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Ice is a challenge, not a problem

Aker Arctic Technology is a unique player in designing ships for navigating in ice and/or breaking through it. Comprehensive ice model testing facilities and decades of field data give its designers a very good understanding of the problems involved – and have led to a number of landmark technologies, such as double-acting tankers.
Aker Arctic Technology Inc.

Aker Arctic Technology (AARC) has over 50 years of experience in developing ships for efficient operation in ice, and has been involved in the development of over 60% of all the icebreakers ever built.

Working with ABB, for example, AARC has brought electric azimuthing thrusters (Azipods) to ice-going ships. Used in combination with modern hull forms optimised for ice conditions, these units have revolutionised vessel operations in ice and have overcome the shortcomings associated with conventional shafts and propellers that limit steering in ice dramatically.

The introduction of Azipods led to the development of the double-acting principle that allows vessels to proceed ahead in thinner ice and astern in heavier ice. The first of these vessels, the Arcticaborg and Antarcticaborg supply vessels based in the Caspian Sea, now have 10 years of successful operation behind them.

The 1AS ice-classified Tempera and Mastera Aframax tankers, delivered by Sumitomo Heavy Industries to Neste Oil in 2002 and 2003, featured Azipods and a double-acting design.

When double-acting vessels operate astern, the milling action of the propeller helps cut a path for the ship through the ice, and the water flow automatically flushes the hull, easing the ship’s progress. Until this type of operation became possible, ice-going ships needed to have an ice-going bow, totally different from an open-water bow and much less hydrodynamic, leading to higher fuel consumption.

The Vasily Dinkov and her two sister ships will transport crude from Varandey in the Pechora Sea to Murmansk without icebreaker assistance – the first time this route has been handled in this way.

As double-acting vessels operate astern in heavy ice, the stern needs to be optimised for ice operation, not the bow, which can be given a traditional bulbous bow optimised for open-water operation. Since up to 95% of a ship’s time at sea is spent in open water, this makes enormous sense in terms of fuel efficiency and the environment.

In the Russian Far East and Far North

In 2003, FESCO of Vladivostok, with design and support from Aker Arctic, won a contract from Exxon Neftegaz to deliver and operate an icebreaking platform support and standby vessel for the Sakhalin 1 project in the Sea of Okhotsk, where 1.5 meter-thick ice creates rubble formations 20 meters deep. Based on a double-acting design, the 13 MW Fesco Sakhalin is now serving her third successful winter season.

Following the delivery of the Norilskiy Nickel Arctic container vessel, with a 13 MW azipod and built to the highest LU7 Arctic ice class so far, Norilsk Nickel awarded an order to Aker Yards for four more similar vessels – to form a totally new logistic system designed to operate independently of high-cost icebreaker assistance.

Transporting oil by tanker in the Arctic area was originally carried out by fleets of nuclear icebreakers and relatively small oil tankers. After Azipod propulsion had been tried and tested in the region through retrofits of the Uikku and Lunni. Naryanmarneftegaz – a joint venture between LUKoil and Conoco?Phillips – launched a project to develop a direct marine export system for onshore oil production in the Timan Pechora region together with Aker Arctic in 2005.

This work led to the preliminary design of vessels now being built by Samsung Heavy Industries. Based on a cooperation agreement on the double-acting concept with AARC signed in 2004, Samsung Heavy Industries is building a pioneering trio of Arctic icebreaking shuttle tankers for Sovcomflot.

The first vessel of the trio, the Vasily Dinkov, was delivered on New Year’s Day 2008 The ship will transport crude from Varandey in the new oilfields of the Pechora Sea to Murmansk without icebreaker assistance – the first time such a journey has been handled in this way.

These new designs will be able to break ice up to 1.5m thick with a 0.2m snow covering at a speed of approximately 3 knots either forward or astern. Icebreaking and open water performance have been verified at AARC’s model ship tank and model basins in Sweden. The ships will be powered by twin Azipods (2 x 10MW), and the hull structure has been ice-strengthened in accordance with RMRS Ice Class LU6. The ships will be fully winterised to cope with extremely cold weather down to -45 °C. The bow loading system, capable of operating at 10,000m3/h, will ensure no spills at sea, protecting the sensitive Arctic environment.

And in the Baltic too

The latest fruit of AARC´s intensive product development in icebreaking technology is a contract awarded by the Estonian Maritime Administration, on the last day of 2007, for the design of a new-generation multipurpose icebreaker. This includes the development of the conceptual design, the basic design, preparation of the tender documents needed for a public procurement contract, and construction supervision.

The brief is for a vessel with a total length of 108 metres and a breadth of 28 metres capable of breaking 1.2 metre-thick level ice forward and astern at a continuous speed of 3 knots, as well as moving smoothly through heavy ice ridges due to her novel stern design. The vessel’s twin azimuthing drives will have a total shaft power of 17 MW; and the ship will be fitted with equipment for oil spill, fire fighting, and towing duties, as well as offshore operations, outside the winter season.

This multipurpose icebreaker for the Estonian government is the latest fruit of AARC’s intensive product development.
> Mikko Niini
(Published in HighTech Finland 2008)