Boating: How to Boat: Advanced: Sailing
Nautical Chart Reading 101
| Many
recreational boaters in small boats don't consider it important to have
charts onboard. Bad idea,
even if you are just operating on your local lake. Perhaps you are not
yet a navigator, but a chart onboard allows you to compare what you are
seeing with what you should be seeing and can help you keep your bearings.
I did
an instructor's clinic a year or so ago on Lake Lanier in Georgia. This
is a huge lake north of Atlanta. The school that hosted the clinic had
to borrow a few boats from another location on the lake and several
of the instructor candidates volunteered to move the boats. I happened
to be on the lead boat with the school's owner who was familiar with
the lake, however, the trailing boats all had skippers who had never
been on Lake Lanier before and none of the boats had charts. Needless
to say, as the other boats leisurely sailed around and got lost, we
had more and more radio calls asking for directions.
Nautical
charts are different from maps in that they specifically depict water
areas, while maps concentrate on land area, roads, landmarks, etc. Land
areas and features on charts are sketchy and are noted only for their
interest to the boater. Unlike maps, the nautical chart conveys much
information specifically designed to assist in safely navigating the
area that the chart covers.
Several
of our visitors (that includes you Judy, in your brand new spiffy boat)
have asked for a tip on reading nautical charts so we thought we would
take a "non-navigators" trip from the Shark River out to the
Atlantic, down the Jersey Shore, in the Manasquan Inlet and down the
Intracoastal to Ortley Beach.
Important
tips:
- Study
your chart thoroughly.
- Look
at the position from which you will start and visually follow along
the course you wish to take.
- Look
for "notes" - water depths, obstructions (especially under
water), bridges, power lines or any other unusual items that may be
a hazard to your progress.
- Make
a note of each of these on a separate piece of paper.
- Make
note of all buoys and markers you may pass in the order they will
appear. This will give you a documented picture of your route and
what you should expect to see without having to continually try to
find a small marker on the chart.
- Look
for visual objects featured on your chart that you should be able
to observe and identify to confirm your position.
- Always
check the weather before departing - in this case, also to make sure
you will be safe in navigating the Shark River Inlet.
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| Disclaimer:
This trip is for demonstration purposes only and is taken from charts
which may not be up to date. Boaters should not rely on the information
presented here for navigation in this area and should consult current
local charts for specific details and directions.
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Using
the Shark River detailed inset, let's assume that we are departing the
Municipal Boat Basin on the south side of Shark River Island. We can see
from the chart note that we have a controlling width of 50 feet and 7.5'
depth from the Boat Basin to the jetty channel. The channel then widens
to 100 feet with a depth of 18 feet.
Click to see enlarged chart.
*Note: This information may not be currently valid. |
As
we proceed toward the Atlantic, our first concern will be the power lines
and two bridges that we will encounter.
| The
power lines have a clearance of 31 feet so we are okay in our small cuddy
cabin cruiser. The first bridge has a horizontal clearance of 50 feet
and a vertical clearance of 8 feet. The second bridge has a horizontal
clearance of 50 feet and a vertical clearance of 13 feet. Since the highest
point on our boat is the VHF antenna and that is only 6 feet above the
water we're okay for the bridges. |
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Once we
have cleared these first two bridges we will be passing the Belmar Basin
on the right and the Shark River CG on the left. We then will traverse
another bridge with a horizontal clearance of 90 feet and a vertical
clearance of 15 feet. Once again, we are okay as we pass under the bridge.
We are
now approaching a FL R 4sec 33ft 4M "2" HORN marker and a
FL G 4sec 10ft 4M "1". What do these series of letters and
numbers mean? Simply put, we will be passing, on our port side, a flashing
(FL) red (R) lighted buoy that flashes (at night) every four seconds
(4sec), which is 33 feet tall (33ft), can be seen for 4 miles (4M),
is marked with the number 2 ("2"), and is equipped with a
horn (which blasts once every 15 seconds during reduced visibility,
according to the Light List, Vol. 1, Atlantic Coast). We also will be
passing, on our starboard side, a flashing green lighted buoy that flashes
every four seconds (at night), is 10 feet tall, can be seen for 4 miles
and carries the number 1. There is an imaginary line between these two
markers that represents the COLREGS demarcation line. Remember what
this is? This is where the Inland rules end and International rules
begin when leaving and vice-versa when returning.
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| Once we
have cleared the markers and the Shark River Inlet we have in site the
RW "SI" Mo(A) WHIS. This is the red and white vertically striped
safe water mark. We won't go out this far. We will note our depths on
the chart and our depth finder and turn south when we have reached the
30 foot contour line. This is the solid line running parallel to the beach.
This should be far enough out to keep us out of any breaking waves and
far enough to keep away from some of the wrecks that we see noted closer
to shore to the south. Make a note of the time. Let's assume that we are
just going to go on a leisurely cruise down to the Manasquan River Inlet
at 10 nautical miles per hour. A little quick math and you figure this
to be 1 nautical mile every 6 minutes.
As we
proceed south following the 30 foot contour line and watching our depth
finder can enjoy the view of the beach. We make note of the distance
legend on the chart and find that one nautical mile equals approximately
one and one-half inches on the chart. After traveling south for approximately
six minutes you should be able to see the radio tower just off your
starboard beam. Another eight minutes or so and you should be able to
see the hotel dome to starboard. Another seven minutes and you should
see to starboard a yellow (Y) privately maintained spar marker labeled
with the letter "A". Six more minutes and you will be approaching
another yellow privately maintained spar this time labeled with the
letter "D".
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From
this point, you now have the Manasquan Inlet entrance markers in site.
(Click to see enlarged chart) You
will turn west to enter the Inlet between the FL R 4sec 30ft 5M "4"
and the FL 6 sec 35 ft 15M HORN. Be sure to steer clear of the jetty, as
marked "Rks" on the chart.
Remember "Red Right Returning"
Coming
in the Inlet you are again passing a COLREGS demarcation line and once
you have cleared the markers you are again obeying Inland rules. |
Once inside the inlet we will just follow the channel with a depth of
8.5 feet until we reach R"2" Fl R 4sec marker. This is where
the channel begins to narrow until we are filtered into the very narrow
channel at marker C"3" just before the first bridge we see returning
from sea. This has only a 3 feet vertical clearance but since it is a
railroad bridge, it is usually open to navigation except when there is
a train coming. Continuing to follow the channel, the next obstructions
are another bridge with a 30 foot vertical clearance and power lines crossing
the channel with a clearance of 107 feet. No problem here. |
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Even though the channel now starts to enter a physically wider area of
the Manasquan River, you note that the channel is marked more frequently.
This is because the water is very shallow (1- 1.5 feet in some areas)
outside the channel. We pass the G"1" marker to port and FL
R"2" to starboard. We continue inland keeping the red, even-numbered
markers to starboard and the green, odd-numbered markers to port. |
Just
after we have passed R N"6A" and C "7A" we turn
south into the Point Pleasant Canal, which begins the ICW, keeping
FL R"8" to starboard. This marker should have a yellow triangle
indicating that it is also a marker in the ICW. Once inside the ICW
going generally south, we will keep the red markers to starboard and
green markers to port. We notice that as we approach the first bridge
with 10 foot of vertical clearance, there is a special note on the
chart (Note: D) which advises that we should use extreme caution because
of turbulent waters around bridges over the Point Pleasant Canal.
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From
here we are cautious and continually check our chart for markers
and objects from which we can visually note our position - keeping
red markers to starboard and green to port. You will notice on the
chart that there are areas of very shallow water depth (the bluer
areas). In approximately 10 - 12 miles we see the Spire and Tank
to port as we approach the causeway which runs from the mainland
to the beach. This should be recognized as the area between Ortley
Beach and Seaside Heights. In order to get into the beach area it
will be necessary to follow the privately maintained channel which
runs north of, and parallel to, the causeway. (The chart indicates
"see note B". Note B reads: Channel is marked by privately
maintained seasonal aids.) From here, we would want either local
knowledge or a more detailed chart than we have been able to consult
on this adventure. |
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Many
chart symbols are shown on the back of the chart. Chart #1 is a
collection of all the symbols found on nautical charts. Some common
chart symbols are depicted here.
Although
this was a boater-friendly trip covering only about 20 miles, hopefully
you get the idea how important your nautical chart can be in making
your trips safer. Would you have thought about overhead powerlines,
bridges and their heights, looking for specific markers to use as
"road signs" which indicate where to turn, using depth
contour lines as a roadway in the Atlantic, sighting objects on
land to keep track of where you are? If not, perhaps you should.
Just make sure you have charts onboard.
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