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National Ocean Service
Datums Page Page 1 of 5
Station ID: 8447180 PUBLICATION DATE: 08/09/2004
Name: SANDWICH MARINA, CAPE COD CANAL
MA
NOAA Chart: 13236 Latitude: 41° 46.3' N ( 41.77170)
USGS Quad: POCASSET Longitude: 70° 30.4' W ( -70.50670)
To reach the tidal bench marks from U.S. Highway 6A in Sandwich, proceed NW on
U.S. Highway 6, then turn right on Tupper Road and continue NW to Freezer road,
turn right and proceed north on Freezer road, then turn right on a paved road
leading around the east side of the boat basin to its end at the parking lot on
the Cape Cod Canal. The bench marks are located at the south end of the boat
basin near the launch ramp and on the east side of the East Boat Basin in the
vicinity of the Coast Guard Station. The tide gage was located on the first
pier inside the entrance to the boat basin on its east side.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7180 H 1976
DESIGNATION: 844 7180 H
MONUMENTATION: Tidal Station disk VM#: 1528
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 41° 46.4' N ( 41.77330) LONGITUDE: 70° 30.1' W ( -70.50170)
The primary bench mark is a disk located along the south side of the parking lot
of Joe's Lobster Mart, 91 m (299 ft) north of the U.S. Coast Guard Station, 7 m
(23 ft) east of the center of power pole 6-85, 3.66 m (12.0 ft) NW of a fire
hydrant, and 2.62 m (8.6 ft) south of the curb of at the south end of the
parking lot. The bench mark is crimped to the top of a steel rod driven an
unspecified depth and encased in a PVC pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8447180 PUBLICATION DATE: 08/09/2004
Name: SANDWICH MARINA, CAPE COD CANAL
MA
NOAA Chart: 13236 Latitude: 41° 46.3' N ( 41.77170)
USGS Quad: POCASSET Longitude: 70° 30.4' W ( -70.50670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5 1965
DESIGNATION: 844 7180 NO 5
MONUMENTATION: Tidal Station disk VM#: 1524
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Step OPUS PID:
LATITUDE: 41° 46.3' N ( 41.77170) LONGITUDE: 70° 30.0' W ( -70.50000)
The bench mark is a disk set in the west end of the bottom concrete step at the
main entrance to the U.S. Coast Guard Station on the east side of the East Boat
Basin.
BENCH MARK STAMPING: 6 1965
DESIGNATION: 844 7180 NO 6
MONUMENTATION: Tidal Station disk VM#: 1525
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID#: BBBJ45
LATITUDE: 41° 46.3' N ( 41.77170) LONGITUDE: 70° 30.0' W ( -70.50000)
The bench mark is a disk set in the top of a rock outcrop, 28 m (92 ft) SSW of
bench mark 5 1965, 4.11 m (13.5 ft) north of a large rock outcrop, and 0.61 m
(2.0 ft) south of a small concrete walk running NW-SE.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8447180 PUBLICATION DATE: 08/09/2004
Name: SANDWICH MARINA, CAPE COD CANAL
MA
NOAA Chart: 13236 Latitude: 41° 46.3' N ( 41.77170)
USGS Quad: POCASSET Longitude: 70° 30.4' W ( -70.50670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7 1971
DESIGNATION: 844 7180 NO 7
MONUMENTATION: Tidal Station disk VM#: 1526
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Step OPUS PID:
LATITUDE: 41° 46.2' N ( 41.77000) LONGITUDE: 70° 30.3' W ( -70.50500)
The bench mark is a disk set in the concrete step at the entrance to the ladies
room at the Cape Cod Marina public rest room building, at the south end of the
East Boat Basin, 40.54 m (133.0 ft) south of a light pole at entrance to Pier A,
25 m (82 ft) SSW of a round storm drain at the east corner of the parking lot,
6.71 m (22.0 ft) west of NE corner of the building, 2.68 m (8.8 ft) SE of the
north corner of the building, and 0.46 m (1.5 ft) east of the NE face of the
building.
BENCH MARK STAMPING: 7180 G 1976
DESIGNATION: 844 7180 G
MONUMENTATION: Tidal Station disk VM#: 1527
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Unspecified deep rod OPUS PID:
LATITUDE: 41° 46.2' N ( 41.77000) LONGITUDE: 70° 30.3' W ( -70.50500)
The bench mark is a disk 47 m (154 ft) NE of bench mark 7 1971, 38 m (125 ft) NW
of the entrance to Pier A, 23.01 m (75.5 ft) north of a storm drain at the east
corner of the parking lot, 20.27 m (66.5 ft) SE of the centerline of Freezer
Road, 12 m (39 ft) SW of the rockline of the boat basin, and 0.76 m (2.5 ft) NW
Of power pole #490 VMP A. The bench mark is crimped to the top of a steel rod
driven 5.0 m (16 ft), and encased in a PVC pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8447180 PUBLICATION DATE: 08/09/2004
Name: SANDWICH MARINA, CAPE COD CANAL
MA
NOAA Chart: 13236 Latitude: 41° 46.3' N ( 41.77170)
USGS Quad: POCASSET Longitude: 70° 30.4' W ( -70.50670)
T I D A L D A T U M S
Tidal datums at SANDWICH MARINA, CAPE COD CANAL based on:
LENGTH OF SERIES: 7 YEARS
TIME PERIOD: January 1970 - December 1976
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8443970 BOSTON, BOSTON HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (03/17/1956) = 3.978
MEAN HIGHER HIGH WATER MHHW = 2.880
MEAN HIGH WATER MHW = 2.732
MEAN SEA LEVEL MSL = 1.434
MEAN TIDE LEVEL MTL = 1.400
MEAN LOW WATER MLW = 0.069
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/30/1963) = -0.990
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7180 H 1976 4.907 2.175
5 1965 6.871 4.139
6 1965 7.045 4.313
7 1971 6.154 3.422
7180 G 1976 5.548 2.816
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8447180 PUBLICATION DATE: 08/09/2004
Name: SANDWICH MARINA, CAPE COD CANAL
MA
NOAA Chart: 13236 Latitude: 41° 46.3' N ( 41.77170)
USGS Quad: POCASSET Longitude: 70° 30.4' W ( -70.50670)
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.