U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8417948 PUBLICATION DATE: 04/29/2004 Name: PRINCE POINT, YARMOUTH ME NOAA Chart: 13290 Latitude: 43° 45.7' N ( 43.76170) USGS Quad: YARMOUTH Longitude: 70° 10.4' W ( -70.17330) To reach the tidal bench marks from Portland, Maine, proceed 3.2 km (2 mi) north on US Route 1 to the intersection of State Road 88, bear right onto State Route 88 and travel 9.7 km (6 mi) to Princess Point road, and turn right (south) and continue 1.6 km (1 mi) to Prince Point located in the SW section of Casco Bay. The bench marks were located in the vicinity of the Princes Point Association Pier and extend east along the shoreline. The tide gage and staff were located on the pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 841 7948 A 1979 DESIGNATION: 841 7948 A TIDAL MONUMENTATION: Tidal Station disk VM#: 1910 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete support piling OPUS PID: LATITUDE: 43° 45.7' N ( 43.76170) LONGITUDE: 70° 10.4' W ( -70.17330) The primary bench mark is a disk set flush in a concrete support piling for the Princes Point Association Pier, 1.6 m (5.2 ft) above beach level, bearing NW from the large stack at the power plant on Cousins Island and NNE from a small island known as Nubbin which is just off the coast from the pier.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8417948 PUBLICATION DATE: 04/29/2004 Name: PRINCE POINT, YARMOUTH ME NOAA Chart: 13290 Latitude: 43° 45.7' N ( 43.76170) USGS Quad: YARMOUTH Longitude: 70° 10.4' W ( -70.17330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 841 7948 B 1979 DESIGNATION: 841 7948 B TIDAL MONUMENTATION: Tidal Station disk VM#: 1911 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 43° 45.7' N ( 43.76170) LONGITUDE: 70° 10.4' W ( -70.17330) The bench mark is a disk set flush on a rock ledge east of the Princes Point Association Pier, 2.2 m (7.3 ft) NW of the shoreline, 1.7 m (5.7 ft) SE of the seawall, bearing NE from bench mark 841 7948 A 1979, and NW of the large stack at the power plant on Cousins Island. BENCH MARK STAMPING: 841 7948 C 1979 DESIGNATION: 841 7948 C TIDAL MONUMENTATION: Tidal Station disk VM#: 1912 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 43° 45.7' N ( 43.76170) LONGITUDE: 70° 10.4' W ( -70.17330) The bench mark is a disk set flush on a rock ledge east of the Princes Point Association Pier, 17.5 m (57.3 ft) NE of bench mark 841 7948 B 1979, bearing NW from the large stack at the power plant on Cousins Islands, NNE from a small island knows as Nubbins off the coast from the pier, and NNE from the NE corner of the seawall that is located along the rock ledge.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8417948 PUBLICATION DATE: 04/29/2004 Name: PRINCE POINT, YARMOUTH ME NOAA Chart: 13290 Latitude: 43° 45.7' N ( 43.76170) USGS Quad: YARMOUTH Longitude: 70° 10.4' W ( -70.17330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 841 7948 D 1979 DESIGNATION: 841 7948 D TIDAL MONUMENTATION: Tidal Station disk VM#: 1913 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID#: BBBG16 LATITUDE: 43° 45.7' N ( 43.76170) LONGITUDE: 70° 10.4' W ( -70.17330) The bench mark is a disk set flush on a rock ledge east of the Princes Point Association Pier, 32.3 m (106 ft) NE of bench mark 841 7948 C 1979, 7.0 m (23.0 ft) west of the shoreline, 1.2 m (4.0 ft) from the edge of a small cliff, bearing NW of the large stack at the power plant on Cousins Island and NE from a small island known as Nubbin off the coast from the pier. BENCH MARK STAMPING: 841 7948 E 1979 DESIGNATION: 841 7948 E TIDAL MONUMENTATION: Tidal Station disk VM#: 1914 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Rock ledge OPUS PID: LATITUDE: 43° 45.7' N ( 43.76170) LONGITUDE: 70° 10.4' W ( -70.17330) The bench mark is a disk set flush on a rock ledge east of the Princes Point Association Pier, 14.8 m (48.5 ft) NE of bench mark 841 7948 D 1979, and bears north NW from the large stack at the power plant on Cousins Island.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8417948 PUBLICATION DATE: 04/29/2004 Name: PRINCE POINT, YARMOUTH ME NOAA Chart: 13290 Latitude: 43° 45.7' N ( 43.76170) USGS Quad: YARMOUTH Longitude: 70° 10.4' W ( -70.17330) T I D A L D A T U M S Tidal datums at PRINCE POINT, YARMOUTH based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: October 1979 - October 1979 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8418150 PORTLAND, CASCO BAY Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 3.031 MEAN HIGH WATER MHW = 2.894 MEAN SEA LEVEL MSL = 1.507 MEAN TIDE LEVEL MTL = 1.494 MEAN LOW WATER MLW = 0.095 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 841 7948 A 1979 4.438 1.544 841 7948 B 1979 3.892 0.998 841 7948 C 1979 3.441 0.547 841 7948 D 1979 3.571 0.677 841 7948 E 1979 4.115 1.221
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8417948 PUBLICATION DATE: 04/29/2004 Name: PRINCE POINT, YARMOUTH ME NOAA Chart: 13290 Latitude: 43° 45.7' N ( 43.76170) USGS Quad: YARMOUTH Longitude: 70° 10.4' W ( -70.17330) 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.