This paper presents operational experience and ice measurement results from Finnish Icebreaker Polaris propulsion system. Icebreaker Polaris applies a novel three propulsion unit concept. During the shipbuilding period an extensive ice load measurement system was installed on two of the Azipod units. The paper will present key findings from the measurements from the winter periods 2017-2018.
The target of the ice load measurement campaign is to increase the designer knowledge of propulsor ice loads in different ship operations. The purpose is to understand in more detail the load distribution for component life estimations and clarify differences between bow and stern propulsor ice loads and frequencies. Due to non-linear load distribution in propulsor at extreme loads, strain gauges were installed at two levels in propulsor hull.
This paper will highlight some measurement results of propulsion system behavior during the ice trials and long term measurements from the winters 2017 and 2018. The full-scale ice operation data collected in the Baltic Sea ice conditions can be further utilized in a development vessel and its propulsion system of heavy polar icebreaker type.
The measurement campaign onboard the Polaris is planned to continue during coming winters. The aim is to collect statistical ice load data to improve the understanding of the fatigue and ultimate design loads. One of the goals is also to clarify how much load the bow mounted propulsion unit will experience compared to the stern units. Based on the measurement results so far, we can conclude that icebreaker with bow mounted Azipod propulsor can be operated without limitations in all ice conditions, just like all the other icebreakers in the Baltic.
Ships transporting different liquids have been around for as long as there has been the need to trade between countries and nations. The first liquid transport happened in drums loaded into the ships like any cargo. During the last 120 years as ships have been built of steel/iron it has been possible to transport liquids in tanks built in to the structure of the ships.
During the 20th century cargo ships sailing in ice were assisted seasonally mostly by icebreakers. Most of the liquid transport did not really need any assistance in ice conditions as there was hardly any winter traffic. The continuous need for utilizing oil lead to new territories and the oil discovered in Alaska in the late 1960ies brought up the crude oil transport in ice conditions and Esso started the Manhattan project. This unfortunately did not start the arctic tanker transport. This paper discusses the development history of the propulsion of tankers working in ice conditions.
In the early 1970ies the winter traffic in Finland exploded as the Finnish government decided to keep all the major ports open year-round. This started serious development of ships capable of more independent ice operation. The first propulsion solutions were modifications of well proven technology. We had fixed pitch and controllable pitch propellers connected directly to low speed diesel engines or through a gearbox. In some applications the propeller was equipped with a nozzle. In the 1970ies and 1980ies we were already drafting different tankers with electric propulsion with huge power. However, it was needed a decade more and the development of the propulsion devices from direct shaft lines to azimuth devices to get the propulsion revolution going at full speed.
Today we have available and most commonly used; traditional fixed pitch propellers with conventional shaft lines, mechanical Z-drives and podded propulsors driven by electric motors. The operational profile and mission of the vessel will dictate how the tanker will be furbished.
Most of the new concepts have been tested and developed in conjunction of icebreaker development, where tankers have been closely following. Recently there have been delivered and designed new icebreakers, icebreaking shuttle tankers and LNG carriers. Many of these vessel concepts are relying on podded propulsion system. AZIPOD propulsion has been selected to many of these vessels as it provides excellent ice performance for the vessel, good torque characteristics for the propeller and there already exists proven track record of ice operations. This paper will introduce some outstanding full-scale experience from the revolutionary icebreaking LNG carrier Christopher de Margerie.
Icebreaker technology has undergone significant advances over the last 25 years. This development have led to building of new generation icebreaking fleet: both icebreakers and ice capable cargo vessels. This article will concentrate on some key aspects in designing of optimum propulsion system for icebreaker.
This paper will present Finnish Icebreaker Polaris propulsion system, which is based on well-proven podded propulsion. Icebreaker Polaris applies novel three propulsion unit concept, where one 6.0 MW unit is at the bow and two 6.5 MW units at the stern. The icebreaker is the first with pod unit at the bow and it will considerably enhance vessel’s maneuverability and icebreaking operations.
During the shipbuilding period extensive ice load measurement system was installed on the bow and the other stern mounted Azipod units. The measurement data is currently collected and analyzed for research and development purposes.
Icebreaker Polaris was delivered September 2016 from Arctech Helsinki Shipyard. The first operational experience was gathered during winter period 2016-2017 in the Northern Baltic Sea ice conditions. This paper will highlight some measurement results of propulsion system behavior during the ice tests. The full-scale ice operation data collected in Baltic conditions can be further utilized in development vessel and its propulsion system of heavy polar icebreaker. Paper will also present a case study of propulsion concept suitable for polar icebreakers.
Acoustically the submerged components of an Azipod propulsion unit comprise two uncorrelated noise sources, namely the propeller and the electrial motor. The propeller hydrodynamic noise is highly dependent on the load & speed whereas the magnetic noise of the electric motor exhibits a smoother dependency on the load & speed. The electromagnetic noise of the motor is highly dependent on the converter supply properties such as the number of voltage levels and current/voltage modulation parameters.
The paper deals with the challenge of estimating the total underwater sound emission of an Azipod unit using both the airborne sound power measurements and underwater sound emission simulations and current hydrodynamical tools available.
The airborne electromagnetic noise emission of the unit can be measured at a factory testbed using the designed converter supply together with correct shaft loading. Sound intensity based methods are favoured in the paper due to their ability to exclude the extraneous noise from the results (factory background noise & noise from the loading machine). Once the airborne noise figures are obtained, a conversion to corresponding underwater noise figures is needed. This is accomplished by computing the airborne and underwater noise radiation with same electromagnetic loading using FE-method for the structural dynamics and BEM for the acoustic radiation. The conversion factor K from airborne to waterborne sound emission is finally obtained for each of the electomagnetic excitation patterns. The accuracy or goodness of K is then validated by comparing future underwater noise measurements during sea-trials and the measured airborne emission at the test floor.
Separate analysis of hydrodynamic acoustic characteristics are performed with three different tools and finally combined to total URN level with electromagnetic noise emission estimation.
In this work, the underwater fluid loading on the Azipod unit surface plates is included by using a very simple approach, which is to be addressed in future studies.
Recently there have been delivered and designed new icebreakers, icebreaking shuttle tankers, container vessels and LNG carriers. Many of these vessel concepts are relying on podded propulsion system. Azipod propulsion has been selected to many of these vessels as it provides excellent ice performance for the vessel, good torque characteristics for the propeller and there already exists proven track record of ice operations. Currently the demand for even bigger icebreaking vessels with higher capacity is increasing. Due to increasing market need ABB Marine have further developed Azipod propulsion concept to meet the demands of arctic ice classes and power requirements of more than 15 000 kW per thruster unit. This paper will give an overview of 25 year of development of azimuth podded propulsion, Azipod, for icebreaking vessels and introduce latest breakthrough projects in arctic shipping.
After Columbus has sailed to the West Indies also the search for the northern alternative to reach India became attractive. Over four hundred years ago Dutch Willem Barentz started to sail the North East passage towards east, but he did not get very far. After mapping Spitsbergen and Frantz Josef land he stranded on Novaya Zemilya. After this it took awhile until next expeditions became true, and even in the 19th century, nobody understood the northern environment and its challenges to people and equipment. Today we know perhaps too much. Today nobody would go and risk his life without having a heavily strengthened vessel around him. We have moved all the way from wooden sailing ships to nuclear powered vessels and year-round navigation. Part of this is due to climate change but also because the search for oil is moving further north. This paper brings us back from history to modern times and discusses the recent history what we have accomplished during the last decades and also tries to give some future views.
A major part of world’s oil and gas reserves are located in Arctic and Subarctic seas, such as Sakhalin fields in Okthosk Sea as well in Chuchki Sea, Beaufort Sea Alaska. Year around operations in these areas results increasing need for special designed icebreaking offshore support vessels and tankers. Important characteristic of these vessels is the capability in ice managent duties.
Azimuth thruster offers great flexibility in different ice management using the thruster wake and propeller close contact with ice. Electric propulsion with Azipod propulsors has been used in such vessels with good success for many years and the system itself has shown to be reliable and very good characteristics when operated in ice. In Sakhalin region there has accumulated experience from 7 icebreaking vessels with ABB electric propulsion many equipped with Azipods. Recently two new icebreaking vessels with Azipod have been built for Arkutun-Dagi field. Electric Azipod propulsion system have been playing an important part in several arctic ship projects making the demanding projects technically and economically feasible. In this paper will be presented characteristics as well some full-scle test results where Azipod units are used in ice management type operations.
Copyright 2012, Offshore Technology Conference This paper was prepared for presentation at the Arctic Technology Conference held in Houston, Texas, USA, 3-5 December 2012. This paper was selected for presentation by an ATC program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Offshore Technology Conference and are subject to correction by the author(s). Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Offshore Technology Conference is prohibited. The abstract must contain conspicuous acknowledgment of OTC copyright. The recent growth in activities in the Arctic region has materialized in several projects, where Azipod propulsion system is playing an important role in making the projects technically possible and economically feasible. Azipod propulsion offers a very attractive and efficient propulsion solution for most of these vessels. However, there is an evident need for azimuthing propulsion units with power in excess of 15 MW with highest ice classes, such as the "new" IACS PC1.