U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
To reach the tidal bench marks from the Catholic Church in Key West, proceed NE
on U. S. Highway 1 for 11.7 km (7.3 mi) to the road leading to Boca Chica Naval
Air Station, then turn right and proceed SW on the road to the main gate of the
Naval Air Station and the weapons storage area. The bench marks are located in
the weapons storage area. The tide gage and staff were located on a short dock
in the western section of the weapons storage area.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: H 329 1970
DESIGNATION: H 329
MONUMENTATION: Bench Mark disk VM#: 11028
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0070
SETTING CLASSIFICATION: Loading ramp OPUS PID:
LATITUDE: 24° 34.9' N ( 24.58170) LONGITUDE: 81° 42.8' W ( -81.71330)
The primary bench mark is a disk set in the top of the east end of the loading
ramp along the north side of building #A 1116, 49.96 m (163.9 ft) east of bench
mark J 329 1970, 6.86 m (22.5 ft) NW of the NE corner of the building, 3.66 m
(12.0 ft) north of the north face of the building, 0.5 m (0.15 ft) west of the
east end of the ramp, and 1.07 m (3.5 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: J 329 1970
DESIGNATION: J 329
MONUMENTATION: Bench Mark disk VM#: 11029
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0069
SETTING CLASSIFICATION: Concrete step OPUS PID:
LATITUDE: 24° 34.9' N ( 24.58170) LONGITUDE: 81° 42.8' W ( -81.71330)
The bench mark is a disk set in the north end of the top of 5 steps leading to
the loading dock for building #A 1116, 49.96 m (163.9 ft) west of bench mark H
329, 5 m (18 ft) east of the NW corner of the building, 1.10 m (3.6 ft) north of
the north face of the building, 0.3 m (1 ft) south of the north end of the
step, and 0.82 m (2.7 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: L 329 1970
DESIGNATION: L 329
MONUMENTATION: Bench Mark disk VM#: 11030
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0065
SETTING CLASSIFICATION: Outcropping bedrock OPUS PID:
LATITUDE: 24° 33.9' N ( 24.56500) LONGITUDE: 81° 42.9' W ( -81.71500)
The bench mark is a disk set in the top of a mass of outcropping bedrock about
0.2 km (0.1 mi) west of the west end of building #A 1116, 9.14 m (30.0 ft) east
of the waters edge of a cove, and level with the ground.
BENCH MARK STAMPING: 4499 F 1982
DESIGNATION: 872 4499 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 11031
AGENCY: National Ocean Survey (NOS) IDB PID#: AA1001
SETTING CLASSIFICATION: Outcropping rock OPUS PID:
LATITUDE: 24° 34.9' N ( 24.58170) LONGITUDE: 81° 42.8' W ( -81.71330)
The bench mark is a disk set in the top of a rock outcrop on the north side of
the weapons storage area, 32.13 m (105.4 ft) WNW of the NE corner of a chainlink
fence, 12.59 m (41.3 ft) north of the east/west fence, 8.02 m (26.3 ft) north of
the centerline of a track road, and level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4499 G 1982
DESIGNATION: 872 4499 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 11032
AGENCY: National Ocean Survey (NOS) IDB PID#: AA1000
SETTING CLASSIFICATION: Outcropping bedrock OPUS PID:
LATITUDE: 24° 34.9' N ( 24.58170) LONGITUDE: 81° 42.7' W ( -81.71170)
The bench mark is a disk set in the top of a bedrock outcrop in the weapons
storage area, 22.10 m (72.5 ft) SE of the center of the entrance gate to the
weapons storage area, 18.87 m (61.9 ft) south of the centerline of the paved
road to the weapons storage area, and 11.40 m (37.4 ft) east of the chainlink
fence on the east side of the weapons storage area.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
T I D A L D A T U M S
Tidal datums at BOCA CHICA, SOUTHWEST END based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: February 1971 - January 1972
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8724580 KEY WEST
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (11/03/1971) = 0.640
North American Vertical Datum NAVD88 = 0.438
MEAN HIGHER HIGH WATER MHHW = 0.392
MEAN HIGH WATER MHW = 0.309
MEAN SEA LEVEL MSL = 0.184
MEAN TIDE LEVEL MTL = 0.177
MEAN LOW WATER MLW = 0.045
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (04/26/1971) = -0.272
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
H 329 1970 2.900 2.591
J 329 1970 2.762 2.453
L 329 1970 0.557 0.248
4499 F 1982 1.189 0.880
4499 G 1982 1.105 0.796
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8724499 PUBLICATION DATE: 02/05/2004
Name: BOCA CHICA, SOUTHWEST END
FL
NOAA Chart: 11445 Latitude: 24° 33.8' N ( 24.56330)
USGS Quad: BOCA CHICA KEY Longitude: 81° 42.8' W ( -81.71330)
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.