The Rocksteady tensioning tool (TT) is a subsea mooring line tensioning system to simplify the installation and replacement of mooring lines on floating offshore assets.

The key benefits of TT are that it does not require any external tensioning interface and no tensioning equipment is left in the system.

Only a single rental Rocksteady TT is required to tension an entire mooring system.

The two halves of Rocksteady TT are drawn together by a surface winch to make a quick connection under final tension, quickly, easily, and repeatably.

Lowest capital cost

  • No chain stoppers or tensioning systems to maintain on the offshore asset. The mooring lines attach to padeyes, with an option to include lever arms to manage chain OPB.
  • No expensive and heavy fairlead systems subsea on either the hull or in-line tensioning system.
  • The Rocksteady TT is rented as part of the installation service, so you don’t pay for equipment that you use once.
  • The only component left behind is a type approved Rocksteady subsea mooring connector (SMC).

Simple & accurate line tensioning

Rocksteady TT is perfect for catenary mooring systems and can also be used effectively with taut leg polyester mooring lines

  • The required tension is calculated from accurate survey, catenary calculations and advanced system analysis.
  • We use this analysis to directly set the installed chain lengths, rather than measuring tension.
  • Tension is verified by the surface vessel winch and optional load cells subsea or on the offshore asset hull.
  • This simplifies the installation process, enabling crews to accurately set final mooring line tensions irrespective of hookup procedure.
  • Polyester lines that require creep control are fitted with a short length of chain that is simply removed or shortened following the same tensioning process.


  • Permanent production facility installation
  • Mooring line replacement
  • MODUs without mooring line tensioning equipment (DP conversion)
  • Floating wind and other renewable energy systems

Contact us for more information, or reach out to our sister company InterMoor for a full installation service using Rocksteady TT.

Rocksteady tensioning tool and the method described are patent pending, United Kingdom Patent Publication No. 2585985A.