U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8723355                         PUBLICATION DATE:  02/26/2004
Name:       RAGGED KEY NO. 5, BISCAYNE BAY                    
            FL
NOAA Chart: 11465                           Latitude:   25° 31.4' N (  25.52330)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 10.5' W ( -80.17500)


To reach the tidal bench marks from the Florida Turnpike overpass of U.S.
Highway 1 in Florida City, proceed north on U.S. Highway 1 for 1.0 km (0.6 mi)
to Lucy Street, then east on Lucy Street for 14.2 km (8.8 mi) to the Biscayne
National Park boat ramp.  From there, proceed ENE by boat for 16.9 km (10.5
statute mi) to Boca Chita Key (also known as Ragged Key No. 5).  The bench marks
are in the vicinity of the boat basin.  The tide gage and staff were SW of the
boat basin near a stone wall.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  3355 E 1987
                         DESIGNATION:          872 3355 E

MONUMENTATION:           Tidal Station disk                    VM#:         5818
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete flagpole base                OPUS PID:        
LATITUDE:   25° 31.4' N (  25.52330)          LONGITUDE:  80° 10.6' W ( -80.17670)


The primary bench mark is a disk set in a 2 m (6 ft) diameter concrete flag pole
base, 91 m (300 ft) south of the lighthouse across from the boat basin entrance,
9.30 m (30.5 ft) NE of the NW corner of a stone fence, 9.02 m (29.6 ft) NNE of
the NW corner of a gate opening, and 2.38 m (7.8 ft) SE of a sea wall.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8723355                         PUBLICATION DATE:  02/26/2004
Name:       RAGGED KEY NO. 5, BISCAYNE BAY                    
            FL
NOAA Chart: 11465                           Latitude:   25° 31.4' N (  25.52330)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 10.5' W ( -80.17500)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  3355 D 1987
                         DESIGNATION:          872 3355 D

MONUMENTATION:           Tidal Station disk                    VM#:         5817
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete walkway                      OPUS PID:        
LATITUDE:   25° 31.4' N (  25.52330)          LONGITUDE:  80° 10.6' W ( -80.17670)


The bench mark is a disk set in the south side of a concrete walkway surrounding
an ornamental lighthouse, 4.36 m (14.3 ft) north of the north end of a cannon,
2.47 m (8.1 ft) south of the south side of the lighthouse, and 0.15 m (0.5 ft)
east of a 0.91 m (3.0 ft) high pillar.



                         BENCH MARK STAMPING:  3355 F 1987
                         DESIGNATION:          872 3355 F

MONUMENTATION:           Tidal Station disk                    VM#:         5819
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   25° 31.4' N (  25.52330)          LONGITUDE:  80° 10.6' W ( -80.17670)


The bench mark is a disk SE of the SE end of the boat basin, 43.28 m (142.0 ft)
NNW of the north corner of the Captains Roost cabin, 41.03 m (134.6 ft) ENE of
the NE corner of a stone and concrete foot bridge, 5.82 m (19.1 ft) SSE of the
north edge of the boat basin sea wall, and 0.55 m (1.8 ft) SSE of a utility
pole.  The bench mark is set 6 cm (0.2 ft) below ground level, crimped to the
top of a stainless steel rod driven 3.4 m (11 ft), and encased in a PVC pipe and
concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8723355                         PUBLICATION DATE:  02/26/2004
Name:       RAGGED KEY NO. 5, BISCAYNE BAY                    
            FL
NOAA Chart: 11465                           Latitude:   25° 31.4' N (  25.52330)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 10.5' W ( -80.17500)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  3355 G 1987
                         DESIGNATION:          872 3355 G

MONUMENTATION:           Tidal Station disk                    VM#:         5820
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   25° 31.4' N (  25.52330)          LONGITUDE:  80° 10.6' W ( -80.17670)


The bench mark is a disk SE of the boat basin, 46 m (150 ft) south of the SE
corner of the "Gunkhole" cabin, 3 m (10 ft) SSE of the NE corner of a wall, and
0.55 m (1.8 ft) ENE of the east face of a 1.07 m (3.5 ft) high rock wall.  The
bench mark is set 6 cm (0.2 ft) below ground level, crimped to the top of a
stainless steel rod driven 3.0 m (10 ft), and encased in a PVC pipe projecting 6
cm (0.2 ft) and a concrete kickblock.



                         BENCH MARK STAMPING:  3355 H 1987
                         DESIGNATION:          872 3355 H

MONUMENTATION:           Tidal Station disk                    VM#:         5821
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete ramp                         OPUS PID:        
LATITUDE:   25° 31.4' N (  25.52330)          LONGITUDE:  80° 10.6' W ( -80.17670)


The bench mark is a disk set in the concrete ramp of a large garage-type
building SE of the boat basin, 98 m (321 ft) east of bench mark 3355 G 1987,
0.43 m (1.4 ft) NE of the NW corner of the building, and 0.15 m (0.5 ft) NNW of
the north side of the building.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8723355                         PUBLICATION DATE:  02/26/2004
Name:       RAGGED KEY NO. 5, BISCAYNE BAY                    
            FL
NOAA Chart: 11465                           Latitude:   25° 31.4' N (  25.52330)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 10.5' W ( -80.17500)


                            T I D A L   D A T U M S 


Tidal datums at RAGGED KEY NO. 5, BISCAYNE BAY based on:

     LENGTH OF SERIES:      2 MONTHS
     TIME PERIOD:           August 1987 - September 1987
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8723962 KEY COLONY BEACH


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  0.511
     MEAN HIGH WATER                            MHW    =  0.510
     MEAN TIDE LEVEL                            MTL    =  0.277
     MEAN SEA LEVEL                             MSL    =  0.272
     MEAN LOW WATER                             MLW    =  0.044
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     3355 E 1987                                 1.236    0.726
     3355 D 1987                                 1.373    0.863
     3355 F 1987                                 0.957    0.447
     3355 G 1987                                 1.412    0.902
     3355 H 1987                                 2.397    1.887


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 8723355                         PUBLICATION DATE:  02/26/2004
Name:       RAGGED KEY NO. 5, BISCAYNE BAY                    
            FL
NOAA Chart: 11465                           Latitude:   25° 31.4' N (  25.52330)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 10.5' W ( -80.17500)


                             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.