A chemical tanker in the service of Norway-based Odfjell will soon be fitted with a wind-assisted propulsion system engineered by bound4blue. When completed in 2024, the vessel will be the first of its class to deploy this new suction sail technology.

The autonomous rigid sail system – eSAIL-- is a complementary propulsion system that produces effective thrust from existing winds, reducing the main engine power required and delivering fuel consumption and pollutant emissions reductions of up to 40%.

The technology is based on active boundary layer control using suction. When exposed to wind, with the suction mechanism off, it only produces drag as with any other non-lifting structure. When the mechanism is activated, a small amount of air is sucked in, which re-adheres the airflow to the sail and generates enormous amounts of lift with low drag.

Tanker pictured with suction sails. Source: NagellD

The eSAIL produces six to seven times more lift than a conventional sail, with minimal power consumption. The suction fan is a standard axial compressor driven by an electric motor to support the intake of air via a porous skin composed of marine-grade materials and ensure the airflow remains attached to the sail.

A rotation system based on a standard slew-bearing actuated by an electric motor ensures that the eSAIL can rotate to orient toward any existing wind direction. An autonomous control system efficiently operates the eSAIL with no intervention from the crew.