Let’s Discover the Characteristics of this System Copy

It differs from the previous azimuths. Its electric propulsion motor is now in a watertight torpedo-shaped shell – the “pod” – placed under the ship’s keel and connected to a four or five-blade fixed-pitch propeller.

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It is commonly known as Azipod™ (Azimuthing Podded Drive); the name ABB was first marketed in the 1990s, even if later other major brands proposed their version.

While losing something in terms of course stability compared to a traditional system, the possibility of rotating the pod 360 degrees around its vertical axis allows the ship extreme manoeuvrability, encompassing the functions of a propeller, rudder and thruster.

Typically the azipods work in pairs and are flanked by bow thrusters. It guarantees excellent manoeuvrability, but the variants are different. They can pull or push, equipped with counter-rotating or tandem propellers and in variable numbers, to ensure moving large ships or dynamic positioning of particular vessels.

A frequency converter controls the engine and allows the propeller to rotate rapidly from zero to maximum speed and in any direction.

At the end of the 90s, the mature system appears on large Cruise ships with diesel/electric propulsion. It allows savings of over 10% during construction on the entire cost of the vessel and further maintenance costs compared to traditional systems because the conventional rudder is no longer necessary and a large and hot engine room. The absence of mechanical connections between the diesel generators and the pods determines sound insulation and a lack of vibrations that automatically increase passenger comfort.

The optimised hydrodynamic shapes of the stern, which flattens to accommodate the pods, is another element favouring this type of engine. The azipods have revolutionised the maritime world and spread on merchant units of all kinds. They have had considerable success on icebreakers, as they allow more effective stern navigation, eliminating the problems of traditional ships, i.e. directionality and vulnerability of the rudder. Still, they are also engaged on vehicles that operate in DP like other azimuth thrusters and on fast ferries in Hybrid configuration CRP (Counter-rotating Azipod® Propulsion). Ultimately, the advantages of using azipods are:

• Elimination of the rudder.
• Elimination of the stern thruster.
• Shortening of the shaft line.
• Simplification of hull shapes.
• Improvement of the wake disturbance.
• Improvement of propulsion efficiency.
• Fuel savings.
• Improve handling, especially at low speeds.
• Reduction of emergency stopping distance.
• Reduction of turning circle.
• Increase passenger comfort.
• Reduction of polluting emissions.

The weak points of the azipod system mainly concern the risk of damage during navigation when misused. For example, if rotated quickly at high speed or during manoeuvring due to possible contact with the seabed. Impact damages can affect the propellers and the engine if the watertight seals of the pod are compromised.

Also, unlike conventional engines placed in the engine room and quickly inspected, pods are difficult to access. In case of damage and the need for intervention, the ship must necessarily be in a dry dock.