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Bench Mark Sheet for 9457407, Nachalni Island 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 9457407                         PUBLICATION DATE:  09/05/2014
Name:       NACHALNI ISLAND                                   
            AK
NOAA Chart: 16594                           Latitude:   57° 58.7' N (  57.97830)
USGS Quad:  KODIAK D-3 ALASKA               Longitude: 152° 55.5' W (-152.92500)


To reach the tidal bench marks from Port Lions, AK, by boat, start at the rock
jetty protecting the small boat harbor, and proceed for 6.95 km (3.75 nm)
heading towards the SE corner of Whale Island to 57  54'18.76"N, 152 
45'45.43"W, then proceed through the pass for 13.2 km (7.1 nm) towards the south
end of Raspberry Island, then proceed 1.1 km (.57 nm)  into the small bay
separating Raspberry Island from Nachalni Island. The bench marks are located on
the north side of Nachalni Island, set in bedrock along the beach, shore-side of
the vegetation and tree line. The tide gauge was installed approximately 400 m
(1,320 ft) to the north of the bench marks across the small bay at the obvious
rock outcrop on the beach on the southeast edge of Raspberry Island. The tide
staff was located on Nachalni Island.


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


                 PRIMARY BENCH MARK STAMPING:  BM 2 1941
                         DESIGNATION:          945 7407 BM2

MONUMENTATION:           Survey disk                           VM#:        15208
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Rock ledge                            OPUS PID#: BBDP28
LATITUDE:   57° 58.8' N (  57.97928)          LONGITUDE: 152° 55.6' W (-152.92628)


The primary bench mark is a disk set flush in bedrock, located approximately
380.5 m (1,248.4 ft) SSE from the obvious rock outcropping on the beach across
the small bay, 37.56 m (123.23 ft) NE from bench mark 945 7404 D, and 7.58 m
(24.87 ft) north of the ledge and tree line. 

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

                                                                                
Station ID: 9457407                         PUBLICATION DATE:  09/05/2014
Name:       NACHALNI ISLAND                                   
            AK
NOAA Chart: 16594                           Latitude:   57° 58.7' N (  57.97830)
USGS Quad:  KODIAK D-3 ALASKA               Longitude: 152° 55.5' W (-152.92500)


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


                         BENCH MARK STAMPING:  7407 A 1981
                         DESIGNATION:          945 7407 A

MONUMENTATION:           Tidal Station disk                    VM#:        15210
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Bedrock Outcrop                       OPUS PID:        
LATITUDE:   57° 58.7' N (  57.97911)          LONGITUDE: 152° 55.6' W (-152.92717)


The bench mark is a disk set flush in bedrock, located approximately 395.0 m
(1,296.0 ft) SE from the obvious rock outcrop on the beach across the bay, 19.16
m (62.86 ft) WSW from benchmark 945 7407 D, and 10.94 m (35.89 ft) north of the
ledge and tree line.



                         BENCH MARK STAMPING:  7407 B 1981
                         DESIGNATION:          945 7407 B

MONUMENTATION:           Tidal Station disk                    VM#:        15211
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Bedrock Outcrop                       OPUS PID:        
LATITUDE:   57° 58.7' N (  57.97869)          LONGITUDE: 152° 55.6' W (-152.92747)


The bench mark is a disk set flush in bedrock, located at the obvious ledge
above the beach, just below and under the vegetation and tree line, and 52.73 m
(172.99 ft) NNE from bench mark 945 7407 C. 

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

                                                                                
Station ID: 9457407                         PUBLICATION DATE:  09/05/2014
Name:       NACHALNI ISLAND                                   
            AK
NOAA Chart: 16594                           Latitude:   57° 58.7' N (  57.97830)
USGS Quad:  KODIAK D-3 ALASKA               Longitude: 152° 55.5' W (-152.92500)


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


                         BENCH MARK STAMPING:  7407 C 1981
                         DESIGNATION:          945 7407 C

MONUMENTATION:           Tidal Station disk                    VM#:        15212
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Bedrock Outcrop                       OPUS PID:        
LATITUDE:   57° 58.7' N (  57.97833)          LONGITUDE: 152° 55.7' W (-152.92803)


The bench mark is a disk set flush in a bedrock outcrop, located approximately
487.0 m (1,598.0 ft) SSE from the obvious rock outcrop on the beach across the
bay, 52.73 m (172.99 ft) SSW from bench mark 945 7407 B , and 9.65 m (31.66 ft)
WNW from the vegetation and tree line.



                         BENCH MARK STAMPING:  7407 D 2012
                         DESIGNATION:          945 7407 D

MONUMENTATION:           Tidal Station disk                    VM#:        20584
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Bedrock Outcrop                       OPUS PID:        
LATITUDE:   57° 58.7' N (  57.97908)          LONGITUDE: 152° 55.6' W (-152.92683)


The bench mark is a disk set flush in bedrock, approximately 393.0 m (1,289.0
ft) SE from the obvious rock outcrop on the beach across the bay, 37.56 m
(123.23 ft) SW from bench mark 945 7407 BM 2, 19.16 m (62.86 ft) east from bench
mark 945 7407 A, and 0.54 m (1.77 ft) north from the vegetation.

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

                                                                                
Station ID: 9457407                         PUBLICATION DATE:  09/05/2014
Name:       NACHALNI ISLAND                                   
            AK
NOAA Chart: 16594                           Latitude:   57° 58.7' N (  57.97830)
USGS Quad:  KODIAK D-3 ALASKA               Longitude: 152° 55.5' W (-152.92500)


                            T I D A L   D A T U M S 


Tidal datums at NACHALNI ISLAND based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           June 2014 - June 2014
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9457804 ALITAK,  LAZY BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  4.166
     MEAN HIGH WATER                            MHW    =  3.908
     MEAN TIDE LEVEL                            MTL    =  2.224
     MEAN SEA LEVEL                             MSL    =  2.215
     MEAN LOW WATER                             MLW    =  0.541
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     BM 2 1941                                   3.887   -0.021
     7407 A 1981                                 3.804   -0.104
     7407 B 1981                                 5.109    1.201
     7407 C 1981                                 4.544    0.636
     7407 D 2012                                 5.253    1.345


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

                                                                                
Station ID: 9457407                         PUBLICATION DATE:  09/05/2014
Name:       NACHALNI ISLAND                                   
            AK
NOAA Chart: 16594                           Latitude:   57° 58.7' N (  57.97830)
USGS Quad:  KODIAK D-3 ALASKA               Longitude: 152° 55.5' W (-152.92500)


                             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 9457407 Nachalni Island, AK

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