Mechanical azimuth thrusters transmit engine or motor power through right-angle gears to a steerable propeller, giving tugs, offshore and DP vessels 360-degree thrust vectoring. The market is small, roughly USD 0.5 to 0.6 billion a year by aggregator estimates, so growth comes from permanent-magnet, hybrid and underwater-mountable designs rather than volume.
What it is and how it works
A mechanical azimuth thruster transmits engine or motor power through right-angle gears to a propeller that can be steered through a full circle. In a Z-drive the power enters horizontally and passes through two gear sets; in an L-drive a vertical motor sits above a single gear set. Steerprop's main products are Z-drive and L-drive units for offshore vessels, tugs and icebreakers, per Wikipedia. Thrust vectoring through 360 degrees provides the bollard pull, escort steering force and station-keeping that a shaft-and-rudder layout cannot. Schottel's RudderPropeller dates from 1950, and around 1,300 units of its current mid-size SRP 460 and SRP 490 will have been delivered by 2025, according to Schottel.
Why it matters now
Growth in this segment is technological substitution rather than volume. Aggregator estimates put the 2025 market at only USD 504 to 576 million with a compound growth rate of 1.5 to 2.7 percent, and Asia-Pacific at 45 to 51 percent of demand, per Fortune Business Insights and IMARC; one outlier claims USD 3.56 billion, so these figures carry low confidence. The money is instead moving into electrification through permanent-magnet and rim-drive units, mechanical hybrids that let one engine drive two thrusters, and underwater-mountable units that avoid drydocking, the largest lifecycle cost for offshore operators.
Key players and products
Schottel dominates tugs: it passed a 500-tug collaboration milestone with designer Robert Allan Ltd, reports MarineLink. Kongsberg Maritime, Wärtsilä (whose flagship steerable thruster is listed as the ST-60), Steerprop and Thrustmaster of Texas serve offshore and ice applications. Kongsberg's underwater-mountable UUC PM thruster uses a permanent-magnet motor with built-in sensors for live condition monitoring, per Kongsberg Maritime. Its December 2025 UUC PM 405 additions offer 3.8 m and 4.1 m propellers delivering 86 and 91 tonnes of thrust, with future models planned to 5.5 m and 6,000 kW, reports World Oil. Kongsberg has also marked ten years of its RD-AZ rim-drive azimuth series.
Figures that matter
Two Schottel SRP 710 units at 3,700 kW each give a 42 m salvage tug for Kenya Ports Authority an expected bollard pull above 120 tonnes, according to Schottel. Saltchuk Marine's four RApport 2600 escort tugs take SRP 510 units with 2,800 mm propellers behind 2,610 kW Caterpillar 3516E engines for 2026 delivery, reports Workboat. No independent Z-drive versus L-drive efficiency comparison was found, and no reliable dollar split between tugs, offshore and ferries exists.
| Metric | Value | Source type | Source |
|---|---|---|---|
| Market size 2025 (aggregator range) | USD 504-576 million | aggregator | Fortune Business Insights, IMARC, Expert Market Research |
| Forecast CAGR | 1.5-2.7% | aggregator | Fortune Business Insights, Expert Market Research |
| Asia-Pacific share 2025 | 45-51% | aggregator | IMARC, Fortune Business Insights |
| SRP 460/490 units delivered by 2025 | about 1,300 | vendor | Schottel |
| UUC PM 405 thrust, 3.8 m and 4.1 m | 86 and 91 tonnes | vendor | Kongsberg via World Oil |
| SRP 710 input power, KPA tug | 2 x 3,700 kW | vendor | Schottel |
| KPA salvage tug bollard pull | more than 120 t | vendor | Schottel |
| Robert Allan and Schottel tugs | 500 | trade-press | MarineLink |
Developments 2023-2026
- 2025: Schottel delivered its SYDRIVE-M mechanical hybrid on KOTUG's methanol-fuelled, Sanmar-built escort tugs, where one main engine can drive both SRP 710 thrusters; the tugs deliver more than 120 tonnes bollard pull and 14 knots, and Schottel calls the four-unit package its most powerful hybrid system to date.
- May 2025: Kongsberg launched a range of dry-dock-free underwater-mountable azimuth thrusters and a modular TTH tunnel thruster series.
- December 2025: Kongsberg added the UUC PM 405 sizes with 86 and 91 tonnes of thrust.
- 2025: Steerprop released the SP 45 R, its largest retractable thruster, for offshore and renewables vessels, per Workboat, and won a package of two main azimuth thrusters, two tunnel thrusters and a retractable unit for a DOF field support vessel built in Poland for harsh Canadian waters.
- Q4 2025: Kongsberg booked a rim-drive package of two RD-AZ2600 azimuth and two RD-TT1600 tunnel thrusters for an Indian research vessel.
- June 2025: Schottel was chosen to fit two SRP 100 units to a Silverback Marine OX-series aluminium tractor tug for the US Department of Defense.
Outlook
No Wärtsilä or Thrustmaster azimuth thruster launch for 2025-2026 surfaced in the research. With low single-digit market growth, suppliers will compete on condition monitoring, drydock avoidance, permanent-magnet efficiency and hybrid drivetrains rather than on unit volume.
