Bench Mark Sheet for 8452944, Conimicut Light 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Superseded Epoch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Small blue map location marker Unpublished bench mark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  4

                                                                                
Station ID: 8452944                         PUBLICATION DATE:  01/14/2013
Name:       CONIMICUT LIGHT, NARRAGANSETT BAY                 
            RI
NOAA Chart: 13221                           Latitude:   41° 43.0' N (  41.71670)
USGS Quad:  BRISTOL                         Longitude:  71° 20.6' W ( -71.34330)


To reach the Conimicut Light tidal station head north in boat towards
providence, RI, lighthouse is just south of the city in the Narragansett Bay.


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


                 PRIMARY BENCH MARK STAMPING:   
                         DESIGNATION:          845 2944 BOLT
                         ALIAS:                BOLT

MONUMENTATION:           Bolt                                  VM#:        16300
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Steel bolt                            OPUS PID:        
LATITUDE:   41° 43.0' N (  41.71697)          LONGITUDE:  71° 20.7' W ( -71.34508)


The primary bench mark is a steel bolt with a chiseled X in the top of it,
located on the south side of the lighthouse in the third handrail pole from the
catwalk, 4.22 m (13.8 ft) south of the south side of handrail, 1.22 m (4.0 ft)
SE of the side of the lighthouse, and 0.05 m (0.2 ft) NE of the bottom outer
steel bulkhead around the lighthouse.



                         BENCH MARK STAMPING:   
                         DESIGNATION:          845 2944 SRM

MONUMENTATION:           Chiseled Square                       VM#:        16017
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Metal pier I-beam                     OPUS PID:        
LATITUDE:   41° 43.0' N (  41.71708)          LONGITUDE:  71° 20.7' W ( -71.34511)


The bench mark is a chiseled square at the NW corner of the catwalk to the
lighthouse, 7.65 m (25.1 ft) north of the north side of the lighthouse base,
1.80 m (5.9 ft) NW of the 4" protective well, and 1.45 m (4.8 ft) NNW of the SE
corner of the walkway.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                                                
Station ID: 8452944                         PUBLICATION DATE:  01/14/2013
Name:       CONIMICUT LIGHT, NARRAGANSETT BAY                 
            RI
NOAA Chart: 13221                           Latitude:   41° 43.0' N (  41.71670)
USGS Quad:  BRISTOL                         Longitude:  71° 20.6' W ( -71.34330)


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


                         BENCH MARK STAMPING:  2944 A 2004
                         DESIGNATION:          845 2944 A

MONUMENTATION:           Tidal Station disk                    VM#:        17662
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Lighthouse foundation                 OPUS PID:        
LATITUDE:   41° 43.0' N (  41.71697)          LONGITUDE:  71° 20.7' W ( -71.34511)


The bench mark is a disk set in the concrete walkway around the lighthouse near
the top of the stairs, 7.95 m (26.1 ft) south of the north end of the catwalk
leading to the lighthouse, 4.03 m (13.2 ft) NNE of the center of the door
leading into the lighthouse, and 0.98 m (3.2 ft) north of the lighthouse wall.



                         BENCH MARK STAMPING:  2944 B 2004
                         DESIGNATION:          845 2944 B

MONUMENTATION:           Tidal Station disk                    VM#:        17663
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete walkway                      OPUS PID:        
LATITUDE:   41° 43.0' N (  41.71694)          LONGITUDE:  71° 20.7' W ( -71.34508)


The bench mark is a disk set in the concrete walkway around the lighthouse, 1.80
m (5.9 ft) SSW of the center of the three solar panels mounted on the handrail,
0.79 m (2.6 ft) ESE of the lighthouse wall, and 0.50 m (1.6 ft) WNW of the outer
edge of the lighthouse base.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                                                
Station ID: 8452944                         PUBLICATION DATE:  01/14/2013
Name:       CONIMICUT LIGHT, NARRAGANSETT BAY                 
            RI
NOAA Chart: 13221                           Latitude:   41° 43.0' N (  41.71670)
USGS Quad:  BRISTOL                         Longitude:  71° 20.6' W ( -71.34330)


                            T I D A L   D A T U M S 


Tidal datums at CONIMICUT LIGHT, NARRAGANSETT BAY based on:

     LENGTH OF SERIES:      10 YEARS
     TIME PERIOD:           August 2001 - July 2009 & June 2010 - May 2012
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8454000 PROVIDENCE, PROVIDENCE RIVER


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

     HIGHEST OBSERVED WATER LEVEL (10/29/2012)         =  2.743
     MEAN HIGHER HIGH WATER                     MHHW   =  1.398
     MEAN HIGH WATER                            MHW    =  1.322
     MEAN TIDE LEVEL                            MTL    =  0.687
     MEAN SEA LEVEL                             MSL    =  0.642
     MEAN LOW WATER                             MLW    =  0.051
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (02/11/2001)         = -0.851

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     845 2944 BOLT                               4.882    3.560
     845 2944 SRM                                3.107    1.785
     2944 A 2004                                 4.883    3.561
     2944 B 2004                                 4.892    3.570


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

                                                                                
Station ID: 8452944                         PUBLICATION DATE:  01/14/2013
Name:       CONIMICUT LIGHT, NARRAGANSETT BAY                 
            RI
NOAA Chart: 13221                           Latitude:   41° 43.0' N (  41.71670)
USGS Quad:  BRISTOL                         Longitude:  71° 20.6' W ( -71.34330)


                             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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