Laboratory Study of UKC for
Charleston Harbor Entrance
Description
A comprehensive series of laboratory experiments were conducted using a model ship and
generic physical model of Charleston Harbor, SC entrance channel to validate a probabil-
istic design tool CADET (Channel Analysis and Design Evaluation Tool) for predicting
underkeel clearance (UKC) and to compare to field measurements.
In April 1999 the Coastal and Hydraulics Laboratory (CHL) conducted a series of field
Issue
measurements of UKC at the Charleston, SC, entrance channel. Eighteen vessels were
boarded and Global Positioning
System (GPS) measurements
were collected of the ship
motions during inbound and
outbound transits of the
channel. Wave and current data
were also collected. UKC is the
required minimum distance
between the ship's keel and
the bottom of the channel. It is
Preparing "President Lincoln" model containership for
a function of the ship size and
a following seas test physical model run
hydrodynamic characteristics,
the channel cross-section and shape, and the ship speed.
In FY04, a comprehensive series of laboratory experiments were conducted at the CHL to
Products
determine UKC response for a model ship (1:75 scale) in a generic model of the
Charleston Harbor entrance channel. A model of the "APL President Lincoln"
containership was instrumented with an inertial motion analysis system to measure the six
degree-of- freedom ship motions of surge, sway, heave, roll, pitch, and yaw. The charac-
teristic dimensions of the model ship are representative of the Alligator Liberty (outbound)
and Munkebo Maersk (inbound) containerships during the 1999 field trials. Seven wave
conditions were simulated with the unidirectional wave generator. These waves were
calibrated using an array of nine-wave gages array in the basin. The data set of over 168
runs included runs for each of the 7 wave conditions, 3 wave approach angles, 2 vessel
speeds, 2 transect directions, and 2 repeats.
The CADET (Channel Analysis and Design Evaluation Tool) can be used to predict under-
Supporting Technology
keel clearance in entrance channels for a range of ship, depth, and wave conditions.
Since every foot of dredging costs millions of dollars, considerable savings can be realized
Benefits
if the UKC can be safely reduced. This dataset are being used to validate the CADET
probabilistic model for predicting UKC.
U.S. Army Corps of Engineers Navigation Systems Research Program.
Sponsors
Dr. Michael J. Briggs, CEERD-HN-HH, 3909 Halls Ferry Road, Vicksburg, MS 39180-
Point of Contact
6199, e-mail: . Additional information can be
found at http://chl.erdc.usace.army.mil.
U.S. Army Engineer Research and Development Center
August 2004
Coastal and Hydraulics Laboratory (Project/Mission Support)
www.erdc.usace.army.mil