105.2 Reading Nautical Charts Flashcards
Chart Number 1
legend or key to all US and international nautical charts
Four characteristics of a buoy or marker
Color, Shape, Number, for some, Flashing Rhythm of Light
In the US, the word “returning” has two meanings
Coastal — returning to port
ICW – running south and west (NJ to Texas)
A yellow triangle on a marker is
An ICW mark that should be left to starboard if returning (NJ to TX) (triangle, right, returning)
Buoys and beacons for the ICW will have a _____ band to identify them as such.
yellow
A yellow square on a marker is
An ICW mark that should be left to port if returning (NJ to TX)
North and South America are Region __ in the IALA system
B - red right returning
Everywhere EXCEPT North and South America are Region __ in the IALA system
A – green right returning
Green buoys called ____; red buoys called ____
cans (flat-topped); nuns (conical top)
All red buoys have ____ numbers
even
All green buoys have ____ numbers
odd
Buoys are numbered from 0 at the ___ ___ ___ ___, and increase as move further _____
entrance to a harbor, inland
It is important to never ____ the sequence of buoy numbers
skip
Looking backward at buoys already passed can help determine if being ____ outside the channel by wind, tide, current.
set
“Day Beacons”
permanently built piling structure with signs function exactly like cans and nuns
“Transit Lights”
Two lights separated by distance and height to be aligned when entering.
If transit lights are not aligned, steer toward the…
lower light to get back into alignment
Pro / con of transit lights
Pro: direct entrance to harbor; Con: 1. do not indicate when to turn (i.e., a hazard could be further in to the harbor); 2. Usually established for commercial traffic
When following transit lights, remember to
- Look out behind you for Commercial traffic; 2. Determine when must turn from the transit light line.
The orderly marking of buoys along a channel is called
the LATERAL system of buoyage
Red and white vertical buoy
mid-channel, safe water markers
Red over green or green over red
Junction point. The top color should be used for the primary path forward; bottom color secondary path
Junction buoys are typically not ______ but have a _____.
numbered; letter
Yellow buoys two functions
Mark specific areas of interest
Traffic separation zones
Two features of a lighted buoy
Color and Timing of flashing
Five type of buoy / beacon light charateristics
Flashing (e.g., one second on, four off)
Occulting (e.g., longer on, equal off)
Quick Flashing (e.g., one per second)
Composite Group Flashing (e.g., two then one then two then one)
Short Long Flashing (dot dash, Morse code A)
White light showing short-long flashing indicates a
mid-channel buoy
Figures in quotes on a chart indicate
buoy or marker numbers
Unlighted can buoys on a chart are indicated with a
C
Unlighted nun buoys on a chart are indicated with a
R
Buoy color abbreviations
R, G, W, RG, GR, RW, Y, etc
If no color is indicated for a lighted buoy, it’s light color is
white
The flash of a buoy is typically ___ second in duration
one
A buoy’s flash is typically visible for (distance)
a mile or two, four at most
The chart’s indicated time for a lighted buoy should be measured from
the start of two successive flashes, including the ON time – use a watch!
One con of lighted buoys is that they can…
fail. Slow down the boat immediately if at night and lighted buoy isn’t appearing
Day Beacon is a really dumb name for what they are since there is no
light or “beacon” – the sign itself is called the beacon of the daytime
A larger circle around, say, a lighthouse indicates
there is a radio beacon there. The frequency and pattern of the broadcast is noted nearby
The height of a lighthouse (or other object) is measured above
mean high tide
Lights flashing more quickly typically indicate
a change in direction may be needed (ie. the turning of a channel)
Sound devices on buoys include
Bell, Gong, Whistle, Fog
Lighted buoys can get lost in the midst of
background light clutter
Major lights (who, visibility, mark what, location can be, operate X hours, multi-colored)
- placed by USCG
- 20 mile or more visibility
- key coastal features (headlands, islands, major harbor entrances)
- Can be on-shore or off-shore
- 24 hours pe
A major light may have a directional
red sector, indicating danger
The visibility of a buoy or beacon is at most
3 to 4 miles
Unlighted buoys and markers have ____ tape, so one can
reflective tape, shine a light on them
In fog or at night if “lost” among buoys can’t see them clearly (three things)
- Slow down, stop or even backtrack
- Use spotlight
- CHECK SOUNDINGS
When encountering fog in a channel, determine _____ _____ from buoy to buoy, favoring the ____ side of the channel, but remember to guard against ___ or ___ out of the channel proper.
magnetic courses; right; set/drift
In taking and following soundings in fog or otherwise, remember that the readings on the chart are at ___ ____, so your reading may be _____.
low tide; higher
In a confusing area of a chart, draw ___ ___ from 1, 3, 5 and 2, 4, 6 etc.
guide lines
Depth on a chart can be given in (three choices)
feet, fathoms, or meters
A fathom is
six feet
A meter is X feet. Rule of thumb is X% longer
3.28 feet (so, ~10% bigger than a yard)
Sounding in fathoms may be shown as a combination of
fathoms plus feet (so 5/2 or 5^2), or fathoms plus fractions of a fathom (5-1/2 fathoms)
“Chart Datum Level” typically means
Low Tide Depth
Heights of objects are always given
above High Tide levels
