AMC hydrodynamic facilities have been extensively used to conduct a comprehensive series of ship model experiments to quantify the waves generated by marine vessels. One outcome of this study has been the development of a database of experimental wave wake measurements for a large variety of hull forms to provide a useful tool for designers and researchers. This database presently includes approximately 90 hull form conditions, from which plots like that shown in the figure below can readily be produced.

Figure 1 - Wake Database

Some of the activities that this database has been used to assist the Australian ship building industry to date include:

• make direct and fair comparisons between competing designs or against specific limits
• assist in determining the most appropriate vessel form for a specific purpose
• investigate the effect that a particular design variable, such as waterline length or displacement, has on the waves generated
• assist in determining an achievable and rational criteria for any specific location for a proposed vessel and vessel speed.

AMC facilities have been extensively used to conduct a comprehensive series of ship model experiments to quantify the waves generated by marine vessels. Work completed in the last five years has included the following tasks:

• development of a method by which the major characteristics of the waves generated can be measured and presented in a way that best represents the problems that these waves cause, and can be used to directly and fairly compare one vessel against another vessel;
• development of a database of experimental wave wake measurements for a variety of hull forms to provide a useful tool for designers and researchers alike for the development of hull forms that display low wash characteristics. This database presently includes approximately 90 hull form conditions, from which plots like that shown in the figure below can readily be produced.

Some of the activities that this database has been used to assist the Australian ship building industry to date include:

• make direct and fair comparisons between competing designs or against specific limits
• assist in determining the most appropriate vessel form for a specific purpose
• investigate the effect that a particular design variable, such as waterline length or displacement, has on the waves generated
• assist in determining an achievable and rational criteria for any specific location for a proposed vessel and vessel speed.

Figure 2. Scale model of a passenger cruise vessel
during testing in the AMC Model Test Basin


Figure 3. Testing conducted to investigate
FPSO offloading operability

The experimental program has also included the conduct of full-scale experiments on a number of existing vessels. The conduct of scale model experiments within a controlled environment can be seen in Figure 2. The combination of both model and full scale experiments has resulted in the development of correction/scaling techniques to enable accurate predictions of wave wake properties to be made from model experiments. Also developed are a series of procedures to assist in the development of rational vessel operational criteria in order to minimise the effects of vessel wash.

When operating in restricted water the behaviour of a ship can be significantly influenced by the presence of nearby lateral banks. The restrictions due to the banks force the fluid flow around the ship to be asymmetrical. This creates a net sway force and yaw moment, which can lead to potentially dangerous situations. In order to optimise port design and predict the maximum size of ship that can be safely operated in a given port it is necessary to understand the effect that lateral banks have on the manoeuvring characteristics of a ship.

A series of model tests have been conducted in both the Towing Tank and Model Test Basin with the model constrained in surge, sway and yaw to enable the measurement of the resultant bank induced sway force and yaw moment. The effect of vessel draught, bank height, water depth, bank slope and ship to bank distance have been investigated.

This data has also been used to provide more realistic simulations within AMC's shiphandling simulator. This has enhanced its use as a tool to evaluate dredging requirements, conduct channel design, harbour pilot training and nautical risk analysis.

A series of physical experiments were undertaken within the Model Test Basin as part of a study to quantify the lateral motions of a Floating Production Storage Offloading (FPSO) and shuttle tanker during an offloading operation. The motions of both vessels and the forces on the FPSO mooring lines and hawser were measured for a number of different sea states. A photograph from these experiments is shown in figure 3.

Designs for a wave energy device have been constructed to a scale of 1/25th in order to investigate the hydrodynamic loads and motions on the structure and mooring systems. This work has been conducted for Energetech Australia Pty Ltd who are developing a unique near-shore system for converting ocean wave energy into usable electricity. To date, three phases of tests have been conducted within the AMC Model Test Basin by AMC staff specialising in experimental hydrodynamics. The models are geometrically and kinematically similar to the 300kW prototype demonstration wave energy plant to be installed off the south breakwater at Port Kembla, New South Wales in October 2004. A photo of one of the models during these experiments is shown below.

Tests were conducted over a wide range of both operational and extreme storm conditions. Wave heights were varied from 1m up to 6m, and wave periods ranged from 6s to 12s. The structure was tested at three different headings (0, 22.5 and 45 degrees). Continuous measurements of mooring line forces, structure motions and loads, chamber and turbine pressures and wave elevations.

Acknowledgement is given to Energetech Australia for their permission to publish the above details.

Figure 4. Testing 1/25th scale wave energy device.

Figure 5. Testing 1/25th scale wave energy device.