U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8727648 PUBLICATION DATE: 04/01/2004
Name: HORSESHOE POINT
FL
NOAA Chart: 11408 Latitude: 29° 26.2' N ( 29.43670)
USGS Quad: HORSESHOE BEACH Longitude: 83° 17.6' W ( -83.29330)
To reach the tidal bench marks from the Horseshoe Beach Post Office, proceed
south on County Road C-351 for 0.8 km (0.5 mi) to the Dockside Marina. The
bench marks are in area around Horseshoe Beach. The tide gage and staff were
located on the Dockside Marina Pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7648 A 1978
DESIGNATION: 872 7648 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 8220
AGENCY: National Ocean Survey (NOS) IDB PID#: AR1635
SETTING CLASSIFICATION: Concrete porch OPUS PID:
LATITUDE: 29° 26.2' N ( 29.43670) LONGITUDE: 83° 17.5' W ( -83.29170)
The primary bench mark is a disk set in the NW corner of a concrete porch
located at the Dockside Marina, 11 m (37 ft) south of the centerline of C-351, 3
m (10 ft) north of the NW corner of the building, 0.43 m (1.4 ft) south of the
north edge of a concrete porch, and 0.18 m (0.6 ft) east of the west edge of
concrete. NOTE: Mark not found in 1998 by US Power Squadron.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8727648 PUBLICATION DATE: 04/01/2004
Name: HORSESHOE POINT
FL
NOAA Chart: 11408 Latitude: 29° 26.2' N ( 29.43670)
USGS Quad: HORSESHOE BEACH Longitude: 83° 17.6' W ( -83.29330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SHELTON 1933
DESIGNATION: SHELTON
MONUMENTATION: Triangulation Station disk VM#: 8221
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AR1607
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 29° 26.4' N ( 29.44000) LONGITUDE: 83° 17.4' W ( -83.29000)
The bench mark is a disk set in a concrete monument, 0.2 km (0.1 mi) west along
Rainwater Avenue from County Road C-351, 44.81 m (147.0 ft) south of the
centerline of 8th Avenue, 30.48 m (100.0 ft) north of the center line of
Rainwater Drive, 6 m (20 ft) south of the SE corner of an abandoned frame house,
0.6 m (2 ft) east of a lone cedar tree, and 0.2 m (0.5 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8727648 PUBLICATION DATE: 04/01/2004
Name: HORSESHOE POINT
FL
NOAA Chart: 11408 Latitude: 29° 26.2' N ( 29.43670)
USGS Quad: HORSESHOE BEACH Longitude: 83° 17.6' W ( -83.29330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SHELTON 1933 AZIMUTH
DESIGNATION: SHELTON AZ MK
MONUMENTATION: Azimuth Mark disk VM#: 8223
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AR1608
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 29° 26.4' N ( 29.44000) LONGITUDE: 83° 17.3' W ( -83.28830)
The bench mark is a disk set in a concrete monument, 0.3 km (0.2 mi) south of
the Horseshoe Beach Post Office on County Road C-351, 20 m (67 ft) WNW of the
junction of County Road C-351 and the road to Horseshoe Marina, 15 m (50 ft) NE
of the east corner of a frame house, 14 m (46 ft) west of the centerline of
County Road C-351, and 0.12 m (0.4 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8727648 PUBLICATION DATE: 04/01/2004
Name: HORSESHOE POINT
FL
NOAA Chart: 11408 Latitude: 29° 26.2' N ( 29.43670)
USGS Quad: HORSESHOE BEACH Longitude: 83° 17.6' W ( -83.29330)
T I D A L D A T U M S
Tidal datums at HORSESHOE POINT based on:
LENGTH OF SERIES: 6 MONTHS
TIME PERIOD: July 1978 - December 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8727520 CEDAR KEY, GULF OF MEXICO
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.091
MEAN HIGH WATER MHW = 1.001
North American Vertical Datum NAVD88 = 0.623
MEAN TIDE LEVEL MTL = 0.591
MEAN SEA LEVEL MSL = 0.577
MEAN LOW WATER MLW = 0.180
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7648 A 1978 2.316 1.315
SHELTON 1933 2.097 1.096
SHELTON 1933 AZIMUTH 1.963 0.962
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8727648 PUBLICATION DATE: 04/01/2004
Name: HORSESHOE POINT
FL
NOAA Chart: 11408 Latitude: 29° 26.2' N ( 29.43670)
USGS Quad: HORSESHOE BEACH Longitude: 83° 17.6' W ( -83.29330)
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.