23 terms.
- Magnetic Bearing
A bearing measured clockwise from magnetic north, requiring correction for variation to obtain a true bearing.
- Magnetic Compass
A compass that aligns with Earth's magnetic field to indicate magnetic north; required as backup on all SOLAS vessels.
- Main Engine
The primary propulsion engine driving the ship's propeller shaft, typically a large slow-speed two-stroke diesel on cargo ships.
- Mandatory Pilotage
A legal requirement in certain ports or waterways that a licensed pilot must be employed to navigate a vessel through that area.
- Marine Diesel Oil
A distillate fuel oil with low sulfur content, used in auxiliary engines and during port operations where ECA rules apply.
- Marine Superintendent
A senior shore-side manager responsible for the nautical operations, safety, and compliance of vessels in a company fleet.
- Maritime Labour Convention 2006
ILO convention establishing minimum working, living, and social security standards for seafarers worldwide.
- MARPOL Annex I
The annex of MARPOL regulating prevention of pollution by oil, covering operational discharges and accidental spills from ships.
- MARPOL Annex II
The annex of MARPOL controlling discharge of noxious liquid substances carried in bulk, applicable to chemical tankers.
- MARPOL Annex V
The annex of MARPOL governing disposal of garbage from ships, prohibiting most plastics discharge into the sea.
- MARPOL Annex VI
The annex of MARPOL setting limits on sulphur oxides, nitrogen oxides, and other air pollutant emissions from ships.
- Mast Riser
A large-diameter high-velocity vent pipe fitted to a tanker's mast to discharge cargo vapours safely above ignition sources.
- Master
The certificated officer in overall command of a vessel, legally responsible for the safety of the ship, crew, cargo, and environment.
- Material Safety Data Sheet
A document providing information on the hazards, handling precautions, and emergency procedures for a chemical or dangerous cargo.
- Mercator Sailing
A method of solving rhumb line problems using the properties of a Mercator chart to find course and distance between positions.
- Metacentric Height
The vertical distance between the centre of gravity (G) and the metacentre (M), the primary indicator of a vessel's initial stability.
- METAREA
One of twenty-one geographic areas for which meteorological services co-ordinate the broadcast of marine weather forecasts.
- MMSI Number
A nine-digit Maritime Mobile Service Identity used to identify a ship's radio and AIS transmissions uniquely.
- Moment to Change Trim 1 cm
The trimming moment in tonne-metres needed to alter a vessel's trim by one centimetre, used in stability calculations.
- Monsoon
A seasonal reversal of prevailing winds affecting the Indian Ocean and western Pacific, bringing heavy rainfall on its wet phase.
- Mooring
Securing a vessel to a berth, buoy, or anchor using lines, chains, or anchors to keep it stationary.
- Motorman
An engine room rating who assists engineers with machinery operation, maintenance, and watchkeeping duties.
- Muster Station
A designated assembly point where crew and passengers gather when an emergency alarm is sounded prior to abandoning ship.