Abstract: A heave compensating support system is disclosed for positioning a subsea work package. The present invention provides a subsurface buoy with a lift line connected to the subsea work package and a compensating lift line having a catenary loop below its connection to the subsurface buoy on one end and connected to a surface vessel on the other end, whereby the heave compensating support system elements cooperate to establish a natural frequency for the suspended subsea work package which materially differs from the average wave frequency acting upon the surface vessel.

Abstract: A clamp is disclosed which is capable of latching on to a buckle arrestor on a subsea pipeline which has been severed in the vicinity of the buckle arrestor. By severing the pipe in this location and utilizing the buckle arrestor to latch the clamp on to the pipe, a simple and reliable clamp is used. A method to recover such a subsea pipeline by severing the pipeline in the vicinity of the buckle arrestor and utilizing such a clamp is also disclosed.

Abstract: Tendon segments are fabricated on a laybarge, then temporarily stored on seabottom. When a tension leg platform is moored, two tow vessels pick up one end each of the finished tendon and tow it to deep water, with the tendon in a catenary shape. Upon arrival in deep water, one end of the tendon is released and allowed to free fall to its uprighted position. A special work boat then transfers the tendon to the tension leg platform for final installation.

Abstract: Subsea pipelay is accomplished by flying the pipestring underwater with the use of wings which provide sufficient lift to maintain the pipestring off bottom as it is towed.

Abstract: A remotely operable apparatus and method for determining from a remote location the distance and angular orientation between two structurally unconnected members, such as two sections of a subsea pipeline, is disclosed. The apparatus of the invention comprises generally two remotely releasable guide posts disposed, respectively, in known spaced relationships to the two structurally unconnected members and a remotely operable measuring template. The remotely operable measuring template is adapted to telescope axially and includes two ball and socket joints to compensate for misalignment or differences in elevation between the guide posts. In practicing the method of the invention, the remotely operable measuring template is positioned over and firmly attached to the guide posts. All movable joints of the template are then locked and the guide posts are remotely released. The guide posts may then be retrieved to the remote location in the same spaced relationship as originally disposed.