Text Box: aback   with sails backed or trimmed to windward; on square sails when the sails are pressured against the mast
abaft   towards the stern of a vessel;  back of;  behind
a-beam  at right angles to the keel; bearing approximately 90° or 270° to the wind
able bodies seaman   trained and qualified seaman
ablock   tackle taken in until both blocks come together
aboard – on a vessel
about   on the other tack
abox	  when a square rigged vessel maintains a stable position by bracing for and after yards on opposite tacks.
abreast   along side of
a-cock-bill  yards at an angle, i.e. one end pointed skyward; anchor hanging loose slamming against the cathead.
ADM   abbreviation for sailcloth woven to admiralty specifications.
admeasure   measurement of a vessel for documentation.
Admiral   specifically is an administrative naval officer of high rank controlling personnel and policy
admiral of the blue   in the RN, the seventh level among admirals, who wore a blue flag at the truck.
adrift   at the will of the wind and tide; without fasts
afloat  any buoyant object (i.e. a vessel) resting on the surface of water
aft	(after) at, near or towards the stern
afloat   on the surface of the water

Text Box: after bow spring line     mooring line fixed to the bow of the boat and leading aft where it is attached to the wharf or pier. This prevents the boat from moving forward in its berth. Its opposite, the forward quarter spring line, is used to keep the boat from moving aft in its berth
against the sun    Anti-clockwise circular motion. left-handed ropes are coiled against the sun.
aground   when a vessel is touching the bottom
ahoy    a hailing call to  a vessel or person
a-hull  lying hull abeam - at sea when the sails are lowered and the hull is lying broadside to the seas and wind
aldis lamp  a hand lamp used to signal i.e. morse code
a-lee   to leeward, away from the wind
alidade   a device mounted over a compass for taking sights.
all a taut  vessel fully rigged, everything in place
all hands   th e entire crew
all in the wind    when the sails are not drawing and are shaking in the wind
aloft    above the deck; up the mast or in the rigging.
alongside  close beside a vessel, wharf,  pier etc.
alow	   below the deck, or the low in the rigging near the deck
alow & aloft  when all sails, including studding
sails are set.
altar    a step in a dry dock
ama hulls  the outer (floater) hulls of a trimaran
a-peek   when a vessel's anchor rode is brought taut over the anchor; in a vertical or nearly vertical position; yards are a-peak when they are topped by contrary lifts.
arm  the end of a yard on a sailing vessel (yard arm); to place tallow over the bottom of a lead line.
astern   towards the rear
a-trip    anchor immediately it is broken clear of  the bottom;  sails are a-trip when sheeted home;  yards are a-trip when they are in place;  an upper mast is a-trip when the fid is loose.
a-weigh   free - i.e. an anchor unhooked from the bottom
avast   stop; cease
acrofoil   the power source of a sailing vessel above the deck i.e. the sails.
altar   one of the steps or ledges the flight of which forms the side of a dry dock.

Text Box: anti-trip chine  flared out aft section of the side/bottom of a vessel
ama   the float of an outrigger canoe
amas   the outboard hulls of a trimaran.
amidship   at the middle of a vessel
an-end   when a mast is perpendicular to the deck
anabasis    military expedition
anchor   (killick) a device for holding a vessel stationary by securing it to the bottom of the body of water.  There are many types of anchors, including admiralty, fisherman, C.Q.R. or plough. danforth, bruce, mushroom, folding;  anchors are some times referred to as a hook. (See also bower, stream anchor, grapnel anchor and kedge anchor)
anchorage-  a designated area where a vessel may anchor; toll or duty assessed for the privilege of anchoring.
anchor ball   a black ball displayed  in the forward part of a vessel  to indicate she is at anchor.
anchor chock  a fitting designed to receive and hold an anchor in a fixed position when not in use.
anchor hoy   small vessel used to set anchors
anchor ice   ice, of any form, that is aground in the sea.
anchor light   a white riding light at the mast head  shown when a vessel is at anchor after sunset and before dawn, when anchored at other than an established mooring, or as required by law.
anchor rode    small boat's anchor line;  the length of an anchor line from the bow of a vessel to the anchor.  (rode)
anchor watch   crew detailed to watch a vessel anchored at night
anemometer   instrument or  device that measures wind velocity.
angle of heel   the angle of the vessel from the vertical when sailing
annie oakley   slang name for a billowing spinnaker
answer    the response to a movement of the rudder.
anti-trip chine   flared out section a vessel’ hull to prevent the hard chine catching a wake or small wave on a sharp turn.
apeak:   when anchor cable is taut and vertical
apparent wind   the direction from which the wind appears to come once a vessel has started to move.

Text Box: appendage	 rudder, keel, centreboard or skeg (on a vessel)
á portoise   on the gunwale - (see definition of portoise)
*apron   curved timber behind the lower part of the stem, above the foremost end of the keel
aspect ratio   ratio of the length of the foot of a sail, to the length of it's luff.  (a tall narrow sail would have a high aspect ratio)
astay   short stay  when the anchor cable is in line with the forestay
ata     supporting brace between the amas (floater hulls) and the vacca (the main hull) of a trimaran.
astrolabe  forerunner of a sextant; an instrument  to determine the altitude of celestial bodies.
athwart   athwartship   from one side of a vessel to another; at right angles to the centre line
athwarthawse   lying across the bow
try	vessel in gale without sails set
avast   stop;  hold fast
average  apportionment of a loss incurred by a vessel at sea or to its cargo.  (see averages )
awash  just above the surface of the water
aye   yes; reply when an officers orders are understood.