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Datums Page Page 1 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
To reach the tidal bench marks from the intersection of State Routes 3 and 44,
proceed east on State Route 44 to Court Street (Route 3A), then turn right onto
Court Stree to North Street, turn on North Street to Water Street, then turn
left onto Water Street and proceed to State Pier. The bench marks are located
near the State Pier. The tide gage and staff were located on the SW corner of
the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BM NO 10 1954
DESIGNATION: 844 6493 TIDAL 10
MONUMENTATION: Bench Mark disk VM#: 1496
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LW1544
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 41° 57.6' N ( 41.96000) LONGITUDE: 70° 39.7' W ( -70.66170)
The primary bench mark is a disk set in the east end of a concrete sea wall
located at the east side of the State Pier entrance, 20.88 m (68.5 ft) SE of the
flagpole in a circular grassy plot at the State Pier entrance, 2 m (6 ft) east
of a utility pole, and 0.21 m (0.7 ft) NE of the SE edge of the sea wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 9 1916
DESIGNATION: 844 6493 TIDAL 9
MONUMENTATION: Tidal Station disk VM#: 1497
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LW1543
SETTING CLASSIFICATION: Marble wall OPUS PID:
LATITUDE: 41° 57.4' N ( 41.95670) LONGITUDE: 70° 39.8' W ( -70.66330)
The bench mark is a disk set vertically in the east corner of the foundation of
the mail receiving room located at the rear of the post office, 23.32 m (76.5
ft) SSE of the centerline of Leyden Street, 11 m (36 ft) SE of the NE corner of
the post office, 4.36 m (14.3 ft) SSW of the SW corner of a 2-story building at
17 Leyden Street, and 0.85 m (2.8 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: STATION NO STATE ELEV 11.367 FEET
DESIGNATION: STATE
MONUMENTATION: Survey disk VM#: 1498
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LW1545
SETTING CLASSIFICATION: Concrete monutment OPUS PID:
LATITUDE: 41° 57.6' N ( 41.96000) LONGITUDE: 70° 39.8' W ( -70.66330)
The bench mark is a disk set in a concrete monument located in the SE area of
the circular grass plot at the State Pier entrance, 23.26 m (76.3 ft) NE of a
light pole at the north side of the State Pier entrance, 12.25 m (40.2 ft) SSE
of the NE corner of a comfort station, and 2.74 m (9.0 ft) NNW of a flagpole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 844 6493 CHISELED CROSS
ALIAS: NO STAMPING 1
MONUMENTATION: Chiseled Cross VM#: 1499
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Marble step OPUS PID:
LATITUDE: 41° 57.6' N ( 41.96000) LONGITUDE: 70° 39.7' W ( -70.66170)
The bench mark is a chiseled cross in the first step of the entrance located at
the south side of the main entrance to First Church of Plymouth, 18.20 m (59.7
ft) WNW of the NW corner of a two- story frame building, 5.18 m (17.0 ft) north
of the SE corner of the church, 2.38 m (7.8 ft) west of the curb in front of the
church, 0.06 m (0.2 ft) east of the church wall, and 1 m (4 ft) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 844 6493 CHISELED TRIANGL
ALIAS: NO STAMPING 2
MONUMENTATION: Chiseled Triangle VM#: 1500
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Marble portico OPUS PID:
LATITUDE: 41° 57.6' N ( 41.96000) LONGITUDE: 70° 39.7' W ( -70.66170)
The bench mark is a chiseled triangle located in the SE portico of Plymouth
County Courthouse, 7.71 m (25.3 ft) NNW of the SE corner of the courthouse, 0.3
m (1 ft) east of the east courthouse wall, 0.03 m (0.1 ft) south of the outside
base of the southwestern pillar at the courthouse entrance, and 1 m (4 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
T I D A L D A T U M S
Tidal datums at PLYMOUTH, PLYMOUTH HARBOR based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: June 1990 - August 1990
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 = 3.211
MEAN HIGH WATER MHW = 3.077
North American Vertical Datum NAVD88 = 1.758
MEAN SEA LEVEL MSL = 1.640
MEAN TIDE LEVEL MTL = 1.590
MEAN LOW WATER MLW = 0.103
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
BM NO 10 1954 4.795 1.718
NO 9 1916 16.819 13.742
STATION NO STATE ELEV 11.367 FEET 4.845 1.768
844 6493 CHISELED CROSS 21.979 18.902
844 6493 CHISELED TRIANGL 22.817 19.740
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8446493 PUBLICATION DATE: 02/05/2004
Name: PLYMOUTH, PLYMOUTH HARBOR
MA
NOAA Chart: 13253 Latitude: 41° 57.6' N ( 41.96000)
USGS Quad: PLYMOUTH Longitude: 70° 39.7' W ( -70.66170)
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.