Abstract: The device according to the invention comprises an anchor, a chain connecting the anchor to a craft and a heavy stabilizing piece which, when the anchor is on the sea-bed, is fast with the chain in an immersed zone of the chain. The stabilizing piece consists of an assembly composed of two masses of the same triangular shape, connected together at one apex of the triangle by the pin of a pulley, allowing the piece to slide on the chain. This stabilizing piece is maintained fast with the chain above the sea-bed, thanks to a rope of which one end is fixed to the piece by a support and of which the other end is fixed to the craft. The invention is more particularly applicable in the domain of craft of low tonnage.