Page 41: of Marine News Magazine (May 2026)

40 42

Tech Feature

An example of an azimuth thruster, a ZF AT50 rated at 815kW.

Thrusters • Tunnel Thrusters, are installed A major use of thrusters is for sta- creased by adding further sensors within the hull transversely in the tion keeping or dynamic positioning and positioning them in different bow or stern, singly or in parallel (DP), which controls both heading locations. Dynamic sensor fusion, as a pair. A single impeller is more and position automatically. Dynamic provides input to the PMS comput- common, but there are designs with Positioning (DP) is categorised by the er which disseminates the data into two impellers providing greater IMO into DP1, DP2, and DP3 and separate commands to the individual thrust and also run quieter by re- prescribes exactly the accuracy, tol- propulsion system and thrusters to ducing cavitation. Some models use erance and reliability of the system. maintain the vessel’s position, within a rim drive type of impeller. Simpli? ed, non-redundant systems prescribed limits. • Azimuth Thrusters allow full go under the description of station- or 360-degree rotation of the propeller position-keeping. Commercial Considerations generating thrust in any horizontal Station keeping systems use a va- For all but a few special circum- direction, thereby eliminating the riety of sensors such as GPS, wind stances, the use of tugs in congested need for a rudder. Installed singly speed and direction, and IMU (In- waters, decreased as vessels equipped or in multiples, they are more com- ertial Measurement Units). Greater with thrusters became able to ma- monly used for propulsion rather accuracy and reliability can be in- noeuvre alone. This reduces operat- than manoeuvring. ANS are able to control multiple thruster arrange- ments in a wide variety of sizes, larger units can propel workboats, tugs, right up to large cruise ships. A special variation, instead of the usu- al ? xed installation, is the portable version comprising propeller, with or without a nozzle, drive shaft and engine. The unit is self-contained and permits self-propulsion of a barge for example. The engine, fuel tank and transmission are all part of the propulsion package, which may also be remotely controlled and op- erate with an ANS. • Retractable Thrusters that re- main protected within the hull yet can be deployed when required, pro- 254,000 members viding additional manoeuvrability.

• Pumpjets are a special variety of waterjet thrusters mounted with- in the hull, are used for propulsion, with their thrust being vectored as required. Their impellers are en- closed and remain protected while vectoring thrust to allow the vessel to manoeuvre in any direction.

www.marinelink.com MN 41|