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Bench Mark Sheet for 9451263, Point Lockwood AK

Superseded Epoch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Small blue map location marker Unpublished bench mark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: 9451263                         PUBLICATION DATE:  11/13/2003
Name:       POINT LOCKWOOD, WRANGELL NARROWS                  
            AK
NOAA Chart: 17375                           Latitude:   56° 33.5' N (  56.55830)
USGS Quad:  PETERSBURG (C-3)                Longitude: 132° 57.8' W (-132.96300)


To reach the tidal bench marks from the Petersburg, Alaska, South Harbor public
boat launch, proceed 16.0 km (8.7 nm) south down Wrangell Narrows past Papke's
Landing state warf, continue 4.6 km (2.5 nm) south past Anchor Point, continue
10.1 km (5.6 nm) south past Beecher Pass . The Point Lockwood tide gauge was
located in a small cove, immediately north of the Point Lockwood beacon.  The
tidal bench marks are located in the rock outcrop on shore. 


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1925
                         DESIGNATION:          945 1263 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:        17234
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   56° 33.5' N (  56.55830)          LONGITUDE: 132° 58.0' W (-132.96700)


The bench mark is a disk set in top of small rock shelf on northerly side of
first rock outcrop, 69 m (225 ft) south of bench mark NO 1 1925, immediately
north of cobble beaches on north side of Point Lockwood, and 3.54 m (11.6 ft) NW
of bench mark 1263 A 2003.

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

                                                                                
Station ID: 9451263                         PUBLICATION DATE:  11/13/2003
Name:       POINT LOCKWOOD, WRANGELL NARROWS                  
            AK
NOAA Chart: 17375                           Latitude:   56° 33.5' N (  56.55830)
USGS Quad:  PETERSBURG (C-3)                Longitude: 132° 57.8' W (-132.96300)


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


                         BENCH MARK STAMPING:  NO 1 1925
                         DESIGNATION:          945 1263 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:        17235
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   56° 33.5' N (  56.55830)          LONGITUDE: 132° 58.0' W (-132.96700)


The bench mark is a disk set in top of boulder, 2 m x 2m x 1 m (5 ft x 5 ft x 3
ft) high which is on shore of first cove north of Point Lockwood, 91 m (300 ft)
south of stream into head of this cove, 69 m (225 ft) north of bench mark NO 2
1925, and 3.14 m (10.3 ft) SW of bench mark NO 3 1929.    



                         BENCH MARK STAMPING:  NO 3 1929
                         DESIGNATION:          945 1263 TIDAL 3

MONUMENTATION:           Reference Mark disk                   VM#:        17236
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:        
SETTING CLASSIFICATION:  Granite boulder                       OPUS PID:        
LATITUDE:   56° 33.5' N (  56.55830)          LONGITUDE: 132° 58.0' W (-132.96700)


The bench mark is a reference mark disk set in well-embedded flat granite
boulder measuring 2 m x 1 m (5 ft x 3 ft), the boulder is in grass, 3.14 m (10.3
ft) NE of bench mark NO 1 1925, and 3 m (10 ft) from tree line.

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

                                                                                
Station ID: 9451263                         PUBLICATION DATE:  11/13/2003
Name:       POINT LOCKWOOD, WRANGELL NARROWS                  
            AK
NOAA Chart: 17375                           Latitude:   56° 33.5' N (  56.55830)
USGS Quad:  PETERSBURG (C-3)                Longitude: 132° 57.8' W (-132.96300)


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


                         BENCH MARK STAMPING:  1263 A 2003
                         DESIGNATION:          945 1263 A

MONUMENTATION:           Tidal Station disk                    VM#:        17237
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock ledge                            OPUS PID:        
LATITUDE:   56° 33.5' N (  56.55830)          LONGITUDE: 132° 58.0' W (-132.96700)


The bench mark is a disk set in small level rock ledge, 3.54 m (11.6 ft) SE of
bench mark NO 2 1925, and 1 m (4 ft) SE of "x" chiseled in rock at apparent high
water line facing Wrangell Narrows immediately NW of cobble beaches on north
side of Point Lockwood.    



                         BENCH MARK STAMPING:  1263 B 2003
                         DESIGNATION:          945 1263 B

MONUMENTATION:           Tidal Station disk                    VM#:        17238
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Schist rock outcrop                   OPUS PID:        
LATITUDE:   56° 33.4' N (  56.55670)          LONGITUDE: 132° 57.9' W (-132.96500)


The bench mark is a disk set in prominent schist bedrock outcrop located at
apparent high water line in the SE corner of the first small cobble beach NW of
the north side of Point Lockwood, and about 1 m (3 ft) above beach level.

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

                                                                                
Station ID: 9451263                         PUBLICATION DATE:  11/13/2003
Name:       POINT LOCKWOOD, WRANGELL NARROWS                  
            AK
NOAA Chart: 17375                           Latitude:   56° 33.5' N (  56.55830)
USGS Quad:  PETERSBURG (C-3)                Longitude: 132° 57.8' W (-132.96300)


                            T I D A L   D A T U M S 


Tidal datums at POINT LOCKWOOD, WRANGELL NARROWS based on:

     LENGTH OF SERIES:      2 MONTHS
     TIME PERIOD:           August 2003 - September 2003
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9450460 KETCHIKAN, TONGASS NARROWS


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

     MEAN HIGHER HIGH WATER                     MHHW   =  4.599
     MEAN HIGH WATER                            MHW    =  4.330
     MEAN TIDE LEVEL                            MTL    =  2.400
     MEAN SEA LEVEL                             MSL    =  2.355
     MEAN LOW WATER                             MLW    =  0.469
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1925                                   5.146    0.815
     NO 1 1925                                   5.219    0.889
     NO 3 1929                                   5.132    0.802
     1263 A 2003                                 4.254   -0.076
     1263 B 2003                                 5.310    0.980


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

                                                                                
Station ID: 9451263                         PUBLICATION DATE:  11/13/2003
Name:       POINT LOCKWOOD, WRANGELL NARROWS                  
            AK
NOAA Chart: 17375                           Latitude:   56° 33.5' N (  56.55830)
USGS Quad:  PETERSBURG (C-3)                Longitude: 132° 57.8' W (-132.96300)


                             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 9451263 Point Lockwood, AK

Revised: 10/15/2013
NOAA / National Ocean Service
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