Advanced propulsion engines: What are Azimuth Thrusters?

Introduction

Ship Propulsion system is changing rapidly and so is the propulsion mechanism system. Maneuverability of any type of ship is a product of impeccable propulsion system and efficient technology. Confined waters and narrow channels have always been traumatic for captains, desperately trying to avoid any kind of accident during maneuvering. We have seen bow and stern thrusters working with propellers and controlled pitch propellers to provide as smooth maneuvering as possible. But how about a mechanism that performs the work of all these mechanisms?

Azimuth thrusters are advanced propulsion engines (mechanisms) that have outshone all the conventional forms of mechanisms.Azimuth thrusters couples purposes of all these mechanisms to produce a single structure that not only performs more efficiently than all of the mechanisms taken together, but also assists in conserving money and energy to a larger extent.

Construction and Working

Azimuth Thrusters are such a fine piece of mechanism that it has totally eradicated the use of conventional form of propulsion systems. Just imagine, a ship with just azimuth thrusters, no need of a rudder, bow or stern thruster or a controlled pitch propeller. All jobs done by just one mechanism. Isn’t it amazing? Just imagine the savings in material costs and ship’s space and energy. Not only that, they give better maneuverability than any of the conventional systems.

Azimuth Thruster is an arrangement in which the the propeller is placed in pods that can be rotated in any horizontal direction. This eradicates the use of a rudder. The stem of the thruster accommodates shafts that are connected to a motor located inside the ship. The Azimuth thrusters are divided into two types based on the position of the motor.

Azimuth Thrusters are fixed or re-tractable type and are available as controlled or fixed pitch propellers. Fixed pitch are generally used for small sized boats such as tugs and ferries. Retractable thrusters are used for heavy structures such as offshore drilling or DP structures and even military vessels.

Mechanical Transmission Thrusters

This type of thrusters consists of a system in which the pods are connected to the motor inside the ship by means of a mechanical system, i.e gearing. The motor can be diesel or electric- diesel operated. On the basis of the shafting arrangement, the thrusters are divided into Z drive and L drive. The L-drive consists of a vertical input shaft and a horizontaloutput shaft, which are attached with the help of a right angle gear. Thus the power transmission system involves just two shafts. While a Z- drive’s power transmission system consists of three shafts. A horizontal input shaft which is connected to a vertical intermediate shaft which isthen connected to a horizontal output shaft with the help of two right angled gears and thus making a Z shape.

Electrical Transmission Thrusters

An electrical transmission thruster doesn’t consist of a mechanical gear system. The Electrical Motor is located in the pod itself which is connected to the shaft without using gears. The power required by the electric motor can be derived from the main power system, i.e diesel engine or gas turbine. All these thrusters can move 360 degrees , thus making the process of docking and maneuvering through channels, a smooth one.

Image Credits

https://www.mpsys.ru/i/b3_.jpg

https://img.nauticexpo.com/images_ne/photo-g/azimuth-thruster-for-ships-z-drive-193132.jpg

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