Wärtsilä Underwater Mountable Thrusters (WST-U)

Wärtsilä Underwater Mountable Thrusters (WST-U) are steerable thrusters for dynamic positioning or main propulsion that can be mounted and demounted with the vessel afloat, removing the need for dry-docking. They feature the Wärtsilä thruster nozzle for high bollard pull and an 8° tilted propeller gearbox that directs the jet away from the hull and other thrusters, giving about 15% more effective bollard thrust in DP operation (up to 20% depending on vessel configuration) compared with conventional non-tilted units.

Key features

• Exchangeable underwater with diver support, optionally ROV-operated mounting
• Electric L-drive up to 6500 kW
• 8° tilted propeller shaft or 3° tilted nozzle for effective DP
• Compact, light design optimised with FEM analysis
• Optional compliance with CLEAN notations and US EPA VGP2013
• Compatible with Wärtsilä PCMS (Propulsion Condition Monitoring Service), recognised by main class societies for condition-based overhaul intervals

Technical data

| Type | Power [kW] | Input speed [rpm] | Propeller dia. [mm] |

|---|---|---|---|

| WST-45U | 4000 / 4500 | 720 / 600 | 3600 |

| WST-55U | 4500 / 5500 | 720 / 600 | 3900 |

| WST-65U | 5500 / 6500 | 720 / 600 | 4200 |

Outboard part weights (dry): WST-45U 51,000 kg; WST-55U 63,500 kg; WST-65U 77,500 kg.

WST-65RU retractable version

The WST-65RU combines retractable and underwater mountable functionality, with power up to 6500 kW. It can be retracted during transit or in shallow water, and its outboard part is exchangeable with the WST-65U. A telescopic shaft allows static mounting of the e-motor.

Applications

Large offshore construction vessels, semi-submersible drilling and accommodation rigs, drillships, crane vessels, pipe layers and other vessels needing thrusters mountable afloat.