Dynamic positioning holds a vessel's position and heading with computer-controlled thrusters, and offshore wind has turned a near-standard DP2 package of azimuth, retractable and tunnel thrusters into a volume product. Spinergie counted 85 active SOVs in August 2025 with 48 more due, while cruise ships are pushing tunnel thrusters to 4,000 kW.
What it is and how it works
Dynamic positioning (DP) holds a vessel's position and heading with computer-controlled thrusters instead of anchors or moorings. IMO MSC.1/Circ.1580 of June 2017 defines three equipment classes: Class 1 may lose position after a single fault; Class 2 tolerates any single fault in an active component; Class 3 adds physical separation so that fire or flooding in one compartment cannot cause loss of position (IMO via USCG; USCG). Lloyd's Register writes DP1, DP2 and DP3, while DNV uses DYNPOS notations; DP2 and DP3 are the classes most used (One Step Power).
The thrusters do the work. A tunnel thruster is a propeller in a transverse duct through the hull, used for sideways force at low speed. A retractable azimuth thruster drops below the hull and rotates through 360 degrees. For wind-service vessels, the near-standard DP2 package is two azimuth main thrusters aft, two retractable azimuth thrusters and one or two tunnel thrusters forward.
Why it matters now
Offshore wind has made DP packages a volume product. Spinergie counted 85 active SOVs in August 2025 with 48 more due, 32 of them in 2025 alone, and forecasts a need for 64 full-time CSOVs by 2030, up 230% on 2024, with 37% of demand unmet in 2029-2031 (Spinergie; Spinergie). Offshore Engineer, by contrast, warns of oversupply around 2030 with charter rates yielding single-digit IRRs (Offshore Engineer). Tunnel thrusters are also scaling with cruise-ship size, and class work has shifted from thruster hardware to closed-bus operation and changeover logic.
Key players and products
Brunvoll dominates the sourced 2023-2025 CSOV packages from Vard, supplying Purus Wind, Windward Offshore, North Star and Esvagt vessels with two azimuth propulsion thrusters, two retractable azimuth thrusters and one tunnel thruster each. Schottel supplies Edda Wind's CSOVs with two SRP 460 D rudderpropellers, one retractable SRP 380 R and two STT 5 transverse thrusters per ship (OE Digital). Kongsberg trialled rim-drive azimuth units on Norwind's CSOVs and launched the TTH tunnel series in May 2025. Brunvoll also supplies shock-qualified electric retractable azimuth thrusters for the Spanish Navy's five F-110 frigates built by Navantia (Motorship).
Figures that matter
Fleet figures come from the data provider Spinergie; product and order figures are trade-press reports of supplier announcements. No market size for tunnel thrusters or DP systems was found (Maritimt.com; DredgeWire).
| Metric | Value | Source type | Source |
|---|---|---|---|
| Active SOVs, August 2025 | 85 active, 48 more due, 32 in 2025 alone | aggregator | Spinergie |
| Full-time CSOVs needed by 2030 | 64, up 230% on 2024; 37% of 2029-2031 demand unmet | aggregator | Spinergie |
| Brunvoll FU135 tunnel thrusters for cruise ships | 12 units for three ships, 4,000 kW each, 3.5 m CPP, deliveries from 2027 | trade-press | Maritimt.com |
| Edda Wind CSOV package (Schottel) | Two SRP 460 D, one retractable SRP 380 R, two STT 5 per ship | trade-press | OE Digital |
| Typical DP2 CSOV configuration | Two azimuth aft, two retractable azimuth, one or two tunnel thrusters forward | trade-press | — |
| Vard CSOV transit speed | 14 knots with DP2 | trade-press | DredgeWire |
| Vard CSOV order, July 2025 | Up to three vessels, more than USD 100 million | trade-press | TradeWinds |
| Charter economics warning | Oversupply around 2030, single-digit IRRs | trade-press | Offshore Engineer, January 2025 |
Brunvoll's FU135 order, 12 units at 4,000 kW driving 3.5 m controllable-pitch propellers, is the largest tunnel-thruster reference in the research and was described as a response to the growing size of cruise vessels.
Developments 2023-2026
- August 2023: Brunvoll packages ordered for Purus Wind CSOVs at Vard, deliveries in 2025 and 2026.
- 2023: Schottel wins full propulsion packages for Edda Wind's new CSOVs.
- 2024: ABL Group secures DNV approval for a DP2 stern-thruster changeover concept; DNV OTG-10 covers closed bus-tie operation (ABL Group).
- 2024: Brunvoll launches the FU135 tunnel-thruster series; 12 units sold to three cruise ships for delivery from 2027.
- May 2025: Kongsberg launches the TTH tunnel series, interchangeable with existing TT units.
- July 2025: Vard books up to three CSOVs worth more than USD 100 million from an undisclosed owner (TradeWinds).
- October 2025: Brunvoll's North Star CSOV package adds a combined retractable azimuth/tunnel thruster that acts as a tunnel thruster when retracted and a 360-degree azimuth when lowered (MarineLink).
- August 2026: Kongsberg adds 2,300 mm and 2,600 mm RD-TT rim-drive tunnel models for offshore DP.
Outlook
The DP2 CSOV template has become a near-standard across Brunvoll, Schottel and Kongsberg, and the combined retractable azimuth/tunnel unit is the configuration trend to watch because it saves hull space without giving up redundancy. The two product axes are power, with 4 MW tunnel thrusters for cruise ships, and electrification through permanent-magnet and rim-drive units. The demand risk is timing: Spinergie's shortage and Offshore Engineer's oversupply warning both point at the years around 2030.
