U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 07/19/1988
Station ID: 9451849 SUPERCEDED DATE: 04/21/2003
Name: POINT SINBAD, SULOIA BAY
ALASKA
NOAA Chart: 17323 Latitude: 57° 24.3' N
USGS Quad: SITKA B-5 Longitude: 135° 39.0' W
To reach the tidal bench marks from Sitka, proceed by boat 17.5 statute miles
(28.2 km) west of the Gulf of Alaska, then 21 statute miles (34 km) north to
Salisbury Sound, then 9.5 statute miles (15.3 km) east and north in Salisbury
Sound to Point Sinbad. The bench marks are in the area between the water and
the tree line. The tide gage orifice and staff were located NW of Bench Mark
1849 A 1976.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1849 A 1976
MONUMENTATION: Survey Disk VM#: 9397
AGENCY: PID:
SETTING CLASSIFICATION: Unspecified
The bench mark is approximately 40 feet (12 m) NW of Triangulation Station BOON
2 1950, 8 feet (2 m) south of the tree line, and approximately 8 feet (2 m)
above the approximate high water line.
BENCH MARK STAMPING: BOON 2 1950
MONUMENTATION: Survey Disk VM#: 9394
AGENCY: PID#: UV0891
SETTING CLASSIFICATION: Bedrock
The bench mark is cemented in a drill hole in an outcropping of bedrock on the
southernmost tip of Point Sinbad, 20 feet (6 m) SE of the tree line, and 6 feet
(2 m) above the approximate high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 07/19/1988
Station ID: 9451849 SUPERCEDED DATE: 04/21/2003
Name: POINT SINBAD, SULOIA BAY
ALASKA
NOAA Chart: 17323 Latitude: 57° 24.3' N
USGS Quad: SITKA B-5 Longitude: 135° 39.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BOON 2 RM 1 1950
MONUMENTATION: Survey Disk VM#: 9395
AGENCY: PID#: AE6470
SETTING CLASSIFICATION: Bedrock
The bench mark is cemented in a drill hole in an outcropping of bedrock on the
southernmost tip of Point Sinbad, 20 feet (6 m) west of Reference Mark BOON 2 RM
2 1950, 2 feet (1 m) south of the tree line, and 8 feet (2 m) above the
approximate high water line.
BENCH MARK STAMPING: BOON 2 RM 2 1950
MONUMENTATION: Survey Disk VM#: 9396
AGENCY: PID#: AE6471
SETTING CLASSIFICATION: Bedrock
The bench mark is cemented in a drill hole in an outcropping of bedrock on the
southernmost tip of Point Sinbad, 10 feet (3 m) NE of Triangulation Station BOON
2 1950, 5 feet (2 m) south of the tree line, and 8 feet (2 m) above the
approximate high water line.
BENCH MARK STAMPING: 1849 B 1976
MONUMENTATION: Survey Disk VM#: 9398
AGENCY: PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is cemented in a drill hole in an outcropping of bedrock 70 feet
(21 m) NE of Triangulation Station BOON 2 1950, 8 feet (2 m) above the
approximate high water line, and directly under the tree line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 07/19/1988
Station ID: 9451849 SUPERCEDED DATE: 04/21/2003
Name: POINT SINBAD, SULOIA BAY
ALASKA
NOAA Chart: 17323 Latitude: 57° 24.3' N
USGS Quad: SITKA B-5 Longitude: 135° 39.0' W
T I D A L D A T U M S
Tidal datums at POINT SINBAD, SULOIA BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: JUNE 1976
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9451600 SITKA
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (06/30/1976) = 12.50
MEAN HIGHER HIGH WATER MHHW = 10.23
MEAN HIGH WATER MHW = 9.42
MEAN TIDE LEVEL MTL = 5.49
MEAN LOW WATER MLW = 1.56
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (06/13/1976) = -3.60
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
1849 A 1976 11.87 2.45
BOON 2 1950 9.71 0.29
BOON 2 RM 1 1950 11.98 2.56
BOON 2 RM 2 1950 10.88 1.46
1849 B 1976 10.93 1.51
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 07/19/1988
Station ID: 9451849 SUPERCEDED DATE: 04/21/2003
Name: POINT SINBAD, SULOIA BAY
ALASKA
NOAA Chart: 17323 Latitude: 57° 24.3' N
USGS Quad: SITKA B-5 Longitude: 135° 39.0' W
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 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.