Method for installing an anchor that is released in the sea, especially for installation of in soft seabed sediments. An anchor is rebased in free fall from an at rest position or nearly at rest position and with the longitudinal axis vertical from a position in the water, and that ensures directional stability and nonroutional acceleration during movement towards the seabed. The anchor body (14) has a main member or shank (22) with a regular cross section, especially circular or regular polygon form, with tip (23) and with upward projecting shank (25) with lower average density than the main anchor body has. The anchor body is shaped such that the center-of-gravity lies lower than the middle of the total anchor length and below the average distance to the sum of all the fluid forces which ensures directional stability and nonrotational acceleration during free fall and penetration into the seabed sediments.
Methods for installation, connection to, and use of anchors for mooring of marine structures, especially although not exclusively for gravity installed anchors, and accompanying apparatus. One embodiment comprises an anchor having recovery and load lines attached thereto, both lines held by a trailing buoy and with subsea connectors at their upper ends, held up by the buoy. The trailing buoy is held in a release frame, the anchor is lowered to a desired height above a seabed, then the release mechanism is shifted and the anchor is permitted to free fall and penetrate into the seabed. The trailing buoy and subsea connectors remain above the seabed, and a mooring line from a structure can be connected to the load line via the subsea connector. A second embodiment comprises a launch frame attached to the lowering line. A length of chain or rope is looped from the base of the launch frame to a remote release near the end of the launch frame arm, and from there to a recovery line assembly connected to the anchor. A load line assembly is also connected to the anchor. Once the anchor is lowered to a desired height, the remote release is actuated, and the anchor plunges downward into the seabed. Subsea connectors on both the recovery line assembly and the load line assembly permit attachment and detachment of the lowering line and the mooring line. The apparatus and method of this invention requires only a single vessel and a single deployment line.
