U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 Station ID: 8448558 PUBLICATION DATE: 06/12/2009 Name: EDGARTOWN, MARTHA'S VINEYARD MA NOAA Chart: 13233 Latitude: 41° 23.3' N ( 41.38830) USGS Quad: EDGARTOWN Longitude: 70° 30.7' W ( -70.51170) From Woods Hole, take the ferry to Oaks Bluff on Martha's Vineyard, then take Seaview Avenue south, then Beach Road south, then Edgartown Oaks Bluff Road south to Edgartown. The bench marks are downtown, in the vicinity of the ferry to Chappaquiddick Island. The tide gauge was located on the Edgartown Memorial Pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 9 1960 DESIGNATION: 844 8558 TIDAL 9 MONUMENTATION: Bench Mark disk VM#: 17666 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete seawall OPUS PID#: BBBJ75 LATITUDE: 41° 23.3' N ( 41.38830) LONGITUDE: 70° 30.7' W ( -70.51170) The bench mark is a disk set in an old concete seawall adjacent to the public piers, 31 m (102 ft) south of the center of the Dock Street, 23 m (75 ft) west of a yard arm shaped flagpole located in front of the JYC yacht club building, and 0.3 m (1.0 ft) from the junction of a brick walkway and wooden quay.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 Station ID: 8448558 PUBLICATION DATE: 06/12/2009 Name: EDGARTOWN, MARTHA'S VINEYARD MA NOAA Chart: 13233 Latitude: 41° 23.3' N ( 41.38830) USGS Quad: EDGARTOWN Longitude: 70° 30.7' W ( -70.51170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 6 1928 DESIGNATION: 844 8558 TIDAL 6 MONUMENTATION: Bench Mark disk VM#: 17667 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete foundation OPUS PID#: LATITUDE: 41° 23.3' N ( 41.38830) LONGITUDE: 70° 30.7' W ( -70.51170) The bench mark is a disk set vertically in the concrete foundation of the Edgartown National Bank located on Martha's Vineyard, 4.2 m (13.8 ft) north from the center of Main Street, 2.8 m (9.2 ft) west of the center of Water Street, 0.5 m (1.6 ft) west of the SE corner of the building, and 0.3 m (1.0 ft) from the base of the building. BENCH MARK STAMPING: NO 11 1961 DESIGNATION: 844 8558 TIDAL 11 MONUMENTATION: Bench Mark disk VM#: 17668 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Curb OPUS PID#: BBDN12 LATITUDE: 41° 23.4' N ( 41.39000) LONGITUDE: 70° 30.7' W ( -70.51170) The bench mark is a disk set in a roadside curb on the SE corner of the intersection of Mayhew Lane and Dock Street, 30 m (98.4 ft) north of bench mark NO 9 1960, 24 m (78.7 ft) SE of a red and white fire hydrant located at the NW corner of Mayhew Lane and Dock Street, 10 m (32.8 ft) SE of the intersection of Mayhew Lane and Dock Street, and 0.75 m (2.5 ft) west of a powerline pole.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 Station ID: 8448558 PUBLICATION DATE: 06/12/2009 Name: EDGARTOWN, MARTHA'S VINEYARD MA NOAA Chart: 13233 Latitude: 41° 23.3' N ( 41.38830) USGS Quad: EDGARTOWN Longitude: 70° 30.7' W ( -70.51170) T I D A L D A T U M S Tidal datums at EDGARTOWN, MARTHA'S VINEYARD based on: LENGTH OF SERIES: 31 Days TIME PERIOD: August 6, 2004 - September 6, 2004 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8449130 NANTUCKET ISLAND, NANTUCKET SOUND Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.816 MEAN HIGH WATER MHW = 0.719 MEAN SEA LEVEL MSL = 0.435 MEAN TIDE LEVEL MTL = 0.394 MEAN LOW WATER MLW = 0.069 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 9 1960 1.098 0.379 NO 6 1928 3.708 2.989 NO 11 1961 1.436 0.716
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 Station ID: 8448558 PUBLICATION DATE: 06/12/2009 Name: EDGARTOWN, MARTHA'S VINEYARD MA NOAA Chart: 13233 Latitude: 41° 23.3' N ( 41.38830) USGS Quad: EDGARTOWN Longitude: 70° 30.7' W ( -70.51170) 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.