U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8654572 PUBLICATION DATE: 12/20/2012
Name: OCRACOKE ISLAND
NC
NOAA Chart: 11555 Latitude: 35° 10.3' N ( 35.17133)
USGS Quad: Green Island, NC Longitude: 75° 49.0' W ( -75.81744)
To reach the bench marks from the Ocracoke-Hatteras ferry terminal at the NE end
of Ocracoke Island, proceed SW on North Carolina 12 4.2 km (2.6 mi) to a washed
out sand road on right, proceed north on foot on washed out road 0.2 km to
Pamlico Sound. The bench marks are along the shore, along the washed out road
and along North Carolina Highway 12. The tide gauges are located 0.05 km west
of the north end of the washed out road along Pamlico Sound.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4572 A 2012
DESIGNATION: 865 4572 A
MONUMENTATION: Flange-encased Rod VM#: 20432
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Flange encased rod OPUS PID#: BBCS93
LATITUDE: 35° 10.3' N ( 35.17103) LONGITUDE: 75° 49.0' W ( -75.81706)
The primary bench mark is a flange encased rod set in tall grass near the edge
of Pamlico Sound, 66.85 m (219.3 ft) west of bench mark NC 12 8, 18.05 m (59.2
ft) south of the edge of Pamlico Sound, 13.31 m (43.7 ft) southeast of a 4x4
wooden post with white sign, 3.59 m (11.8 ft) south of the centerline of a 2
track sand path and 0.38 m (1.2 ft) north of an orange carsonite National Ocean
Service witness post. The datum point is set 8 cm (3 inches) below ground,
being the top of a stainless steel rod driven 26.8 m (87.9 ft) to refusal, in a
sleeve extending to a depth of 0.9 m (3.0 ft) and encased in a 5-inch (13 cm)
National Ocean Service logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8654572 PUBLICATION DATE: 12/20/2012
Name: OCRACOKE ISLAND
NC
NOAA Chart: 11555 Latitude: 35° 10.3' N ( 35.17133)
USGS Quad: Green Island, NC Longitude: 75° 49.0' W ( -75.81744)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NC12 8 2000
DESIGNATION: NC12 8
MONUMENTATION: Survey disk VM#: 20433
AGENCY: North Carolina Geodetic Survey IDB PID#:
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: 35° 10.3' N ( 35.17092) LONGITUDE: 75° 49.0' W ( -75.81631)
The bench mark is a survey disk set level with parking area and recessed 15 cm
(6 inches) below the ground, 247.3 m (811.5 ft) northeast of a power pole, 216.0
m (708.5 ft) north of the centerline of NC 12, 205.7 m (675.0 ft) northeast of a
power pole and 1.0 ft (0.3 m) north of a carsonite witness post.
BENCH MARK STAMPING: 4572 B 2012
DESIGNATION: 865 4572 B
MONUMENTATION: Flange-encased Rod VM#: 20434
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Flange encased rod OPUS PID:
LATITUDE: 35° 10.2' N ( 35.17031) LONGITUDE: 75° 49.0' W ( -75.81597)
The bench mark is a flange encased rod set in low grass and sand west of a sand
road, 142.8 m (468.5 ft) north of the centerline of North Carolina Highway 12,
76.85 m (252.1 ft) south of bench mark NC 12 8, 67.10 m (220.1 ft) north of
bench mark 865 4572 C, 4.60 m (15.1 ft) west of the centerline of a washed over
sand road and 0.44 m (1.4 ft) east of an orange carsonite National Ocean Service
witness post. The datum point is set 10 cm (4 inches) below ground, being the
top of a stainless steel rod driven 26.8 m (87.9 ft) to refusal, in a sleeve
extending to a depth of 0.9 m (3.0 ft) and encased in a 5-inch (13 cm) National
Ocean Service logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8654572 PUBLICATION DATE: 12/20/2012
Name: OCRACOKE ISLAND
NC
NOAA Chart: 11555 Latitude: 35° 10.3' N ( 35.17133)
USGS Quad: Green Island, NC Longitude: 75° 49.0' W ( -75.81744)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4572 C 2012
DESIGNATION: 865 4572 C
MONUMENTATION: Flange-encased Rod VM#: 20435
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Flange encased rod OPUS PID:
LATITUDE: 35° 10.2' N ( 35.16972) LONGITUDE: 75° 49.0' W ( -75.81589)
The bench mark is a flange encased rod set in low grass and sand west of a sand
road, 137.2 m (450.1 ft) northeast of bench mark 865 4572 D, 73.65 m (241.6 ft)
north-northeast of a power pole with 2 guy wires, 67.10 m (220.1 ft) south of
bench mark 865 4572 B, 75.70 m (248.4 ft) north of the centerline of North
Carolina Highway 12, 30.40 m (99.7 ft) north of a brown carsonite post adjacent
the sand road, 29.50 m (96.8 ft) east-northeast of the most western brown
carsonite post stating no motor vehicles, 6.80 m (22.3 ft) west of a sand road
and 0.49 m (1.6 ft) east of an orange carsonite National Ocean Service witness
post. The datum point is set 8 cm (3 inches) below ground, being the top of a
stainless steel rod driven 24.4 m (80.1 ft) to refusal, in a sleeve extending to
a depth of 0.9 m (3.0 ft) and encased in a 5-inch (13 cm) National Ocean Service
logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8654572 PUBLICATION DATE: 12/20/2012
Name: OCRACOKE ISLAND
NC
NOAA Chart: 11555 Latitude: 35° 10.3' N ( 35.17133)
USGS Quad: Green Island, NC Longitude: 75° 49.0' W ( -75.81744)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4572 D 2012
DESIGNATION: 865 4572 D
MONUMENTATION: Flange-encased Rod VM#: 20436
AGENCY: NOS IDB PID#:
SETTING CLASSIFICATION: Flange encased rod OPUS PID:
LATITUDE: 35° 10.1' N ( 35.16886) LONGITUDE: 75° 49.0' W ( -75.81708)
The bench mark is a flange encased rod set in sand and low bushes, 137.2 m
(450.1 ft) southwest of bench mark 865 4572 C, 30.55 m (100.2 ft) north of the
centerline of North Carolina Highway 12, 9.60 m (31.5 ft) north of a power pole
and 0.40 m (1.3 ft) south of an orange carsonite National Ocean Service witness
post. The datum point is set 9 cm (4 inches) below ground, being the top of a
stainless steel rod driven 25.6 m (84.0 ft) to refusal, in a sleeve extending to
a depth of 0.9 m (3.0 ft) and encased in a 5-inch (13 cm) National Ocean Service
logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8654572 PUBLICATION DATE: 12/20/2012
Name: OCRACOKE ISLAND
NC
NOAA Chart: 11555 Latitude: 35° 10.3' N ( 35.17133)
USGS Quad: Green Island, NC Longitude: 75° 49.0' W ( -75.81744)
T I D A L D A T U M S
Tidal datums at OCRACOKE ISLAND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: May 2012 - July 2012
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8654467 USCG STATION HATTERAS, PAMLICO SOUND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.145
MEAN HIGH WATER MHW = 0.122
MEAN SEA LEVEL MSL = 0.071
MEAN TIDE LEVEL MTL = 0.068
MEAN LOW WATER MLW = 0.013
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4572 A 2012 0.478 0.356
NC12 8 2000 0.671 0.549
4572 B 2012 1.128 1.006
4572 C 2012 1.244 1.122
4572 D 2012 1.256 1.134
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8654572 PUBLICATION DATE: 12/20/2012
Name: OCRACOKE ISLAND
NC
NOAA Chart: 11555 Latitude: 35° 10.3' N ( 35.17133)
USGS Quad: Green Island, NC Longitude: 75° 49.0' W ( -75.81744)
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.