U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 10/09/1985
Station ID: 8669167 SUPERCEDED DATE: 04/21/2003
Name: PORT ROYAL PLANTATION, HILTON HEADISLAND, PORT ROY
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 13.2' N
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W
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 5.6 miles (9.0
km) to the entrance of Port Royal Plantation, turn left and proceed through Port
Royal Plantation gates onto Coggins Point Road for 1.7 miles (2.7 km), turn
right and proceed east on South Port Royal Drive for 0.2 mile (0.3 km). The
tide gage and staff were located on the end of a rock jetty. The bench marks
are located along South Port Royal Drive between the jetty and the intersection
of Coggins Point Road.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9167 A 1979
MONUMENTATION: Survey Disk VM#: 4563
AGENCY: PID#: CK2064
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located along the east side of South Port Royal Drive nearly
in line with the rock jetty, 138 feet (42 m) west of the shoreline, 35.6 feet
(10.8 m) south of a 1.0-foot (0.3 m) diameter palmetto tree, 19.1 feet (5.8 m)
ENE of the centerline of South Port Royal Drive, 16.5 feet (5.0 m) NNW of a
0.3-foot (0.1 m) diameter short leaf pine tree, and 6.4 feet (2.0 m) ENE of a
wooden fence. The bench mark is 0.1 foot (0.03 m) below ground level, crimped
to a stainless steel rod driven 48 feet (15 m) 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
PUBLICATION DATE: 10/09/1985
Station ID: 8669167 SUPERCEDED DATE: 04/21/2003
Name: PORT ROYAL PLANTATION, HILTON HEADISLAND, PORT ROY
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 13.2' N
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9167 C 1979
MONUMENTATION: Survey Disk VM#: 4564
AGENCY: PID#: CK2063
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located near 603 South Port Royal Drive on the east side of
the road, 70.6 feet (21.5 m) NE of the centerline of South Port Royal Drive,
56.8 feet (17.3 m) NW of the center of a 2.0-foot (0.6 m) diameter four- trunked
oak tree, 27.2 feet (8.3 m) SSW of the SE corner of the porch at 603 South Port
Royal Drive, and 5.3 feet (1.6 m) SE of the center of the SE face of a steel
high voltage box. The bench mark is 0.1 foot (0.03 m) below ground level,
crimped to a stainless steel rod driven 42 feet (13 m) to refusal and encased in
a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 9167 E 1979
MONUMENTATION: Survey Disk VM#: 4565
AGENCY: PID#: CK2060
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located at the intersection of South Port Royal Drive and
Sumter Road, between the corner and a pond, 44.2 feet (13.5 m) ESE of the edge
of the pond, 37.3 feet (11.4 m) SW of the centerline of South Port Royal Drive,
31.1 feet (9.5 m) NNW of the centerline of Sumter Road, 15.4 feet (4.7 m) north
of 1.0-foot (0.3 m) diameter maple tree, and 12.1 feet (3.7 m) NW of the
2.2-foot (0.7 m) tall Golf Villas/Pro Shop sign. The bench mark is at ground
level, crimped to a stainless steel rod driven 42 feet (13 m) 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 3 of 5
PUBLICATION DATE: 10/09/1985
Station ID: 8669167 SUPERCEDED DATE: 04/21/2003
Name: PORT ROYAL PLANTATION, HILTON HEADISLAND, PORT ROY
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 13.2' N
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9167 F 1981
MONUMENTATION: Survey Disk VM#: 4566
AGENCY: PID#: CK2062
SETTING CLASSIFICATION: Concrete Monument
The bench mark is 59.0 feet (18.0 m) SSE of the centerline of South Port Royal
Drive, 23.0 feet (7.0 m) SW of the centerline of a dirt road leading to the
parking lot and Port Royal Beach House, and 1.5 feet (0.5 m) SSE of the south
face of a 4.5-foot (1.4 m) tall Private Property sign. The bench mark is set in
concrete at ground level.
BENCH MARK STAMPING: 9167 G 1981
MONUMENTATION: Survey Disk VM#: 4567
AGENCY: PID#: CK2061
SETTING CLASSIFICATION: Concrete Monument
The bench mark is located near the north corner of Port Royal Beach House porch,
16.5 feet (5.0 m) SSE of a 16-foot (5 m) tall lone piling supporting 2 x 12
cross pieces, 12.1 feet (3.7 m) SSW of the most northwestern piling supporting
the beach house (piling is just below the SW corner of the house), and 2.3 feet
(0.7 m) north of the most northwestern piling supporting the porch of the beach
house. The bench mark is set in concrete, 0.2 foot (0.06 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 10/09/1985
Station ID: 8669167 SUPERCEDED DATE: 04/21/2003
Name: PORT ROYAL PLANTATION, HILTON HEADISLAND, PORT ROY
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 13.2' N
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W
T I D A L D A T U M S
Tidal datums at PORT ROYAL PLANTATION, HILTON HEADISLAND, PORT ROY based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: JULY-AUGUST 1979
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8667630 EDISTO BEACH
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (07/10/1979) = 8.52
MEAN HIGHER HIGH WATER MHHW = 6.81
MEAN HIGH WATER MHW = 6.37
MEAN TIDE LEVEL MTL = 3.30
MEAN LOW WATER MLW = 0.22
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (08/11/1979) = -1.53
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
9167 A 1979 11.52 5.15
9167 C 1979 10.51 4.14
9167 E 1979 10.32 3.95
9167 F 1981 10.06 3.69
9167 G 1981 12.77 6.40
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 10/09/1985
Station ID: 8669167 SUPERCEDED DATE: 04/21/2003
Name: PORT ROYAL PLANTATION, HILTON HEADISLAND, PORT ROY
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 13.2' N
USGS Quad: HILTON HEAD Longitude: 80° 40.1' W
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 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.