U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9462719 PUBLICATION DATE: 06/07/2010 Name: AKUN COVE, AKUN ISLAND AK NOAA Chart: 16520 Latitude: 54° 14.0' N ( 54.23330) USGS Quad: Unimak (A-5) Longitude: 165° 32.0' W (-165.53300) To reach the tidal bench marks from Dutch Harbor, travel NNE 26 km (14 nm) to the north side of Akutan Island, then proceed NE for 37 km (20 nm) to the entrance to Akutan Pass between Akutan and Akun islands, then proceed east 26 km (14 nm) to Billings Head at the NE point of Akun Island, then proceed 5 km (3 nm) south to Akun Bay, then proceed SW 6 km (3 nm) to Helianthus Cove. The bench marks are located on a rock ledge/bluff facing north. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 1 1937 DESIGNATION: 946 2719 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 19210 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock ledge OPUS PID: LATITUDE: 54° 14.4' N ( 54.23947) LONGITUDE: 165° 32.4' W (-165.53989) The primary bench mark is set flush on a bedrock ledge projecting into the sea from the NW point of the headland, 30.08 m (98.7 ft) west of bench mark 946 2719 TIDAL 3, 14.67 m (48.1 ft) NNE from 946 2719 Tidal 2, 6.48 m (21.3 ft) ENE of the highest point in the middle of the finger like prolongation stretching seaward in a NE orientation, and 1.37 m (4.5 ft) above the High Water Line denoted by the barnacles.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9462719 PUBLICATION DATE: 06/07/2010 Name: AKUN COVE, AKUN ISLAND AK NOAA Chart: 16520 Latitude: 54° 14.0' N ( 54.23330) USGS Quad: Unimak (A-5) Longitude: 165° 32.0' W (-165.53300) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2 1937 DESIGNATION: 946 2719 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 19211 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 54° 14.4' N ( 54.23931) LONGITUDE: 165° 32.4' W (-165.54003) The bench mark is set flush on a rock ledge or bluff forming shoreline, 35.91 m (117.8 ft) WSW from bench mark 946 2719 TIDAL 3, 15.01 m (49.2 ft) ENE of bench mark 946 2719 TIDAL 4, 14.67 m (48.1 ft) east from bench mark 946 2719 TIDAL 1, 11.34 m (37.20 ft) south from the highest point in the middle of a bedrock prolongation stretching seaward on a NE, 1.49 m (4.9 ft) south of the edge of the rock ledge on which the rock is set, and 2.20 m (7.2 ft) slant height above the mean high water line denoted by the bottom of the green algae and the top of the barnacles. BENCH MARK STAMPING: 3 1937 DESIGNATION: 946 2719 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 19212 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 54° 14.4' N ( 54.23944) LONGITUDE: 165° 32.4' W (-165.53953) The bench mark is set flush on a rock ledge or bluff forming shoreline, 35.91 m (117.9 ft) ENE of bench mark 946 2719 TIDAL 2, 35.78 m (117.39 ft) east of the highest point in the middle of a bedrock prolongation stretching seaward in a NE orientation, 30.08 m (98.6 ft) east of bench mark 946 2719 TIDAL 1, and 2.5 m (8.2 ft) above the mean high water ling denoted by the barnacles.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9462719 PUBLICATION DATE: 06/07/2010 Name: AKUN COVE, AKUN ISLAND AK NOAA Chart: 16520 Latitude: 54° 14.0' N ( 54.23330) USGS Quad: Unimak (A-5) Longitude: 165° 32.0' W (-165.53300) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4 1938 DESIGNATION: 946 2719 TIDAL 4 MONUMENTATION: Tidal Station disk VM#: 19213 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock ledge OPUS PID: LATITUDE: 54° 14.4' N ( 54.23925) LONGITUDE: 165° 32.4' W (-165.54025) The bench mark is set flush on a bedrock ledge projecting into the sea from the NW point of the headland, 26.89 m (88.2 ft) SW from bench mark 946 2719 TIDAL 1, 21.06 m (69.1 ft) SW from the highest point in the middle of the fingerlike bedrock prolongation stretching seaward in a NE orientation, 15.01 m (49.3 ft) WSW from bench mark 946 2719 TIDAL 4, and 2.78 m (9.12 ft) slant height above the mean high water line denoted by green algae and barnacles. BENCH MARK STAMPING: 2719 A 2009 DESIGNATION: 946 2719 A MONUMENTATION: Tidal Station disk VM#: 19214 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBBH93 LATITUDE: 54° 14.3' N ( 54.23803) LONGITUDE: 165° 32.5' W (-165.54108) The bench mark is located 144 m (472 ft) north of the northern intersection between a storm berm and a west facing bluff, 40.32 m (132.2 ft) SSW of a 2.0 m (6.6 ft) high rock outcropping that protrudes NW from a NNW facing rock cliff, 2.48 m (8.1 ft) east of a grass ledge. The bench mark is set 9 cm (0.3 ft) below the top of the logo cover, crimped to the top of a stainless steel rod, and driven 6.96 m (22.8 ft) to refusal in the NOS logo cover.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9462719 PUBLICATION DATE: 06/07/2010 Name: AKUN COVE, AKUN ISLAND AK NOAA Chart: 16520 Latitude: 54° 14.0' N ( 54.23330) USGS Quad: Unimak (A-5) Longitude: 165° 32.0' W (-165.53300) T I D A L D A T U M S Tidal datums at AKUN COVE, AKUN ISLAND based on: LENGTH OF SERIES: 4 MONTHS TIME PERIOD: May 2009 - August 2009 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 = 0.940 MEAN HIGH WATER MHW = 0.880 MEAN SEA LEVEL MSL = 0.523 MEAN TIDE LEVEL MTL = 0.515 MEAN LOW WATER MLW = 0.150 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 1 1937 1.943 1.063 2 1937 2.620 1.740 3 1937 2.609 1.729 4 1938 2.766 1.886 2719 A 2009 3.128 2.248
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9462719 PUBLICATION DATE: 06/07/2010 Name: AKUN COVE, AKUN ISLAND AK NOAA Chart: 16520 Latitude: 54° 14.0' N ( 54.23330) USGS Quad: Unimak (A-5) Longitude: 165° 32.0' W (-165.53300) 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.