U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 10/17/1985
Station ID: 8453999 SUPERCEDED DATE: 04/21/2003
Name: BEAVERTAIL POINT, CONANICUT ISLAND,NARRAGANSETT BA
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.1' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 24.1' W
To reach the tidal bench marks from Newport, Rhode Island, travel west across
the Newport Bridge (toll) to Conanicut Island, go south on State Road 138 and
the road becomes Beavertail Road, follow Beavertail Road south to Beavertail
Point at the extreme southern end of the Island, at the Point take the last
turnoff on the right to a dirt road, 600 feet (183 m) north of the light at the
Point. On the dirt road take the first left fork and continue down to a small
parking area overlooking the tide station site. The bench marks are set in rock
at the base of a small cliff. The tide gage was mounted on top of the drop off
and the orifice and tubing extended offshore. The tide staff was bolted to
bedrock west of Bench Mark 3999 A 1977.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3999 A 1977
MONUMENTATION: Survey Disk VM#: 2195
AGENCY: PID:
SETTING CLASSIFICATION: Rock Outcrop
The bench mark is set flush in concrete in a large rock outcrop NW of Beavertail
Point, 30 feet (9 m) east of the shoreline, 18.5 feet (5.6 m) west of a 9-foot
(3 m) high rock face, 2 feet (1 m) north of a southern drop off and bears NNW
(340 ) from Beavertail Light.
BENCH MARK STAMPING: 3999 B 1977
MONUMENTATION: Survey Disk VM#: 2196
AGENCY: PID:
SETTING CLASSIFICATION: Rock Outcrop
The bench mark is set flush in concrete in a large rock outcrop NW of Beavertail
Point, 45 feet (14 m) south of a ravine leading to the beach, 41 feet (12 m)
west of the vegetation line, 16 feet (5 m) east from a drop off to a small
gravel beach and bears NNW (344 ) of Beavertail Light.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 10/17/1985
Station ID: 8453999 SUPERCEDED DATE: 04/21/2003
Name: BEAVERTAIL POINT, CONANICUT ISLAND,NARRAGANSETT BA
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.1' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 24.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3999 C 1977
MONUMENTATION: Survey Disk VM#: 2197
AGENCY: PID:
SETTING CLASSIFICATION: Rock Outcrop
The bench mark is set flush in concrete in a large rock outcrop NW of Beavertail
Point, 50 feet (15 m) west from a dirt foot path west of a vegetation line, 6
feet (2 m) north of a drop off to the beach, 3 feet (1 m) south of a steep drop
off and bears NNW (329 ) of Beavertail Light.
BENCH MARK STAMPING: 3999 D 1977
MONUMENTATION: Survey Disk VM#: 2198
AGENCY: PID:
SETTING CLASSIFICATION: Rock Outcrop
The bench mark is set flush in concrete in a large rock outcrop NW of Beavertail
Point, 45 feet (14 m) east from the western shoreline, 36 feet (11 m) west of
the vegetation line, 15 feet (5 m) north of a steep drop off to the beach, 8
feet (2 m) south from a 2-foot (1 m) drop off, and bears NNW (341 ) of
Beavertail Light.
BENCH MARK STAMPING: 3999 E 1977
MONUMENTATION: Survey Disk VM#: 2199
AGENCY: PID:
SETTING CLASSIFICATION: Rock Outcrop
The bench mark is set flush in concrete in a large rock outcrop NW of Beavertail
Point, 32 feet (10 m) west of the drop off to the beach, 29 feet (9 m) south of
a rock ravine, 21 feet (6 m) west of a foot path at the edge of the vegetation
line, and bears NNW (343 ) from Beavertail Light.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 10/17/1985
Station ID: 8453999 SUPERCEDED DATE: 04/21/2003
Name: BEAVERTAIL POINT, CONANICUT ISLAND,NARRAGANSETT BA
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.1' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 24.1' W
T I D A L D A T U M S
Tidal datums at BEAVERTAIL POINT, CONANICUT ISLAND,NARRAGANSETT BA 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 (09/22/1977) = 4.96
MEAN HIGHER HIGH WATER MHHW = 3.85
MEAN HIGH WATER MHW = 3.58
MEAN TIDE LEVEL MTL = 1.88
MEAN LOW WATER MLW = 0.18
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (09/15/1977) = -1.34
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
3999 A 1977 9.22 5.64
3999 B 1977 12.56 8.98
3999 C 1977 20.68 17.10
3999 D 1977 19.91 16.33
3999 E 1977 14.34 10.76
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 10/17/1985
Station ID: 8453999 SUPERCEDED DATE: 04/21/2003
Name: BEAVERTAIL POINT, CONANICUT ISLAND,NARRAGANSETT BA
RHODE ISLAND
NOAA Chart: 13223 Latitude: 41° 27.1' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 24.1' 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.