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61 terms

glossary

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abaft
in a direction toward the stern
abeam
on the beam; a direction at right angles to the keel.
aboard
in or on board a vessel
abreast
side by side
afloat
a vessel wholly supported by water and off the bottom
aft
at or towards the stern
ahead
in the direction of the vessel's head or bow
aid to navigation
a device or object, external to the vessel, located to assist safe navigation. It may be man-made or natural
amidships
in the middle of the ship, whether longitudinally or laterally.
anchor
a device designed to hold a ship in any desired location by temporarily attaching it to the seabed by means of a rode
angle of cut
the angle at which two lines of position on a chart intersect
angular distance
the size of an angle, measured in degrees and fractions of a degree
apparent wind
the direction of the wind as it appears on board. It differs from the true wind direction due to the vessel's motion
astern
(1) in back of, or behind the boat; (2) the movement of a ship going backwards
ballast
added weight in a ship's bottom to provide stability and trim
beacon
a distinctive artificial structure erected as an aid to navigation
beam
the maximum width of a vessel
bearing
the direction in which an object lies with respect to a reference direction
belay
to make fast a line without knots by taking turns round a cleat or belaying pin
bifurcation buoy
a buoy marking where a channel divides
buoy
a floating mark anchored to the bottom, used as an aid to navigation
cardinal buoy
an aid to navigation that indicates the cardinal direction of safe water
chart
a "map" of a sea area showing any coastal lines and used specifically for nautical navigation
chock
(1) a deck fitting used to change the direction of tension of an anchor rode or mooring line; (2) a fitting designed to receive an object and hold it securely
cleat
a fitting with two arms or horns to which lines are made fast
close aboard
beside, close to, alongside
close-hauled
sailing as close as possible to the direction of the wind
con
to steer the boat by direct observation of landmarks
correcting
the conversion of courses or bearings from compass to magnetic to true
current
the horizontal movement of the water
danger zone
the sector extending from dead ahead to 22.5 degrees abaft the starboard beam, an arc of 112.5 degrees in all
dead reckoning
the process of determining a vessel's position, using only knowledge of speed, elapsed time, course steered, and a point of departure
deviation
the angular difference between magnetic north and compass north
discharge current
the water expelled by the propeller
displacement
the weight of the volume of water displaced by a floating vessel
downwind
to leeward. The direction in which the wind is blowing
ebb
a current generally from the land towards the open ocean, associated with a falling tide
fairway buoy
a buoy that marks a landfall, the entrance to a channel, or the centre of a channel
fender
a device hung over the side of a vessel to protect the hull from other objects
fix
an accurately known position found by taking new observations
flood
a current generally from the open ocean towards the land, associated with a rising tide
freeboard
the minimum vertical distance between the gunwale and the waterline
give way
to keep out of the way of another vessel
knot
(1) a unit of speed equal to one nautical mile per hour; (2) the tucks and loops in a line used to fasten it to an object or to itself
lateral buoyage system
a buoyage system in which different coloured buoys are used to mark the sides of a channel
latitude
the angular distance of any point on the earth's surface north or south of the equator, as measured at the earth's centre
lee side
the side opposite to the direction from which the wind blows
leeward
away from the wind
line of position
a line on which the vessel is known to be
longitude
the angular distance of any point on the earth's surface east or west of the prime meridian, as measured at the polar axis
magnetic north
the north direction indicated by an isolated magnetic compass for which the deviation is nil
magnetic pole
one of the two geographical areas, north and south, where the earth's magnetic field enters or leaves the earth
meridian
an imaginary line on the surface of the earth joining the north and south geographic poles
nautical mile
a unit of distance defined as 1852 metres, equivalent to the length of one minute of latitude
navigational aid
an apparatus on board a boat that will assist in navigating
pillar buoy
a very large structural buoy that may have a light, bell or whistle.
plot
to draw lines on a chart, indicating bearings, courses and positions.
port
a vessel's left side when facing forward
prime meridian
the meridian of longitude that passes through Greenwich, England
range
(1) two aids to navigation which, when seen to be in line establish a line of position; (2) the difference in height between high and low tides
reaching
sailing with the wind approximately on the beam