U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8661529 PUBLICATION DATE: 07/26/2004
Name: CAPT. ALEX'S MARINA, MURRELLS
SC
NOAA Chart: 11535 Latitude: 33° 33.1' N ( 33.55170)
USGS Quad: BROOKGREEN Longitude: 79° 2.2' W ( -79.03670)
To reach the tidal bench marks from the intersection of U.S. Highway 17 and
State Highway 707 in Murrells Inlet, proceed east on State Highway 707 for 0.6
km (0.4 mi) to U.S. Highway 17 Business, then turn right and proceed south on
U.S. Highway 17 Business for 1.1 km (0.7 mi) to Captain Alex's Marina. The
bench marks are along U.S. Highway 17 Business and in the vicinity of Captain
Alex's Marina. The tide gage and staff were on the NE side of the dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: CA NO 4 1975
DESIGNATION: 866 1529 TIDAL CA 4
MONUMENTATION: Tidal Station disk VM#: 3783
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1479
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID#: DD1479
LATITUDE: 33° 33.3' N ( 33.55500) LONGITUDE: 79° 2.1' W ( -79.03500)
The primary bench mark is a disk located at the intersection of U.S. Highway 17
Business and State Road S-22-188, 0.3 km (0.2 mi) SW of bench mark NO 3 1975,
24.51 m (80.4 ft) SW of a lone cedar tree in the front yard of the Belin
Methodist Educational Building, 10.21 m (33.5 ft) NNW of the centerline of the
U.S. Highway 17 Business, 8.99 m (29.5 ft) ENE of the centerline of State Road
S-22-188, and 4.39 m (14.4 ft) south of utility pole #A-L1A. The bench mark is
set 6 cm (0.2 ft) below ground level, crimped to the top of a copper-clad steel
rod driven 12.2 m (40 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: 8661529 PUBLICATION DATE: 07/26/2004
Name: CAPT. ALEX'S MARINA, MURRELLS
SC
NOAA Chart: 11535 Latitude: 33° 33.1' N ( 33.55170)
USGS Quad: BROOKGREEN Longitude: 79° 2.2' W ( -79.03670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: CA NO 3 1975
DESIGNATION: 866 1529 TIDAL CA 3
MONUMENTATION: Tidal Station disk VM#: 3782
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1480
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 33° 33.4' N ( 33.55670) LONGITUDE: 79° 2.0' W ( -79.03330)
The bench mark is a disk located at the intersection of U.S. Highway 17 Business
and State Road S-22-559, 10.42 m (34.2 ft) NW of the centerline of U.S. Highway
17 Business, 8.93 m (29.3 ft) NE of State Road S-22-559, 4 m (13 ft) ESE of
utility pole #17683, 2.35 m (7.7 ft) ESE of the south corner of a fence for the
Bay Harbor property, and 1.01 m (3.3 ft) SSE of a witness post with sign. The
bench mark is set 3 cm (0.1 ft) below ground level, crimped to the top of a
copper-clad steel rod driven 12.2 m (40 ft) to refusal, and encased in a PVC
pipe and concrete kickblock.
BENCH MARK STAMPING: 1529 F 1982
DESIGNATION: 866 1529 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 3784
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1482
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 33° 33.5' N ( 33.55830) LONGITUDE: 79° 1.9' W ( -79.03170)
The bench mark is a disk located near a utility pole without wires in the west
corner of a gravel parking lot for Anchor Inn, 27.37 m (89.8 ft) NE of utility
pole #39-12A, 25.97 m (85.2 ft) west of the west corner of Anchor Inn, 12.34 m
(40.5 ft) SE of the centerline of U.S. Highway 17 Business, 2.74 m (9.0 ft) NW
of a 0.61 m (2.0 ft) diameter live oak tree, and 0.94 m (3.1 ft) SE of a witness
post with sign. The bench mark is crimped to the top of a stainless steel rod
driven 10.7 m (35 ft) to refusal, and encased in a 5-inch PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8661529 PUBLICATION DATE: 07/26/2004
Name: CAPT. ALEX'S MARINA, MURRELLS
SC
NOAA Chart: 11535 Latitude: 33° 33.1' N ( 33.55170)
USGS Quad: BROOKGREEN Longitude: 79° 2.2' W ( -79.03670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1529 G 1982
DESIGNATION: 866 1529 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 3785
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1483
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 33° 33.6' N ( 33.56000) LONGITUDE: 79° 1.8' W ( -79.03000)
The bench mark is a disk located 0.24 km (0.15 mi) NE of bench mark 1529 F 1982,
17.59 m (57.7 ft) NNE of the centerline of a sand drive leading east to a two
story house, 16.79 m (55.1 ft) east of a manhole cover, 10.45 m (34.3 ft) SE of
the centerline of U.S. Highway 17 Business, 0.85 m (2.8 ft) SE of utility pole
#36 1/2 A, and 0.21 m (0.7 ft) SW of a witness post with sign. The bench mark
is crimped to the top of a stainless steel rod driven 7.9 m (26 ft) to refusal,
and encased in a 5-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8661529 PUBLICATION DATE: 07/26/2004
Name: CAPT. ALEX'S MARINA, MURRELLS
SC
NOAA Chart: 11535 Latitude: 33° 33.1' N ( 33.55170)
USGS Quad: BROOKGREEN Longitude: 79° 2.2' W ( -79.03670)
T I D A L D A T U M S
Tidal datums at CAPT. ALEX'S MARINA, MURRELLS based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: December 1974 - December 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8661419 GARDEN CITY BRRIDGE, MURRELLS INLET
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.476
MEAN HIGH WATER MHW = 1.349
North American Vertical Datum NAVD88 = 0.822
MEAN SEA LEVEL MSL = 0.703
MEAN TIDE LEVEL MTL = 0.694
MEAN LOW WATER MLW = 0.039
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
CA NO 4 1975 3.382 2.033
CA NO 3 1975 3.342 1.993
1529 F 1982 3.292 1.943
1529 G 1982 2.868 1.519
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8661529 PUBLICATION DATE: 07/26/2004
Name: CAPT. ALEX'S MARINA, MURRELLS
SC
NOAA Chart: 11535 Latitude: 33° 33.1' N ( 33.55170)
USGS Quad: BROOKGREEN Longitude: 79° 2.2' W ( -79.03670)
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.