U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 10/30/1985
Station ID: 8454341 SUPERCEDED DATE: 04/21/2003
Name: BOSTON NECK, NARRAGANSETT BAY
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.6' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W
To reach the tidal bench marks from the Town of Narragansett Pier, Rhode Island,
proceed north on Scenic Highway 1A, 5 miles (8 km) to the entrance gates for
Anawan Cliff (on the right side of the road). Turn right (east) and continue to
the end of the paved access road. The bench marks are located around the cliff
line perimeter of the grass turnaround. The tide gage and staff were located at
the junction of the shoreline and the grass road, with the bubbler orifice and
tubing extending offshore. The tide staff was mounted to a rock just offshore
Bench Mark 4341 A 1977.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4341 B 1977
MONUMENTATION: Survey Disk VM#: 2201
AGENCY: PID:
SETTING CLASSIFICATION: Rod Mark
The bench mark is located at the junction of the grass entrance road and the
cliff line, 71.5 feet (21.8 m) SE (135 ) from Bench Mark 4341 C 1977, 63.5 feet
(19.4 m) NW (300 ) of Bench Mark 4341 A 1977 and bears NE (40 ) from the cupola
atop the adjacent yellow house and west (280 ) of the rock the staff was
attached to. The bench mark is crimped to the top of a rod driven 5.5 feet (1.7
m) to refusal and is encased in PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4341 A 1977
MONUMENTATION: Survey Disk VM#: 2200
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Culvert
The bench mark is set flush in the top of the concrete collar of a culvert,
located at the junction of the grass entrance road and the cliff line, 200 feet
(61 m) east (80 ) of the centerline of the asphalt portion of the entrance road,
115.5 feet (35.2 m) south (180 ) of the shoreline of Anchor Bay, 63.5 feet (19.4
m) SE (125 ) of Bench Mark 4341 B 1977, and bears ENE (60 ) from the cupola atop
the adjacent yellow house.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 10/30/1985
Station ID: 8454341 SUPERCEDED DATE: 04/21/2003
Name: BOSTON NECK, NARRAGANSETT BAY
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.6' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4341 C 1977
MONUMENTATION: Survey Disk VM#: 2202
AGENCY: PID:
SETTING CLASSIFICATION: Rod Mark
The bench mark is located on the east side of the grass turnaround, 71.5 feet
(21.8 m) NW (315 ) from Bench Mark 4341 B 1977, 62 feet (19 m) SE (131 ) from
Bench Mark 4341 D 1977, and bears NNE (25 ) from the cupola atop the adjacent
yellow house. The bench mark is crimped to the top of a rod driven 8 feet (2 m)
to refusal, and is encased in PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4341 D 1977
MONUMENTATION: Survey Disk VM#: 2203
AGENCY: PID:
SETTING CLASSIFICATION: Rod Mark
The bench mark is located on the north side of the grass turnaround, 176 feet
(54 m) NNE (17 ) from Bench Mark 4341 E 1977, 62 feet (19 m) NW (312 ) from
Bench Mark 4341 C 1977, and bears NNE (18 ) from the cupola atop the adjacent
yellow house. The bench mark is crimped to the top of a rod driven 8 feet (2 m)
to refusal, encased in a PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 10/30/1985
Station ID: 8454341 SUPERCEDED DATE: 04/21/2003
Name: BOSTON NECK, NARRAGANSETT BAY
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.6' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4341 E 1977
MONUMENTATION: Survey Disk VM#: 2204
AGENCY: PID:
SETTING CLASSIFICATION: Rod Mark
The bench mark is located at the junction of the paved access road and the grass
road, 176 feet (54 m) SSW (199 ) from Bench Mark 4341 D 1977, 100 feet (30 m) NE
(19 ) from the NE corner of the yellow house with the cupola atop it, 23.9 feet
(7.3 m) east (80 ) from the corner of the stone fence, and 16.5 feet (5.0 m)
north of the centerline of the asphalt access road. The bench mark is crimped
to the top of a rod driven 10 feet (3.0 m) to refusal encased in PVC pipe and
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 10/30/1985
Station ID: 8454341 SUPERCEDED DATE: 04/21/2003
Name: BOSTON NECK, NARRAGANSETT BAY
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.6' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W
T I D A L D A T U M S
Tidal datums at BOSTON NECK, NARRAGANSETT BAY based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: AUGUST-SEPTEMBER 1977
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8452660 NEWPORT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (10/14/1977) = 5.84
MEAN HIGHER HIGH WATER MHHW = 3.76
MEAN HIGH WATER MHW = 3.50
MEAN TIDE LEVEL MTL = 1.81
MEAN LOW WATER MLW = 0.12
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (08/28/1977) = -0.79
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
4341 B 1977 25.61 22.11
4341 A 1977 20.34 16.84
4341 C 1977 28.63 25.13
4341 D 1977 29.68 26.18
4341 E 1977 36.33 32.83
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 10/30/1985
Station ID: 8454341 SUPERCEDED DATE: 04/21/2003
Name: BOSTON NECK, NARRAGANSETT BAY
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.6' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' 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.