Baltika is the world's first oblique icebreaking vessel. Designed by Aker Arctic Technology, Baltika is used for icebreaking, rescue and oil-spill-combat operations in the Gulf of Finland. The vessel represents completely new technology; a patented oblique design with an asymmetric hull equipped with three azimuth propulsors. This allows the vessel to operate efficiently, forwards and backwards, in up to 1-meter-thick ice levels. In oblique mode (sideways), the vessel is able to clear a 50-meter-wide channel in up to 0.6-metre-thick ice, creating a wider channel for larger vessels.
Three azimuth propulsors were chosen for the main propulsion system instead of a traditional hydraulic steering system. 18 VACON® NXP AC drives (72 A) are used to control the azimuth thrusters that maintain the vessel's correct position and to steer the propulsors that enable the vessel to move forwards, backwards and sideways.
We use VACON® AC drives in three roles: to control vessel steering and lubrication pump motors and for controlling slipping clutches. In total, we have more than 2250 VACON® NXS and VACON® NXP AC drives in the power range of 3–205 A in our projects. For us, a Finland-based AC drive manufacturer is a great benefit. We have developed together many new items and features, and it has been easy to get in contact with the best experts.Aarno Niemi, Automation Manager, Steerprop
Compared to a traditional, hydraulic steering system, modern AC drive control has many benefits. Noise levels are extremely low, installation is easier and less space is required. The VACON® NXP AC drives are installed in close vicinity of the propulsion thruster system and they communicate via a PROFINET fieldbus. Thanks to the IP54 enclosure, they can be installed on the wall and no switchgear is needed.
Maintenance functions are simpler. Oil and oil filters are not necessary in the azimuth propulsor's steering gear, and there is less mechanical wear which results in decreased costs and maintenance needs.
Control of the azimuth thruster is more accurate as there is no crawling due to valve leakage. And reliability is increased. There is always a minimum of two or more parallel motor + AC drive combinations in use. If one combination stops, the steering system continues to operate.
The motor + drive combination consumes energy only when the azimuth propulsors are actively turned. This improves the overall efficiency of the propulsion system by 1–2% compared to a hydraulic steering system, which has a major economic impact during the entire lifecycle of the vessel.
propulsion system efficiency improvement