U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8725649 PUBLICATION DATE: 02/26/2004
Name: TURTLE BAY
FL
NOAA Chart: 11426 Latitude: 26° 47.8' N ( 26.79670)
USGS Quad: PUNTA GORDA SW Longitude: 82° 11.0' W ( -82.18330)
To reach the tidal bench marks, proceed by boat to the SE corner of the largest
island on the west side of Turtle Bay and the west side of Charlotte Harbor. The
bench marks are located near the southernmost tip of the island a short distance
inland. The tide gage and staff were located on pile supports westerly of the
southernmost tip of the island.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5649 A 1977
DESIGNATION: 872 5649 A
MONUMENTATION: Tidal Station disk VM#: 7369
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 47.8' N ( 26.79670) LONGITUDE: 82° 11.0' W ( -82.18330)
The primary bench mark is a disk located 0.6 km (0.4 mi) north of the
southernmost tip of the island, 91 m (300 ft) NW of a house at the easternmost
point of the island, 4.88 m (16.0 ft) NE of the shoreline, and 0.30 m (1 ft) SW
of a witness post. The bench mark is set 30 cm (1 ft) above ground level,
crimped to the top of a copper-clad steel rod driven 7.3 m (24 ft) to refusal,
and encased in a PVC protector pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8725649 PUBLICATION DATE: 02/26/2004
Name: TURTLE BAY
FL
NOAA Chart: 11426 Latitude: 26° 47.8' N ( 26.79670)
USGS Quad: PUNTA GORDA SW Longitude: 82° 11.0' W ( -82.18330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5649 B 1977
DESIGNATION: 872 5649 B
MONUMENTATION: Tidal Station disk VM#: 7370
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 47.8' N ( 26.79670) LONGITUDE: 82° 11.0' W ( -82.18330)
The bench mark is a disk located 11.58 m (38.0 ft) SE of bench mark 5649 A 1977,
7.62 m (25.0 ft) NE of the shoreline, and 0.30 m (1 ft) west of a witness post.
The bench mark is set 0.37 m (1.2 ft) above ground level, crimped to the top of
a copper-clad steel rod driven 7.3 m (24 ft) to refusal, and encased in a PVC
protector pipe with concrete kickblock.
BENCH MARK STAMPING: 5649 C 1977
DESIGNATION: 872 5649 C
MONUMENTATION: Tidal Station disk VM#: 7371
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 47.8' N ( 26.79670) LONGITUDE: 82° 11.0' W ( -82.18330)
The bench mark is a disk located 13.41 m (44.0 ft) SE of bench mark 5649 B 1977,
9.14 m (30.0 ft) NE of the shoreline, and 0.30 m (1 ft) SW of a witness post.
The bench mark is set 0.34 m (1.1 ft) above ground level, crimped to the top of
a copper-clad steel rod driven 7.3 m (24 ft) to refusal and encased in a PVC
protector pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8725649 PUBLICATION DATE: 02/26/2004
Name: TURTLE BAY
FL
NOAA Chart: 11426 Latitude: 26° 47.8' N ( 26.79670)
USGS Quad: PUNTA GORDA SW Longitude: 82° 11.0' W ( -82.18330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5649 E 1977
DESIGNATION: 872 5649 E
MONUMENTATION: Tidal Station disk VM#: 7372
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 47.8' N ( 26.79670) LONGITUDE: 82° 11.0' W ( -82.18330)
The bench mark is a disk located 13.26 m (43.5 ft) SSE of bench mark 5649 C
1977, 5.49 m (18.0 ft) NE of the shoreline, and 0.30 m (1 ft) east of a witness
post. The bench mark is set 0.24 m (0.8 ft) above ground level, crimped to the
top of a copper-clad steel rod driven 7.3 m (24 ft) to refusal and encased in a
PVC protector pipe with concrete kickblock.
BENCH MARK STAMPING: 5649 F 1977
DESIGNATION: 872 5649 F
MONUMENTATION: Tidal Station disk VM#: 7373
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 26° 47.8' N ( 26.79670) LONGITUDE: 82° 11.0' W ( -82.18330)
The bench mark is a disk located 16.15 m (53.0 ft) east of bench mark 5649 E
1977, 12.19 m (40.0 ft) NE of the shoreline, and 0.30 m (1.0 ft) NW of a witness
post. The bench mark is set 0.34 m (1.1 ft) above ground level, crimped to a
copper-clad steel rod driven 7.3 m (24 ft) to refusal and encased in a PVC
protector pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8725649 PUBLICATION DATE: 02/26/2004
Name: TURTLE BAY
FL
NOAA Chart: 11426 Latitude: 26° 47.8' N ( 26.79670)
USGS Quad: PUNTA GORDA SW Longitude: 82° 11.0' W ( -82.18330)
T I D A L D A T U M S
Tidal datums at TURTLE BAY based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: September 1977 - January 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8725744 PUNTA GORDA
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.474
MEAN HIGH WATER MHW = 0.418
MEAN SEA LEVEL MSL = 0.264
MEAN TIDE LEVEL MTL = 0.263
MEAN LOW WATER MLW = 0.109
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
5649 A 1977 0.748 0.330
5649 B 1977 0.787 0.369
5649 C 1977 0.759 0.341
5649 E 1977 0.825 0.407
5649 F 1977 0.984 0.566
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8725649 PUBLICATION DATE: 02/26/2004
Name: TURTLE BAY
FL
NOAA Chart: 11426 Latitude: 26° 47.8' N ( 26.79670)
USGS Quad: PUNTA GORDA SW Longitude: 82° 11.0' W ( -82.18330)
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.