Stability Calculations for the Norne and Johan Castberg FPSOs
Published: March 12th 2026
As part of our framework agreement since 2005, Polarkonsult has been responsible for the maintenance and continuous updating of all stability documentation for the Norne FPSO. The stability work is carried out in accordance with the applicable regulations issued by the Norwegian Maritime Authority for floating installations with a ship-shaped hull, as well as the requirements from the classification society DNV and the International Maritime Organization (IMO).
The stability calculations cover both intact and damaged conditions and require continuous monitoring and updating of the vessel’s technical basis.
Professional support in complex maritime procurements
“The calculations include stability in both intact and damaged conditions. As part of the work, we update weight distribution, wind moments, and the overview of all openings and air pipes, as well as other details that affect stability. We also develop and update loading and offloading procedures for both summer and winter conditions,” says Arne Markussen, Project Engineer at Polarkonsult.
The work is performed using advanced stability calculation software from two different suppliers. In addition, Polarkonsult provides the calculation basis for the stability calculator installed on board and actively used in daily operations.
“As part of our scope, we also deliver the calculation basis for the onboard stability calculator. It is essential that the calculator is based on updated and accurate documentation,” Markussen continues.
The stability documentation forms a central part of the operational procedures on the installation. Throughout the entire period, we have maintained close and highly professional cooperation with specialists at Equinor, both in Bergen and Harstad.
Experience from Norne Transferred to Johan Castberg
A similar delivery for the Johan Castberg FPSO has recently been initiated, also as part of the framework agreement.
“The work includes complete follow-up of the stability documentation in accordance with applicable authority and class regulations, based on the same methodology and quality level established for Norne,” Markussen concludes.
The start-up represents a continuation of Polarkonsult’s long-term work within stability analysis for complex floating production units. In this work, precise calculations, systematic updates, and close cooperation with the operator are essential to ensuring safe and efficient operations.
