Abstract: A method for positive locking of a tension leg platform tendon bottom connector C in a tendon receptacle R contained in a tendon foundation pile P, the bottom connector and receptacle having mating locking elements. A vertical space S is provided in the foundation pile between the tendon receptacle and the soil level inside the pile sufficient to allow vertical entry and locking of the bottom connector and receptacle locking elements, and a material M of sufficient density is placed into the space beneath the tendon bottom connector in the tendon receptacle and the soil level inside the pile to limit downward vertical motion of the bottom connector and prevent accidental release of the locking elements. When required, a sufficient amount of the material may be removed to allow the requisite vertical motion of the bottom connector to release the locking elements.

Abstract: A tendon for mooring a tension leg platform having an uppermost pipe segment with a reduced diameter compared to at least one of the lower pipe segments. The tendon is watertight and sealed from the ocean environment, preferably filled with air at one atmosphere of pressure. One or more interior bulkheads may be included to divide the tendon into multiple compartments. The reduced outer diameter of the uppermost pipe segment provides reduced drag due to waves and currents and accommodates smaller tendon support buoys and vortex fairings, while the greater diameter of the lower pipe segment provides for increased tendon buoyancy.