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Underwater Mountable Thrusters
Reliability and performance

Wärtsilä Underwater Mountable Thrusters

The Wärtsilä underwater mountable thruster are designed for safe and reliable operation under demanding conditions. The proven underwater mounting method enable maintenance to the thrusters with the vessel afloat, taking out the need for dry-docking of the vessel.

The underwater mountable thruster features an optimised design and the Wärtsilä Thruster Nozzle to provide excellent bollard pull performance. By the 8° tilted propeller gearbox the thruster-hull interaction losses are significantly reduced. The benefits of the underwater mountable thrusters enable superior and reliable DP performance.

    Application
    • The Wärtsilä Underwater Mountable Thruster series can offer a tailor-made solution to meet customer requirements, for example: bollard pull, vessel speed or vessel propeller size limitations.
    • The underwater mountable series has a high maximum power output of up to 6500 kW.
    • The underwater mounting and the high performance make the thruster favourable for use on large offshore construction vessels (OCV), semi-submersible drilling rigs, drillships, semi-submersible accommodation rigs, crane vessels, pipe layers and other vessels requiring thrusters that can be mounted while the vessel is afloat.
    Key benefits
    • Exchangeable underwater for vessels that do not have access to dry docking facilities
    • Underwater mounting with diver support, optionally ROV operated mounting method
    • High bollard thrust and propulsion efficiency
    • Effective DP operations thanks to the 8° tilted propeller shaft or 3° tilted nozzle
    • Electric L-drive up to 6500 kW
    • First class reliability
    • Wide power range
    • Compact and light design
    • Easy installation
    • Optional compliance with CLEAN notations and US EPA VGP2013 requirements
    Technical Info
    Main technical data
    Thruster type  Power (1)
    [kW]
     Input speed
    [rpm]
     Propeller
    diameter (A)
    [mm]
     Tilt
    WST-45U 4000
    4500
    720
    600
    3600  8°
    WST-55U 4500
    5500
    720
    600
    3900   8°
    WST-65U  5500
    6500
    720
    600
    4200  8°
    1 - The maximum power level depends on input speed and is given for dynamic positioning (DP) application. Other power levels are available on request
    Power ranges
    Underwater Mountable Thrusters main technical data
    Dimensions and weights 
    Thruster type  C M  H Outboard part1
     Well2
    dry  in water 
    WST-45U 3600 3300  2518 2324 2570 1241 51000 34500 9500
    WST-55U 3900  3625  2648 2516 2763  1390 63500 41800 11900
    WST-65U  4200 3820  3006 2719 3025  1390 77500 49500 13200
    1 - Indicative weight, with oil
    2 - Including top, bottom, and pipe covers plus valves and position sensor 
    Weight and dimensions 2
    WST-RU
    The Wärtsilä Retractable Underwater Mountable Thruster (WST-65RU) has been designed to meet the needs of large offshore construction vessels (OCVs) as well as semi-submersible rigs and drill ships.

    With its power output up to 6500kW it is typically designed for vessels that require thrusters that can be retracted during transit of while entering shallow waters, to increase the level of operational flexibility. Additionally, the WST-65RU thruster can be mounted or de-mounted while the vessel is afloat, to facilitate thruster maintenance and overhaul during the operational lifecycle meaning there is no requirement for drydocking. The WST-65RU is the first retractable thruster in the market to feature the unique combination of retractable and underwater mountable functionality.

    The WST-65RU is based on the WST-65U underwater mountable thruster which has been designed with performance and reliability as key requirements. The 8° tilted propeller shaft solution is a feature which is also found on Wärtsilä Underwater Mountable thrusters and reduces the interaction between the thrusters and hull significantly, thereby enhancing the dynamic positioning performance of the vessel. The outboard part of WST-65RU is exchangeable with WST-65U, optimizing maintenance and spare part strategies.

    In combination with Wärtsilä’s PCMS (Propulsion Condition Monitoring Service) downtime and maintenance costs can be minimized.


    Key benefits:

    • Optimised thrust enabling effective DP operations
    • Retractable
    • Thruster outboard part can be exchanged without dry docking the vessel
    • A telescopic shaft allows a static mounting of the E-motor and ease
    • Integrated solution provides smallest possible area footprint and overall lighter construction
    • Based on proved recognizable technology and in-house propeller design know-how
    Wärtsilä-WST65-RU

    Product hologram

    Why choose Wärtsilä

    Each component and aspect of the underwater mountable thruster series has been selected to achieve a high level of reliability. With the Wärtsilä PCMS (Propulsion Condition Monitoring Service), the reliability and availability of the thruster can be improved even further. As this service is recognized by the main marine class societies, the thruster overhaul intervals can be extended according to the condition of the equipment

    The Wärtsilä Underwater Mountable Thruster series feature an 8 degree tilted propeller shaft and nozzle, which direct the propeller jet away from the hull and other thrusters. In addition to reducing hull interaction losses, this also greatly reduces interaction between the thrusters, thus making the so-called ‘forbidden zones’ considerably smaller. The unique design means that customers can expect up to 20% more effective thrust than conventional non-tilted thrusters, depending on vessel configuration and application.

    The excellent efficiency and performance of Wärtsilä Underwater Mountable Thruster is further enhanced by the capability to design and configure the optimal configuration and power requirements to fit the vessel actual operating profile and needs of the owner. This is achieved through the use of advanced calculations including hydrodynamics and computational fluid dynamics (CFD) and includes the ability to add system failures to ensure safe operation. The result of these calculations and analysis allow for an accurate view of the thruster position, combination of thruster type, and most importantly the power required to deliver the thrust to support vessel operations safely and efficiently – this detailed insight allows the correct total vessel power requirement to be calculated rather than estimated, which can reduce the cost of the total power train configuration.

    By bringing together these technologies and expertise in a single configurable solution approach, the optimal solution can be agreed, which when combined with Wartsila’s thruster performance results in reduced overall weight and increased performance. This ensures that owners, operators and yards benefit from significant savings and efficiencies not before possible.

    Effective DP operations
    Effective DP operations 2
    Effective DP operations 4

    Effective DP operations
    The three largest thrusters within the Wärtsilä Underwater Mountable Thruster series feature an 8 degree tilted propeller shaft and nozzle, which direct the propeller jet away from the hull and other thrusters. In addition to reducing hull interaction losses, this also greatly reduces interaction between the thrusters, thus making the so-called ‘forbidden zones’ considerably smaller. The overall gain in effective bollard pull thrust for dynamic positioning operations is about 15% when compared to conventional units.

    High efficiency
    The Wärtsilä Underwater Mountable Thruster series features the Wärtsilä thruster nozzle to provide excellent bollard pull performance.


    First class reliability
    Each component and aspect of the underwater mountable thruster series has been selected to achieve a high level of reliability. With the Wärtsilä PCMS (Propulsion Condition Monitoring Service), the reliability and availability of the thruster can be improved even further. As this service is recognized by the main marine class societies, the thruster overhaul intervals can be extended according to the condition of the equipment.


    Compact and with less weight
    Detailed FEM analyses have been made to optimize the strength of the components so as to keep the overall weight as low as possible. Compact dimensions result in less space requirements in the thruster room and more payload capacity for the vessel.

    Effective DP operations 3

    References

    • Offshore construction vessel Orion
      The world’s first LNG fuelled offshore construction vessel being built for DEME will be powered by Wärtsilä.

      Offshore construction vessel Orion

    • The world’s largest retractable thrusters
      Performance of the propulsion solutions supplied by the technology group Wärtsilä exceeded the design specification and contributed to the success of the sea trials for the world’s largest semi-submersible crane vessel (SSCV). The ‘Sleipnir’ was built at Sembcorp Marine’s Tuas Boulevard Yard in Singapore for the Dutch offshore contractor Heerema Offshore Services (HOS). It was delivered from the yard in July.

      The world’s largest retractable thrusters

    • LNG fuelled drilling rig
      Wärtsilä has the technology and the expertise to make a switch to LNG fuel both technically feasible and economically appealing.

      LNG fuelled drilling rig

    Press releases

    Articles

    Trusted thruster performance – 50 years...

    When it comes to thrusters it’s all about maneuvering and station keeping in the safest, most accurate...
    14 March 2021
    • Article

    Wärtsilä gives a boost to world’s largest...

    Creating state-of-the-art features for Sleipnir, which will remove and install structures in the open...
    14 November 2019

    The new age Propulsion Condition Monitoring...

    When Wärtsilä’s PCMS was launched in 2010, it was first of its kind. The latest version of the service...
    13 March 2019
    • In Detail article

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