U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8454341 PUBLICATION DATE: 07/12/2004
Name: BOSTON NECK
RI
NOAA Chart: 13223 Latitude: 41° 27.6' N ( 41.46000)
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W ( -71.42830)
To reach the tidal bench marks from the Town of Narragansett Pier, Rhode Island,
proceed north on Scenic Highway 1A, 8 km (5 mi) 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
DESIGNATION: 845 4341 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 2201
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rod mark OPUS PID:
LATITUDE: 41° 27.6' N ( 41.46000) LONGITUDE: 71° 25.7' W ( -71.42830)
The primary bench mark is a disk located at the junction of the grass entrance
road and the cliff line, 21.79 m (71.5 ft) SE (135 magnetic) from bench mark
4341 C 1977, 19.35 m (63.5 ft) NW (300 magnetic) of bench mark 4341 A 1977 and
bears NE (40 magnetic) from the cupola on top of the adjacent yellow house and
west (280 magnetic) of the rock the staff was attached to. The bench mark is
crimped to the top of a rod driven 1.7 m (5.5 ft) to refusal and is encased in
PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8454341 PUBLICATION DATE: 07/12/2004
Name: BOSTON NECK
RI
NOAA Chart: 13223 Latitude: 41° 27.6' N ( 41.46000)
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W ( -71.42830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4341 A 1977
DESIGNATION: 845 4341 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 2200
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Culvert OPUS PID:
LATITUDE: 41° 27.6' N ( 41.46000) LONGITUDE: 71° 25.7' W ( -71.42830)
The bench mark is a disk 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,
61 m (200 ft) east (80 magnetic) of the centerline of the asphalt portion of
the entrance road, 35.20 m (115.5 ft) south (180 magnetic) of the shoreline of
Anchor Bay, 19.35 m (63.5 ft) SE (125 magnetic) of bench mark 4341 B 1977, and
bears ENE (60 magnetic) from the cupola atop the adjacent yellow house.
BENCH MARK STAMPING: 4341 C 1977
DESIGNATION: 845 4341 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 2202
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rod mark OPUS PID:
LATITUDE: 41° 27.6' N ( 41.46000) LONGITUDE: 71° 25.7' W ( -71.42830)
The bench mark is a disk located on the east side of the grass turnaround, 21.79
m ( 71.5 ft) NW (315 magnetic) from bench mark 4341 B 1977, 19 m (62 ft) SE
(131 magnetic) from bench mark 4341 D 1977, and bears NNE (25 magnetic) from
the cupola on top of the adjacent yellow house. The bench mark is crimped to
the top of a rod driven 2.4 m (8 ft) to refusal, and is encased in PVC pipe and
concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8454341 PUBLICATION DATE: 07/12/2004
Name: BOSTON NECK
RI
NOAA Chart: 13223 Latitude: 41° 27.6' N ( 41.46000)
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W ( -71.42830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4341 D 1977
DESIGNATION: 845 4341 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 2203
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rod mark OPUS PID:
LATITUDE: 41° 27.6' N ( 41.46000) LONGITUDE: 71° 25.7' W ( -71.42830)
The bench mark is a disk located on the north side of the grass turnaround, 54 m
(176 ft) NNE (17 magnetic) from bench mark 4341 E 1977, 19 m (62 ft) NW (312
magnetic) from bench mark 4341 C 1977, and bears NNE (18 magnetic) from the
cupola on top of the adjacent yellow house. The bench mark is crimped to the
top of a rod driven 2.4 m (8 ft) to refusal, encased in a PVC pipe and concrete
kickblock.
BENCH MARK STAMPING: 4341 E 1977
DESIGNATION: 845 4341 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 2204
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Rod mark OPUS PID:
LATITUDE: 41° 27.6' N ( 41.46000) LONGITUDE: 71° 25.7' W ( -71.42830)
The bench mark is a disk located at the junction of the paved access road and
the grass road, 54 m (176 ft) SSW (199 magnetic) from bench mark 4341 D 1977,
30 m (100 ft) NE (19 magnetic) from the NE corner of the yellow house with the
cupola on top of it, 7.28 m (23.9 ft) east (80 magnetic) from the corner of the
stone fence, and 5.03 m (16.5 ft) north of the centerline of the asphalt access
road. The bench mark is crimped to the top of a rod driven 3.0 m (10 ft) 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
Station ID: 8454341 PUBLICATION DATE: 07/12/2004
Name: BOSTON NECK
RI
NOAA Chart: 13223 Latitude: 41° 27.6' N ( 41.46000)
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W ( -71.42830)
T I D A L D A T U M S
Tidal datums at BOSTON NECK based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: August 1977 - September 1977
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 = 1.127
MEAN HIGH WATER MHW = 1.050
MEAN TIDE LEVEL MTL = 0.544
MEAN SEA LEVEL MSL = 0.502
MEAN LOW WATER MLW = 0.038
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4341 B 1977 7.739 6.689
4341 A 1977 6.135 5.085
4341 C 1977 8.660 7.610
4341 D 1977 8.981 7.931
4341 E 1977 11.005 9.955
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8454341 PUBLICATION DATE: 07/12/2004
Name: BOSTON NECK
RI
NOAA Chart: 13223 Latitude: 41° 27.6' N ( 41.46000)
USGS Quad: NARRAGANSETT PIER Longitude: 71° 25.7' W ( -71.42830)
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.