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National Ocean Service
Datums Page Page 1 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
To reach the tidal bench marks from Southport, proceed by boat 4.0 km (2.5
statute mi) to Bald Head Island. The bench marks are parallel to the shoreline
of the island. The tide gauge and staff where on a dredge range marker piling.
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 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: KIMBERLY 1974
DESIGNATION: KIMBERLY
ALIAS: 1
MONUMENTATION: Tidal Station disk VM#: 3625
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 33° 52.8' N ( 33.88000) LONGITUDE: 78° 0.1' W ( -78.00170)
The primary bench mark is a disk, the first (northeastern most) of five marks in
a straight line parallel to the shoreline witness posts at each end, 197 m (647
ft) SW of a concrete base of the Old Baldhead Shoal Channel Front Range, 32 m
(105 ft) inland of the approximate high water line on the first row of sand
dunes, and 0.15 m (0.5 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BARBS 1974
DESIGNATION: BARBS
ALIAS: 3
MONUMENTATION: Tidal Station disk VM#: 3622
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 33° 52.8' N ( 33.88000) LONGITUDE: 78° 0.1' W ( -78.00170)
The bench mark is a disk, the middle of five marks in a straight line parallel
to the shoreline with witness posts at both ends, SW of bench mark PEGGY ANN
1974, and NE of bench mark DAVID 1974
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: CRISTIN 1974
DESIGNATION: CRISTIN
ALIAS: 5
MONUMENTATION: Tidal Station disk VM#: 3623
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 33° 52.8' N ( 33.88000) LONGITUDE: 78° 0.1' W ( -78.00170)
The bench mark is a disk, the fifth (southwestern most) of five marks in a
straight line parallel to the shoreline with witness posts at each end, 32 m
(105 ft) inland of the mean high water line on the first row of sand dunes, SW
of bench mark DAVID 1974, and NE of a witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: DAVID 1974
DESIGNATION: DAVID
ALIAS: 4
MONUMENTATION: Tidal Station disk VM#: 3624
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 33° 52.8' N ( 33.88000) LONGITUDE: 78° 0.1' W ( -78.00170)
The bench mark is a disk, the fourth of five marks in a straight line parallel
to the shoreline with witness posts at each end, 32 m (105 ft) inland of the
mean high water line on the first row of sand dunes, SW of bench mark BARBS
1974, and NE of bench mark CRISTIN 1974.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: PEGGY ANN 1974
DESIGNATION: PEGGY ANN
ALIAS: 2
MONUMENTATION: Tidal Station disk VM#: 3626
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 33° 52.8' N ( 33.88000) LONGITUDE: 78° 0.1' W ( -78.00170)
The bench mark is a disk, the second of five marks in a straight line parallel
to the shoreline with witness posts at both ends, 32 m (105 ft) inland of the
mean high water line on the first row of sand dunes, SW of bench mark KIMBERLY
1974.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
T I D A L D A T U M S
Tidal datums at BALD HEAD ISLAND based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: November 1974 - November 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8658120 WILMINGTON, CAPE FEAR RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.530
MEAN HIGH WATER MHW = 1.419
MEAN SEA LEVEL MSL = 0.779
MEAN TIDE LEVEL MTL = 0.735
MEAN LOW WATER MLW = 0.051
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
KIMBERLY 1974 2.748 1.329
BARBS 1974 2.753 1.334
CRISTIN 1974 2.750 1.331
DAVID 1974 2.813 1.394
PEGGY ANN 1974 2.912 1.493
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
Station ID: 8658901 PUBLICATION DATE: 08/03/2004
Name: BALD HEAD ISLAND
NC
NOAA Chart: 11537 Latitude: 33° 52.8' N ( 33.88000)
USGS Quad: SOUTHPORT Longitude: 78° 0.1' W ( -78.00170)
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.