Azipods Are a Ship’s Best Friend, Essay Example

Abstract

Time changes and so does technology. It was never thought that oceans would be traversed and seas would be envisaged. In the preliminary stage of evolution, people used wooden logs to meet their transport needs. Then discovery of ships made it possible to cover vast stretches and long journeys around the world. However, ships had to face the grunt and current of the mighty oceans, and eventually reported large number of shipwrecks. With the advancement of time, ships were crafted with technological expertise and metamorphosed the entire concept of sailing. It tried to eradicate the dangers of the sea and make the journey or passage of sailing comfortable and safe. This paper would divulge in the facts that the idea of a marine revolution that has surpassed and minimized the risks of sea life. It would evaluate the modern technology of Azipod as the mechanism that has changed the interface of marine technology.

Introduction

An Azipod system was first planned and developed by the Finnish Maritime Administration, which were looking in for new technologies for assisting in the icebreakers operation. These ships needed to have the extra advantage of breaking the ice in the existing ice channels and move around the other ships, while providing assistance to the merchant ships to travel without hindrance. Thus they wanted to create a propulsion motor that would direct the thrust of the current to the desired direction. Hence a project was undertaken by the Finnish Maritime Administration, and evolved the origin of Azipods in 1989.

Azipods were built in joint collaboration of Kvaener Masa-Yards and ABB Industry of Finland. They made an agreement in 1992, and in the following year Azipod was registered. The first ship to be converted was a product tanker, and it became the first western cargo to brave through the North east sea route. It served to be the single most alternative to bridge the north east sea, as it is completely frozen during the winter. The ship now could operate safely without potential risk and without the assistance of ice breakers. It made travel more economically viable. Azipods became successful with the cargo ships but the good news was the acceptance of Azipods in the Carnival Cruise Lines in 1995. The capability to mitigate the level of risks lead to more and more acceptance of azipods .

Concept of Azipods

Azipods are a boon to the marine technology. The aftermath of Titanic Britannic, Lusitania and others were potent and it necessitated the need of urgent yet concrete technological revolution that could minimize the risks of maritime travel. Various changes in physical designs were included, and among them was the introduction of Azipods.

Azipods are a recent feather in the cap of marine technology. It is a propulsion unit, better known as ‘Azipod( Azimuth Podded Drive) Electric Propulsion Drive’. According to ABB “ Azipod  is the registered trademark of a family of electric propulsion systems for ships, the first of which was developed by ABB about two decades ago. The latest product in the range is the most energy-efficient electric propulsion system on the market.” Azipod has replaced the traditional rudders, propeller-shaft, stern thrusters and shaft tunnels which lead to constraint in maneuvering in narrow ports or in difficult conditions. Azipod have comprehensively removed these obsolete methods and have adopted a new approach. The pod can be rotated to a full 360 degrees and is often used for steering the unit. It has minimized the use of other associated equipments, and only requires a engine room, to place the diesel generators that provides the power for the azipods to work in momentum. Moreover, it has a scientific design, which optimizes space, reduces noise and the allied vibrations. It is enhanced with user friendly features and even allows the scope of increasing the cargo capacity.

Azipods have introduced the concept that has changed the interface of safety and redundancy in ships, has introduced low operating costs, has reduced the maintenance problem, it pertains to low exhaust emissions, gives the ship an over the edge scientific layout, technology and cost effective utilization of the marine resources. . The Azipod usually is in a hanging position beneath the stern of the vessel.

What Are the Benefits of Azipods?

Reduced Emissions: The load of the gensets in the Azipods can withstand different levels of load and helps the speed engines to be operated with optimum efficiency in fuel, lowers the overall maintenance costs and helps to fight the emission of harmful gases in the environment. It makes the vessels eco friendly and reduces the level of damage in global warming.

Higher levels of safety and reduced redundancy: The combination of a diesel-electric power station helps to combat multiple redundancies. In case of malfunction of the main engine, there is sufficient power in the rest of the system to help the ship operate back safely to the shores. The reliability of the plant increases, since the numbers of ancillary support mechanisms are reduced. Thus the two electric propulsion units, drives and reduces the dangers of the sailing as well as manages the redundancy levels.

Combats with weather conditions: It operates smoothly in heavy weather without much tug assistance. The movement of the ship is also lubricated and smart during dynamic positioning, due to the excellent support by the torque characteristics of the azipod.  It is also easy sailing at low speeds for the electric propulsion drive.

The Design Layout Allows Greater Flexibility

The design layout of the Azipods provides more scope for space. The azipods being handy and compact can be placed in any feasible place by the ship designers. It saves on the space that can accommodate more cargo or more passengers. It also does not impede the need for preparing large sized ships to accommodate the azipods.

According to ABB, “Improved hydrodynamics yield significant savings in operational costs and cause less strain on the environment. Superior manoeuvrability and dynamic performance are delivered: excellent reversing capability and steering during astern navigation, and enhanced crash stop performance. Low noise and vibration characteristics associated with a conventional electric drive system are enhanced by the Azipod motor’s underwater location; and hull excitations induced by the propellers are very low. Space within the hull otherwise taken by the propulsion motors and shaftlines is saved or released for other purposes; stern thrusters can be eliminated along with the rudder(s) and long shaftline(s).”

How Does the Azipod Work?

They basically help the ship in pullying..the propellers are usually in the front of the ship just like the system in the airplane. The advantage is that propellers work in all environments. The water flow, in interaction with the propeller hits the waves in a much more laminated way than that used when there are shafts at the back of the ships. The Azipods are characterized with special features that has the ability to direct the thrush where they are exactly needed, it has the ability to do a crash stop keeping the propellers rotating the way they are and simply reverses the direction of the propeller 180 degree, which is a major challenge that all ship faces. The two propellers are in fixed position and both of them can do a turn to 360 degrees.

These pods turn in momentum to help in the maneuvering of the ship. They compensate the function of a rudder.  It holds the ship to stabilize and stay in its position while tendering. The azipods also helps in the joint side thrust in simultaneous action with its three bow thrusters of the ship. This means that inspite of strong winds or currents, the ship can reach the dock without the assistance of tug boats.

The Background and Technology of Azipods

A cargo ship has a typical arrangement of diesel generators and diesel engine. While the diesel generators supply power on board, the latter is used to drive the main propeller shaft. This system is known as diesel mechanical propulsion system. ABB thus invented the Diesel-electric propulsion system which is much better equipped and ensure better fuel efficiency of the ship. It consists of a large electrical power plant, diesel-engine driven generators, a electrical driven motor that drives the main propeller. Thus the electric propulsion system ensures that there is optimum utilization of the diesel engine independent of the speed of the ship. Since it uses electric cables it helps to reduce the vibration on the ship. The first Azipod propulsion system was completed in 1990. In 2002, ABB launched the CRP Azipod, and according to ABB, “ The CRP concept, which stands for contra-rotating propeller, involves two propellers facing each other and rotating in opposite directions and is achieved when an Azipod unit is installed in the place of the rudder in a conventional shaft line arrangement. It is most suitable for fast ferries and other ships that need very large propulsion power.”

The CRP Azipod was first implemented in Japan’s leading ferry operator, ShinNihonkai, in 2004. The company has recorded to have a 20 percent savings on fuel and 15 percent increased transportation capacity as compared to the ships of similar size and stature using diesel engines.

Physical Structure of the Azipod

According to ABB, “The Azipod Propulsion Module and the associated Steering Module are of fabricated steel construction. The Steering Module is welded to the ship’s hull as a structural member. The submerged Propulsion Module incorporates a three-phase electric propeller motor in a dry environment, directly driving a fixed-pitch propeller. The Propulsion Module is to be bolted to the azimuthing part of the Steering Module. It consists of the following parts; a propulsion power drive for each azipod, a remote controls system and a generator and switchboard power network.

Design Philosophy

The Azipod is designed to give maximum safety and leverage to the vessels. Its consists of four modules:

Propeller with or without Nozzle Propellers : This category contains two groups mainly the Fixed Pitch Propellers (FPP), which is a single block made of copper alloy. The blades and the pitch position are permanently fixed. The other is Controllable Pitch Propellers( CPP) that has a catapulted hydraulically served mechanism for controlling the pitch. These are mostly used in vessels which haul large ships to the ports.

Electric Motor Module: According to Barun Gupta of Marine Engineering and Research Institute, “In this module the electric the electric power is controlled by an onboard frequency converter, and transmitted to the electric motor via power slip rings at the power transmission and steering module. The compact Azipod incorporates a Permanent Magnet Synchronous Motor with a Fixed Pitch Propeller (FPP) that is mounted directly onto the motor shaft. Permanent magnet technology has many benefits over the conventional one. The outer diameter of POD can be decreased, which improves hydrodynamic efficiency. The uniform frame design enables the motor to be directly cooled via convection to the surrounding seawater, thus eliminating the use of cooling system (and problems attached to it too).”

The Strut Module: The strut module is again a single structure, which helps being the connective element in Compact Azipods. It contains the control cables and power supply bus bars of the system.

Power Transmission and Steering Module: This module is responsible for the 360 degree azimuthization of the ships. This system consists of equipment box, local control of the system, cable drum, gear boxes and steering motors. It is usually found inside the hull of the ship. The power transmission and steering module helps the shaft to rotate 360 degree .. this angular movement helps the ship to steer in its desired direction or helps it to sail straight ahead. The total movement is determined and controlled by the marine officers.

Compact Azipod Control System

According to Jari Ylitalo, ABB Azipod, OY, Finland, “The control system of the Azipod contains the thrust motor controller in the frequency converter, dual azimuth control system in the azimuth steering converters, and local/remote manual controls. These control functions are implemented in standard automation and drive controllers of the Industrial IT platform.” This mechanism helps in the synchronization and compliance with the on-board automotive systems; like power management, controlling the dynamic positioning systems, and stimulating the joy stick controllers. Yari says that “ the use of configurable units and standardized communication protocols increases the robustness, reduces start-up times, and yet maintains a high degree of flexibility for adaptation to the specific vessel configurations.”

The other important parts of the control system consist of Electronic Remote Control Panel, Azimuth Motor control and frequency converter, Joystick, PMS, Field bus Communication and Compact Azipod. Joysticks help in the docking of the ships.

Azipods family includes the following products as given by the ABB:

Azipod CO: Open Water Applications up to 4.5 MW

Azipod VO and Azipod XO: Open Water Applications up to 20 MW

Azipod CZ: Thruster Unit for high thrust applications, 3.3 MW

Azipod VI: For Ice going ships

Azipod XC: For Contra Rotating Applications

Azipods are used in different numbers and forms depending on the size and stature of the vessel. It can be mainly divided into:

Single Azipods: It is provided to vessels like tankers and cargo ships. These type of vessels have a double wound motor.

Twin Azipods; since it helps in greater manoeuvring it is mostly used for the cruise ships

Fixipod?: This is used in combination with twin Azipod?, and is suitable for vessels that have  high power recourse and redundancy.

CRP Azipod?: This Azipod has a unique quality known as contra-rotating propulsion system that is specifically made for ultra large containers, LNG carriers and RoPax Ferries.

Vessels That Use Azipods

Cruise Ships : Carnival Cruise Lines, Costa Cruises, P&O Cruises, Holland America Line (HAL), Cunard Line, Royal Caribbean Cruises Ltd. (RCL), Celebrity Cruises, Norwegian Cruise Line (NCL), Hapag-Lloyd, Shinnihonkai Ferry.

Cargo Vessels: Fortum Shipping Company

Ice Breaking Vessels: Sovcomflot

Utility Vessels: United States Coast Guard

What Is the Influence of Azipods on the Industry Today?

According to a report by ABB Communications “Royal Caribbean International has launched three models of the world’s largest cruise ship over the past three years and is preparing to launch a fourth, all of them powered and propelled by an energy-efficient power and propulsion solution from ABB.” The growth and intensity of Azipods are growing at a rapid pace, since it is a major component of safety as well as helpful in the preservation of an environment. Ships get more preference when they are Azipod imbedded.

Reference

D K Sanyal ,(2005) ‘Marine Diesel Engines’, Last Retrieved on October 29, 2009 .

HD McGeorge (1999) ‘Marine auxiliary machnies’ Last Retrieved on October 29, 2009

Frederick P. Brooks, Jr.,(1995) The mythical man-month (anniversary ed.), Last Retrieved on October 29, 2009

J.P.Strand (2001), The Azipod Propulsion System, Last Retrieved on October 29, 2009

ABB, Last Retrieved on October 29, 2009 from www.abb.com/marine

Jan Bosch, (2000),Design and use of software architectures: adopting and evolving a product-line approach,  Last Retrieved on October 29, 2009.