Deep Draft Navigation Underkeel
Clearance Study (DDNav)
Description
In FY98 the Coastal and Hydraulics Laboratory began a program to improve the underkeel
clearance (UKC) requirements through a series of field and laboratory measurements of
6 degree of freedom (DOF) ship motions for a range of entrance channel configurations,
ship, and wave conditions.
Field data were collected
for a variety of ships in the
entrance channels at
Barbers Point, HI, and
Charleston, SC, using
Global Positioning Systems
(GPS). Laboratory data
were collected in a 1:75
scale of the Barbers Point
and Charleston entrance
channels using a state-of-
the-art motion analysis
system (MOTAN) of
accelerometers and angular
rate sensors for surge, sway,
heave, roll, pitch, and yaw.
World Utility bulk carrier entering Barbers Point Harbor,
The next generation of ships
Issue
HI. Inset of CADET underkeel clearance numerical model
will require deeper drafts
and more costly dredging to maintain coastal entrance channels to insure safe navigation.
UKC is the required minimum distance between the ship's keel and the bottom of the
channel. The UKC is a function of the ship size and hydrodynamic characteristics, the
channel cross-section and shape, and the ship speed. Since every foot of dredging costs
millions of dollars, considerable savings can be realized if the UKC can be safely.
The probabilistic design tool CADET (Channel Analysis and Design Evaluation Tool) for
Products
predicting UKC for different wave, ship, and channel combinations.
Improve entrance channel design and reduce construction and O&M costs using field and
Benefits
laboratory data and CADET probabilistic model. Provide input to CHL's ship simulator.
Navigation Research Program.
Corps Program
Dr. Michael J. Briggs, CEERD-HN-H, 3909 Halls Ferry Road, Vicksburg, MS 39180-
Point of Contact
6199; e-mail: . Additional information can be
Naval Surface Warfare Center, Carderock Division.
Partners
U.S. Army Engineer Research and Development Center
August 2004
Coastal and Hydraulics Laboratory (Research)
www.erdc.usace.army.mil
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