A vessel for laying a pipeline includes a plurality of workstations disposed along a pipelaying path that includes an upstream portion away from a first end of the vessel and a plurality of ramps, includes a first ramp and a downstream second ramp disposed along the pipelaying path, in the region of the first end of the vessel. Each of the plurality of ramps has a first upstream end, a second downstream end, and an adjustable inclination. The downstream end of the first ramp is positioned inboard of the first end of the vessel and above the bottom of the vessel and the upstream end of the second ramp is positioned inboard of the first end of the vessel and above the bottom of the vessel. An external ramp assembly includes ramps that can be pivoted relative to one another and locked in a selected position.

A laying tower for laying pipelines on the bed of a body of water has a supporting structure extending along a longitudinal axis and provided with guides parallel to the longitudinal axis; a first clamp, which is mounted on the supporting structure and configured for selectively clamping and releasing the pipeline in a given point along the longitudinal axis; and a second clamp, which is selectively movable along a path, which extends along a first section above the first clamp; and a second section below the first clamp and, partly, below the supporting structure and configured for selectively clamping and releasing the pipeline along the path.

A laying tower for laying pipelines on the bed of a body of water has a supporting structure extending along a longitudinal axis and provided with guides parallel to the longitudinal axis; a first clamp, which is mounted on the supporting structure and configured for selectively clamping and releasing the pipeline in a given point along the longitudinal axis; and a second clamp, which is selectively movable along a path, which extends along a first section above the first clamp; and a second section below the first clamp and, partly, below the supporting structure and configured for selectively clamping and releasing the pipeline along the path.

A pipelay vessel having two pipe string manufacturing lines and a firing line, wherein the pipe string manufacturing lines are designed for simultaneously handling two different pipe outer diameters for use as an inner pipe and an outer pipe respectively. Further, the vessel has a pipe-in-pipe assembly workstation for assembling the inner pipe and the outer pipe in a pipe-in-pipe configuration. The vessel is designed with a lay-out which allows for producing offshore pipe-in-pipe strings from single joints, wherein available space is optimally used and pipe-in-pipe strings can be produced safely offshore.

A release mechanism for a tether assembly. A circular base ring has a central opening sized to accept a connecting member, and a plurality of radial slots. Dogs are disposed in the radial slots, and movable radially inwardly and outwardly. A cam ring having angled slots is operatively connected to the base ring, with upturned ends on the dogs engaged in the angled slots. Relative rotation between the cam ring and the base ring, by hydraulic cylinders connecting the two rings, moves the dogs radially inwardly and outwardly. In their radially inward position the dogs engage a circumferential groove in an elongated connecting member, thereby connecting the tether assembly.

A method of converting a subsea laying system of a surface vessel from a laying mode to an abandonment or recovery mode Includes clamping at least one tubular sleeve in at least one clamp of the laying system. A winch wire can then run longitudinally through the or each clamped sleeve when suspending an elongate subsea element such as a pipe string during abandonment or recovery operations. The sleeve protects gripping pads of the clamp from damage due to dashing with the wire and so makes it unnecessary to remove the pads in preparation for abandonment or recovery.

A method of converting a subsea laying system of a surface vessel from a laying mode to an abandonment or recovery mode Includes clamping at least one tubular sleeve in at least one clamp of the laying system. A winch wire can then run longitudinally through the or each clamped sleeve when suspending an elongate subsea element such as a pipe string during abandonment or recovery operations. The sleeve protects gripping pads of the clamp from damage due to dashing with the wire and so makes it unnecessary to remove the pads in preparation for abandonment or recovery.

A stinger including a first member formed from a first non-metallic material, a second body member formed from a second non-metallic material, and a plurality of cross-support members disposed between the first body member and the second body member. The first body member includes a first lower portion, a first upper portion, and a first intermediate portion disposed between the first lower portion and the first upper portion. A width of the first lower portion is greater than a width of the first intermediate portion and a width of the first upper portion, and wherein the width of the first upper portion is greater than the width of the first intermediate portion. The second body member includes a second lower portion, a second upper portion, and a second intermediate portion disposed between the second lower portion and the second upper portion.

A stinger including a first member formed from a first non-metallic material, a second body member formed from a second non-metallic material, and a plurality of cross-support members disposed between the first body member and the second body member. The first body member includes a first lower portion, a first upper portion, and a first intermediate portion disposed between the first lower portion and the first upper portion. A width of the first lower portion is greater than a width of the first intermediate portion and a width of the first upper portion, and wherein the width of the first upper portion is greater than the width of the first intermediate portion. The second body member includes a second lower portion, a second upper portion, and a second intermediate portion disposed between the second lower portion and the second upper portion.

A pipelay vessel having two pipe string manufacturing lines and a firing line, wherein the pipe string manufacturing lines are designed for simultaneously handling two different pipe outer diameters for use as an inner pipe and an outer pipe respectively. Further, the vessel has a pipe-in-pipe assembly workstation for assembling the inner pipe and the outer pipe in a pipe-in-pipe configuration. The vessel is designed with a lay-out which allows for producing offshore pipe-in-pipe strings from single joints, wherein available space is optimally used and pipe-in-pipe strings can be produced safely offshore.