Coast pilot 4 Chapter 12
The Intracoastal Waterway is a the toll-free canal
which affords continuous protected passage behind the Atlantic
Coast and the Florida Keys for more than 1,243 statute miles
between Norfolk, VA, and Key West, FL. Shortly after Norfolk,
the waterway bifurcates and offers 2 alternative routes: Route
1, the basic route, follows Albemarle and Chesapeake Canal to
Albemarle Sound; Route 2, the alternate route, is through Great
Dismal Swamp Canal to the sound.
The Intracoastal Waterway is used by commercial light-draft vessels
and tows unable to navigate long stretches in the open ocean,
and by pleasure craft. Small-boat and recreation facilities are
found along the waterway. Supervision of the waterway s
construction, maintenance, and operation is divided among five
U.S.Army Engineer Districts (Norfolk,Wilmington,Charleston,Savannah,and
The Intracoastal Waterway mileage is zeroed in 36 °50.9'N.,
76 °17.9'W., off the foot of West Main Street, Norfolk, VA,
and progresses southward to I.W. Mile 1243.8 at Key West, FL,
in 24 °33.7'N.,81 °48.5'W. Distances along the Intracoastal
Waterway are in statute miles to facilitate reference to the
small-craft charts; all other distances are nautical miles.
The Federal project for
the Intracoastal Waterway via Albemarle and Chesapeake Canal
provides for a least depth of 12 feet from Norfolk, VA, (I.W.Mile
0.0) to Fort Pierce, FL, (I.W.Mile 965.6), thence 10 feet to
Miami, FL, (I.W.Mile 1089.0), and thence 7 feet to Key
West, FL, (I.W.Mile 1243.8). The Miami to Key West section of
the waterway has been completed only as far as Cross Bank (I.W.Mile
1152.5); the remainder has been deferred for restudy. Although
no work has been performed on this section of the waterway, a
channel, marked in accordance with I.W. markings, leads from
Cross Bank to Big Pine Key along the northwesterly side of the
Florida Keys. At Big Pine Key, the waterway bifurcates going
north through Florida Bay or souththrough Hawk Channel to Key
West. The channel has a controlling depth of about 5 feet and
is exposed to winds from the northwest.(See Local Notice to Mariners
and latest editions of charts for controlling depths of the Intracoastal
The minimum overhead clearance of fixed bridges
over the Intracoastal Waterway is 56 feet at the Julia
Tuttle Causeway at Miami, Mile 1087.1, but most fixed bridges
have a clearance of 65 feet.
The minimum clearance of overhead cables cross-
ing the Intracoastal Waterway is 68 feet in Snows Cut, Mile 295.8
. An overhead cable car at Mile 356.4 has a least clearance of
67 feet under the low point of travel of the cabin.
Caution: When running with a fair tide or in windy weather, exercise
caution when approaching and passing bridges and sharp turns.
Regulation:General drawbridge regulations and
opening signals for bridges over the Intracoastal Waterway are
given in 117.1 through 117.49 ,chapter 2.
Unnecessary opening of the draw.
No vessel owner or operator shall signal a drawbridge to open
if the vertical clearance is sufficient to allow the vessel,
after all lowerable nonstructural vessel appurtenances that are
not essential to navigation have been lowered, to safely pass
under the drawbridge in the closed position; or signal a drawbridge
to open for any purpose other than to pass through the drawbridge
General .The operator of each vessel requesting a drawbridge
to open shall signal the drawtender and the drawtender shall
acknowledge that signal. The signal shall be repeated until acknowledged
in some manner by the drawtender before proceeding.
The signals used to request the opening of the
draw and to acknowledge that request shall be sound
signals, visual signals, or radiotelephone communica &SHY;
Great Bridge Lock (mile 11.5)is the only lock on
the Intracoastal Waterway between Norfolk and Key
West via Albemarle and Chesapeake Canal. It is 600 feet long
(530 usable),75 feet wide (72 feet usable),16 feet over the sills,and
has a lift of 2.7 feet.
Aids to navigation
Intracoastal Waterway aids have characteristic yel &SHY;
low markings which distinguish them from aids to nav &SHY;
igation marking other waters.
Lights and daybeacons should not be passed close
aboard because those marking dredged channels are
usually placed back from the bottom edge of the channel and others
may have rip-rap mounds around them to protect the structures.
Navigation of the Intracoastal Waterway can be made easier by
use of the special small-craft series which the National Ocean
Charts #: From North to South, 12206, 11553, 11541, 11534, 11518,
11507, 11489, 11485, 11472, 11467, 11451, 11445, 11446, 11448.
Under ordinary conditions the mean range of tide
in the waterway is from nontidal to about 7 feet. In
many sections, the tide depends on the force and direction of
The Intracoastal Waterway affords protection from
the winds and waves of the offshore Atlantic. Land creates friction
that reduces windspeeds by as much as 30 percent of those over
the open sea. Wave heights are reduced by shallow depths and
limited fetch. When severeweather does strike,shelter is usually
close by,either up a protected river or at a nearby port. However,navi
gation becomes more critical in many restricted reaches along
this route, so that weather, as well as tides and currents, is
important. The waterway is covered by a network of National Weather
Service VHF-FM radio stations that provide continuously updated
forecasts and warnings.
There are many small-craft facilities along the
Navigation on the waterways requires a knowledge of the channel
conditions and other factors restricting navigation.
Where two streams cross,the current will have a
greater velocity in the deeper channel. This is noticeable along
the Intracoastal Waterway where it follows a dredged canal cutting
across a winding stream. Cross currents will also be noticed
where either an inlet from the ocean or a drainage canal enters
Cross currents are especially strong at New River
Inlet and Bogue Inlet, N.C. Failure to allow for cross
currents when passing these and other inlets is the
cause of many rescue calls to the Coast Guard.
Bends or Curves
In the Intracoastal and adjoining waterways there
are many sharp bends which are dangerous to vessels
meeting or passing. On approaching a bend, a vessel
should reduce speed sufficiently to be able to stop
within half the distance to a ship coming from the opposite direction.
Under no circumstances should a vessel attempt to overtake and
pass another at a bend.
Stumps and sunken
Reports are frequently made that vessels have struck shoals or
rocks in rivers which have later proved to be stumps or sunken
logs.Mariners are warned against navigating too close to the
banks of streams where submerged stumps are known or may be expected
On receiving advisory notice of a tropical distur &SHY;
bance small boats should seek shelter in a small wind &SHY;
ing stream whose banks are lined with trees,preferably
cedar or mangrove.Moor with bow and stern lines fas &SHY;
tened to the lower branches;if possible snug up with
good chafing gear.The knees of the trees will act as
fenders and the branches,having more give than the
trunks,will ease the shocks of the heavy gusts.If the
banks are lined only with small trees or large shrubs,
use clumps of them within each hawser loop.Keep
clear of any tall pines as they generally have shallow
roots and are more apt to be blown down.
channel shall at all times
be left open to permit free and unobstructed navigation by all
types of vessels and rafts that normally use the various waterways
or sections thereof.
in waterway, anchorage or mooring.
No vessels or rafts shall anchor or moor in any of the
land cuts or other narrow parts of the waterway, except in case
of an emergency. Whenever it becomes necessary for a vessel or
raft to stop in any such portions of the waterway it shall be
securely fastened to one bank and as close to the bank as possible.
This shall be done only at such a place and under such conditions
as will not obstruct or prevent the passage of other vessels
or craft. Stoppages shall be only for such periods as may be
When tied up, all vessels must be moored by bow and stern lines,
to insure their not being drawn away from the bank by winds,currents
or the suction of passing vessels.In narrow sections,no vessel
or raft shall be tied abreast of another.
No vessel, regardless of size, shall anchor in a dredged channel
or narrow portion of a waterway for
the purpose of fishing, if navigation is obstructed,
Speed:Vessels shall proceed at a speed which
will not endanger other vessels or structures and will not interfere
with any work in progress incident to
maintaining, improving, surveying or marking the
Official signs indicating limited speeds through critical portions
of the waterways shall be strictly obeyed. Vessels approaching
and passing through a bridge shall so govern their speed as to
insure passage through the bridge without damage to the bridge
or its fenders.
No vessel or tow shall navigate through a drawbridge until the
movable span is fully opened.
and passing .
Vessels, on meeting or overtaking, shall give the proper signals
and pass in accordance with the Navigation Rules. All vessels
approaching dredges, or other plant engaged on improvements to
a waterway, shall give the signal for passing and slow down sufficiently
to stop if so ordered or if no answering signal is received.
On receiving the answering signal, they shall then proceed to
a pass at a speed sufficiently slow to insure safe navigation.