U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8661559 PUBLICATION DATE: 02/13/2004
Name: SMITH'S DOCK, MURRELLS INLET
SC
NOAA Chart: 11535 Latitude: 33° 32.7' N ( 33.54500)
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W ( -79.04500)
To reach the tidal bench marks from South Myrtle Beach proceed 22.2 km (13.8 mi)
SW on US Highway 17 Business to Vauxhall Avenue, proceed 0.18 km (0.11 mi) SE on
Vauxhall Avenue to its end, then turn right and proced south on Creek Drive to
Smiths Dock. The bench marks are located along US Highway 17 Business and along
Vauxhall Avenue (State Route S-22-63). The tide gage and staff were located on
a dock behind Dr. Smiths House.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: SD NO 1 1975
DESIGNATION: 866 1559 TIDAL SD 1
MONUMENTATION: Tidal Station disk VM#: 3793
AGENCY: National Ocean Survey IDB PID#: DD1478
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 33° 33.0' N ( 33.55000) LONGITUDE: 79° 2.4' W ( -79.04000)
The primary bench mark is a disk located near the intersection of Vauxhall
Avenue and Creek Drive, 15.79 m (51.8 ft) east of the east corner of the porch
of a brick house, 7.77 m (25.5 ft) south of the intersection of Vauxhall Avenue
and a sandy marsh front road, 6.19 m (20.3 ft) NW of a 0.3 m (1 ft) embankment
in the marsh, and 4 m (13 ft) SE of the centerline of the marsh front road. The
bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top of a
copper-clad steel rod driven 14.6 m (48 ft) to refusal, encased in PVC pipe and
a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8661559 PUBLICATION DATE: 02/13/2004
Name: SMITH'S DOCK, MURRELLS INLET
SC
NOAA Chart: 11535 Latitude: 33° 32.7' N ( 33.54500)
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W ( -79.04500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SD NO 2 1975
DESIGNATION: 866 1559 TIDAL SD 2
MONUMENTATION: Tidal Station disk VM#: 3794
AGENCY: National Ocean Survey IDB PID#: DD1477
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 33° 33.0' N ( 33.55000) LONGITUDE: 79° 2.6' W ( -79.04330)
The bench mark is a disk located along the NE side of Vauxhall Avenue, 114 m
(375 ft) NW of Bench Mark SD NO 1 1975, 59 m (195 ft) east of US Highway 17
(business) along Vauxhall Avenue, 30.63 m (100.5 ft) east of the east corner of
Murrells Inlet Post Office, 4.27 m (14.0 ft) ENE of the centerline of Vauxhall
Road, and 1.13 m (3.7 ft) WSW of utility pole #A-H 1/2 A. The bench mark is
0.06 m (0.2 ft) below ground level, crimped to a copper-clad steel rod driven
13.7 m (45 ft) to refusal, encased in PVC pipe and a concrete kickblock.
BENCH MARK STAMPING: SD NO 3 1975
DESIGNATION: 866 1559 TIDAL SD 3
MONUMENTATION: Tidal Station disk VM#: 3795
AGENCY: National Ocean Survey IDB PID#: DD4661
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 33° 32.7' N ( 33.54500) LONGITUDE: 79° 2.7' W ( -79.04500)
The bench mark is a disk set in a concrete monument at the north corner of
Murrells Inlet Post Office, 17.89 m (58.7 ft) south of utility pole #A17, 16.76
m (55.0 ft) SE of the centerline of US Highway 17 (business), 10.21 m (33.5 ft)
SW of the centerline of Vauxhall Avenue, 0.27 m (0.9 ft) NE of the NE wall of
the post office, and level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8661559 PUBLICATION DATE: 02/13/2004
Name: SMITH'S DOCK, MURRELLS INLET
SC
NOAA Chart: 11535 Latitude: 33° 32.7' N ( 33.54500)
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W ( -79.04500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SD NO 4 1975
DESIGNATION: 866 1559 TIDAL SD 4
MONUMENTATION: Tidal Station disk VM#: 3796
AGENCY: National Ocean Survey IDB PID#: DD1470
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID#: DD1470
LATITUDE: 33° 33.1' N ( 33.55170) LONGITUDE: 79° 2.5' W ( -79.04170)
The bench mark is a disk located near the north corner of the intersection of US
Highway 17 Business and Vauxhall Avenue, 37 m (120 ft) NNW of Bench Mark SD NO 3
1975, 15.76 m (51.7 ft) NW of the centerline of US Highway 17 Business, 7 m (23
ft) NE of Vauxhall Avenue, 2.01 m (6.6 ft) south of a large pine tree, and 1.07
m (3.5 ft) SE of utility pole #U1A. The bench mark is level with the ground,
crimped to the top of a copper-clad steel rod driven 14.0 m (46 ft) to refusal,
encased in PVC pipe and a concrete kickblock.
BENCH MARK STAMPING: 1559 F 1982
DESIGNATION: 866 1559 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 3797
AGENCY: National Ocean Survey IDB PID#: DD4662
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 33° 32.7' N ( 33.54500) LONGITUDE: 79° 2.7' W ( -79.04500)
The bench mark is a disk located near the intersection of US Highway 17 Business
and Beaty Street, 11.83 m (38.8 ft) SE of the centerline of US Highway 17
Business, 7.10 m (23.3 ft) east of the center of a manhole cover, 5.49 m (18.0
ft) ENE of the centerline of Beaty Street, 2.62 m (8.6 ft) SW of utility pole
#12763, 0.91 m (3.0 ft) south of telephone junction box #2-20, and 0.27 m (0.9
ft) NW of a witness post and sign. The bench mark is crimped to the top of a
stainless steel rod driven 12.8 m (42 ft) to refusal, encased in PVC pipe and a
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8661559 PUBLICATION DATE: 02/13/2004
Name: SMITH'S DOCK, MURRELLS INLET
SC
NOAA Chart: 11535 Latitude: 33° 32.7' N ( 33.54500)
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W ( -79.04500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1559 G 1982
DESIGNATION: 866 1559 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 3798
AGENCY: National Ocean Survey IDB PID#: DD4663
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 33° 32.7' N ( 33.54500) LONGITUDE: 79° 2.7' W ( -79.04500)
The bench mark is a disk located 0.40 km (0.25 mi) NE of Murrells Inlet Post
Office, 25.76 m (84.5 ft) NW of utility pole #13657, 15.12 m (49.6 ft) north of
the NW corner of a two-story tan dwelling, 9.75 m (32.0 ft) SE of the centerline
of US Highway 17 Business, and 2.16 m (7.1 ft) NE of utility pole #48 A. The
bench mark is crimped to the top of a stainless steel rod driven 11.6 m (38 ft)
to refusal, encased in PVC pipe and a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8661559 PUBLICATION DATE: 02/13/2004
Name: SMITH'S DOCK, MURRELLS INLET
SC
NOAA Chart: 11535 Latitude: 33° 32.7' N ( 33.54500)
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W ( -79.04500)
T I D A L D A T U M S
Tidal datums at SMITH'S DOCK, MURRELLS INLET based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: February 1975 - January 1976
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8665530 CHARLESTON, COOPER RIVER ENTRANCE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (06/10/1975) = 2.074
MEAN HIGHER HIGH WATER MHHW = 1.481
MEAN HIGH WATER MHW = 1.362
North American Vertical Datum NAVD88 = 0.835
MEAN SEA LEVEL MSL = 0.737
MEAN TIDE LEVEL MTL = 0.708
MEAN LOW WATER MLW = 0.055
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (01/01/1976) = -0.444
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
SD NO 1 1975 2.655 1.293
SD NO 2 1975 3.116 1.754
SD NO 3 1975 3.757 2.395
SD NO 4 1975 3.342 1.980
1559 F 1982 2.748 1.386
1559 G 1982 2.281 0.919
Foot Notes:
Bench marks 1559 F 1982 and 1559 G 1982 are based on one differential leveling
connection and do not meet the quality control standards of the NOS. Therefore,
caution should be used when deriving elevations for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8661559 PUBLICATION DATE: 02/13/2004
Name: SMITH'S DOCK, MURRELLS INLET
SC
NOAA Chart: 11535 Latitude: 33° 32.7' N ( 33.54500)
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W ( -79.04500)
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.