U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9450815 PUBLICATION DATE: 02/15/2011
Name: RATZ HARBOR, CLARENCE STRAIT
AK
NOAA Chart: 17420 Latitude: 55° 52.8' N ( 55.88000)
USGS Quad: CRAIG (D-2) Longitude: 132° 35.7' W (-132.59500)
To reach the tidal bench marks from Wrangell via boat, proceed 14.5 km (7.9 nm)
SW through Stikine Strait, then proceed 34.6 km (18.8 nm) SW to Clarence Strait,
then proceed SW across Clarence Strait to the RW flashing 4 s 20 ft 5 M
daymarker that is located at the entrance of Ratz Harbor, then to Prince of
Wales Island located on the SW shore of the Ratz Harbor. The bench marks are
located on the beach in the vicinity on the western shore. The tide gauge was
located on the eastern shore because of the security concerns because the
western shore had camping facilities and road access.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 2 1971
DESIGNATION: 945 0815 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 16476
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 52.8' N ( 55.88000) LONGITUDE: 132° 35.7' W (-132.59500)
The primary bench mark is a disk set in a large rock near the summit of a small
hill, bordered on the north by small pine trees, 37 m (120 ft) south of a small
creek, 7.16 m (23.5 ft) south of bench mark NO 3 1971, 7 m (23 ft) north of the
eastern edge of the gravel road that runs parallel to the shoreline, and 2 m (8
ft) west of the highest point of the small hill.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9450815 PUBLICATION DATE: 02/15/2011
Name: RATZ HARBOR, CLARENCE STRAIT
AK
NOAA Chart: 17420 Latitude: 55° 52.8' N ( 55.88000)
USGS Quad: CRAIG (D-2) Longitude: 132° 35.7' W (-132.59500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1971
DESIGNATION: 945 0815 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 16477
AGENCY: IDB PID#:
SETTING CLASSIFICATION: Rock Outcrop OPUS PID:
LATITUDE: 55° 52.8' N ( 55.88000) LONGITUDE: 132° 35.7' W (-132.59500)
The bench mark is a disk set in a rock outcropping, 17 m (56 ft) from the
eastern edge of the gravel road that runs parallel to the shoreline, 6 m (20
ft) north of a gravel road bridge that extends over a small creek which runs
through a metal culvert east of the rock outcropping, and 6 m (20 ft) south of a
wooded area.
BENCH MARK STAMPING: 0815 A 2001
DESIGNATION: 945 0815 A
MONUMENTATION: Tidal Station disk VM#: 16478
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 55° 52.8' N ( 55.88000) LONGITUDE: 132° 35.7' W (-132.59500)
The bench mark is a disk set into a prominent boulder on the rock beach, 22 m
(73 ft) east of a small creek pouring through a large metal culvert that runs
under the gravel road, 7 m (23 ft) south of the apparent high water line, and 6
m (20 ft) north of the eastern edge of the gravel road that runs parallel to
shore.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9450815 PUBLICATION DATE: 02/15/2011
Name: RATZ HARBOR, CLARENCE STRAIT
AK
NOAA Chart: 17420 Latitude: 55° 52.8' N ( 55.88000)
USGS Quad: CRAIG (D-2) Longitude: 132° 35.7' W (-132.59500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0815 B 2001
DESIGNATION: 945 0815 B
MONUMENTATION: Tidal Station disk VM#: 16479
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Boulder OPUS PID:
LATITUDE: 55° 52.8' N ( 55.88000) LONGITUDE: 132° 35.7' W (-132.59500)
The bench mark is a disk set into a boulder, 55 m (180 ft) SE (80 degrees
magnetic) of bench mark 0815 A 2001, 5.40 m (17.7 ft) south of the eastern edge
of a gravel road, and 2 m (7 ft) south of the tree line.
BENCH MARK STAMPING: 0815 C 2001
DESIGNATION: 945 0815 C
MONUMENTATION: Tidal Station disk VM#: 16480
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 52.8' N ( 55.88000) LONGITUDE: 132° 35.7' W (-132.59500)
The bench mark is a disk set into a rock outcropping on the gravel beach that
surrounds the SE shore, 41 m (133 ft) NNW (324 degrees magnetic) of the NE edge
of a gravel road that runs north-south parallel to the shoreline, measured from
the point where the road forks, and 15 m (48 ft) from the apparent high water
line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9450815 PUBLICATION DATE: 02/15/2011
Name: RATZ HARBOR, CLARENCE STRAIT
AK
NOAA Chart: 17420 Latitude: 55° 52.8' N ( 55.88000)
USGS Quad: CRAIG (D-2) Longitude: 132° 35.7' W (-132.59500)
T I D A L D A T U M S
Tidal datums at RATZ HARBOR, CLARENCE STRAIT based on:
LENGTH OF SERIES: 25 Days
TIME PERIOD: April 20 2001 - May 14 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9450460 KETCHIKAN, TONGASS NARROWS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 4.851
MEAN HIGH WATER MHW = 4.586
MEAN TIDE LEVEL MTL = 2.530
MEAN SEA LEVEL MSL = 2.529
MEAN LOW WATER MLW = 0.473
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 2 1971 11.661 7.075
NO 3 1971 6.687 2.101
0815 A 2001 7.558 2.971
0815 B 2001 10.128 5.541
0815 C 2001 7.072 2.486
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9450815 PUBLICATION DATE: 02/15/2011
Name: RATZ HARBOR, CLARENCE STRAIT
AK
NOAA Chart: 17420 Latitude: 55° 52.8' N ( 55.88000)
USGS Quad: CRAIG (D-2) Longitude: 132° 35.7' W (-132.59500)
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.