A line that is Transferred along the Vessel's Track on a Chart, (i.e., when
taking a Bearing from only one Landmark or only one Heavenly Body, during
the time that elapses before a second Position Line is obtained) and drawn
parallel to the original position line at a distance that is derived from
the Log of the Vessel's speed and Course-Made-Good.
(Also, see RETIRED-LINE-OF-POSITION)
ADVECTION FOG
(See FOG)
ADRIFT
A Vessel floating loose and not Anchored, Moored, or Under Command.
(Also, see VESSEL-NOT-UNDER-COMMAND and
VESSEL-UNDER-COMMAND)
AFT
Situated toward and/or at the Stern inside and On Board the boat.
(Also, see ABAFT and ASTERN)
AFTER-BOW SPRING LINE
A Mooring Line fixed to the Bow Cleat and leading Aft and Secured
to the Dock Stanchion. This prevents the boat from moving forward
in its Berth.
(Also, see FORWARD-QUARTER SPRING LINE)
AFTERDECK
The Deck Abaft the Cockpit.
(Also, see FOREDECK and SIDE DECK)
AGLUB
A Vessel with negative Freeboard.
AGONIC LINE
A line on a global map representing the location around the earth where
there is no Deviation between Magnetic North and True North.
AGROUND
A Vessel with its Keel stuck in the Bottom.
(Also, see HARD AGROUND and RUN AGROUND)
AHOY
The traditional mariner greeting for Hailing other Vessels.
(Also, see HAIL)
A-HULL
(See LIE A-HULL)
AIDs-TO-NAVIGATION
(ATON)
Any of several types of external devices (floating or standing) such as
permanent land or sea markers, Buoys, Radio Beacons, and Lighthouses,
designed to assist boaters in determining Vessel positions, safe courses,
and as warning signals of dangers or obstructions to navigation in and
on the water.
AIRFOIL
The state of a Sail, when properly Trimmed, where it functions as a
vertical wing, with the Wind propelling the Vessel. When the Sail is
Trimmed to a specific Angle-Of-Attack, the air flow on the Windward
side of the Sail is decelerated where pressure rises, and the air
flow on the Leeward side of the Sail is accelerated where
pressure drops resulting in Lift.
ALEE
Away from the Wind and toward the Lee side of a Vessel.
ALL-AROUND LIGHT
(See ANCHOR LIGHT)
ALOFT
Above the boat, usually with regard to Rigging.
ALONGSIDE
A Mariner's term used to denote when two Vessels are beside each
other to the point that both Vessels may be in contact with one
another.
ALTITUDE
As measured with the Sextant, it is the elevation angle of the
Celestial Body that is used as a reference point above the
Horizon.
(Also, see CELESTIAL NAVIGATION)
AMA
A single outboard Hull of a Trimaran.
AMAS
The two outboard Hulls of a Trimaran.
AMIDSHIPS
The middle of the Vessel along the Fore-And-Aft centerline between
Stem and Stern, and the middle Athwartships between the Port and
Starboard sides of the Vessel.
ANCHOR
(Hook)
Any one of the various types of heavy or light metal devices dropped
to the Bottom of a body of water, connected by Rode, to restrict the
motion of the Vessel-At-Anchor.
(Also, see DANFORTH ANCHOR, KEDGE ANCHOR, and PLOW ANCHOR)
ANCHOR AWEIGH
(See, WEIGH ANCHOR)
ANCHOR BED
A large Deck Fitting, usually installed at the Bow, designed such
that its shape Secures the entire Anchor.
(Also, see ANCHOR CHOCKS)
ANCHOR BELL
A bell required On Board a Vessel-At-Anchor to be rung at specific
intervals when in fog and at night.
ANCHOR BUOY
A small Buoy or float attached to the end of a Trip Line Secured to
the Crown of a Deployed Anchor indicating its position.
ANCHOR CABLE
(Cable)
(See RODE)
ANCHOR CHAIN
(See GROUND TACKLE)
ANCHOR CHOCKS
Large Chocks, usually installed at the Bow, designed to Secure the
Anchor at its Crown, Fluke, and Shaft.
(Also, see ANCHOR BED)
ANCHOR LIGHT
(Riding Light)
A Navigation Light displayed on a Vessel-At-Anchor. An Anchor Light is
an All-Around Light, visible for at least two miles from all directions.
The Anchor Light is usually mounted on the Masthead of large Sailing
Vessels, or attached and exhibited Aloft about two-thirds up the
Forestay or Headstay On Sailboats less than fifty meters (50 m) in length.
(Also, see RUNNING LIGHTS)
ANCHOR LINE
(Anchor Rope)
Double braided or braid-on-braid nylon with the outboard or Working
End connected to the Chain Leader that is attached to the Anchor,
and the inboard or Bitter End to the Bow Cleat. Nylon is used
because it is durable and made to stretch when the Vessel-At-Anchor
Snubs on the Hook.
(Also, see RODE, SCOPE, and WARP)
ANCHOR KNOT
(See FISHERMAN'S BEND)
ANCHOR RING
The ring attached at the Head of an Anchor.
(Also see GROUND TACKLE)
ANCHOR RODE
Rope, Warp, or Chain attached to the Anchor and Secured to the Vessel.
(Also, see ANCHOR LINE)
ANCHOR ROPE
(See ANCHOR LINE)
ANCHOR WATCH
The periodic check during a Watch to ensure that the Anchor is Holding.
ANCHOR WINCH
(See WINDLASS)
ANCHORAGE
A protected body of water within a Bay, Cove, or Harbor, to
facilitate a Vessel-At-Anchor.
ANCHORING
The process of maneuvering a Vessel to discover the appropriate
place to drop and Secure the Anchor in good Holding Ground.
(Also, see VESSEL-AT-ANCHOR)
ANEMOMETER
A device that measures Wind Velocity.
ANEROID BAROMETER
A device that measures Atmospheric Pressure by the action of air
on the elastic lid of a box containing a partial vacuum, and not
by the height of a fluid column.
(Also, see MERCURY BAROMETER)
ANGLE-OF-ATTACK
(A0A)
When the Wind makes contact with the Luff (The Leading Edge) of the Sail,
and proper Angle-Of-Attack (AOA) is achieved, the angle between the
direction of the Apparent Wind and the Chord of the Sail is such that
there is optimum Lateral Lift. Lift is then maintained by Feathering,
which is either Heading-Up the Vessel or Sheeting Out the Sail to
the point where the Sail just begins to Depower, then Falling Off or
Sheeting In to the point where AOA is propagating Lateral Lift. AOA
varies along the height of the Luff. For example, AOA at the Luff
of the upper half of a correctly Trimmed Sail will always be
different than the AOA at the lower half of the Sail.
(Also, see TWIST)
ANGLE-OF-INCIDENCE
(See ANGLE-OF-ATTACK)
ANTICYCLONE
(See ANTICYCLONIC WIND)
ANTICYCLONIC WIND
(Anticyclone)
Circular Wind motion (clockwise in the Northern Hemisphere,
counter-clockwise in the Southern Hemisphere) around a
central region of High Atmospheric Pressure.
(Also, see CYCLONIC WIND)
ANTIFOULING PAINT
A special paint applied to the underwater surface of a Vessel
to prevent Marine Fouling on the Hull.
APPARENT TIME
Time based upon the true position of the Sun as distinguished from
Mean Time, which is measured by a fictitious Sun moving at a
uniform rate. Apparent Time is that shown by the sundial,
and its noon is the time when the Sun is at the Zenith of
the Local Meridian. The difference between Apparent Time
and Mean Time is known as the Equation-Of-Time.
APPARENT WIND
1. The vector sum of Relative Wind plus True Wind.
2. The Wind direction as it is "felt" while the boat is in motion.
3. Apparent Wind and True Wind coincide when Sailing Dead-Down-Wind.
(Also, see RELATIVE WIND and TRUE WIND)
ARM
The appendage connecting the Fluke to the Shank at the Crown of the Anchor.
ASPECT RATIO
The length of Luff squared divided by Sail Area.
[e.g., Å fully Hoisted triangular Sail has higher Aspect Ratio than a
shortened or reefed Sail, being broader in width than in height.]
ASHORE
On land near the Shore.
ASSUMED POSITION
(See ESTIMATED POSITION)
ASTERN
Situated toward the Stern outside and behind the Vessel.
(Also, see ABAFT and AFT)
ASTRO-NAVIGATION
(See CELESTIAL NAVIGATION)
ASTRONOMICAL TIME
Previous to 1925, Astronomical Time commenced at noon with the hours
numbered consecutively from 00:00 hundred hours (12:00 Noon) to
23:59 hundred hours (11:59 a.m.) the following day. In 1925,
Astronomical Time was replaced by Greenwich-Mean-Time (GMT)
with 00:00 hundred hours beginning at 12:00 Midnight, ending
with 23:59 hundred hours at 11:59 p.m. on the same day.
ATHWART
1. From side to side and at right angles to the Fore-And-Aft
centerline within the Vessel.
2. Broadside to the Wind because of equal and opposite pressures
of Wind and Tide.
ATHWARTSHIPS
Running laterally across the width inside the boat.
(Also, see ABEAM)
ATMOSPHERE
The air enveloping the earth.
ATMOSPHERIC PRESSURE
(Barometric Pressure)
The pressure exerted by the earth's atmosphere at any given point,
being the product of the mass of the atmospheric column of the
unit area above the given point and of the gravitational
acceleration at the given point.
ATRIP
(See AWEIGH)
AUTOMATIC PILOT
(Auto Pilot)
Equipment that is attached to the Rudder to automatically Steer the Vessel.
AUTUMNAL EQUINOX
(See EQUINOX)
AUXILIARY POWER
(Auxiliary Engine)
A Sailing Vessel with an inboard or outboard engine.
AVAST
(Sometimes uttered: "Vast")
A Command to cease an action immediately.
[e.g., "Avast, the Hoisting of the Mains'il!"]
(Also, see BELAY)
AWEIGH
(Atrip)
To Break Out an Anchor, which is no longer Holding the Vessel and
lying on the Bottom ready to be raised.
AYE
(Aye, Aye)
An antiquated term meaning "Yes."
"Aye" repeated twice (e.g., "Aye, aye, Sir."), was used mostly by
junior officers and enlisted men in the old English naval service
to indicate that a Command or Order from a superior officer was
acknowledged and would be carried out. The single "Aye" or
double "Aye, Aye" is used today more as a traditional
affirmation of Maritime Directives.
AZIMUTH
The True Bearing of a Heavenly Body measured in degrees from north
or south.
(Also, see MAGNETIC AZIMUTH)
