U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9449904 SUPERCEDED DATE: 04/21/2003
Name: SHAW ISLAND FERRY, HARNEYCHANNEL
WASHINGTON
NOAA Chart: 18425 Latitude: 48° 35.1' N
USGS Quad: SHAWISLAND Longitude: 122° 55.7' W
To reach the tidal bench marks proceed by boat to Shaw Island Ferry Terminal.
The bench marks are located at the ferry terminal and extend along both sides of
Blind Bay Road, between the ferry terminal pier, the general store, and the
marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BM 1 1974
MONUMENTATION: Survey Disk VM#: 9320
AGENCY: PID:
SETTING CLASSIFICATION: Retaining Wall
The bench mark is set flush in the northwest end of a concrete retaining wall,
59.5 feet (18.1 m) northwest of the third piling on the northwest face of the
dock, 40 feet ( 12 m) southeast of fuel intake headers, and west of a telephone
booth.
BENCH MARK STAMPING: BM 2 1974
MONUMENTATION: Survey Disk VM#: 9321
AGENCY: PID:
SETTING CLASSIFICATION: Retaining Wall
The bench mark is set flush in a concrete retaining wall on the north side of
Blind Bay Road, 29.3 (8.9 m) feet northeast of Bench Mark 1 1974, and 25.0 feet
(7.6 m) east from edge of wooden ferry landing.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9449904 SUPERCEDED DATE: 04/21/2003
Name: SHAW ISLAND FERRY, HARNEYCHANNEL
WASHINGTON
NOAA Chart: 18425 Latitude: 48° 35.1' N
USGS Quad: SHAWISLAND Longitude: 122° 55.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM 3 1974
MONUMENTATION: Survey Disk VM#: 9322
AGENCY: PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is set flush in bedrock on south side of Blind Bay Road, near
shore line, 53.0 feet (16.2 m) south of Bench Mark 2 1974, and south of a
telephone booth.
BENCH MARK STAMPING: BM 4 1974
MONUMENTATION: Survey Disk VM#: 9323
AGENCY: PID:
SETTING CLASSIFICATION: Pavement
The bench mark is set flush in the southeast corner of an 8-foot x 10-foot
uncovered concrete slab with hydraulic auto lift, 52.3 feet (15.9 m) northeast
of Bench Mark 3 1974, and 10.0 feet (3.0 m) west of gas pumps.
BENCH MARK STAMPING: BM 5 1974
MONUMENTATION: Survey Disk VM#: 9324
AGENCY: PID:
SETTING CLASSIFICATION: Retaining Wall
The bench mark is set flush in a concrete retaining wall, 93.0 feet (28.3 m)
east-southeast of Bench Mark 4 1974, 20.0 feet (6.1 m) south of the east corner
of the general store porch corner post, and 0.5 foot (0.2 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9449904 SUPERCEDED DATE: 04/21/2003
Name: SHAW ISLAND FERRY, HARNEYCHANNEL
WASHINGTON
NOAA Chart: 18425 Latitude: 48° 35.1' N
USGS Quad: SHAWISLAND Longitude: 122° 55.7' W
T I D A L D A T U M S
Tidal datums at SHAW ISLAND FERRY, HARNEYCHANNEL based on:
LENGTH OF SERIES: 68 HW & 68 LW
TIME PERIOD: SEPTEMBER 23 -OCTOBER 28, 1974
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 9444900 PORT TOWNSEND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (10/20/1974) = 7.79
MEAN HIGHER HIGH WATER MHHW = 7.63
MEAN HIGH WATER MHW = 6.93
MEAN TIDE LEVEL MTL = 4.73
MEAN LOW WATER MLW = 2.53
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (10/17/1974) = -1.86
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
BM 1 1974 13.96 7.03
BM 2 1974 13.33 6.40
BM 3 1974 8.86 1.93
BM 4 1974 14.99 8.06
BM 5 1974 17.72 10.79
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 05/18/1982
Station ID: 9449904 SUPERCEDED DATE: 04/21/2003
Name: SHAW ISLAND FERRY, HARNEYCHANNEL
WASHINGTON
NOAA Chart: 18425 Latitude: 48° 35.1' N
USGS Quad: SHAWISLAND Longitude: 122° 55.7' 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.