Method and apparatus for reducing set-down of a tension leg platform

An Auxiliary Mooring System (AMS) supplements a Tension Leg Platform (TLP) tendon-based mooring system, to provide lateral resistance to offset movement of the TLP in extreme survival events with minimum impact to the TLP or permanent tendon system design. Limiting platform offset also limits set-down of the platform. The mooring system of the invention provides a method and apparatus for supplementary mooring of a Tension Leg Platform. The apparatus includes a plurality of catenary mooring lines attached to the platform's lower columns or pontoons and secured to the seabed by means of piles or other established anchoring means. The method of the AMS includes installing compensating buoyancy devices on the platform.