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Datums Page Page 1 of 5
Station ID: 8447685 PUBLICATION DATE: 04/21/2003
Name: CHAPPAQUOIT POINT, BUZZARDS BAY
MA
NOAA Chart: 13230 Latitude: 41° 36.3' N ( 41.60500)
USGS Quad: WOODS HOLE Longitude: 70° 39.1' W ( -70.65170)
To reach the tidal bench marks from the intersection of State Route 28A and
Chappaquoit Road in West Falmouth, proceed west and north on Chappaquoit Road
for 1.6 km (1.0 mi) , along the beach and through the Chappaquoit Point entrance
gate, then left on Associates Road for 0.2 km (0.1 mi) to a path on the left
just east of No. 20 Associates Road. The bench marks are located in the vicinity
of Associates Road and the Chappaquoit Association Wharf. The tide gage was
located on the NE corner of the wharf.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 2 1931
DESIGNATION: 844 7685 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 2067
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 41° 46.3' N ( 41.77170) LONGITUDE: 70° 39.1' W ( -70.65170)
The primary bench mark is a disk set in the top of a 2 m x 8 m (6 ft x 26 ft)
sharp pointed granite boulder in the NW area of the lawn of No. 20 Associates
Road, the first house south of the Chappaquoit Point Big Pier, 17 m (56 ft)
north of the NW door of the house porch, and 0.43 m (1.41 ft) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8447685 PUBLICATION DATE: 04/21/2003
Name: CHAPPAQUOIT POINT, BUZZARDS BAY
MA
NOAA Chart: 13230 Latitude: 41° 36.3' N ( 41.60500)
USGS Quad: WOODS HOLE Longitude: 70° 39.1' W ( -70.65170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1931
DESIGNATION: 844 7685 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 2068
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 41° 36.3' N ( 41.60500) LONGITUDE: 70° 39.1' W ( -70.65170)
The bench mark is a disk set in top of a 2 m x 3 m (6 ft x 8 ft) granite boulder
in the south lawn of No. 18 Associates Road, the second house south of the
Chappaquoit Association Big Pier, 8.38 m (27.5 ft) south of the SW corner of the
house, and 1 m (3 ft) above ground level.
BENCH MARK STAMPING: NO 4 1931
DESIGNATION: 844 7685 TIDAL 4
MONUMENTATION: Tidal Station disk VM#: 2069
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 41° 36.3' N ( 41.60500) LONGITUDE: 70° 39.1' W ( -70.65170)
The bench mark is a disk set in the flat top of a 2 m x 2 m (6 ft x 6 ft)
granite boulder in the south lawn of No. 50 Associates Road, the middle of a
group of three closely set houses about 275 m (902 ft) ESE of the Chappaquoit
Associates Big Pier, 15.57 m (51.1 ft) north of the center of Associates Road,
11.36 m (37.3 ft) SSW of the SE corner of the house, and 0.73 m (2.4 ft) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8447685 PUBLICATION DATE: 04/21/2003
Name: CHAPPAQUOIT POINT, BUZZARDS BAY
MA
NOAA Chart: 13230 Latitude: 41° 36.3' N ( 41.60500)
USGS Quad: WOODS HOLE Longitude: 70° 39.1' W ( -70.65170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7685 D 1976
DESIGNATION: 844 7685 D
MONUMENTATION: Tidal Station disk VM#: 2070
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete walkway OPUS PID:
LATITUDE: 41° 36.3' N ( 41.60500) LONGITUDE: 70° 39.1' W ( -70.65170)
The bench mark is a disk set in the top of the west edge of the concrete walkway
of the pier, 7.53 m (24.7 ft) north of the beginning of the concrete walkway,
1.95 m (6.4 ft) NW of the NW corner of the southernmost wooden observation
platform, 1 m (3 ft) west of the east edge of the walkway, and 0.40 m (1.3 ft)
south of the second wood pole along the west side of the walkway.
BENCH MARK STAMPING: 7685 E 1976
DESIGNATION: 844 7685 E
MONUMENTATION: Tidal Station disk VM#: 2071
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 41° 36.3' N ( 41.60500) LONGITUDE: 70° 39.1' W ( -70.65170)
The bench mark is a disk set in top of a 2 m x 3 m (6 ft x 10 ft) granite
boulder located in the SW lawn of No. 40 Associates Road, the westernmost house
of a group of three closely set houses ESE of the Chappaquoit Associates Big
Pier, 36.52 m (119.8 ft) SSW of the wooden bulkhead at the water's edge, 18.20 m
(59.7 ft) north of the center of Associates Road, 12.56 m (41.2 ft) west of the
SW corner of the house, and 11.92 m (39.1 ft) north of a stone fence.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8447685 PUBLICATION DATE: 04/21/2003
Name: CHAPPAQUOIT POINT, BUZZARDS BAY
MA
NOAA Chart: 13230 Latitude: 41° 36.3' N ( 41.60500)
USGS Quad: WOODS HOLE Longitude: 70° 39.1' W ( -70.65170)
T I D A L D A T U M S
Tidal datums at CHAPPAQUOIT POINT, BUZZARDS BAY based on:
LENGTH OF SERIES: 2 Months
TIME PERIOD: August 2000 - September 2000
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8452660 NEWPORT, NARRAGANSETT BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.295
MEAN HIGH WATER MHW = 1.215
MEAN TIDE LEVEL MTL = 0.632
MEAN SEA LEVEL MSL = 0.563
MEAN LOW WATER MLW = 0.049
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 2 1931 4.940 3.725
NO 3 1931 4.798 3.583
NO 4 1931 7.083 5.868
7685 D 1976 2.531 1.317
7685 E 1976 7.176 5.961
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8447685 PUBLICATION DATE: 04/21/2003
Name: CHAPPAQUOIT POINT, BUZZARDS BAY
MA
NOAA Chart: 13230 Latitude: 41° 36.3' N ( 41.60500)
USGS Quad: WOODS HOLE Longitude: 70° 39.1' W ( -70.65170)
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.