact with the water, the ballast mass is configured to rest on the seabed. The main line has a first section descending from the fishing rod to a guide passage of the ballast mass, and a second section ascending from the guide passage to the float body, which is able to remain immersed, at a distance from the water surface, with a terminal line extending upwards, starting from the float body, to an auxiliary float with which the hook is associated.
