How do stern and tunnel thrusters work in manoeuvring ships?

25 Aug 2021

Electric Thrusters for Boat


The boats and ships of today have thrusters that help to improve their manoeuvrability. The most common types are tunnel thrusters (also known as bow thrusters) and azimuth stern thrusters.


Azimuth stern thrusters and tunnel thrusters are propulsion devices installed in the aft and forward sides of the ship that aid in the sideward movement of a boat, as well as provide total 360-degree manoeuvrability. They were not widely used prior to the mid-1980s and were only developed after that when boat equipment manufacturers realised the numerous advantages they provided.


About Azimuth Stern and Tunnel Thrusters


Azimuth stern thrusters are built into or mounted onto the aft end of the ship while tunnel thrusters are located at the forward of the ship. They generally aid in improving docking, manoeuvring the ship near coastal waters, in tight areas, emergency steering, and when entering or leaving a port. 


Electric Thrusters for Boats


Stern thrusters and tunnel thrusters have different configurations – Mechanical Diesel Engine-driven, Hydraulic Driven and Electric Driven Configurations. Since electric thrusters for boats are a preferred choice now due to marine electrification, many thrusters are now driven by electricity.


Electric thrusters for boats are usually controlled by joysticks in the control panels. Thrust and speed control is done by variable frequency drive, which provides high manoeuvrability and excellent speed control response.


How Do Azimuth Stern Thrusters and Tunnel Thrusters Work?


Tunnel Thrusters


Tunnel thrusters are designed with propellers facing the sides so that when operated, they push the ship’s bow in transverse direction by taking water in by suction from one side of the ship and pushing it out on the other.


Azimuth Stern and tunnel thrusters are usually used together because when only one thruster is used, the ship cannot be easily manoeuvred. When both thrusters are used simultaneously, the ship can move sideways simultaneously. 


Electric thrusters for boats are typically powered by an electric motor in the thruster. The motor couples with an FPP propeller and runs at variable speed which is controlled via Variable Frequency Drive, VFD.


When azimuth stern thrusters and tunnel thrusters are used in tandem, they provide ship operators with added advantages, including better control in demanding conditions, a lower risk of collision in crowded waters, and easier manoeuvrability. This configuration has high flexibility and manoeuvrability, making it ideal for Dynamic Position. 


Not sure how to start installing thrusters on your boat? Contact us today to find out more about our electric thrusters for boats.