The following information was obtained from Lowrance.

LOWRANCE NAVAIDS DATA

GENERAL DESCRIPTION
The Lowrance Navaids database contains data on marine navigational aids in
U.S. waters.  These navaids help boaters to stay in safe channels and to
avoid obstructions while on the water.  The main navaids included are listed
below. A few instances of some less commonly used navaids, such as Sound
Signals, may appear as Radiobeacon symbols.

Lighted Buoy--An unmanned floating device moored or anchored to the bottom
as an aid to navigation, and equipped with a light for visibility at night.
The color(s) of the buoy, the color of the light, and the flashing
characteristic of the light indicate the purpose of the buoy.
Unlighted Buoy--An unmanned floating device moored or anchored to the bottom
as an aid to navigation, not equipped with a light.  The color(s) and shape
of the buoy indicate its purpose.
Light--An apparatus emitting light of a distinctive character for use as an
aid to navigation.
Daybeacon, Square--A fixed, unlighted aid to navigation, typically
consisting of a square-shaped, colored, lettered sign atop a post.
Daybeacon, Triangle-- A fixed, unlighted aid to navigation, typically
consisting of a triangle-shaped, colored, lettered sign atop a post.
Radiobeacon--A radio transmitting station which emits a distinctive or
characteristic signal so a navigator can determine the direction of the
source using a radio direction finder, providing a line of position.
Platform--A large horizontal flat surface supported above the water surface,
used for oil drilling operations.

Each feature appears as a small symbol on the Lowrance mapping products, and
appears at the same zoom range as the IMS SmartMap data.  Below is a picture
showing how each type of symbol looks on the product.  Most of the navaids
have text associated with them that is useful to the mariner, such as light
flashing characteristics, aid color, aid marking, sound signal, etc.  This
text appears just under the symbol when the cursor is placed near the
symbol. The symbols and text look similar to that on the National Ocean
Service (NOS/NOAA) nautical charts.

The coverage area includes the coastal regions of all U.S. states that have
coastline, as well as the District of Columbia, the Great Lakes, some large
rivers near the coast, and some large inland lakes.  The data currently
contains about 60,000 marine navaids.  The aids are most heavily
concentrated on the east coast of the U.S. and the Gulf of Mexico.  Data is
more sparse on the west coast, Alaska, and Hawaii.

Unlike the MapSelect navaids coverages shown below, navaids data viewed with
and downloaded to a unit using the MapCreate program contains aids
maintained by the Coast Guard at some U.S. territories and military bases
including Midway Islands, Puerto Rico, American Samoa, Guam, Cuba, Haiti,
Virgin Islands, Bahamas, and Mariana Islands.  The data is relatively sparse
in these areas compared to the U.S. coast.


OIL DRILLING PLATFORMS
The data also includes navaids and oil platforms registered with the Coast
Guard that are associated with drilling operations near the Gulf coast.  The
data includes about 10,000 drilling platforms and various other aids put out
by the oil companies, such as buoys warning of abandoned well heads, etc.
WATER BODIES COVERED
The following is a list of some of the major inland bodies of water where
Marine Navaid data is found.  Only navaids registered with the U.S. Coast
Guard will appear on these lakes and rivers.

Columbia River (WA, OR)
Lake Mead (NV, AZ)
Lake Havasu (CA, AZ)
Lake Tahoe (NV, CA)
Lake Powell (UT)
Lake of the Woods (MN)
Fort Peck Lake (MT)
Lake Okeechobee (FL)
Lake Livingston (TX)
Lake Pend Oreille (ID)


LIMITATIONS
The navaids data does not contain aids along the Mississippi River system,
except those very near the coast.  It may not contain aids that are often
moved when these changes are not published by the Coast Guard.  It does not
contain changes or aids designated by the Coast Guard as "temporary or
seasonal." It does not contain all features found on nautical charts.  Not
included are rocks, obstructions, tanks, towers, inland lights, soundings,
and wrecks.  The data should be used with caution, as it contains many aids
that are "privately" maintained by companies and individuals, not by the
Coast Guard.  The reliability of the existence and the position of these
privately maintained aids is unknown.