The United States infrastructure system is deteriorating and in dire need of improvements in order to maintain competitive within the global economy. The 2017 infrastructure report card from the American Society of Civil Engineers (ASCE) narrowly passed the ports and inland waterways of the U.S, stating the facilities were beyond design life and inadequate for the demands of modern vessels. The U.S. Army Corps of Engineers is tasked with the challenging job of maintaining all U.S. ports and waterways with a limited budget. A large part of improving the waterways of the U.S. includes the work to deepen and widen ship channels and inland waterways. In order to efficiently utilize the limited improvement resources, efficient dredging techniques are required, therefore this paper focuses on the hydrodynamic aspects of waterway design and operation.
As a ship sails through a waterway there are many considerations that influence the path of the ship. Obvious culprits include the bathymetry of the waterway, the presence of waterborne traffic, the availability of maneuvering devices, such as tugs and thrusters, and the environment. The less obvious factors include the hydrodynamic effects of maneuvering within confined waterways. Hydrodynamic phenomena including bank suction, passing vessel and shallow water effects can be significant and are often the dominant force contribution on a vessel in a waterway. To assess all of the hydrodynamic effects, a combination of simulation tools is required. Model tests, potential flow codes, and complete Navier-Stokes CFD methods are needed to develop high fidelity models that can accurately predict the hydrodynamic effects encountered by vessels in ports and waterways. To study in detail all the hydrodynamic effects present on a single vessel or maneuver is not a cost effective option. Fortunately, software programs are available that use hydrodynamic databases to predict the motions of vessels in response to confined space hydrodynamics. A combination of software packages is required to assess the full cycle, from transit to berthing, of a vessel in a waterway. Programs such as SHIPMA utilize the combination of depth-to-draft dependent vessel maneuvering models, bank suction models, maneuvering devices (thrusters, tugs), and an autopilot to assess the accessibility of waterways designs for a variety of vessels and environments. The ROPES software can be used to predict the effect of a passing vessels on a moored vessel’s motion response and programs such as aNySIM XMF can be used to study mooring systems and vessel response to environmental and mechanical loading. In addition to the hydrodynamic effects experienced in waterways, it is important to also address the operational feasibility of the maneuvers being simulated. Real-time bridge simulations combined with sophisticated maneuvering models can be used to assess the operational feasibility of maneuvers with input and feedback from operators such as pilots, captains and tug masters. This allows for operational input to be considered in the design process. The models produced at each stage of a study can be used in combination to produce a final maneuvering model that can be used in time domain simulation software in both real-time and fast-time. This complete model can be efficiently transferred between simulation platforms to allow for accurate and consistent results.
This paper will discuss the use of software to aid and improve the design of waterways and waterway infrastructure. Cases will be discussed to demonstrate the importance of modeling the complex hydrodynamic effects experienced by vessels in confined water. A passing vessel case will be discussed for multiple speeds and passing distances. A mooring design study will be combined with the results of the passing ship simulations to assess the effect of passing vessels on the mooring system. Finally, a waterway feasibility analysis will be presented for vessels sailing with and without the effect of bank suction and depth to draft dependent maneuvering models. The use of software to improve waterway design and operation will be demonstrated by a waterway feasibility case study that focuses on vessel dependent spatial and environmental limits, tug requirements, and identification of waterway hazards.