U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 02/19/1986
Station ID: 8447277 SUPERCEDED DATE: 04/21/2003
Name: ONSET BEACH, ONSET BAY
MASSACHUSETTS
NOAA Chart: 13246 Latitude: 41° 44.5' N
USGS Quad: ONSET Longitude: 70° 39.5' W
To reach the tidal bench marks from the intersection of U.S. Highway 195 and
U.S. Route 6 on Cape Cod, proceed east on U.S. Route 6 to the town of Onset.
The bench marks are in the vicinity of the Municipal Wharf. The tide gage and
staff were at the NE end of the Municipal Wharf.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7277 D 1976
MONUMENTATION: Survey Disk VM#: 5611
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set flush in the top of a concrete wall separating the parking
lot from the wharf, 59.6 feet (18.2 m) east of the SW wharf light, 2.3 feet (0.7
m) north of the Harbor Master's office, and 1.5 feet (0.5 m) above ground level.
BENCH MARK STAMPING: NO 2 1931
MONUMENTATION: Survey Disk VM#: 5612
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Curb
The bench mark is set in the concrete curb, 4 feet (1 m) from the corner in the
NW corner of Bay View Park at the corner of Onset Avenue and wharf parking area,
and 1 foot (0.3 m) east of the street.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 02/19/1986
Station ID: 8447277 SUPERCEDED DATE: 04/21/2003
Name: ONSET BEACH, ONSET BAY
MASSACHUSETTS
NOAA Chart: 13246 Latitude: 41° 44.5' N
USGS Quad: ONSET Longitude: 70° 39.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7277 E 1976
MONUMENTATION: Survey Disk VM#: 5613
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is set flush in the top of a concrete curbing wall parallel to
the sidewalk on Onset Avenue, across the street from the town wharf, 183.7 feet
(56.0 m) east of the NE corner of Union and Onset Avenues, 36 feet (11 m) SE of
the entrance to Ebb Tide Restaurant, 33.5 feet (10.2 m) north of the centerline
of Onset Avenue, and 0.5 foot (0.2 m) above ground level.
BENCH MARK STAMPING: 7277 F 1976
MONUMENTATION: Survey Disk VM#: 5614
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Step
The bench mark is set flush in the top of the first concrete landing step
leading to the park on the west end of Hungry Beach Comber Snack Bar adjacent to
the town wharf, 73.1 feet (22.3 m) west of the centerline of a driveway that
surrounds the wharf parking lot, 39 feet (12 m) north of the beach line, and 8.4
feet (2.6 m) NE of the NE corner of the snack bar.
BENCH MARK STAMPING: NO 1 1931
MONUMENTATION: Survey Disk VM#: 5615
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Curb
The bench mark is set in the center of the top of a concrete curb, 59 feet (18
m) south of the center of Onset Avenue, 3 feet (1 m) from the east end of the
curb, and 2 feet (1 m) from the street level in line with the west side of
Kenny's Pier and Salt Water Taffy stand.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 02/19/1986
Station ID: 8447277 SUPERCEDED DATE: 04/21/2003
Name: ONSET BEACH, ONSET BAY
MASSACHUSETTS
NOAA Chart: 13246 Latitude: 41° 44.5' N
USGS Quad: ONSET Longitude: 70° 39.5' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7277 F 1977
MONUMENTATION: Survey Disk VM#: 5616
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Sidewalk
The bench mark is set in the concrete sidewalk near the NW corner of the wharf
parking lot at the NE edge of Bay View Park, by the entrance to the access road
to the snack bar/bath house, and 30 feet (9 m) north of the concrete curb along
the western side of the parking lot.
BENCH MARK STAMPING: 7277 H 1977
MONUMENTATION: Survey Disk VM#: 5617
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wharf
The bench mark is set on the western edge of the concrete wharf parking lot,
approximately halfway between the foot and the end of the pier, 10 feet (3 m)
west of the cement curbstone, and 1 foot (0.3 m) east of the west edge of the
wharf.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 02/19/1986
Station ID: 8447277 SUPERCEDED DATE: 04/21/2003
Name: ONSET BEACH, ONSET BAY
MASSACHUSETTS
NOAA Chart: 13246 Latitude: 41° 44.5' N
USGS Quad: ONSET Longitude: 70° 39.5' W
T I D A L D A T U M S
Tidal datums at ONSET BEACH, ONSET BAY based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: AUGUST-OCTOBER 1976
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8447930 WOODS HOLE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (10/21/1976) = 7.07
MEAN HIGHER HIGH WATER MHHW = 4.17
MEAN HIGH WATER MHW = 3.81
MEAN TIDE LEVEL MTL = 2.02
MEAN LOW WATER MLW = 0.23
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (10/23/1976) = -1.44
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
7277 D 1976 12.06 8.25
NO 2 1931 15.75 11.94
7277 E 1976 13.82 10.01
7277 F 1976 13.69 9.88
NO 1 1931 9.86 6.05
7277 F 1977 10.09 6.28
7277 H 1977 9.66 5.85
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 02/19/1986
Station ID: 8447277 SUPERCEDED DATE: 04/21/2003
Name: ONSET BEACH, ONSET BAY
MASSACHUSETTS
NOAA Chart: 13246 Latitude: 41° 44.5' N
USGS Quad: ONSET Longitude: 70° 39.5' W
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 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.