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WÄRTSILÄ
Encyclopedia of Marine Technology

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Mevis duct

see POWER-SAVING DEVICES.

Mezzanine decks

Lightweight, movable decks used on fast ferries. If traffic is freight dominated, the crew can hydraulically raise the mezzanine deck up to the deckhead to allow clearance for high freight vehicles.

Midship section

1. The cross section through the ship, midway between the forward and after perpendiculars. 2. A drawing showing standard cross sections of the hull at, or near amidships, and presenting the scantlings of the principal structural members.

Midship section modulus

The section modulus of a transverse section of a hull girder amidships, evaluated by taking into account the longitudinally effective material.

Mill scale

An oxide of iron which appears on the metal surface during manufacture. It is usually removed by suitable surface treatment prior to priming and painting.

Miller timing

In Wärtsilä engines the inlet valves close just before the piston reaches the bottom dead centre.

Mimic diagram

A line diagram of a pipe system or items of equipment which includes miniature alarm lights or operating buttons for the relevant point or item in the system.

Minimum breaking load of a mooring line (MBL)

The minimum breaking load of a mooring line as declared by the manufacturer for a new line.

Minimum comfortable condition of habitability

A condition in which at least services such as cooking, heating, domestic refrigeration, mechanical ventilation, sanitary and fresh water are adequately provided.

Minor failure of tanker

Local fracture of a tank boundary weld.

Misalignment

The distance between the axes of two shafts to be coupled together.

Mitsubishi Stator Fin

A device aimed primarily at improving propulsive performance. It consists of fixed-type steel fins at the rear of the propeller which are fitted onto the forward side of the rudder horn.

Mixed stowage

A system to stow 20-feet containers into 40-feet cell guides. Starting from tank top you can stow from 1 to 4 tiers 20-feet containers (only secured by single stacking cones) and top them up with at least one 40-feet container.

MMBTU

One million British Thermal Units. BTU is a traditional unit of energy equal to 1055.06 joules. It is the amount of energy needed to cool or heat one pound of water one degree Fahrenheit.

MMSCFD

Million standard cubic feet per day is a unit of measurement mainly used in the USA. Mainly used as a measure for natural gas. One MMSCFD equals 1180 m3/h.

MOB RETRIEVAL EQUIPMENT

There are several types of man overboard retrieval equipment like ladders, scrambling nets, A-frames, Jason’s cradle, hydraulically operated platforms, etc.

Mobdock

A steel box (mobile mini drydock) provided with an access hatch and used as an external enclosure to carry out dry work to be done underwater.

MOBILE OFFSHORE DRILLING UNIT (MODUs)

If geological predictions based on seismic surveys show that a particular offshore area offer promising prospects for finding oil, a well is drilled to examine these predictions.

MOBILE OFFSHORE UNITS (MOUs)

Mobile Offshore Units – Self-elevating or column-stabilized units, not fitted with drilling equipment, production facilities, hydrocarbon storage, or any other system onboard handling hydrocarbons.

Model testing tanks

Towing tanks, manoeuvring and seakeeping basins used to carry out experiments with models.

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