In 1995, Norwegian engineers moved a 1.2 million-tonne gas platform over 200 km using Archimedes' buoyancy principle, a feat that still influences the region's energy production today.
Historic move of a massive gas platform
In May 1995, Norwegian engineers moved a gas platform weighing 1.2 million tonnes over 200 kilometers on water using the buoyancy principle discovered by Archimedes. The platform, known as Troll A, stood 472 meters high and was towed using only the buoyancy of Archimedes, without the use of powerful engines or giant cranes. A record not surpassed
Troll A is not, however, the heaviest structure ever moved. That record belongs to Gullfaks C, which displaced between 1.4 and 1.5 million tonnes. Troll A, a concrete tower heavier than three aircraft carriers combined, was built to exploit one of the largest gas fields in the North Sea. Engineering for stability
Its structure alone weighed 683,600 tonnes, but once its compartments were filled with water to stabilize it during transport, the total displacement reached 1.2 million tonnes. This is equivalent to the mass of three American aircraft carriers placed end to end. The platform's design involved columns with walls more than one meter thick, poured in a single continuous operation to ensure a wall without joints from the top down to the seabed at a depth of 300 meters. Buoyancy in action
The principle of buoyancy discovered by Archimedes states that any body submerged in a liquid experiences an upward vertical force equal to the weight of the volume of liquid displaced. Troll A functions like a huge concrete iceberg, with its hollow columns filled with air before the towing, giving it a colossal volume compared to its actual mass. This allows the platform to displace enough water to float despite its massive weight. Final positioning
Once the platform had arrived at its destination, engineers used the principle in reverse by allowing water to gradually enter the columns, lowering Troll A by more than 50 meters in a few hours to stabilize it at 278 meters below the surface before finally placing it at a depth of 303 meters. The initial departure was planned for May 2, 1995, but technical constraints delayed the operation until the afternoon of May 10. A slow journey with global attention
The convoy departed from Yrkesfjorden, near Vats in the north of Rogaland, and headed toward the Troll field, located 80 kilometers northwest of Bergen. The cruising speed remained modest, between one and two knots, or just 1.8 to 3.6 kilometers per hour. This gave time for 80 journalists from nine different countries to follow the slow progress of the platform toward the open sea. Early success and adjustments
On May 15, five days after departure, the convoy was already 20 hours ahead of the planned schedule. This margin allowed them to start the ballasting operation earlier than planned, a delicate process involving partially flooding the columns to stabilize the platform before its final positioning. A year later, in 1996, Troll A became the first oil and gas installation in Norwegian waters to be directly powered from land, according to Equinor, the site operator. Ongoing significance
Three decades later, the Troll field continues to make headlines. The TWEL land electrification project has reduced emissions in the area by about 330,000 tonnes of CO2 per year, or approximately 75 percent of the initial reduction targets, which aimed for 440,000 tonnes. Equinor has since revised this program downward in October 2026. Meanwhile, gas production has been relaunched through the underwater Troll Phase 3 Stage 2 project, launched on August 22, which is expected to accelerate the extraction of 55 billion cubic meters of gas from the Troll West reservoir. Three decades after its historic towing, the old concrete giant has not finished making headlines.
