MT Mastera

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MT Mastera
Mastera outside the Port of Rotterdam
Name: Mastera
Owner: SEB Leasing Oy[1]
Operator: Neste Oil[2]
Ordered: 2001[3]
Builder: Sumitomo Heavy Industries Ltd., Yokosuka, Japan[2]
In service: 2003[2]
Status: In service[2]
General characteristics [2]
Class and type: Crude oil tanker
Tonnage: 64,259 GT
30,846 NT
106,208 DWT
Length: LOA 252.0 m (826.77 ft)
LPP: 237.59 m (779.49 ft)
Beam: 44.0 m (144.36 ft)
Draught: 15.3 m (50.20 ft)
Ice class: 1A Super
Installed power: 2 × Wärtsilä 9L38B[1], 2 × 6.0 MW
2 × Wärtsilä 6L38B[1], 2 × 4.0 MW
1 × Wärtsilä 6L26A[4], 1 × 1.7 MW (auxiliary)
Propulsion: Diesel electric propulsion
16 MW ABB Azipod unit
Speed: 13.5 knots, max. 15.2 knots[1]

MT Mastera is a Finnish crude oil tanker operated by Neste Oil. She and her sister ship, MT Tempera, are the first ships to utilize the double acting tanker (DAT) concept, developed by Aker Arctic Technology, in which the vessel is designed to travel ahead in open water and astern in severe ice conditions.[3][5]

Although icebreaking tankers have been built in the past, their hull form was always a compromise between open water performance and icebreaking capability because a good icebreaking bow is not hydrodynamically efficient and vice versa. While it was known that traditional icebreakers could run astern in ice even though they weren't designed for that, it wasn't until the development of electric podded propulsion that the concept of double acting ship was developed. The feasibility of such design was further proved by Azipod-converted product tankers MT Lunni and MT Uikku that made several voyages in the Northern Sea Route in the 1990s and sometimes had to run astern to break through the ice.[3] In 2001 Fortum (from which Neste Oil was later separated) ordered two double acting tankers from Sumitomo Heavy Industries Ltd., and the first ship, Tempera, was delivered from Yokosuka shipyard in 2002 and Mastera in the following year.

The bow of the double acting tanker is designed for open water performance with a bulbous bow 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 Mastera and her sister are designed to operate independently in the most severe ice conditions of the Baltic Sea.[3] For this purpose the ship is also equipped with two bridges for navigating in both directions.

Mastera and her sister ship are also the first tankers built with an electrically-driven Azipod propulsion unit, one 16 MW pulling-type pod. The forward-facing propeller increases the propulsion efficiency because of optimal water flow to the propeller and therefore improves fuel efficiency. An azimuthing thruster's ability to direct thrust to any direction also results in excellent manoeuvrability characteristics that exceeds those of ships utilizing mechanical shaftlines and rudders.[6] The turning circle of these two tankers is only half a kilometer, half of that of a traditional oil tanker of the same size.[5]