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National Ocean Service
Datums Page Page 1 of 5
Station ID: 9462948 PUBLICATION DATE: 12/30/2014
Name: NEUMANS COVE, UNIMAK ISLAND
AK
NOAA Chart: 16535 Latitude: 54° 58.0' N ( 54.96670)
USGS Quad: FALSE PASS D-5 Longitude: 163° 26.4' W (-163.44000)
To reach the tidal bench marks by boat from the False Pass small boat harbor,
travel north 11.2 km (6.0 nm) to a small creek south of Rocky Point on the west
side of Bechevin Bay. The bench marks are located on the beach and a small hill
between the two creeks entering Neumans Cove. The orifices for the tide gauges
were located offshore 100 m (328 ft) NE of ruins remaining from Art Newman s
Cabin.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3 1924
DESIGNATION: 9462948 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 21166
AGENCY: US Coast and Geodetic Survey IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 54° 57.8' N ( 54.96394) LONGITUDE: 163° 26.4' W (-163.44006)
The primary bench mark is a disk set in the top of a boulder 2.5 m x 2.5 m x 2.5
m (8 ft x 8 ft x 8 ft), 100 m (328 ft) SE of SE corner of remains of Neuman s
cabin, 58 m (190 ft) SE of the area on the S bank of the nearest creek where the
grass bank transitions to the gravel beach, and 13 m (43 ft) SW of the bluff.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9462948 PUBLICATION DATE: 12/30/2014
Name: NEUMANS COVE, UNIMAK ISLAND
AK
NOAA Chart: 16535 Latitude: 54° 58.0' N ( 54.96670)
USGS Quad: FALSE PASS D-5 Longitude: 163° 26.4' W (-163.44000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2 1924
DESIGNATION: 9462948 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 21167
AGENCY: US Coast and Geodetic Survey IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 54° 57.9' N ( 54.96492) LONGITUDE: 163° 26.5' W (-163.44161)
The bench mark is a disk set in the top of a small boulder half buried in the
bluff, 38.9 m (127.6 ft) sloped distance NNW of the NE corner of the remains of
Neuman s cabin, 21 m (68 ft) NNW of the area on the N bank of nearest creek
where the grass bank transitions to the gravel beach.
BENCH MARK STAMPING: 1 1924
DESIGNATION: 9462948 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 21168
AGENCY: US Coast and Geodetic Survey IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 54° 57.9' N ( 54.96492) LONGITUDE: 163° 26.5' W (-163.44144)
The bench mark is a disk set in the top of a boulder 1 m x 1 m x 1 m (3 ft x 3
ft x 3 ft), 34.9 m (114.5 ft) NNW of the NE corner of the remains of Neuman s
cabin, 16 m (53 ft) NNW of the are on the N bank of the nearest creek where the
grass bank transitions to the gravel beach.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9462948 PUBLICATION DATE: 12/30/2014
Name: NEUMANS COVE, UNIMAK ISLAND
AK
NOAA Chart: 16535 Latitude: 54° 58.0' N ( 54.96670)
USGS Quad: FALSE PASS D-5 Longitude: 163° 26.4' W (-163.44000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2948 B 2014
DESIGNATION: 946 2948 B
MONUMENTATION: Tidal Station disk VM#: 21169
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 54° 57.8' N ( 54.96333) LONGITUDE: 163° 26.4' W (-163.43925)
The bench mark is a disk set in the top of a 1 m x 2 m x 1 m high (3 ft x 7 ft x
3 ft high) W of three boulders parallel to the beach and S of the S creek, 22.3
m (73.2 ft) WNW of the 1 m (3 ft) high middle boulder and 12 m (40.3 ft) NNE of
the bluff.
BENCH MARK STAMPING: 2948 A 2014
DESIGNATION: 946 2948 A
MONUMENTATION: Metal Rod VM#: 21170
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBDN09
LATITUDE: 54° 57.9' N ( 54.96472) LONGITUDE: 163° 26.4' W (-163.44031)
The bench mark is a stainless steel rod set on top of a bluff between two
creeks, 73 m (239 ft) S of willows in the ravine for the N most creek, 57 m (187
ft) SW of a 90-degree bend in the northerly most creek, and 15 m (49 ft) NNW of
the breakline in the slope of the bluff. The datum point is set 13 cm (0.4 ft)
below grade, being the top of a stainless steel rod driven 14.7 m (48 ft) to
refusal, in a sleeve extending to a depth of 0.9 m (3 ft) and encased in a
5-inch (NOS) logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9462948 PUBLICATION DATE: 12/30/2014
Name: NEUMANS COVE, UNIMAK ISLAND
AK
NOAA Chart: 16535 Latitude: 54° 58.0' N ( 54.96670)
USGS Quad: FALSE PASS D-5 Longitude: 163° 26.4' W (-163.44000)
T I D A L D A T U M S
Tidal datums at NEUMANS COVE, UNIMAK ISLAND based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: June 2014 - August 2014
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9462620 UNALASKA, DUTCH HARBOR
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.309
MEAN HIGH WATER MHW = 1.233
MEAN TIDE LEVEL MTL = 0.794
MEAN SEA LEVEL MSL = 0.787
MEAN LOW WATER MLW = 0.354
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3 1924 2.640 1.407
2 1924 4.684 3.451
1 1924 2.726 1.493
2948 B 2014 1.616 0.383
2948 A 2014 14.509 13.276
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9462948 PUBLICATION DATE: 12/30/2014
Name: NEUMANS COVE, UNIMAK ISLAND
AK
NOAA Chart: 16535 Latitude: 54° 58.0' N ( 54.96670)
USGS Quad: FALSE PASS D-5 Longitude: 163° 26.4' W (-163.44000)
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.