U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 6
Station ID: 8723950 PUBLICATION DATE: 02/18/2005
Name: MARTHON SHORES KEY, VACA CUT
FL
NOAA Chart: 11451 Latitude: 24° 43.8' N ( 24.73000)
USGS Quad: MARATHON Longitude: 81° 1.8' W ( -81.03000)
To reach the tidal bench marks from the Post Office in Marathon, proceed NE on
U.S. Highway 1 for 5.1 km (3.2 mi) to the bridge over Key Vaca Cut. The bench
marks are on the bridge and at the Captain Hook Marina facilities. The tide
gage and staff were located south of the bridge on Nick's Sporting Goods pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1966
DESIGNATION: 872 3950 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 14234
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0327
SETTING CLASSIFICATION: Concrete sea wall OPUS PID:
LATITUDE: 24° 43.7' N ( 24.72830) LONGITUDE: 81° 1.8' W ( -81.03000)
The primary bench mark is a disk set in top of a concrete sea wall at the bridge
over Key Vaca Cut, 11 m (36 ft) south of the north end of the sea wall, 10 m (32
ft) east of the NE corner of Captain Hooks Marina, and recessed 0.09 m (0.3 ft)
in the concrete. A concrete patio was built over the sea wall but an opening
was left for access to the mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8723950 PUBLICATION DATE: 02/18/2005
Name: MARTHON SHORES KEY, VACA CUT
FL
NOAA Chart: 11451 Latitude: 24° 43.8' N ( 24.73000)
USGS Quad: MARATHON Longitude: 81° 1.8' W ( -81.03000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2
DESIGNATION: 2 FLHD
ALIAS: 872 3950 TIDAL 2 FLHD
MONUMENTATION: Survey disk VM#: 14235
AGENCY: Florida Highway Department (FLHD) IDB PID#: AA0330
SETTING CLASSIFICATION: Concrete abutment OPUS PID:
LATITUDE: 24° 43.8' N ( 24.73000) LONGITUDE: 81° 1.8' W ( -81.03000)
The bench mark is a disk set in the SW abutment of U.S. Highway 1 bridge over
Key Vaca Cut, 33.38 m (109.5 ft) NE of bench mark NO 1 1966, and 6 m (20 ft)
south of the centerline of the highway.
BENCH MARK STAMPING: 3950 D 1982
DESIGNATION: 872 3950 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 14236
AGENCY: National Ocean Survey (NOS) IDB PID#: AA0885
SETTING CLASSIFICATION: Concrete dock and sea wall OPUS PID:
LATITUDE: 24° 43.8' N ( 24.73000) LONGITUDE: 81° 1.8' W ( -81.03000)
The bench mark is a disk set in the top of a concrete dock at Captain Hook
Marina, 14.05 m (46.1 ft) ESE of the east corner of the Marina Office Building,
3.38 m (11.1 ft) SE of the extended centerline of the alley behind the office
building, 1.55 m (5.1 ft) SW of the most southeastern boat hoist, and 1 m (2 ft)
above the dock walkway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8723950 PUBLICATION DATE: 02/18/2005
Name: MARTHON SHORES KEY, VACA CUT
FL
NOAA Chart: 11451 Latitude: 24° 43.8' N ( 24.73000)
USGS Quad: MARATHON Longitude: 81° 1.8' W ( -81.03000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3950 E 1982
DESIGNATION: 872 3950 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 14237
AGENCY: National Ocean Survey (NOS) IDB PID#: AA0884
SETTING CLASSIFICATION: Concrete platform OPUS PID:
LATITUDE: 24° 43.8' N ( 24.73000) LONGITUDE: 81° 1.8' W ( -81.03000)
The bench mark is a disk set in the top of a concrete platform at Captain Hook
Marina, 30.11 m (98.8 ft) WSW of bench mark 3950 D 1982, 4 m (13 ft) NW of the
centerline of the alley behind the office building, 2.90 m (9.5 ft) SE of the
south corner of the Marina Office Building, and 1 m (2 ft) above the alley.
BENCH MARK STAMPING: 3950 F 1982
DESIGNATION: 872 3950 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 14238
AGENCY: National Ocean Survey (NOS) IDB PID#: AA0886
SETTING CLASSIFICATION: Concrete sea wall and walkway OPUS PID:
LATITUDE: 24° 43.8' N ( 24.73000) LONGITUDE: 81° 1.8' W ( -81.03000)
The bench mark is a disk set in the top of a concrete sea wall and walkway at
Captain Hook Marina, 30.78 m (101.0 ft) NE of the SW end of the sea wall, 10.91
m (35.8 ft) SW of the south corner of the ticket office for the deep sea fishing
boat Marathon Lady, 8.53 m (28.0 ft) SE of the centerline of the alley, and 1 m
(3 ft) above a wooden dock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8723950 PUBLICATION DATE: 02/18/2005
Name: MARTHON SHORES KEY, VACA CUT
FL
NOAA Chart: 11451 Latitude: 24° 43.8' N ( 24.73000)
USGS Quad: MARATHON Longitude: 81° 1.8' W ( -81.03000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3950 G
DESIGNATION: 872 3950 G TIDAL
MONUMENTATION: Survey disk VM#: 14239
AGENCY: Florida Department of Transportation
(FLDT) IDB PID#: AA1640
SETTING CLASSIFICATION: Concrete bridge rail OPUS PID:
LATITUDE: 24° 43.8' N ( 24.73000) LONGITUDE: 81° 1.8' W ( -81.03000)
The bench mark is a disk set in the top of a concrete bridge rail at the SW
corner of the bridge over Key Vaca Cut, 5.97 m (19.6 ft) east of the west end of
the concrete bridge rail, 5.36 m (17.6 ft) south of the centerline of the north
bound lane of U.S. Highway 1, and 0.85 m (2.8 ft) above the highway.
BENCH MARK STAMPING: 3950 H
DESIGNATION: 872 3950 H TIDAL
MONUMENTATION: Survey disk VM#: 14240
AGENCY: Florida Department of Transportation
(FLDT) IDB PID#: AA1639
SETTING CLASSIFICATION: Concrete bridge rail OPUS PID:
LATITUDE: 24° 43.8' N ( 24.73000) LONGITUDE: 81° 1.8' W ( -81.03000)
The bench mark is a disk set in the top of a concrete bridge rail at the NE
corner of the bridge over Key Vaca Cut, 5.94 m (19.5 ft) west of the east end of
the concrete bridge rail, 5.30 m (17.4 ft) north of the centerline of the south
bound lane of U.S. Highway 1, and 0.85 m (2.8 ft) above the highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8723950 PUBLICATION DATE: 02/18/2005
Name: MARTHON SHORES KEY, VACA CUT
FL
NOAA Chart: 11451 Latitude: 24° 43.8' N ( 24.73000)
USGS Quad: MARATHON Longitude: 81° 1.8' W ( -81.03000)
T I D A L D A T U M S
Tidal datums at MARTHON SHORES KEY, VACA CUT based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: August 1975 - September 1975
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8724580 KEY WEST
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
North American Vertical Datum NAVD88 = 0.570
MEAN HIGHER HIGH WATER MHHW = 0.519
MEAN HIGH WATER MHW = 0.458
MEAN SEA LEVEL MSL = 0.266
MEAN TIDE LEVEL MTL = 0.258
MEAN LOW WATER MLW = 0.057
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 1 1966 2.004 1.546
2 4.768 4.310
3950 D 1982 2.091 1.633
3950 E 1982 2.216 1.758
3950 F 1982 1.876 1.418
3950 G 6.379 5.921
3950 H 6.397 5.939
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8723950 PUBLICATION DATE: 02/18/2005
Name: MARTHON SHORES KEY, VACA CUT
FL
NOAA Chart: 11451 Latitude: 24° 43.8' N ( 24.73000)
USGS Quad: MARATHON Longitude: 81° 1.8' W ( -81.03000)
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.