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Encyclopedia of Marine Technology


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A measure of volume denoting one thousand cubic feet of natural gas equal to 28.3168 cubic metres.

Mean time between failures

The ratio of the accumulated operating time for a sample of parts to the total number of failures in the sample, for specified conditions of operation.

Means of rescue (MOR)

Means for rapidly recovering survivors from water and transferring them from rescue units or survival craft to the ship, (mandatory for each ro-ro passenger ship).

Mechanical efficiency

The ratio of shaft power to the indicated power of an internal combustion engine.

Mechanical seal

A shaft sealing arrangement fitted to pumps in place of a stuffing box and gland packing assembly.

Medium-speed engine

An internal combustion engine operating within the range from 250 rev/min to about 1200 rev/min.


The process of changing a solid into liquid.

Membrane BioReactor (MBR)

Wärtsilä Hamworthy’s MBR technology is an advanced wastewater treatment process based on biological degradation and membrane separation.

Membrane containment system of HANJIN MUSCAT

Built in 1999 by Hanjin Heavy Industries Co Ltd, Korea, LNG tanker HANJIN MUSCAT has four cargo tanks contained in a complete double-hull structure, which includes ship sides and bottom, transverse bulkheads and upper deck trunk.

Membrane technology

The membrane technology was developed by the naval engineering firms Gaz Transport and S.N. Technigaz for the transport of liquid methane by sea.

Membrane type Nitrogen Generator System

Built in Japan at the Namura yard, the methanol carrier MILLENNIUM EXPLORER is equipped with the world largest ship-based nitrogen generator system.

Membrane-type LNG cargo containment system

Membrane systems exploit the double hull of the ship as the supporting structure on which a cryogenic liner – performing the two functions of gas tightness and thermal insulation – is applied.

Memorandum of Understanding on Port State Control (MOU)

Agreements on port state control signed in several regions of the world by the coastal states ; 1982 Paris MOU for the European region, 1992 Latin America agreement, 1993 Tokyo MOU for the East Asia region, etc.

Mermaid propulsion unit

The Rolls-Royce’ s podded propulsor developed by Kamewa and Alstom and available from 5 to 25MW.

Messenger line

A light line attached to the end of a main mooring line and used to assist in heaving the mooring to the shore or to another ship.


Dinning room for officers or crew.

Metacentre M (initial transverse metacentre)

When a ship floating at rest in still water is inclined by an external force to a small angle fi, the centre of buoyancy shifts from B to the new position – Bfi.

Metacentric height

The vertical distance between G and M is referred to as the metacentric height. The relative positions of vertical centre of gravity G and the initial metacentre M are extremely important with regard to their effect on the ship’s stability.

Methane hydrate

Methane hydrate is a cage–like lattice of ice inside of which are trapped molecules of methane, the chief constituent of natural gas. If methane hydrate is either warmed or depressurized, it will revert back to water and natural gas.


The double-hulled methanol carrier MILLENNIUM EXPLORER has twice the capacity of any other vessel of its type. Total cargo capacity is around 120,000m3. Methanol is transported in 12 cargo tanks.

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