U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8669167 PUBLICATION DATE: 04/01/2004
Name: PORT ROYAL PLTN., HILTON HEAD
SC
NOAA Chart: 11513 Latitude: 32° 13.2' N ( 32.22000)
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W ( -80.66830)
To reach the tidal bench marks from the east end of James Byrnes Bridge (U.S.
Highway 278) over Skull Creek, proceed SE on U.S. Highway 278 for 9.0 km (5.6
mi) to the entrance of Port Royal Plantation, turn left and proceed through Port
Royal Plantation gates onto Coggins Point Road for 2.7 km (1.7 mi), turn right
and proceed east on South Port Royal Drive for 0.3 km (0.2 mi). The bench marks
are located along South Port Royal Drive between the jetty and the intersection
of Coggins Point Road. The tide gage and staff were located on the end of a rock
jetty.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9167 A 1979
DESIGNATION: 866 9167 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 4563
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2064
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 32° 13.2' N ( 32.22000) LONGITUDE: 80° 40.2' W ( -80.67000)
The primary bench mark is a disk located along the east side of South Port Royal
Drive nearly in line with the rock jetty, 10.85 m (35.6 ft) south of a 0.30 m
(1.0 ft) diameter palmetto tree, 5.82 m (19.1 ft) ENE of the centerline of South
Port Royal Drive, 5.03 m (16.5 ft) NNW of a 0.09 m (0.3 ft) diameter short leaf
pine tree, and 1.95 m (6.4 ft) ENE of a wooden fence. The bench mark is set 3
cm (0.1 ft) below ground level, crimped to the top of a stainless steel rod
driven 14.6 m (48 ft) to refusal and encased in a PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8669167 PUBLICATION DATE: 04/01/2004
Name: PORT ROYAL PLTN., HILTON HEAD
SC
NOAA Chart: 11513 Latitude: 32° 13.2' N ( 32.22000)
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W ( -80.66830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9167 C 1979
DESIGNATION: 866 9167 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 4564
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2063
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 32° 13.3' N ( 32.22170) LONGITUDE: 80° 40.2' W ( -80.67000)
The bench mark is a disk located near 603 South Port Royal Drive on the east
side of the road, 21.52 m (70.6 ft) NE of the centerline of South Port Royal
Drive, 17.31 m (56.8 ft) NW of the center of a 0.61 m (2.0 ft) diameter four-
trunked oak tree, 8.29 m (27.2 ft) SSW of the SE corner of the porch at 603
South Port Royal Drive, and 1.62 m (5.3 ft) SE of the center of the SE face of a
steel high voltage box. The bench mark is set 3 cm (0.1 ft) below ground level,
crimped to the top of a stainless steel rod driven 12.8 m (42 ft) to refusal and
encased in a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 9167 F 1981
DESIGNATION: 866 9167 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 4566
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2062
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 13.2' N ( 32.22000) LONGITUDE: 80° 40.2' W ( -80.67000)
The bench mark is a disk set in a concrete monument, 41.76 m (137.0 ft) SW of a
fire hydrant, 17.83 m (58.5 ft) SSE of the centerline of South Port Royal Drive,
7 m (22 ft) WSW of the centerline of a dirt road leading to the parking lot and
Port Royal Beach House, and 0.46 m (1.5 ft) SSE of the south face of a 1.37 m
(4.5 ft) tall Private Property sign.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8669167 PUBLICATION DATE: 04/01/2004
Name: PORT ROYAL PLTN., HILTON HEAD
SC
NOAA Chart: 11513 Latitude: 32° 13.2' N ( 32.22000)
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W ( -80.66830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9167 G 1981
DESIGNATION: 866 9167 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 4567
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2061
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 13.2' N ( 32.22000) LONGITUDE: 80° 40.2' W ( -80.67000)
The bench mark is a disk set in a concrete monument located near the north
corner of Port Royal Beach House porch, 73 m (240 ft) ESE of a fire hydrant,
5.03 m (16.5 ft) SSE of a 5 m (16 ft) tall lone piling supporting 2 x 12 cross
pieces, 3.69 m (12.1 ft) SSW of the most northwestern piling supporting the
beach house (piling is just below the SW corner of the house), 0.70 m (2.3 ft)
north of the most northwestern piling supporting the porch of the beach house,
and 0.06 m (0.2 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8669167 PUBLICATION DATE: 04/01/2004
Name: PORT ROYAL PLTN., HILTON HEAD
SC
NOAA Chart: 11513 Latitude: 32° 13.2' N ( 32.22000)
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W ( -80.66830)
T I D A L D A T U M S
Tidal datums at PORT ROYAL PLTN., HILTON HEAD based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: July 1979 - August 1979
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8667630 EDISTO BEACH, EDISTO ISLAND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.067
MEAN HIGH WATER MHW = 1.924
North American Vertical Datum NAVD88 = 1.103
MEAN SEA LEVEL MSL = 1.020
MEAN TIDE LEVEL MTL = 0.996
MEAN LOW WATER MLW = 0.067
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9167 A 1979 3.428 1.504
9167 C 1979 3.118 1.194
9167 F 1981 2.982 1.058
9167 G 1981 3.808 1.884
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8669167 PUBLICATION DATE: 04/01/2004
Name: PORT ROYAL PLTN., HILTON HEAD
SC
NOAA Chart: 11513 Latitude: 32° 13.2' N ( 32.22000)
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W ( -80.66830)
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.