U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9462711 PUBLICATION DATE: 12/20/2011
Name: SURF BAY, AKUTAN BAY
AK
NOAA Chart: 16531 Latitude: 54° 9.0' N ( 54.15083)
USGS Quad: UNIMAK (A-5) Longitude: 165° 36.9' W (-165.61500)
To reach the bench marks from the Dutch Harbor City Dock, proceed NNE 14.0 km
(8.7 mi) to Priest Rock, then proceed east for 33.6 km (20.9 mi) crossing Akutan
Pass to Battery Point on the southern point of Akutan Island, then proceed 16.5
km (10.2 mi) ENE thru Avatanak Strait, then proceed 12.1 km (7.5 mi) north thru
Akun Strait passing Swirl Rock, then proceed 1.8 km (1.1 mi) east to Surf Bay
and the northern most rock outcrop at the southern end of the long sand beach.
The tide house is 160 m (524 ft) to the south at the second large rock outcrop
enclosing a small lagoon. The bench marks are located on and between the two
rock outcrops.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2711 A 2011
DESIGNATION: 946 2711 A
MONUMENTATION: Tidal Station disk VM#: 20173
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID#: BBCL54
LATITUDE: 54° 9.0' N ( 54.14958) LONGITUDE: 165° 37.0' W (-165.61619)
The primary bench mark is a disk set on the north side of a bedrock outcrop
enclosing a small lagoon at the south end of the sand beach in Surf Bay, 19.37 m
(63.5 ft) SE from the high point at the end of the second rock outcrop, 13.30 m
(43.6 ft) slope NW of the high point and the beginning of vegetation on the rock
outcrop, 4.70 m (15.4 ft) SSW of the high water line on the north side of the
outcrop, and 4.11 m (13.5 ft) NNE of the high water line on the SW side of the
outcrop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9462711 PUBLICATION DATE: 12/20/2011
Name: SURF BAY, AKUTAN BAY
AK
NOAA Chart: 16531 Latitude: 54° 9.0' N ( 54.15083)
USGS Quad: UNIMAK (A-5) Longitude: 165° 36.9' W (-165.61500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2711 B 2011
DESIGNATION: 946 2711 B
MONUMENTATION: Tidal Station disk VM#: 20174
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Set in rock outcrop OPUS PID:
LATITUDE: 54° 9.0' N ( 54.14925) LONGITUDE: 165° 36.9' W (-165.61522)
The bench mark is a disk set in a conglomerate rock outcrop near the south end
of a sand beach, 52.06 m (170.8 ft) SW from bench mark 946 2711 C, 9.37 m (30.7
ft) NW of the vegetation line at the base of a sand bluff, 3.97 m (13.0 ft) NNE
from the face of the cliff at the base of the rock outcrop, and 1.10 m (3.6 ft)
above the sand beach.
BENCH MARK STAMPING: 2711 C 2011
DESIGNATION: 946 2711 C
MONUMENTATION: Tidal Station disk VM#: 20175
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 54° 9.0' N ( 54.14958) LONGITUDE: 165° 36.9' W (-165.61467)
The bench mark is a disk set flush in a rock outcrop near the high water line
near the south end of a sand beach, 52.06 m (170.8 ft) NE of bench mark 946 2711
B, 24.80 m (81.4 ft) SW of a 5 m (16 ft) high rock face, 6.12 m (20.1 ft) south
of the south end of the larger rock outcrop to the north, 1.95 m (6.4 ft) north
of the south end of the rock outcrop, 0.77 m (2.5 ft) east of the west end of
the rock outcrop, and 1.24 m (4.1 ft) above the sand beach.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9462711 PUBLICATION DATE: 12/20/2011
Name: SURF BAY, AKUTAN BAY
AK
NOAA Chart: 16531 Latitude: 54° 9.0' N ( 54.15083)
USGS Quad: UNIMAK (A-5) Longitude: 165° 36.9' W (-165.61500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2711 D 2011
DESIGNATION: 946 2711 D
MONUMENTATION: Tidal Station disk VM#: 20176
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 54° 9.0' N ( 54.14997) LONGITUDE: 165° 36.9' W (-165.61461)
The bench mark is a disk set in a rock outcrop near the south end of a sand
beach, 109.4 m (359.0 ft) west of the door for a wooden cabin, 34.25 m (112.4
ft) NW of the intersection/edge of two 5.00 m (16.4 ft) high cliff faces, and
6.26 m (20.5 ft) south of the north end rock the rock outcrop.
BENCH MARK STAMPING: 2711 E 2011
DESIGNATION: 946 2711 E
MONUMENTATION: Tidal Station disk VM#: 20177
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 54° 9.0' N ( 54.15058) LONGITUDE: 165° 36.9' W (-165.61469)
The bench mark is a disk set in the furthest north rock outcrop near the south
end of a sand beach, 16.32 m (53.5 ft) north of the south end of the rock
outcrop, 11.77 m (38.6 ft) east of the highest grassy point on the rock outcrop,
2.94 m (9.6 ft) west of the east side of the rock outcrop, and 1.50 m (4.9 ft)
above the sand beach.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9462711 PUBLICATION DATE: 12/20/2011
Name: SURF BAY, AKUTAN BAY
AK
NOAA Chart: 16531 Latitude: 54° 9.0' N ( 54.15083)
USGS Quad: UNIMAK (A-5) Longitude: 165° 36.9' W (-165.61500)
T I D A L D A T U M S
Tidal datums at SURF BAY, AKUTAN BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: August 2011 - August 2011
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 = 1.147
MEAN HIGH WATER MHW = 1.058
MEAN TIDE LEVEL MTL = 0.681
MEAN SEA LEVEL MSL = 0.667
MEAN LOW WATER MLW = 0.304
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
2711 A 2011 2.684 1.626
2711 B 2011 2.758 1.700
2711 C 2011 2.191 1.133
2711 D 2011 1.933 0.875
2711 E 2011 2.374 1.316
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9462711 PUBLICATION DATE: 12/20/2011
Name: SURF BAY, AKUTAN BAY
AK
NOAA Chart: 16531 Latitude: 54° 9.0' N ( 54.15083)
USGS Quad: UNIMAK (A-5) Longitude: 165° 36.9' W (-165.61500)
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.