Wärtsilä Steerable Thrusters

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Wärtsilä Steerable Thrusters - Designed to meet the latest customer needs

The Wärtsilä Steerable Thruster (WST) has been developed in parallel with the latest operating demands for tugs, river-going vessels, and various offshore support vessels.

The aim, as with all Wärtsilä products and solutions, is to ensure optimal efficiency, high hydrodynamic performance, less maintenance and better accessibility for serviceability. With eight thruster types, ranging from 700 to 3200 kW, the WST enables these vessels to meet and exceed the performance levels required for today’s competitive operating environment.

Wärtsilä has the broadest and most complete offering of products, systems and integrated solutions in the global marine industry. We continue to lead the way in innovations that create greater efficiencies, improved safety, and more environmental sustainability.

Key benefits

  • Superior hydrodynamic performance for high bollard pull or maximum propulsion efficiency
  • Compatible with high speed engines (up to 1800 rpm)
  • Compact dimensions with a high level of integration
  • Robust design for reliable operations
  • Ice class up to 1B
  • Maintenance friendly design to minimize downtime
  • Reduced number of external connections and field bus technology for ease of installation
  • Wärtsilä ProTouch controls with ergonomic levers and intuitive touch screen displays

    Superior performance

    Large propellers with a tailored design, a smooth housing shape and slender nozzle connections ensure the superior performance of the Wärtsilä Steerable Thrusters. The hydrodynamic design has been thoroughly optimized, with the use of Wärtsilä’s extensive design experience combined with computational fluid dynamics (CFD) capabilities. Since not all vessel performance requirements are the same, the WST comes with a choice of two nozzle types.

    High-speed engine compatible

    The Wärtsilä Steerable Thruster fits well with Wärtsilä’s own medium-speed engines and is also compatible with high-speed engines of other brands. With a selected range of gear ratios, all common engine speeds between 750 and 1800 rpm can be accommodated, as well as electric motors with speeds between 720 and 1200 rpm.

    Environmental performance

    The thrusters come with an advanced sealing system that includes functionality for seal monitoring. The Wärtsilä Steerable Thrusters are suitable to be operated in US inland and coastal waters under the US EPA VGP2013 regulations. Compliance is achieved by using environmentally acceptable lubricants (EAL).


    • Diesel-mechanical Z-drive configuration compatible with engine speeds ranging from 720 rpm to 1800 rpm (intermediate ratios available)
    • Integrated power take off for steering, lubrication, clutch and pitch hydraulics (DM variant)
    • Diesel-electric Z-drive configuration with electric steering and auxiliary systems
    • 2 propeller diameters per size (3 diameters for WST-14)
    • FP propeller and integrated medium duty clutch (slipping range up to 50% engine rpm) or CP propeller with integrated on/off clutch
    • Two nozzle types: optimized for bollard pull or free sailing (FP propeller only)
    • Finnish-Swedish (Baltic) ice class up to 1B, Russian (RMRS) ice class up to Ice-3 or equivalent Russian river register (RRR) ice class
    • US EPA VGP 2013 compliance
    • Multiple installation options: bolt-in, weld-in, can-mounted or split installation.

    Vessel types

    Multipurpose workboat, pusher tugs, tug boats, small dredgers, platform supply vessels, maintenance vessels and tug-barge (ATB) combinations


    • WST-11 to WST-32
    • FP propellers
    • CP propellers
    • Hybrid Solutions
    • LNG Solutions
    • Cargo vessels (dry bulk, container, tankers) and inland cruise

    Cargo vessels (dry bulk, container, tankers) and inland cruise


    • WST-14 FP (cargo), WST-14 FP and special executions of WST-14 (open Propeller) for cruise
    • Wärtsilä 6L20

    The newly developed WST thruster series is versatile and can be tailored to comply with specific vessel requirements, without compromising on safety, performance, cost, simplicity, reliability or efficiency.


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