U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8467726 PUBLICATION DATE: 04/01/2004
Name: SOUTHPORT, SOUTHPORT HARBOR
CT
NOAA Chart: 12369 Latitude: 41° 8.0' N ( 41.13330)
USGS Quad: WESTPORT Longitude: 73° 17.0' W ( -73.28330)
To reach the benchmarks from the US Route 1 exit for Southport on I-95, proceed
0.2 km (0.1 mi) along the exit ramp to US Route 1, then south on US 1 for 0.40
km (0.25 mi) to Center Street, turn left and continue SE on Center Street for
1.05 km (0.65 mi) to Harbor Road, then turn left and proceed NE on Harbor Road
for 0.2 km (0.1 mi) to the Pequot Yacht Club. The bench marks are on the yacht
club property and along Center Street. The tide gage and sensor were located at
the SW corner of the yacht club.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7726 B 2003
DESIGNATION: 846 7726 B
MONUMENTATION: Tidal Station disk VM#: 17312
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Flagpole Foundation OPUS PID:
LATITUDE: 41° 8.0' N ( 41.13330) LONGITUDE: 73° 17.0' W ( -73.28330)
The primary bench mark is a disk set in the concrete foundation for the club
flagpole, 18.45 m (60.5 ft) north of the stone sea wall, 15.35 m (50.4 ft) west
of the west facing door for the main house of the yacht club, 13.70 m (45.0 ft)
south of light pole 02, and 0.93 m(3.0 ft) SW of the flagpole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8467726 PUBLICATION DATE: 04/01/2004
Name: SOUTHPORT, SOUTHPORT HARBOR
CT
NOAA Chart: 12369 Latitude: 41° 8.0' N ( 41.13330)
USGS Quad: WESTPORT Longitude: 73° 17.0' W ( -73.28330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7726 C 2003
DESIGNATION: 846 7726 C
MONUMENTATION: Tidal Station disk VM#: 17313
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Davit Foundation OPUS PID:
LATITUDE: 41° 8.0' N ( 41.13330) LONGITUDE: 73° 16.9' W ( -73.28170)
The bench mark is a disk set in the concrete foundation for the easternmost boat
davit at the parking lot/boat yard for the Yacht Club, east of the club houses,
37.40 m (122.7 ft) east of the SE corner of the porch at the junior yacht club
house, 9.26 m (30.4 ft) NE of the western boat davit, and 1.26 m (4.1 ft) NW of
the eastern boat davit.
BENCH MARK STAMPING: 7726 D 2003
DESIGNATION: 846 7726 D
MONUMENTATION: Tidal Station disk VM#: 17314
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Transformer Foundation OPUS PID:
LATITUDE: 41° 8.0' N ( 41.13330) LONGITUDE: 73° 17.2' W ( -73.28670)
The bench mark is a disk set in the concrete foundation for transformer number
147278, located at the intersection of Center Street and Pequot Avenue, near the
front entrance of the the Trinity Episcopal Church parish hall, 44.00 m (144.4
ft) east of utility pole 50 at the SE corner of the intersection of Center
Street and Pequot Avenue, 4.60 m (15.1 ft) SE of utility pole 49, and 0.36 m
(1.2 ft) east of the east corner of the transformer.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8467726 PUBLICATION DATE: 04/01/2004
Name: SOUTHPORT, SOUTHPORT HARBOR
CT
NOAA Chart: 12369 Latitude: 41° 8.0' N ( 41.13330)
USGS Quad: WESTPORT Longitude: 73° 17.0' W ( -73.28330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: E 2=155
MONUMENTATION: See descriptive text VM#: 17315
AGENCY: Unknown IDB PID#: LX0821
SETTING CLASSIFICATION: Railroad Bridge Abutment OPUS PID:
LATITUDE: 41° 8.0' N ( 41.13330) LONGITUDE: 73° 17.3' W ( -73.28830)
The bench mark is the chiseled corner of a stone block, outlined in orange
paint, on the east stone abutment for the railroad bridge over Center Street,
55.90 m (183.4 ft) north of utility pole 140, 53.80 m (176.5 ft) NW of light
pole 652, 24.10 m (79.1 ft) SE of light pole 54, and 1.97 m (6.5 ft) above the
level of the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8467726 PUBLICATION DATE: 04/01/2004
Name: SOUTHPORT, SOUTHPORT HARBOR
CT
NOAA Chart: 12369 Latitude: 41° 8.0' N ( 41.13330)
USGS Quad: WESTPORT Longitude: 73° 17.0' W ( -73.28330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: K 33 1965
DESIGNATION: K 33
MONUMENTATION: Bench Mark disk VM#: 17316
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: LX0820
SETTING CLASSIFICATION: Bedrock Outcrop OPUS PID:
LATITUDE: 41° 8.0' N ( 41.13330) LONGITUDE: 73° 17.3' W ( -73.28830)
The bench mark is a disk set in a bedrock outcropping along the west side of
Center Street, 33.80 m (110.9 ft) NW of light pole 52, 32.80 m (107.6 ft) north
of utility pole 140 located at the driveway for 275 Center Street, and 18.99 m
(62.3 ft) south of the second step of the west stone abutment for the railroad
bridge over Center Street.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8467726 PUBLICATION DATE: 04/01/2004
Name: SOUTHPORT, SOUTHPORT HARBOR
CT
NOAA Chart: 12369 Latitude: 41° 8.0' N ( 41.13330)
USGS Quad: WESTPORT Longitude: 73° 17.0' W ( -73.28330)
T I D A L D A T U M S
Tidal datums at SOUTHPORT, SOUTHPORT HARBOR based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: July 2003 - July 2003
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8467150 BRIDGEPORT, BRIDGEPORT HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.260
MEAN HIGH WATER MHW = 2.158
North American Vertical Datum NAVD88 = 1.168
MEAN SEA LEVEL MSL = 1.117
MEAN TIDE LEVEL MTL = 1.116
MEAN LOW WATER MLW = 0.074
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7726 B 2003 3.452 1.294
7726 C 2003 2.682 0.524
7726 D 2003 4.127 1.969
E 2=155 6.321 4.163
K 33 1965 5.735 3.577
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8467726 PUBLICATION DATE: 04/01/2004
Name: SOUTHPORT, SOUTHPORT HARBOR
CT
NOAA Chart: 12369 Latitude: 41° 8.0' N ( 41.13330)
USGS Quad: WESTPORT Longitude: 73° 17.0' W ( -73.28330)
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.