U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 08/19/1988
Station ID: 8726668 SUPERCEDED DATE: 04/21/2003
Name: HOOKERS POINT, SEDDON CHANNEL, HILLSBOROUGH BAY
FLORIDA
NOAA Chart: 11413 Latitude: 27° 55.1' N
USGS Quad: TAMPA Longitude: 82° 26.7' W
To reach the tidal bench marks from the intersection of 22nd Street and Maritime
Boulevard (the entrance of Port of Tampa) proceed south along Maritime Boulevard
for 1.4 miles (2.3 km) to the Illinois Grain Corporation grain elevators. The
bench marks are located around the Illinois Grain Corporation property. The
tide gage and staff were located on a concrete sea wall 414 feet (126 m) SW of
the grain elevators.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6668 A 1977
MONUMENTATION: Survey Disk VM#: 6813
AGENCY: PID#: AG7491
SETTING CLASSIFICATION: Concrete Bulkhead
The bench mark is set flush in the top of a bulkhead 212.0 feet (64.6 m) east of
the NW corner of the northern boat slip, 57.0 feet (17.4 m) west of the SW
corner of an old grain derrick, 1.7 feet (0.5 m) north of the outside edge of
the bulkhead for the boat slip, and 1.2 feet (0.4 m) west of the third boat
cleat east of the NW corner of the boat slip.
BENCH MARK STAMPING: HP 2 1947
MONUMENTATION: Survey Disk VM#: 6810
AGENCY: PID#: AG6074
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in the concrete floor at the base of an iron ladder of the
outermost concrete derrick base of the Hillsborough County Port Authority Pier,
681 feet (208 m) from the inshore end, and 3 feet (1 m) from the southeastern
edge of the pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 08/19/1988
Station ID: 8726668 SUPERCEDED DATE: 04/21/2003
Name: HOOKERS POINT, SEDDON CHANNEL, HILLSBOROUGH BAY
FLORIDA
NOAA Chart: 11413 Latitude: 27° 55.1' N
USGS Quad: TAMPA Longitude: 82° 26.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: HP 3 1947
MONUMENTATION: Survey Disk VM#: 6811
AGENCY: PID#: AG6073
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in a concrete floor at the base of an iron ladder of the
innermost concrete derrick base of the Hillsborough County Port Authority pier,
301 feet (92 m) from the inshore end, 63 feet (19 m) SW of the 3rd boat cleat
and 3 feet (1 m) from the northeastern edge of the pier.
BENCH MARK STAMPING: BM 4 RESET 1963
MONUMENTATION: Survey Disk VM#: 6812
AGENCY: PID#: AG6071
SETTING CLASSIFICATION: Retaining Wall
The bench mark is set in the top of the east end of the retaining wall on the SE
side of the inshore end of the pier at Hillsborough County Port Authority.
BENCH MARK STAMPING: 6668 B 1977
MONUMENTATION: Survey Disk VM#: 6814
AGENCY: PID#: AG7490
SETTING CLASSIFICATION: Concrete Bulkhead
The bench mark is set flush in the top of the bulkhead, 36.0 feet (11.0 m) west
of the sixth boat cleat east of the NW corner of the northern boat slip, 8.0
feet (2.4 m) SW of the SE corner of an abandoned tin building, and 1.7 feet
(0.5 m) north of the outside edge of the bulkhead for the boat slip.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 08/19/1988
Station ID: 8726668 SUPERCEDED DATE: 04/21/2003
Name: HOOKERS POINT, SEDDON CHANNEL, HILLSBOROUGH BAY
FLORIDA
NOAA Chart: 11413 Latitude: 27° 55.1' N
USGS Quad: TAMPA Longitude: 82° 26.7' W
T I D A L D A T U M S
Tidal datums at HOOKERS POINT, SEDDON CHANNEL, HILLSBOROUGH BAY based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: DECEMBER 1978 - MARCH 1979
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8726639 BALLAST POINT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (03/23/1979) = 4.04
MEAN HIGHER HIGH WATER MHHW = 2.57
MEAN HIGH WATER MHW = 2.30
MEAN TIDE LEVEL MTL = 1.35
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 0.99
MEAN LOW WATER MLW = 0.40
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (01/03/1979) = -1.87
* NGVD is based on elevations published in Quad 270821, July 1973 and NOS
leveling of 1982.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
6668 A 1977 6.37 4.07
HP 2 1947 8.54 6.24
HP 3 1947 8.62 6.32
BM 4 RESET 1963 8.32 6.02
6668 B 1977 6.38 4.08
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 08/19/1988
Station ID: 8726668 SUPERCEDED DATE: 04/21/2003
Name: HOOKERS POINT, SEDDON CHANNEL, HILLSBOROUGH BAY
FLORIDA
NOAA Chart: 11413 Latitude: 27° 55.1' N
USGS Quad: TAMPA Longitude: 82° 26.7' W
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 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.