U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8723391 PUBLICATION DATE: 02/26/2004
Name: COON POINT, ELLIOTT KEY
FL
NOAA Chart: 11462 Latitude: 25° 28.8' N ( 25.48000)
USGS Quad: ELLIOTT KEY Longitude: 80° 11.3' W ( -80.18830)
To reach the tidal bench marks by boat from Elliott Key Harbor, proceed 3.1 km
(1.9 statute mi) NNE to the University Yacht Club dock. The bench marks are to
the east and north of the University Yacht Club dock on the west side of Elliott
Key, 1.4 km (0.9 mi) SW of Sands Cut. The tide staff and gage were located on
the south side of the University Yacht Club dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 4 1974
DESIGNATION: 872 3391 TIDAL 4
MONUMENTATION: Tidal Station disk VM#: 5828
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Outcropping coral OPUS PID:
LATITUDE: 25° 28.7' N ( 25.47830) LONGITUDE: 80° 11.4' W ( -80.19000)
The primary bench mark is a disk set flush in an outcropping coral, 20 m (65 ft)
NNE of the north side of the dock, 12 m (39 ft) SSE of bench mark NO 2 1974, and
0.12 m (0.4 ft) above the ground.
BENCH MARK STAMPING: NO 2 1974
DESIGNATION: 872 3391 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 5827
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 25° 28.7' N ( 25.47830) LONGITUDE: 80° 11.4' W ( -80.19000)
The bench mark is a disk set flush in a small square concrete pad, 11.92 m (39.1
ft) NE of bench mark NO 4 1974, 11 m (36 ft) south of the shoreline, and 0.3 m
(1 ft) NW of a steel pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8723391 PUBLICATION DATE: 02/26/2004
Name: COON POINT, ELLIOTT KEY
FL
NOAA Chart: 11462 Latitude: 25° 28.8' N ( 25.48000)
USGS Quad: ELLIOTT KEY Longitude: 80° 11.3' W ( -80.18830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 5 1974
DESIGNATION: 872 3391 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 5829
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Outcropping coral OPUS PID:
LATITUDE: 25° 28.7' N ( 25.47830) LONGITUDE: 80° 11.4' W ( -80.19000)
The bench mark is a disk set flush in an outcropping coral, 11.09 m (36.4 ft) SW
of bench mark NO 1 1974, 5 m (17 ft) east of the shoreline, 0.46 m (1.5 ft)
north of the north edge of the dock, and 0.24 m (0.8 ft) above the ground.
BENCH MARK STAMPING: 3391 F 1984
DESIGNATION: 872 3391 F
MONUMENTATION: Tidal Station disk VM#: 5830
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 25° 28.7' N ( 25.47830) LONGITUDE: 80° 11.4' W ( -80.19000)
The bench mark is a disk set in a bedrock cavity filled with concrete, 10.24 m
(33.6 ft) SSW of the south side of the pier, and 0.3 m (1 ft) SE of the rock
dropoff.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8723391 PUBLICATION DATE: 02/26/2004
Name: COON POINT, ELLIOTT KEY
FL
NOAA Chart: 11462 Latitude: 25° 28.8' N ( 25.48000)
USGS Quad: ELLIOTT KEY Longitude: 80° 11.3' W ( -80.18830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3391 G 1984
DESIGNATION: 872 3391 G
MONUMENTATION: Tidal Station disk VM#: 5831
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete mound on bedrock OPUS PID:
LATITUDE: 25° 28.7' N ( 25.47830) LONGITUDE: 80° 11.4' W ( -80.19000)
The bench mark is a disk set in a concrete mound on bedrock, 36.18 m (118.7 ft)
NNE of the north side of the dock, 16.82 m (55.2 ft) NNW of bench mark NO 4
1974, 8.41 m (27.6 ft) NW of bench mark NO 2 1974, 3 m (10 ft) SE of rock
dropoff and NW end of an old concrete walk, and 6 cm (0.2 ft) above the rock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8723391 PUBLICATION DATE: 02/26/2004
Name: COON POINT, ELLIOTT KEY
FL
NOAA Chart: 11462 Latitude: 25° 28.8' N ( 25.48000)
USGS Quad: ELLIOTT KEY Longitude: 80° 11.3' W ( -80.18830)
T I D A L D A T U M S
Tidal datums at COON POINT, ELLIOTT KEY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: July 1974 - July 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8723350 RAGGED KEY #3
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.494
MEAN HIGH WATER MHW = 0.474
MEAN TIDE LEVEL MTL = 0.253
MEAN SEA LEVEL MSL = 0.242
MEAN LOW WATER MLW = 0.032
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 4 1974 0.970 0.496
NO 2 1974 1.081 0.607
NO 5 1974 0.949 0.475
3391 F 1984 0.736 0.262
3391 G 1984 0.688 0.214
Foot Notes:
Bench marks 3391 F 1984 and 3391 G 1984 are based on one differential leveling
connection and do not meet the quality control standards of the NOS. Therefore,
caution should be used when deriving elevations for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8723391 PUBLICATION DATE: 02/26/2004
Name: COON POINT, ELLIOTT KEY
FL
NOAA Chart: 11462 Latitude: 25° 28.8' N ( 25.48000)
USGS Quad: ELLIOTT KEY Longitude: 80° 11.3' W ( -80.18830)
D E F I N I T I O N S
Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch. It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).
NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint. NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929. Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.
The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed. The NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum. As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.