M   Mike

I have a doctor on board

 
Mae West

During World War II, Allied aircrews called their yellow inflatable, vest-like life preserver jackets "Mae Wests" partly from rhyming slang for "breasts" and "life vest" and partly because of their resemblance to the racy actress' ample torso.

A "Mae West" is also a type of malfunction of a round parachute (partial inversion) which contorts the shape of the canopy into the appearance of an extraordinarily large brassiere.

Magnetic

Certain natural minerals are magnetic;  when floated freely they orientate themselves toward the magnetic North and South poles.

The needle of a magnetic compass is magnetised,  and orientates toward the magnetic poles,  not toward the True poles.

The gridlines (usually latitude and longitude lines) of a nautical chart are orientated to True North and South.   Bearings (in degrees Magnetic) derived from a magnetic compass must,  therefore,  be converted to degrees True before being plotted on a chart.

 
 

Mainmast

The tallest mast on the boat:  the most important mast.

On a ship-rigged vessel the mainmast would have been the one between the foremast (near the bows) and the mizzen mast (the one nearest to the stern).

On a ketch or yawl the mainmast would be the foremost mast whereas on a schooner or a brig the mainmast would be the aftermost mast.

 

Mainsail

At one time,  the largest sail on a vessel.

On a modern-day sloop or cutter,  the sail held between the mast and the boom and,  possibly,  the gaff.

On a square-rigged vessel,  the course sail of the mainmast.

On a fore-and-aft vessel with more than one mast (such as a ketch,  yawl or schooner) the sail attached to the mainmast.

On modern day sloops the foresail (usually a genoa) is bigger than the mainsail.

 
 
 
Mainsheet

The sheet for the mainsail,  usually attached (in a fore-and-aft vessel) to the boom,  not the sail.

 
 
 
 
 
Making way

An interesting phrase used,  but not defined,  in the IRPCS.

It probably means that a vessel is moving through the water under its own power.

Mallet

A wooden hammer,  used for hammering wood.

Metal hammers bruise and split wood;  mallets are springy and resilient and cause less damage than metal hammers.

Manger board

 An athwartship partition aft of the hawseholes that prevents seawater from running aft on the deck of a ship

Man overboard

See MOB,  below.

Someone has fallen off the boat into the water.

Marconi

Guglielmo Marconi made a commercial success of radio by innovating and building on the work of previous physicists.

His tall radio masts were supported by wire stays from the mast to points on the ground some distance from the mast.

This system of supporting a mast is similar to that on many sailing boats,  including many with Bermudan sails,  gaff rigs and others. 

Marconi is not a synonym for Bermudan.

MOB
 
 
 
 
 
Marina

A commercial harbour with floating pontoons for mooring boats.   Ashore,  there are restaurants,  shower & toilet buildings,  repair & storage yards,  chandleries and services:  afloat,  there is usually a fuel bunker on a floating pontoon.   The services (which may be owned by the marina or may be franchised) include boat repair,  craneage,  engine replacement & repair.

Marinas cater for long-term tenants,  usually on annual leases,  but offer facilities by the day or week to visiting yachts.

Unlike ports or harbours,  marinas do not cater for large passenger or cargo ships,  but often offer facilities to small waterborne businesses.

Marine

n   A member of the Royal Marines Corps (or,  in the USA, the United States Marine Corps),  which is an elite infantry unit trained for service afloat and ashore.

adj   Describing a relationship with the sea,  as in marine biology,  the biology of life in the sea.

Mariner

One who sails on the sea:  a sailor.

 
 
 
 
Maritime

adj   pertaining to sea-related activities.

One might refer to 'maritime law' not 'marine law'.

Mark

n   A buoy or beacon in the sea for fixing position and for pilotage.

 

Marks and deeps

n   A hand lead line is 20 fathoms long,  divided into 20 equal parts.   There are 9 marks,  at 2,  3,  5,  7,  10,  13,  15,  17,  and 20 fathoms,  and 7 deeps (absence of mark) at 1,  4,  8,  9,  14,  18 and 19 fathoms.   A depth of 7 fathoms is called as “by the mark seven”.   A depth of 9 fathoms (for which there is no mark) is called as “by the deep nine”.   A depth of 5.5 fathoms would be called as “and a half five”.   A depth of 12.75 fathoms would be called as “and a quarter less thirteen”.

During the Age of Sail the word 'deep' meant 'unknown',  'mysterious'.   The concept of depth,  as we now understand it,  was poorly perceived.   'Plumbing the depths' (lowering a lead weight on a line into the unknown) was a means of fixing a position.

Marl

vb   To secure or contain with a series of marline hitches.

 
 
 
 
Marline

n   A very light rope or twine, usually tarred, made of two strands laid left-handed.

The act of whipping or seizing with marline,  or the result thereof,   may be known as ‘marling’.

A marlin’ spike is a wooden or metal fid used to separate the strands of rope when splicing.

 

Marling

n,  vb,  ng   Seizingwhipping,  serving,  worming or lashing with marline.

 

Marling spike

A wooden or metal fid used to separate the strands of rope when splicing.

 

MARPOL

International Convention for the Prevention of Pollution from Ships

 
 
 
Mast

The vertical (or nearly vertical) pole or poles (spars) which hold up the sailsyards & gaffs and which carry some of the navigation lights.

Until the 20th Century masts were built of wood in several parts.   The lowermost part,  from the keel,  through the deck to the first top,  was,  simply,  the mast.   The next one up,  the topmast,  overlapped the mast (to which it was attached) and continued up to the second top.   The third part,  attached to the top of the topmast,  was the topgallant mast.   The uppermost mast was the royal mast.   Each mast had its own yards,  sails,  shrouds and stays associated with each part.

Small boats of the C19 (such as gaff-rigged sloops and cutters) often had a mast and topmast.   The topmast carried the blocks which supported the gaff and often also carried a topsail.

Where the mast of a gaff-rigged vessel was constructed in one long part (usually from one tree!) it was called a 'pole mast'.

Luce described the 'yard' of a sliding gunter rig as a topmast.

Now (early C21) most masts are made of steel or aluminium and may be as long (tall) as necessary.

Modern techniques of glueing and scarphing allow wooden masts to be constructed as long (tall) as necessary without the need for several parts.

The mainsail of a fore-and-aft rigged vessel may be attached by its luff to the mast by sliders or a bolt-rope in a groove,  or it may be laced to the mast with small line.

 
 
 
 
Master

See Captain.

In Elizabethan times,  and during the Age of Sail,  the sailing master was the person responsible for navigation of the ship.

 

Masthead light

IRPCS Rule 21,  “Definitions”,  says:  "

(a)”Masthead light” means a white light placed on the fore and aft centre-line of the vessel showing an unbroken light over an arc of the horizon  of 225 degrees and so fixed as to show the light from  right ahead to 22.5 degrees abaft the beam on either (each;  both) side of the vessel.

A masthead light is sometimes known as a steaming light.   It is usually on the forward face (ahead) of a mast,  rarely right at the top.   The top of the mast is usually reserved for all-round lights.

It is not a riding light.

Anchor (riding) lights are all-round lights;  they are often at the top of the mast,  but not ahead of it;  they are not masthead lights.

 

MCA

Maritime and Coastguard Agency.

 
 
 
Mercator's projection

Nautical charts are representations,  on a flat piece of paper,  of the 3-dimensionally curved surface of the earth.   Where the area to be represented is small (say,  a harbour) the distortions of scale are trivial.   Where the areas are large (say,  the British Isles) the distortions become significant.   Mercator (a C15 mathematician) devised a distortion which kept the parallels of latitude parallel,  but made them all (including the poles!) equal in length.   His equation made the meridians of longitude parallel instead of converging at the poles.   Features at the Equator are accurately represented,  and the scales become more distorted as one approaches the poles.   On the earth the poles are points with no length in any direction:  Mercators projection turned the poles into parallels of latitude the same length as all the other parallels.

Because of the distortions,  rhumb lines on the projection become straight lines;  this is,  perhaps,  the most valuable feature of Mercator’s projection.   

Navigators (before Mercator) followed rhumb lines by keeping a constant compass course:  unless this course followed the Equator or a meridian the line spiralled around the globe until it infinitesimally approached one of the magnetic poles.   By following a compass course navigators would end their voyage many (tens of) miles from their destination.   

Using Mercator's charts they could draw rhumb lines with a straight-edge and so keep a constant compass heading from origin to destination.   The one disadvantage was that the rhumb line was not the shortest route;  it is not a Great Circle.

Merchant marine,  mariner,  navy,  ship

Not part of the military,  defensive or offensive,  navy.   A 'merchant' is a tradesperson;  one who buys and sells.   Merchant ships carry trading goods.

Mercury

n   A poisonous metal,  liquid at room temperature,  of specific gravity 13.69,  used in barometers and,  at one time,  in thermometers.

n The planet with an orbit closest to the sun.

 

Meridian

An imaginary line across the surface of the earth linking the North and  South poles.   There is an infinite number of possible meridia.

The Prime meridian passes through the North pole,  Greenwich (in East London) and the South pole,  and is the centre of Time Zone zero.   The meridian 15° to the East is the centre of Time Zone (UT+1) or (in nautical terms) -0100hrs.   The meridian 180° to the East (and the West) is the International Date line.

On the surface of the earth all the meridia meet at the North and South poles and diverge at the Equator:  on charts drawn to Mercator's projection the meridia are all parallel to one another.

 
 
 
Mess

n   The place where sailors gather to eat and yarn.

n   A group of sailors who eat together.

n   An unsightly array of debris.

 
 
 
 
Messenger

n   A person who carries messages.

n   The anchor cable of a square-rigged ship was massive;  as much as 20" in diameter:  too big to wrap around a capstan or windlass.   A continuous cable (voyol or messenger) was wrapped around the capstan and ranged alongside the anchor cable,  to which it was nipped by lengths of braided line.   As the capstan was turned the voyol,  nipped to the cable,  drew the cable aboard.   The youngest members of the crew (often children of 10 to 15) constantly carried the nippers from the inboard part of the cable forward so that the nipper-men could attach them again.   These children became known as ‘nippers’.

 

Meteorology

Study of weather,  and of the changes and variations in temperature and air pressure which cause weather,  and of the winds,  clouds and precipitation which are the manifestations of weather.

 

Middle watch

The watch between midnight and 0400 (ship’s time).

 
 
 
 
Midshipman

A person with rank below a lieutenant but above a petty officer.   Not an officer,  but not a seaman.   Someone in training to become an officer.

Midshipmen lived a'midships,  between the officers at the stern and the crew in the forecastle.

Mine

n   An explosive device floating in the sea,  or anchored to the seabottom to be triggered by passing vessels.

Similar devices buried a few inches below ground are land-mines.

n   A deep hole in the ground dug for the purpose of extracting valuable minerals.

v   To mine.   To lay explosive devices in the sea (or the ground);  or to dig deep holes in the ground.

Minute

n   A measure of elapsed time:  one sixtieth of an hour:  1/1440 of a day,  from noon to the following noon.

n   A measure of angular distance:  one sixtieth of a degree:  1/21600 of a circle,

 

Mizzen

An adjective which describes the aftermost mast,  and the rigging and sails associated with it.   The mizzen yards,  gaffs,  booms and sails are carried on the mizzen mast and are controlled by the mizzen braces or  sheet(line)s.

 
 
Miss stays

When a square-rigged ship changes tack* by passing its bows through the wind the sails are necessarily,  at some point in time,  aback.   At this point the ship may stop,  and fail to fall off on the other tack:  it has ‘missed stays’.   It may remain aback,  ‘in irons’, or it may fall off onto the previous tack,  or the captain may choose to club-haul or box-haul.

A modern,  fore-and-aft rigged boat rarely misses stays.

Some sailors refer to changing tack as ‘staying’ the boat.

 

*   With the wind on the starboard side the lower right-hand corner of the course sail would be the tack,  drawn forward by a bowline and tacked down by a tackline:  the lower left-hand corner would be the clew,  drawn aft by the sheet.   In turning the ship to put the wind on the port side,  the tack of each course sail would become the clew,  and vice versa.

Mist

Airborne water droplets which reduce visibility to less than two miles.

 

MMSI

Maritime Mobile Service Identity:  a series of nine digits sent by radio to identify ships and coastal stations.

DSC (Digital Selective Calling) radios use the MMSI number of the vessel as an identifier.   If the MMSI number of a vessel is entered into the keypad of the DSC radio the 'phone rings' only in the vessel identified.   The ensuing conversation,  by VHF radio,  can be heard by any VHF radio within range.

 
 
 
 
 
MOB

Man Over Board (also used for women over board) refers to someone who has fallen (rather than jumped) off the boat.   It is an emergency with serious risk to life.

People fall overboard for many reasons,  most usually carelessness.   Being knocked overboard by the boom reveals carelessness on the parts of the skipper,  the helmsman and of the MOB.   Falling between the boat and the dinghy,  or between the quay and the boat reveals carelessness,  drunkenness or tiredness.   Falling overboard whilst working the foredeck reveals carelessness in the use of a harness and tether.

 

If any of the rest of the crew see the MOB the boat can usually be brought back to the scene to attempt a rescue.

A number of devices (including PLB​) is available for notifying the crew that someone has fallen overboard,  and also for locating the MOB.

Recovering a person from the water,  especially if they are wearing boots and foul-weather clothing,  can be very difficult.

 
 
Mole

A structure of stone or concrete built as a pier or breakwater.

 
Moderate

Moderate visibility is between 2 and 5 miles.

 
Monkey,  brass

An apocryphal brass triangle,  supposedly used to carry four iron cannonballs.

Monkey's fist

A large knot tied in the end of a heaving line.   The knot adds weight to the line which thereby can be thrown further.   Adding extra weight inside the knot makes it a dangerous missile.

Monohull

A vessel with only one hull,  in contrast to the two of a catamaran,  three of a trimaran or one and a bit of a proa.

 
 
 
 
 
Mooring

n   Folkard,  in 1906,  wrote that “A vessel riding by two or more anchors in different directions is said to be moored.   A boat’s moorings consist of a strong mooring-chain,  the two ends of which are anchored in different directions;  a smaller chain,  called a bridle,  is secured to the mooring-chain . . .,  and a buoy is attached to the upper part of the bridle,  to mark . . . the spot where the moorings lie.”   Falconer,  in 1815,  defined mooring as riding to two anchors,  one from each bow;  Tripp,  writing early in C20,  moored with a bower anchor and a kedge from the stern.

The change in the intervening century is that there are many more moorings,  and that many more boats may be moored to one mooring-chain between two anchors.   A row of moorings along a single,  long mooring-chain is a trot.

Above right,  Welkin is aground in the mud at West Mersea.   A mooring chain runs from the right foreground to the middle background;  its anchors cannot be seen.   A row of mooring buoys is attached to the chain:  boats,  aground,  are moored to the buoys.   This is a half-tide mooring.   Local convention says that these boats do not use anchor balls or lights.

 

Boats and ships also moor alongside wharfs.   The recommended method for placing mooring warps is shown in the diagram.   There are breast ropes at 2 and 5.   The springs 1 and 4 prevent the boat surging aft:  the springs 3 and 6 prevent her surging forward.

Many yachts have centre cleats at each beam;  springs may be run from these centre cleats to bollards 2 and 5.

A question arises as to whether a boat moored,  or anchored,  in this way should display a ball during the day and a light at night,  as required by IRPCS Rule 30.

v   To moor.

 
Morning

Between midnight (0000)  and 0800 (local time).   The morning watch is from 0400 to 0800 (ship’s time).

Mould

n   A structure the shape of a section of a boat's hull.

A wooden hull is built upon a series of moulds from stem to stern.   Temporary moulds are removed after the hull has been formed:  others may remain within the hull as bulkheads or frames.

Fibreglass boats are built within a mould which contains the shape of the entire hull.   When the resin mixed with the glass fibres has hardened the hull is removed from the mould for fitting-out.

n  A surface accumulation of fungal mycelium,  which grows because air and moisture (dampness) are available.

 

John Starkie

November 2018

If you disagree,

or can't find a word

please let me know.