The new Wärtsilä Steerable Thruster series (WST) is being introduced to replace the company's Modular Thruster and Compact Thruster series, while the new Wärtsilä Transverse Thruster series (WTT) is replacing the current range of transverse thrusters. The new products have been developed in response to changing market demands, requiring competitive thruster products which are more efficient and cover a wider power range. This major product development project was launched by Wärtsilä's Propulsion R&D already in 2011.