ing the number of people, total weight
of those people; combined weight of
persons, motor, and gear; the maximum
horsepower.
Mayday The term used to signify an
urgent distress communication under
international radiotelephone procedures;
the highest priority transmission,
indicating there is immediate danger to
a vessel or to someone on board.
meridian A great circle of the earth
passing through both poles in the direction
of true north or true south.
Mean High Water (MHW) MHW is
the average of the highest tide water levels
over a number of years.
Mean Low Water (MLW) Older charts
show depths at Mean Low Water (MLW).
In most locations there are two low water
levels each day, and one is usually lower
than the other.
Mean Low Low Water (MLLW ) Newer
charts give depths at (MLLW). MLLW
averages only the lower of the two low
tides each day, so it is a more conservative
measure of depth than MLW
Modified V-Hull This hull has a sharp
entry forward with a deep-V shape that
gradually flattens toward the stern.
mooring Permanent ground tackle to
which a boat is attached or moored. A
place where vessels are kept at anchor.
N
nautical mile A unit of distance equal
to one minute of latitude and equal to
approximately 6,076 feet, or 1.15 statue
miles.
Navigational Lines of Demarcation
International rules apply to all vessels
on the high seas outside established
navigational lines of demarcation.
non-pyrotechnic signals Include orange
distress flags (black square and ball
against an orange background), mirrors,
dye markers, and electric distress lights.
O
offshore A direction away from the
shore, as offshore wind.
outboard Toward the outside of a boat.
outboard motor An engine with propeller
attached, designed to be fastened to
the transom of a boat.
P
Pan-Pan The term used to signify an
urgent communication under international
radiotelephone procedures; the
second highest priority transmission,
indicating that the safety of the vessel or
someone on board is involved, but the
need for assistance is not immediate.
(Pronounced pahn-pahn.)
P.A.S.S. Acronym standing for Pull,
Aim, Squeeze, and Sweep when using a
fire extinguisher.
pay out Slacken or let out a line gradually.
pendant Short rope serving as an extension
of a line, chain, or cable with descriptive
name based on use; e. g., mooring
pendant (usually pronounced “pen’ant”).
pennant A tapering flag.
pier Structure extending into the water
from shoreline to provide dockage.
pile A pole or post driven vertically into
the bottom, usually to support a pier or
float or to moor a boat.
piling A structure of piles often used to
protect wharves and piers.
pitchpole Capsize end-over-end.
pivot point If you look down on a boat
when it turns, you will discover that it
turns about a point called the pivot point.
This point is located along the keel at the
centerline of the boat, but it may move
fore or aft depending upon whether the
boat is going forward or in reverse. For
most powerboats, this pivot point lies
about one-third of the way from the bow
to the stern when going forward, and
about two-thirds of the way (nearer the
stern) when going in reverse. The pivot
point on sailboats and trawlers with
extensive keels may tend to stay close to
one location, determined by the keel. For
example, the point on a sailboat with a fin
keel is likely to remain close to that keel.
planing hull A hull designed to climb
toward the surface of the water as sufficient
power is applied and to skim along
the water at a greatly reduced displacement
attitude.
Glossary 267
plow anchor An anchor shaped like a
farmer’s plow.
plug A piece of wood fitted into a hole
in a vessel, usually below the waterline.
port 1. Left side of a boat when facing
the bow. 2. Toward the boat’s left. 3.
Opening in a boat’s side, e. g., portlight.
4. Harbor.
port communication Port communications
include calls to shore (marinas,
boatyards) to get navigational information
and to arrange for such things as
supplies, accommodations, and repairs.
post-immersion collapse Post-immersion
collapse occurs during or after
rescue from cold water immersion. Once
rescued, after having been immersed in
cold water, you are still in danger from
collapse of arterial blood pressure leading
to cardiac arrest.
power-driven vessel Any vessel propelled
by machinery.
prolonged blast A blast of from four to
six seconds’ duration.
propeller A multi-bladed, rotating
wheel that furnishes propulsion.
pyrotechnic signals Pyrotechnic signals
resemble fireworks. They include red
flares, orange smoke (hand-held or aerial
meteor), and parachute flares.
Q
quarter 1. After part of a boat’s side,
e.g., port quarter. 2. Direction 45° abaft
the beam.
R
radar An electronic navigational system
using reflected radio pulse signals to
determine the relative bearing and distance
of an object from the vessel.
rail A boat’s side above the deck line.
range 1. Two or more objects in line.
2. Maximum distance at which an object
may be seen. 3. Distance between any two
points, such as a radar range to a navigational
aid. 4. Difference in elevation
(height) between any successive pair of
high and low tides.
reciprocal In navigation, a bearing or
direction 180° from another bearing or
direction.