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Bench Mark Sheet for 8450768, SAKONNET RI

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8450768                         PUBLICATION DATE:  05/20/2004
Name:       SAKONNET                                          
            RI
NOAA Chart: 13221                           Latitude:   41° 27.9' N (  41.46500)
USGS Quad:  SAKONNET POINT                  Longitude:  71° 11.6' W ( -71.19330)


To reach the tidal bench marks from the intersection of Rhode Island Highway 24
and State Road 77 in Tiverton, proceed south on State Road 77 for 16 km (10 mi)
to Sakonnet Point Road, then turn right and proceed west on Sakonnet Point Road
and travel to the Sakonnet Yacht Club, located on the west side of Sakonnet
Point Road.  The bench marks are in the vicinity of the Yacht Club.  The tide
gage and staff were located on the west end of the Yacht Club Pier.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  NO 1 1957
                         DESIGNATION:          845 0768 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         2118
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:  LW0620
SETTING CLASSIFICATION:  Mass of bedrock                       OPUS PID:        
LATITUDE:   41° 27.8' N (  41.46330)          LONGITUDE:  71° 11.7' W ( -71.19500)


The primary bench mark is a disk set on the SW slope of a large mass of bedrock
which extends out into the Sakonnet River, located at the Sakonnet Yacht Club,
35 m (115 ft) north of the north side of the Sakonnet Yacht Club Building, 32 m
(104 ft) west of and across the road from power pole #430, 24.54 m (80.5 ft)
west of the centerline of Route 77, 15 m (49 ft) NW of the north end of a long
sea wall, 6 m (20 ft) NE of the SW end of a rock, 3 m (10 ft) east of the
shoreline, and set 0.91 m (3.0 ft) below level of the Highway.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8450768                         PUBLICATION DATE:  05/20/2004
Name:       SAKONNET                                          
            RI
NOAA Chart: 13221                           Latitude:   41° 27.9' N (  41.46500)
USGS Quad:  SAKONNET POINT                  Longitude:  71° 11.6' W ( -71.19330)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  NO 2 1957
                         DESIGNATION:          845 0768 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         2119
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:  LW0622
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   41° 27.8' N (  41.46330)          LONGITUDE:  71° 11.7' W ( -71.19500)


The bench mark is a disk set flush in top of a 0.46 m (1.5 ft) wide concrete sea
wall at the Sakonnet Yacht Club, 101 m (330 ft) south of the south side of the
Sakonnet Yacht Club Building, 16.31 m (53.5 ft) SW of and across the road from
power pole #433, 7 m (23 ft) west of the centerline of Route 77, 6.25 m (20.5
ft) north of south end of the sea wall, and set 0.61 m (2.0 ft) above ground
level.



                         BENCH MARK STAMPING:  NO 3 1957
                         DESIGNATION:          845 0768 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         2120
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:  LW0624
SETTING CLASSIFICATION:  Mass of bedrock                       OPUS PID:        
LATITUDE:   41° 27.8' N (  41.46330)          LONGITUDE:  71° 11.4' W ( -71.19000)


The bench mark is a disk set on the top of the highest part of a large mass of
bedrock which is visible from the Yacht Club Building projecting 3 m (10 ft)
above ground level, in the vicinity of the Sakonnet Yacht Club, 0.2 km (0.1 mi)
east of the Sakonnet Yacht Club Building, 18.44 m (60.5 ft) south of power pole
#1679, 17 m (57 ft) north of the north side of a small building, and about 5 m
(15 ft) above the level of the highway.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8450768                         PUBLICATION DATE:  05/20/2004
Name:       SAKONNET                                          
            RI
NOAA Chart: 13221                           Latitude:   41° 27.9' N (  41.46500)
USGS Quad:  SAKONNET POINT                  Longitude:  71° 11.6' W ( -71.19330)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  0768 D 1977
                         DESIGNATION:          845 0768 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         2121
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   41° 27.9' N (  41.46500)          LONGITUDE:  71° 11.6' W ( -71.19330)


The bench mark is a disk set flush in top of a 0.46 m (1.5 ft) wide concrete sea
wall south of the Sakonnet Yacht Club, 43 m (140 ft) SE (230  magnetic) of bench
mark 0768 E 1977, and 36 m (117 ft) NNE (20  magnetic) of bench mark N0 2 1957.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8450768                         PUBLICATION DATE:  05/20/2004
Name:       SAKONNET                                          
            RI
NOAA Chart: 13221                           Latitude:   41° 27.9' N (  41.46500)
USGS Quad:  SAKONNET POINT                  Longitude:  71° 11.6' W ( -71.19330)


                            T I D A L   D A T U M S 


Tidal datums at SAKONNET based on:

     LENGTH OF SERIES:      7 MONTHS
     TIME PERIOD:           April 1992 - October 1992
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8452660 NEWPORT, NARRAGANSETT BAY


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     HIGHEST OBSERVED WATER LEVEL (09/21/1938)         =
     MEAN HIGHER HIGH WATER                     MHHW   =  1.082
     MEAN HIGH WATER                            MHW    =  1.003
     North American Vertical Datum              NAVD88 =  0.595
     MEAN TIDE LEVEL                            MTL    =  0.519
     MEAN SEA LEVEL                             MSL    =  0.489
     MEAN LOW WATER                             MLW    =  0.036
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (02/03/1976)         =

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1957                                   2.422    1.419
     NO 2 1957                                   2.632    1.629
     NO 3 1957                                   5.456    4.453
     0768 D 1977                                 2.757    1.754


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 8450768                         PUBLICATION DATE:  05/20/2004
Name:       SAKONNET                                          
            RI
NOAA Chart: 13221                           Latitude:   41° 27.9' N (  41.46500)
USGS Quad:  SAKONNET POINT                  Longitude:  71° 11.6' W ( -71.19330)


                             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.

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Products available at 8450768 SAKONNET, RI

Revised: 08/08/2018
NOAA / National Ocean Service
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