MT ''Alma'' is an
Aframax
An Aframax vessel is an oil tanker with a deadweight between 80,000 and 120,000 metric tonnes. The term is based on the Average Freight Rate Assessment (AFRA), a tanker rate system created in 1954 by Shell Oil to standardize shipping contract t ...
crude oil tanker
An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined c ...
. Formerly known as ''Mastera'' for almost two decades and briefly as ''Mikines'' in early 2022, she and her sister ship
''Tempera'' were the first ships to utilize the
double acting tanker (DAT) concept in which the vessel is designed to travel ahead in open water and astern in severe ice conditions.
The icebreaking tanker was built to transport crude oil year-round from the
Russia
Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eigh ...
n oil terminal in
Primorsk Primorsk may refer to:
* Dənizkənarı, Azerbaijan, formerly called Primorsk
* Primorsk, Leningrad Oblast, a town in Leningrad Oblast, Russia, formerly Koivisto or Björkö
* Primorsk, Kaliningrad Oblast, an urban-type settlement in Kaliningrad Ob ...
to Neste Oil refineries in
Porvoo
Porvoo (; sv, Borgå ; la, Borgoa) is a city and a municipality in the Uusimaa region of Finland, situated on the southern coast about east of the city border of Helsinki and about from the city centre. Porvoo was one of the six medieval to ...
and
Naantali
Naantali (; sv, Nådendal) is a town in southwestern Finland, and, as a resort town during the summer, an important tourist centre of the country. The municipality has a population of
(), and is located in the region of Southwest Finland, west ...
.
Concept
Although icebreaking cargo ships had been built in the past, their hull forms were always compromises between open water performance and icebreaking capability. A good icebreaking bow, designed to break the ice by bending it under the ship's weight, has very poor open water characteristics and is subjected to
slamming
Slamming is the impact of the bottom structure of a ship onto the sea surface. It is mainly observed while sailing in waves, when the bow raises from the water and subsequently impacts on it. Slamming induces extremely high loads to ship structure ...
in heavy weather while a hydrodynamically efficient bulbous bow greatly increases the ice resistance.
[Kujala, P and Riska, K: Talvimerenkulku (TKK-AM-13). Department of Applied Mechanics, Helsinki University of Technology, 2010.] However, already in the late 1800s captains operating ships in icebound waters discovered that sometimes it was easier to break through ice by running their vessels astern. This was because the forward-facing propellers generated a water flow that lowered the resistance by reducing friction between the ship's hull and ice.
[Aker Arctic Technology Inc.]
Icebreaking Supply Vessels Arcticaborg and Antarcticaborg
. These findings resulted in the adoption of bow propellers in older icebreakers operating in the
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five la ...
and the
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.
The sea stretches from 53°N to 66°N latitude and fr ...
, but as forward-facing propellers have a very low propulsion efficiency and the steering ability of a ship is greatly reduced when running astern, it could not be considered a main operating mode for merchant ships.
[Juurmaa, K et al.]
New ice breaking tanker concept for the arctic (DAT)
. Kvaerner Masa-Yards Arctic Technology, 1995.[Juurmaa, K et al.: The development of the new double acting ships for ice operation. Kvaerner Masa-Yards Arctic Technology]
2001
an
2002
.
For this reason it was not until the development of electric podded propulsion,
ABB's Azipod
Azipod is a trademark azimuth thruster pod design, a marine propulsion unit consisting of a fixed pitch propeller mounted on a steerable gondola ("pod") containing the electric motor driving the propeller, allowing ships to be more maneuverab ...
, that the concept of double acting ships became feasible. The superiority of podded propulsion in icebreaking merchant ships, especially when running astern, was proved when Finnish
product tanker
An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined crud ...
s
''Uikku'' and
''Lunni'' were converted to Azipod propulsion in 1993 and 1994, respectively. Even though the ships were originally designed with icebreaking capability in mind, after the conversion ice resistance in level ice when running astern was only 40% of that when breaking ice ahead despite the ships being equipped with an icebreaking bow and not designed to break ice astern.
History
Development
Following the successful operation of the Azipod-converted tankers ''Uikku'' and ''Lunni'' in the
Northern Sea Route
The Northern Sea Route (NSR) (russian: Се́верный морско́й путь, ''Severnyy morskoy put'', shortened to Севморпуть, ''Sevmorput'') is a shipping route officially defined by Russian legislation as lying east of No ...
,
Kværner Masa-Yards Arctic Research Centre developed the first double acting tanker concept in the early 1990s. The 90,000 DWT tankers were designed to transport oil and gas condensate from the
Pechora Sea
Pechora Sea (russian: link=no, Печо́рское мо́ре, or Pechorskoye More), is a sea at the northwest of Russia, the southeastern part of the Barents Sea. The western border of the sea is off Kolguyev Island, while the eastern border ...
in the
Russia
Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eigh ...
n
Arctic
The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada ( Yukon, Northwest Territories, Nunavut), Danish Realm ( Greenland), Finland, Iceland ...
, where ice conditions during winter can be considered moderate and the ships would operate mainly in astern mode, first to
Murmansk
Murmansk ( Russian: ''Мурманск'' lit. " Norwegian coast"; Finnish: ''Murmansk'', sometimes ''Muurmanski'', previously ''Muurmanni''; Norwegian: ''Norskekysten;'' Northern Sámi: ''Murmánska;'' Kildin Sámi: ''Мурман ланнҍ ...
and then
Rotterdam
Rotterdam ( , , , lit. ''The Dam on the River Rotte'') is the second largest city and municipality in the Netherlands. It is in the province of South Holland, part of the North Sea mouth of the Rhine–Meuse–Scheldt delta, via the ''"N ...
, where most of the distance can be travelled in open water year round.
Other early double acting concepts included a similar ship with an icebreaking bow that would be utilized in summer time when the ship was traveling in areas with low ice concentration but with a risk of colliding with multi-year ice blocks.
In early 2000s Fortum Shipping, the transportation arm of the Finnish energy company
Fortum
Fortum Oyj is a Finnish state-owned energy company located in Espoo, Finland. In addition to Finland, it focuses on Germany and other countries in Central Europe, Great Britain, Russia and the Nordic region. Fortum operates power plants, inc ...
, started a major fleet renewal program to increase the efficiency and reduce the average age of its vessels.
[NextStop - Merten valtiaat]
Refine 2/06
, page 24. Neste Oil, 2006. The program also included replacing the company's old tankers, such as the 90,000-ton
''Natura'', that were used to transport crude oil to the company's oil refineries in the
Gulf of Finland
The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...
. The old ships had traffic restrictions during the worst part of the winter because of their lower
ice class
Ice class refers to a notation assigned by a classification society or a national authority to denote the additional level of strengthening as well as other arrangements that enable a ship to navigate through sea ice. Some ice classes also have r ...
of 1C and could not deliver their cargo all the way to the refineries in Porvoo and Naantali because they were denied icebreaker assistance. When this happened, the oil had to be transported to smaller ships of higher ice class at the edge of the ice — a practice that was both uneconomical and hazardous.
To solve these problems Kværner Masa-Yards Arctic Research Centre developed a new 100,000 DWT Aframax tanker concept together with Fortum Shipping, which ordered two vessels from
Sumitomo Heavy Industries
(SHI) is an integrated manufacturer of industrial machinery, automatic weaponry, ships, bridges and steel structure, equipment for environmental protection, including recycling, power transmission equipment, plastic molding machines, laser proce ...
in 2001. The new ships were designed to the highest
Finnish-Swedish ice class
Finnish-Swedish ice class is an ice class assigned to a vessel operating in first-year ice in the Baltic Sea and calling at Finnish or Swedish ports. Ships are divided into six ice classes based on requirements for hull structural design, engi ...
, 1A Super, and to be capable of operating in all ice conditions encountered in the
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.
The sea stretches from 53°N to 66°N latitude and fr ...
. The possibility to operate in the Pechora Sea was also taken into account in the design process. Extensive ice model tests confirmed the vessel's operational capability in level ice, rubble fields, ice channels and ridges.
The world's first double acting tanker and the largest 1A Super class oil tanker at that time, ''Tempera'', was delivered from
Yokosuka shipyard in late August 2002.
[TEMPERA Tanker double act](_blank)
. The Motor Ship, 1 October 2002. [Ice-class tankers](_blank)
. Lloyd's Register, 16 April 2004. She was awarded the Ship Of The Year 2002 award by the Society of Naval Architects of Japan (SNAJ).
[The Ship of The Year 2002 Award goes to the Tempera](_blank)
. SEA Japan No. 300, August–September 2003. The second ship, ''Mastera'', was delivered in the following year.
Both ships were named after the company's oil products.
[Refine 1/08, page 23. Neste Oil, 2008.] While the price of the contract was not made public, the company later admitted that the 60–70 million euro estimate was "quite close to the truth". The ships were owned by ABB Credit, which leased them to Fortum for ten years.
The leasing business was later sold to SEB Leasing.
Career

Since the beginning, ''Tempera'' and ''Mastera'' were used mainly for year-round transportation of crude oil from the Russian oil terminal of Primorsk to company's own oil terminals in Porvoo and Naantali,
where they were the only ships capable of operating without delays or problems during the harshest winters.
[Opening up Arctic oil resources](_blank)
High Technology Finland 2006. Occasionally they also carried cargoes in the
Gulf of Bothnia and even outside the Baltic Sea depending on the amount of oil in the refineries' storage tanks.
[Varmoilla jäillä]
Refine 1/07
, pages 25-27. Neste oil, 2007.
Rannikkoseutu, 13 April 2011. However, due to draft restrictions the ships could not carry a full cargo of 100,000 tons to the port of Naantali until April 2010 — they had to stop at Porvoo on the way and unload 20,000 tons of oil to reduce the draft of the vessel.
[Neste Oilin tankkialus ajoi ensimmäisenä uutta syväväylää Naantaliin](_blank)
Helsingin Sanomat, 25 April 2010.
In 2005 Fortum's oil division was transferred to the re-established
Neste Oil
Neste Oyj (international name: Neste Corporation; former names Neste Oil Corporation and Fortum Oil and Gas Oy) is an oil refining and marketing company located in Espoo, Finland. It produces, refines and markets oil products, provides en ...
and the management of the ships, including the double acting tankers, was handed over to a subsidiary company Neste Shipping. On 19 September 2013, Neste Oil announced that it would sell its shipping business and the majority of its ships, including ''Mastera'', to a new company owned by the Finnish insurance company
Ilmarinen
Ilmarinen (), the Eternal Hammerer, blacksmith and inventor in the ''Kalevala'', is a god and archetypal artificer from Finnish mythology. He is immortal and capable of creating practically anything, but is portrayed as being unlucky in love. He i ...
and the
National Emergency Supply Agency
sv, Försörjningsberedskapscentralen
, type =
, logo =
, logo_size =
, logo_caption =
, logo_alt =
, image =
, image_size =
, image_caption ...
. In 2019, ''Mastera'' was resold back to SEB Leasing.
Since 2017, ''Mastera'' was the only double acting tanker operating in the Baltic Sea after ''Tempera'' was sold overseas.
[A passion for ice.](_blank)
High Tech Finland 2011. While other double acting ships have been built, the tankers operated by Neste Shipping were the only ones equipped with a bulbous bow designed primarily with open water performance in mind — the tankers and container ships built for the Russian Arctic have a more traditional icebreaking bow due to the more severe ice conditions.
In September 2021, ''Mastera'' was transferred to the
Norwegian International Ship Register Norwegian International Ship Register or NIS is a separate Norwegian ship register for Norwegian vessels aimed at competing with flags of convenience registers such as Panama and Liberia. Originally proposed by Erling Dekke Næss in 1984, it was est ...
.
In January 2022, she was renamed ''Mikines'' and reflagged to Liberia.
In March 2022, the 19-year-old ''Mikines'' appeared on list of tonnage sold for
demolition
Demolition (also known as razing, cartage, and wrecking) is the science and engineering in safely and efficiently tearing down of buildings and other artificial structures. Demolition contrasts with deconstruction, which involves taking a ...
,
but has since resumed trading and was renamed ''Alma'' in June 2022.
Design
General characteristics
The double acting Aframax tanker is
long overall and
between perpendiculars
Length between perpendiculars (often abbreviated as p/p, p.p., pp, LPP, LBP or Length BPP) is the length of a ship along the summer load line from the forward surface of the stem, or main bow perpendicular member, to the after surface of the stern ...
. The moulded breadth and depth of her hull are and , respectively, and from keel to mast she measures . Her
gross tonnage
Gross tonnage (GT, G.T. or gt) is a nonlinear measure of a ship's overall internal volume. Gross tonnage is different from gross register tonnage. Neither gross tonnage nor gross register tonnage should be confused with measures of mass or weig ...
is 64,259 and
net tonnage 30,846, and the
deadweight tonnage
Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (DWT) is a measure of how much weight a ship can carry. It is the sum of the weights of cargo, fuel, fresh water, ballast water, pro ...
corresponding to the
draft at summer freeboard, , is 106,208 tons, slightly more than that of her sister ship. In ballast, the ship draws only of water.
The foreship of the tanker is designed for open water performance with a
bulbous bow
A bulbous bow is a protruding bulb at the bow (or front) of a ship just below the waterline. The bulb modifies the way the water flows around the hull, reducing drag and thus increasing speed, range, fuel efficiency, and stability. Large ships w ...
to maximize the hydrodynamic efficiency. The ship is, just like any other ice-strengthened vessel, also capable of running ahead in light ice conditions. The stern is, however, shaped like an icebreaker's bow, and the vessel is designed to operate independently in the most severe ice conditions of the
Baltic Sea
The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain.
The sea stretches from 53°N to 66°N latitude and fr ...
.
For this purpose the ship is also equipped with two
bridges
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
for navigating in both directions.
The ship is served by a crew of 15 to 20 depending on operating conditions during winter and maintenance work during summer.
The ship is classified by
Lloyd's Register of Shipping
Lloyd's Register Group Limited (LR) is a technical and professional services organisation and a maritime classification society, wholly owned by the Lloyd’s Register Foundation, a UK charity dedicated to research and education in science and ...
.
Cargo tanks and handling
The ship has six pairs of heated, partially epoxy-coated cargo tanks and one pair of fully coated
slop tanks, all divided by a longitudinal center bulkhead and protected by
double hull
A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some dist ...
, with a combined capacity of at 98% filling. For cargo handling she has three electrically driven cargo oil pumps with a capacity of 3,500 m
3/h × 130 m and one cargo oil stripping pump rated for 300 m
3/h × 130 m. The cargo can be loaded in 10 hours and discharged in 12 hours. Each cargo tank has two and both slop tanks one
automated tank cleaning machine
An automated tank cleaning machine is a machine used to clean cargo, process, underground storage tanks and similar equipment such as those found in tank trucks, railroad cars, barges, oil tankers, food and beverage manufacturing facilities, che ...
s as well as holes for portable tank cleaning machines.
The ship's ballast water capacity of is divided into sixteen segregated ballast tanks, six pairs in the double hull around the cargo tanks, two fore peak tanks and two aft peak tanks.
She has two electrically driven ballast pumps rated at 2,500 m
3/h × 35 m and 3,000 m
3/h × 70 m.
The ballast capacity is needed to maintain correct trim especially during drydocking — the empty ship has an aft trim of and an uneven weight distribution may damage the hull girder.
[Tempera telakalla]
Vapaavahti 4/2010
, pages 4-7. Merimiespalvelutoimisto, 2010.
Power and propulsion
The ship has
diesel-electric powertrain with four main generating sets, two
nine-cylinder Wärtsilä
Wärtsilä Oyj Abp (), trading internationally as Wärtsilä Corporation, is a Finnish company which manufactures and services power sources and other equipment in the marine and energy markets. The core products of Wärtsilä include technol ...
9L38B and two
six-cylinder
The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine bala ...
6L38B four-stroke medium-speed
diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-ca ...
s, with a combined output of . The main engines are equipped with
exhaust gas economizers. In addition ''Mastera'' has one auxiliary diesel generator that can be used when the ship is at port. The auxiliary generator, six-cylinder Wärtsilä 6L26A, has an output of . While underway at , the fuel consumption of the ship's main engines is 56 tons of
heavy fuel oil
Heavy Fuel Oil (HFO) is a category of fuel oils of a tar-like consistency. Also known as bunker fuel, or residual fuel oil, HFO is the result or remnant from the distillation and cracking process of petroleum. For this reason, HFO is contaminate ...
per day when loaded and 40 tons per day in ballast. Her tanks can store of heavy fuel oil for the main engines, of diesel oil for the auxiliary generator, steam boilers and
inert gas system
An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined cru ...
, and of lubrication oil.
When built, ''Mastera'' and her sister ship were the first tankers propelled by ABB Azipod electric
azimuth thruster
An azimuth thruster is a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder unnecessary. These give ships better maneuverability than a fixed propeller and rudder system.
Ty ...
s capable of rotating 360 degrees around the vertical axis. The pulling-type VI2500 pods in these two ships, with a nominal output of 16 MW and fixed-pitch propellers turning at 86 rpm, are the most powerful ice-strengthened Azipod units ABB has ever produced.
[Potkurikeksintö herätti kilpailijat](_blank)
. Tekniikka & Talous, 9 October 2003. [References - Propulsion Products](_blank)
ABB. The forward-facing propeller increases the propulsion efficiency due to optimal water flow to the propeller and thus improves fuel efficiency. In addition an azimuthing thruster's ability to direct thrust to any direction also results in excellent manoeuvrability characteristics that exceeds those of ships utilizing traditional mechanical shaftlines and
rudder
A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw a ...
s.
[Azipod Propulsion](_blank)
ABB The turning circle of the Azipod-equipped double acting ships is only half a kilometer at full speed, half of that of a traditional oil tanker of the same size. This is a significant safety factor as the stopping distance of a traditional tanker can be up to .
[Fortum toi Itämerelle ketterän öljytankkerin](_blank)
Tekniikka & Talous, 2002-11-14
For maneuvering at low speeds in harbours, the ship is also equipped with two 1,750kW
bow thruster
Manoeuvering thruster (bow thruster or stern thruster) is a transversal propulsion device built into, or mounted to, either the bow or stern, of a ship or boat to make it more manoeuvrable. Bow thrusters make docking easier, since they allow th ...
s.
Icebreaking capability
The icebreaking capability of the double acting tankers proved to be superior to other ships since the beginning — in shuttle service between Primorsk, Russia, and the Finnish refineries the tankers require no icebreaker assistance and have even acted as an icebreaker for other merchant ships that have utilized the wide channel opened by the Aframax tanker.
[Anatoly Gorshkovskij & Göran Wilkman]
"Norilskiy Nickel" a Breakthrough in Cost Efficient Arctic Transports
. Aker Arctic Technology Inc, 2007. However, this has not been intentional — when the world's largest 1A Super class ice tanker
''Stena Arctica'', also owned by Neste Shipping, became stuck in ice outside the port of Primorsk during the winter of 2009–2010, a decision was made to leave the assisting to Russian icebreakers.
The ships have performed beyond expectations in both level ice up to thick, which can be broken in continuous motion at ,
and ridges up to deep, which can be penetrated by either allowing the forward-facing propeller to mill (crush) the ice or breaking the ridge apart with the propeller wash.
[Opening up the Arctic](_blank)
High Technology Finland 2005. While the vessels have been immobilized occasionally by pack ice, they have been able to free themselves by using the rotating propeller pod to clear the ice around the hull.
[Oil Tanker Maestra cuts backward course through solid ice](_blank)
. Helsingin Sanomat International Edition, 1 April 2003.
References
{{DEFAULTSORT:Alma
Oil tankers
2002 ships
Ships built by Sumitomo Heavy Industries
Double acting ships