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National Ocean Service
Datums Page Page 1 of 5
Station ID: 8451552 PUBLICATION DATE: 06/28/2004
Name: BRISTOL FERRY
RI
NOAA Chart: 13221 Latitude: 41° 38.2' N ( 41.63670)
USGS Quad: BRISTOL Longitude: 71° 15.3' W ( -71.25500)
To reach the tidal bench marks from the Newport Bridge in Rhode Island, proceed
north on State Route 114, 16 km (10 mi) to the Mount Hope Bridge. The bench
marks are located in the concrete seawall of the Mount Hope Marina, which is
located at the SE end of the Mount Hope Bridge. The tide gage and staff were
located on a small pier on the west side of the Marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1552 D 1977
DESIGNATION: 845 1552 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 2151
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete seawall OPUS PID:
LATITUDE: 41° 38.2' N ( 41.63670) LONGITUDE: 71° 15.3' W ( -71.25500)
The primary bench mark is a disk set flush in a concrete seawall which is
located on the SW side of the Mount Hope Marina House, 27 m (89 ft) south (188
magnetic) of bench mark 1552 B 1977, 21 m (70 ft) SW (236 magnetic) of the
flagpole, and 17 m (55 ft) SSE (146 magnetic) of bench mark 1552 C 1977.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8451552 PUBLICATION DATE: 06/28/2004
Name: BRISTOL FERRY
RI
NOAA Chart: 13221 Latitude: 41° 38.2' N ( 41.63670)
USGS Quad: BRISTOL Longitude: 71° 15.3' W ( -71.25500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: H 27 1969
DESIGNATION: H 27
MONUMENTATION: Bench Mark disk VM#: 2148
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#: LW0571
SETTING CLASSIFICATION: Concrete seawall OPUS PID:
LATITUDE: 41° 38.3' N ( 41.63830) LONGITUDE: 71° 15.2' W ( -71.25330)
The bench mark is a disk set flush in the top of a concrete seawall that runs
east and west, directly adjacent to the parking lot for the Mount Hope Marina
House, 45 m (150 ft) from the SE corner of the Mount Hope Marina House, 17 m (56
ft) south (175 magnetic) of the shoreline, 15 m (49 ft) east (87 magnetic) of
bench mark 1552 E 1977, and 0.9 m (3 ft) NNW (324 magnetic) of power pole
#P-1C.
BENCH MARK STAMPING: 1552 B 1977
DESIGNATION: 845 1552 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 2149
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete seawall OPUS PID:
LATITUDE: 41° 38.2' N ( 41.63670) LONGITUDE: 71° 15.3' W ( -71.25500)
The bench mark is a disk set flush in the top of a concrete seawall located
north of the Mount Hope Marina House, 27 m (89 ft) north (0 magnetic) of bench
mark 1552 D 1977, 19 m (61 ft) NNE (30 magnetic) of bench mark 1552 C 1977, and
3 m (9 ft) north of the NW corner of the Mount Hope Marina House.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8451552 PUBLICATION DATE: 06/28/2004
Name: BRISTOL FERRY
RI
NOAA Chart: 13221 Latitude: 41° 38.2' N ( 41.63670)
USGS Quad: BRISTOL Longitude: 71° 15.3' W ( -71.25500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1552 C 1977
DESIGNATION: 845 1552 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 2150
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete seawall OPUS PID:
LATITUDE: 41° 38.2' N ( 41.63670) LONGITUDE: 71° 15.3' W ( -71.25500)
The bench mark is a disk set flush in top of the NW corner of a concrete seawall
located on the west side of the Mount Hope Marina House, 27 m (90 ft) west (270
magnetic) of the flag pole, 19 m (61 ft) SW (230 magnetic) of bench mark 1552 B
1977, and 17 m (55 ft) NNW (326 magnetic) of bench mark 1552 D 1977.
BENCH MARK STAMPING: 1552 E 1977
DESIGNATION: 845 1552 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 2152
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete seawall OPUS PID:
LATITUDE: 41° 38.2' N ( 41.63670) LONGITUDE: 71° 15.3' W ( -71.25500)
The bench mark is a disk set flush in top of a concrete seawall running east and
west located adjacent to the parking lot for the Mount Hope Marina House, 30 m
(100 ft) SE (128 magnetic) of the SE corner of the Mount Hope Marina House, and
15 m (49 ft) west (267 magnetic) of bench mark H 27 1969.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8451552 PUBLICATION DATE: 06/28/2004
Name: BRISTOL FERRY
RI
NOAA Chart: 13221 Latitude: 41° 38.2' N ( 41.63670)
USGS Quad: BRISTOL Longitude: 71° 15.3' W ( -71.25500)
T I D A L D A T U M S
Tidal datums at BRISTOL FERRY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: October 1977
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8454000 PROVIDENCE, PROVIDENCE RIVER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.368
MEAN HIGH WATER MHW = 1.292
MEAN TIDE LEVEL MTL = 0.671
MEAN SEA LEVEL MSL = 0.616
MEAN LOW WATER MLW = 0.050
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
1552 D 1977 2.497 1.205
H 27 1969 3.281 1.989
1552 B 1977 3.182 1.890
1552 C 1977 3.185 1.893
1552 E 1977 3.265 1.973
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8451552 PUBLICATION DATE: 06/28/2004
Name: BRISTOL FERRY
RI
NOAA Chart: 13221 Latitude: 41° 38.2' N ( 41.63670)
USGS Quad: BRISTOL Longitude: 71° 15.3' W ( -71.25500)
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.