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National Ocean Service
Datums Page Page 1 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
To reach the tidal bench marks and station from City Hall in Gloucester, proceed
0.2 km (0.1 mi) east on Warren Street to Pleasant Street, then 0.2 km (0.1 mi)
south on Pleasant Street to Duncan Street, then 0.2 km (0.1 mi) on Duncan Street
to Harbor Loop Road, then 0.2 km (0.1 mi) on Harbor Loop Road to the U.S. Coast
Guard (USCG) station. The bench marks are in the vicinity of the USCG station
and Harbor Loop Road. The tide gauge and staff were on the SW corner of the
USCG helipad.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: HELIO 1986
DESIGNATION: 844 1841 HELIO
MONUMENTATION: Survey disk VM#: 11839
AGENCY: US Army Corps of Engineers (USE) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The primary bench mark is a disk set near the SW corner of the large concrete
helicopter pad at the USCG station, 28.19 m (92.5 ft) WNW of the bollard at the
SE corner of the pad, 25.88 m (84.9 ft) south of Bench Mark 1841 A 1992, and
0.70 m (2.3 ft) north of the inner edge of the pad curb on the south side of the
pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: MARINE
DESIGNATION: 844 1841 MARINE
MONUMENTATION: Survey disk VM#: 11840
AGENCY: US Army Corps of Engineers (USE) IDB PID#:
SETTING CLASSIFICATION: Concrete pier OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The bench mark is a disk set in the east end of the L shaped concrete USCG pier,
24.87 m (81.6 ft) SE of the interior corner of the pier, 3.99 m (13.1 ft) SW of
the NE corner of the pier, and 1.52 m (5.0 ft) NW of the NW edge of the bollard
on the SE corner of the pier.
BENCH MARK STAMPING: 1841 A 1992
DESIGNATION: 844 1841 A
MONUMENTATION: Tidal Station disk VM#: 11841
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The bench mark is a disk set in the dogleg corner of a concrete sea wall at the
NW corner of the USCG helipad pier, 29 m (95 ft) south of the south corner of
the USCG boathouse building, 27 m (88 ft) NNE of the SW corner of the pier,
12.25 m ( 40.2 ft) SE of the south corner of a small A-frame building, and 0.15
m (0.5 ft) above pier level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1841 B 1992
DESIGNATION: 844 1841 B
MONUMENTATION: Tidal Station disk VM#: 11842
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete flagpole base OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The bench mark is a disk set in the east corner of the concrete USCG flagpole
base, 15.73 m (51.6 ft) ESE of the south corner of the main USCG building, 4.60
m (15.1 ft) SE of a large bronze ship's bell, and 0.46 m (1.5 ft) east of the
flagpole.
BENCH MARK STAMPING: 1841 C 1992
DESIGNATION: 844 1841 C
MONUMENTATION: Tidal Station disk VM#: 11843
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The bench mark is disk set in a large bedrock outcrop on the east side of Harbor
Loop Road, 24.69 m (81.0 ft) NE of the northenmost steel gatepost to Fairtry
Fisheries Inc., 21.79 m (71.5 ft) SE of telephone pole #596, 4.11 m (13.5 ft)
ENE of the east curb of Harbor Loop Road, and 2 m (5 ft) above road level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: AJ52 56.552
DESIGNATION: AJ 52
MONUMENTATION: Survey disk VM#: 11844
AGENCY: Massachusetts Department of Public Works
(MADPW) IDB PID#: MY0240
SETTING CLASSIFICATION: Granite step OPUS PID:
LATITUDE: 42° 36.8' N ( 42.61330) LONGITUDE: 70° 39.8' W ( -70.66330)
The bench mark is a disk set in the east corner of the first granite step at the
Warren Street entrance to Gloucester City Hall, 37 m (121 ft) east of the
centerline of Dale Avenue, and 19 m (61 ft) north of the centerline of Warren
Street.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 844 1841 4899
ALIAS: NO STAMPING 1
MONUMENTATION: Rivet VM#: 11845
AGENCY: Massachusetts Geodetic Survey (MGS) IDB PID#:
SETTING CLASSIFICATION: Concrete retaining wall OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The bench mark is a monel rivet set in the SW end of a concrete retaining wall
located on the north side of Rogers Street opposite the Massachusetts Electric
Company transformers, surrounding a parking lot behind a Gortons quality control
building fronting Main Street, 5.33 (17.5 ft) NNE of light pole #6055, 1.83 m
(6.0 ft) NW of the edge of Rogers Street, and 0.03 m (0.1 ft) NE of the west end
of the retaining wall. NOTE: The bench mark is known as #4899 by Massachusetts
Geodetic Survey.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 844 1841 4898
ALIAS: NO STAMPING 2
MONUMENTATION: Rivet VM#: 11846
AGENCY: Massachusetts Geodetic Survey (MGS) IDB PID#:
SETTING CLASSIFICATION: Pavement OPUS PID:
LATITUDE: 42° 36.6' N ( 42.61000) LONGITUDE: 70° 39.6' W ( -70.66000)
The bench mark is a monel rivet set in the concrete edging at the back of Route
127 sidewalk, on the bayside of a flagpole on the north side of the Blynman
Canal near the canal entrance, 33.07 m (108.5 ft) east of the SE corner of the
bridge tender's house for the Route 127 bridge over the canal, 18.47 m (60.6 ft)
SE of the edge of the pavement for Route 127, and 1.52 m (5.0 ft) SE of the
flagpole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
T I D A L D A T U M S
Tidal datums at GLOUCESTER HARBOR based on:
LENGTH OF SERIES: 3 Months
TIME PERIOD: July 1992 - September 1992
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8443970 BOSTON, BOSTON HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.917
MEAN HIGH WATER MHW = 2.781
MEAN SEA LEVEL MSL = 1.453
MEAN TIDE LEVEL MTL = 1.441
MEAN LOW WATER MLW = 0.101
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
HELIO 1986 4.269 1.488
MARINE 4.244 1.463
1841 A 1992 4.548 1.767
1841 B 1992 4.588 1.807
1841 C 1992 7.386 4.605
AJ52 56.552 18.494 15.713
844 1841 4899 4.911 2.130
844 1841 4898 5.440 2.659
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
Station ID: 8441841 PUBLICATION DATE: 04/21/2003
Name: GLOUCESTER HARBOR
MA
NOAA Chart: 13281 Latitude: 42° 36.6' N ( 42.61000)
USGS Quad: GLOUCESTER Longitude: 70° 39.6' W ( -70.66000)
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.