U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 05/12/1988
Station ID: 8455083 SUPERCEDED DATE: 04/21/2003
Name: POINT JUDITH, HARBOR OF REFUGE
RHODE ISLAND
NOAA Chart: 13219 Latitude: 41° 21.8' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 29.4' W
To reach the tidal bench marks from the intersection of State Highway 108 and
Ocean Road in Point Judith, proceed 0.5 mile (0.8 km) south on Ocean Road, then
bear right at a turn in the road and continue to the entrance of Breakwater
Village, then turn left on a dirt drive after passing through the entrance gate
and continue down the hill, through the trailer park, to the small boat basin.
The bench marks are located in the vicinity of the boat basin and the eastern
breakwater of the Harbor of Refuge. The tide gage is located at the SW corner
of a breakwater on the east side of the small boat basin. The tide staff is
located on a cluster of pilings just inside the mouth of the basin on the east
side.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5083 D 1987
MONUMENTATION: Survey Disk VM#: 2212
AGENCY: PID:
SETTING CLASSIFICATION: Granite Boulder
The bench mark is set in a large granite boulder on the south side of a small
boat basin at Breakwater Village, 124 feet (38 m) WNW of power pole #4584, 41
feet (12 m) WSW of a three pile cluster at the SE corner of the boat basin, 2.8
feet (0.9 m) east of the east edge of a wooden walkway leading to a floating
dock, and 0.7 foot (0.2 m) above the walkway.
BENCH MARK STAMPING: NO 7 1948
MONUMENTATION: Survey Disk VM#: 2210
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Headwall
The bench mark is set in the south end of a 6 foot (2 m) long concrete headwall
on the west side of an abandoned gun emplacement which is located between the
Point Judith Coast Guard Station and the eastern breakwater of the Harbor of
Refuge, 128 feet (39 m) east of the center of a large rock on the beach, 101
feet (31 m) NW of the center of a concrete manhole structure on the beach, 0.4
foot (0.1 m) north of the south end of the headwall, and 2.0 feet (0.6 m) above
ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 05/12/1988
Station ID: 8455083 SUPERCEDED DATE: 04/21/2003
Name: POINT JUDITH, HARBOR OF REFUGE
RHODE ISLAND
NOAA Chart: 13219 Latitude: 41° 21.8' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 29.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 8 1948
MONUMENTATION: Survey Disk VM#: 2211
AGENCY: PID:
SETTING CLASSIFICATION: Granite Boulder
The bench mark is set in a large granite boulder on the eastern breakwater of
the Harbor of Refuge, one-third the length of the breakwater from its shoreward
end, 40 feet (12 m) NNW of the east edge of the breakwater, 13 feet (4 m) SSE of
the west edge of the breakwater, and about level with the top of the breakwater.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 05/12/1988
Station ID: 8455083 SUPERCEDED DATE: 04/21/2003
Name: POINT JUDITH, HARBOR OF REFUGE
RHODE ISLAND
NOAA Chart: 13219 Latitude: 41° 21.8' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 29.4' W
T I D A L D A T U M S
Tidal datums at POINT JUDITH, HARBOR OF REFUGE based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: AUGUST-OCTOBER 1987
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 (11/05/1987) = 4.76
MEAN HIGHER HIGH WATER MHHW = 3.44
MEAN HIGH WATER MHW = 3.18
MEAN TIDE LEVEL MTL = 1.65
MEAN LOW WATER MLW = 0.13
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (11/04/1987) = -1.06
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
5083 D 1987 6.88 3.70
NO 7 1948 17.54 14.36
NO 8 1948 9.67 6.49
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 05/12/1988
Station ID: 8455083 SUPERCEDED DATE: 04/21/2003
Name: POINT JUDITH, HARBOR OF REFUGE
RHODE ISLAND
NOAA Chart: 13219 Latitude: 41° 21.8' N
USGS Quad: NARRAGANSETT PIER Longitude: 71° 29.4' 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.