Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/10762
Title: Review and evaluation of work performed by Stevens Institute of Technology for the Atlantic-Pacific Interoceanic Canal Study Commission
Authors: United States. Atlantic-Pacific Interoceanic Canal Study Commission.
Harrison, John, 1939-
Keywords: Ships
Tows
Manuverability
Hydrodynamics
Canals
Inland waterways
Mathematical models
Numerical models
Evaluation
Stevens Institute of Technology
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; H-70-7.
Description: Miscellaneous Paper
Abstract: While small navigational errors in the open ocean usually require only slight corrective action and have no serious consequences, the same errors made in confined waters could have costly and disastrous results. The knowledge of the maneuverability of ships operating safely under preconceived plans and rules is basic to the design and operation of any confined waterway. The two basic engineering methods for studying ship maneuverability in confined waters are physical scale model testing and mathematical modeling. Staff members of the Davidson Laboratory of Stevens Institute of Technology (SIT) undertook the development of mathematical modeling techniques to describe ship maneuverability in confined waters. The three basic problems studied by SIT were (A.) the motion of a single ship subjected to a small course change while traveling on an equilibrium course either on or off the canal center line, (B.) the passing of two ships in a canal, and (C.) the use of tugboats to increase ship maneuverability. After completion of SIT's study, the Office, Chief of Engineers, requested this review of the work performed. This review (1.) evaluates the basic data used, (2.) evaluates the assumptions used, (3.) evaluates the analytical relations and the solution procedures used, (4.) analyzes the accuracy and validity of results, (5.) judges the applicability of results to crucial design and the development of operational procedures, and (6.) comments on the use of computer simulation as opposed to physical models. In addition, the present work clarifies and consolidates the methodologies developed by SIT. In addition to the ship and canal geometry, two types of data are required to utilize SIT's mathematical model: rudder control gain constants and hydrodynamic coefficients. SIT's assumptions with regard to rudder control gain constants are valid and the values are considered correct and adequate. However, the use of unverified hydrodynamic coefficients as basic data makes the problem solutions questionable. The other limiting assumptions do not impair the derivation and use of the preliminary mathematical model, but should be eliminated for a more general representation. The analytical relations and solution procedure used to develop and apply the simplified two-dimensional linear model are valid. A review and evaluation of SIT's nonlinear model is not possible because no description of this model is contained in the subject reports. The linear model cannot be expected to yield correct quantitative descriptions of ship maneuverability for two reasons: (1.) some nonlinear terms must be included in the hydrodynamic force and moment representations, and (2.) solution of the linear perturbation equations allows only small deviations from the ship's intended course. SIT's composite limiting contour curves should not be used to quantitatively design a canal size for a given ship traveling at a given speed. The mathematical description of ship passing is limited by the fact that the interaction effect of two ships is not included in the mathematical model. Under the current state-of-the-art, mathematical models cannot provide all of the quantitative design and operation information necessary for a sea-level canal project. However, a comprehensive scale model testing program would give accurate answers to all the subject problem areas.
Rights: Approved for public release; distribution is unlimited.
URI: http://hdl.handle.net/11681/10762
Appears in Collections:Miscellaneous Paper

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