Abstract: A protective device (1) of the “floating barrier” type for preventing a floating body from colliding with a construction includes a barrier element (2) consisting of a cable provided with floats (4), each of the two ends (2a) of which cable is connected to a respective one of the posts (3), and at least one of which ends is connected to the respective one of the posts (3) via an energy-dissipation system (5). The energy-dissipation system (5) advantageously includes: at least one chain having a segment that is folded in half, being made up of links that are connected together in pairs by breakable ties; and at least one spring member.