Glossary of Nautical Terms - M

M

Mae West

A Second World War personal flotation device used to keep people afloat in the water; named after the 1930s actress Mae West, well known for her large bosom.

Magnetic bearing

An absolute bearing (qv) using magnetic north.

Magnetic north

The direction towards the North Magnetic Pole. Varies slowly over time.

Mainbrace

One of the braces attached to the mainmast.

Making way

When a vessel is moving under its own power.

Mainmast (or Main)

The tallest mast on a ship.

Mainsheet

Sail control line that allows the most obvious effect on mainsail trim. Primarily used to control the angle of the boom, and thereby the mainsail, this control can also increase or decrease downward tension on the boom while sailing upwind, significantly affecting sail shape. For more control over downward tension on the boom, use a boom vang.

Man-of-war or man o' war

a warship from the Age of Sail

Man overboard!

A cry let out when a seaman has gone 'overboard' (fallen from the ship into the water).

Man the rails

To station the crew of a naval vessel along the rails and superstructure of the vessel as a method of saluting or rendering honors.

Man the yards

To have all of the crew of a sailing vessel not required on deck to handle the ship go aloft and spread out along the yards. Originally used in harbors to display the whole crew to the harbor authorities and the other ships present to show that the vessel's guns were not manned and hence her intentions were peaceful, manning the yards has since became a display used in harbor during celebrations and other special events.

Marconi rig

Another term for Bermudan rig. The mainsail is triangular, rigged fore-and-aft with the lead edge fixed to the mast. Refers to the similarity of the tall mast to a radio aerial.

Marina

a docking facility for small ships and yachts.

Marines

Soldiers afloat. Royal Marines formed as the Duke of York and Albany's Maritime Regiment of Foot in 1664 with many and varied duties including providing guard to ship's officers should there be mutiny aboard. Sometimes thought by seamen to be rather gullible, hence the phrase "tell it to the marines".

Marlinspike

A tool used in ropework for tasks such as unlaying rope for splicing, untying knots, or forming a makeshift handle.

Mast

A vertical pole on a ship which supports sails or rigging. If a wooden, multi-part mast, this term applies specifically to the lowest portion.

Mast stepping

The process of raising the mast.

Masthead

A small platform partway up the mast, just above the height of the mast's main yard. A lookout is stationed here, and men who are working on the main yard will embark from here. See also Crow's Nest.

Master

1. The captain of a commercial vessel.

2. A senior officer of a naval sailing ship in charge of routine seamanship and navigation but not in command during combat.

3. Master, a former naval rank.

Master-at-arms

A non-commissioned officer responsible for discipline on a naval ship. Standing between the officers and the crew, commonly known in the Royal Navy as 'the Buffer'.

Matelot

A traditional Royal Navy term for an ordinary sailor.

Material

Military equipages of all descriptions for the naval services. The bombs, blankets, beans and bulletins of the Navy and Marine Corps. Taken from Nelson’s British navy as the U.S. services became professional. Related: Materiel – the military equipages of the Army and Air Force, taken from Napoleon’s French army as the U.S. services became professional.

Merchantman

Any non-naval passenger- or cargo-carrying vessel, including cargo ships, tankers, and passenger ships but excluding troopships.

Mess

An eating place aboard ship. A group of crew who live and feed together,

Mess deck catering

A system of catering in which a standard ration is issued to a mess supplemented by a money allowance which may be used by the mess to buy additional victuals from the pusser's stores or elsewhere. Each mess was autonomous and self-regulating. Seaman cooks, often members of the mess, prepared the meals and took them, in a tin canteen, to the galley to be cooked by the ship's cooks. As distinct from "cafeteria messing" where food is issued to the individual hand, which now the general practice.

Metacenter

The midway point between a vessel's center of buoyancy when upright and her center of buoyancy when tilted.

Metacentric height (also GM)

A measurement of the initial static stability of a vessel afloat, calculated as the distance between her centre of gravity and her metacenter. A vessel with a large metacentric height rolls more quickly and therefore more uncomfortably for people on board; a vessel with a small metacentric height will roll sluggishly and may face a greater danger of capsizing.

Midshipman

1. During the 17th century, a naval rating for an experienced seaman.

2. From the 18th century, a naval commissioned officer candidate.

3. From the 1790s, an apprentice naval officer.

4. From the 19th century, an officer cadet at a naval academy.

5. In contemporary British usage, a non-commissioned officer below the rank of lieutenant. Usually regarded as being "in training" to some degree. Also known as 'Snotty'. 'The lowest form of rank in the Royal Navy' where he has authority over and responsibility for more junior ranks, yet, at the same time, relying on their experience and learning his trade from them.

6. In contemporary American usage, a naval cadet of either sex at the United States Naval Academy. When plural (Midshipmen), the term refers to the student body of the U.S. Naval Academy and is the name of its sports teams.

Midshipman's nuts

Broken pieces of biscuit as dessert.

Midshipman's roll

A slovenly method of rolling up a hammock transversely, and lashing it endways by one clue.

Midshipman's hitch

An alternative to the Blackwall hitch, preferred if the rope is greasy. Made by first forming a Blackwall hitch and then taking the underneath part and placing over the bill of the hook.

Mile

see nautical mile.

Military mast

Hollow tubular masts used in warships in the last third of the Nineteenth Century, often equipped with a fighting top armed with light-caliber guns.

Mine

A self-contained explosive device intended to damage or sink surface ships or submarines, designed to be placed in water and left to wait until they are triggered by the approach of, or contact with, a surface ship or submarines.

Mizzenmast (or Mizzen)

The third mast, or mast aft of the mainmast, on a ship.

Mizzen staysail

Sail on a ketch or yawl, usually lightweight, set from, and forward of, the mizzen mast while reaching in light to moderate air.

Mole

A massive structure, usually of stone or concrete, used as a pier, a breakwater, or a causeway between places separated by water. May have a wooden structure built upon it and resemble a wooden pier or wharf, but a mole differs from a pier, quay, or wharf in that water cannot flow freely underneath it.

Monitor

1. A turreted ironclad warship of the second half of the 19th century characterized by low freeboard, shallow draft, poor seaworthiness, and heavy guns, intended for riverine and coastal operations.

2. In occasional 19th century usage, any turreted warship.

3. A shallow-draft armored shore bombardment vessel of the first half of the 20th century, designed to provide fire support to ground troops, often mounting heavy guns.

4. Breastwork monitor: A 19th-century monitor designed with a breastwork to improve seaworthiness.

5. River monitor: A monitor specifically designed for riverine operations, used during the 19th and 20th centuries and more recently than other types of monitor. River monitors generally are smaller and lighter than other monitors.

Monkey's fist

a ball woven out of line used to provide heft to heave the line to another location. The monkey fist and other heaving-line knots were sometimes weighted with lead (easily available in the form of foil used to seal e.g. tea chests from dampness) although Clifford W. Ashley notes that there was a "definite sporting limit" to the weight thus added.

Moor

to attach a boat to a mooring buoy or post. Also, to a dock a ship.

Mould

A template of the shape of the hull in transverse section. Several moulds are used to form a temporary framework around which a hull is built.

M.V. (or MV)

Prefix for "Motor Vessel," used before a ship's name.