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 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.