ADCP's Application to Ocean Current Measurement in Fremantle Port

1. Where is Fremantle Port?

Fremantle Port is in Fremantle, West Australia, about 19 km southwest of Perth. It is the major gateway for the trade of Western Australia, facilitating a wide variety of cargoes.

Port Scale and Throughput

Fremantle Port is one of the busiest ports in Australia. It has a high annual throughput, with millions of tons of cargo handled every year. The port has a number of berths that can handle different types of vessels, from large bulk carriers to container ships. It is capable of handling general cargo, bulk cargo such as iron ore, grain, and petroleum products, as well as containers. For many years, the container throughput has gradually increased, mirroring the increase in international trade across the region.

Routes and Business

The port is an important link in several international shipping routes. It has direct links with most key ports in the world: Asia, Europe, and the Americas. The import and export of goods are mainly the business focus of this port. It plays a very significant role in the state's economy, through which resources mined in West Australia, such as iron ore and natural gas, are transported to overseas markets. It also imports consumer goods, machinery, and other essentials into the local and regional markets.

Port Management and Operations

Fremantle Port is controlled by the Fremantle Port Authority. The Authority's mandate covers the efficient management, development, and regulation of the port while ensuring that all requirements regarding safety, environment, and shipping are complied with. This port has its operations highly coordinated in teams allocated to berth allocation, cargo handling, and vessel traffic management. Modern technology optimizes these operations; examples are advanced port management systems used to track cargo and vessels.

Facilities at the Port

The facilities at the port are several. These encompass cargo handling facilities, for example, high-capacity cranes with the ability to handle container cargo and bulk cargo. Storage facilities are also available for various types of goods, with specialized facilities for perishable goods and hazardous materials. There are also fueling facilities for vessels and maintenance and repair facilities to ensure that ships visiting the port are able to operate smoothly.

Channels and Direct Navigation

The shipping channels at Fremantle are well maintained, with the main channel deep and broad enough to accommodate vessels with large drafts. Because of this fact, dredging operations are continuously conducted to maintain the required depth. There are also aids to navigation such as buoys and lighthouses for safe navigation of the port. Direct shipping services are available to a majority of the international major ports, which helps the port in quick turnover and reduction in transit times.

2. Why should we measure the ocean currents in the Fremantle Port?

The measurement of ocean currents in Fremantle Port is important for many aspects of port operations and management.

Safety of Vessel Navigation

Ocean currents can have a great impact on vessel navigation. Strong currents can affect a ship's speed, direction, and maneuverability. In the Fremantle Port, with hundreds of vessels of different sizes and types entering and leaving every day, precise knowledge about the current is very much crucial for safe navigation. For example, when a vessel is approaching the berth, an unexpected current can drive it off from its intended path, probably with collisions with other vessels or port structures. It provides a lot of valuable information to pilots and masters for maintaining speed and course for safe berthing and unberthing.

Efficiency in Cargo Handling

Ocean currents also relate to efficiency in cargo handling in the port. Currents can affect vessels' stability during the loading and unloading process. In a very strong current, this may offset the vessel, so that the accuracy of cranes in placing or retrieving cargo will be badly affected. This leads to slowing down cargo handling operations. If there is real - time information on the currents of the ocean, the operators can schedule the handling of cargo when the current is relatively fair, hence enhancing efficiency at the ports.

Environmental Protection

Knowledge of the ocean currents will help in environmental protection within the port area. Currents are able to carry a pollutant from one location to another. If an accident causing spillage occurs, the direction and speed of the current will come in handy, giving a quicker prediction of where the pollutant is spreading to. This, in turn, allows the port authorities to take necessary counter-measures in time, such as the deployment of oil-skimming equipment or laying containment booms in the areas concerned.

In short, accurate measurement of ocean currents is indispensable for the safe, efficient, and environmentally friendly operation of Fremantle Port. And ADCP has emerged as a more advanced and convenient method for such measurements.

3. How do ADCPs based on the Doppler principle work?

Principle of ADCP Measurement

Working on the principle of the Doppler, ADCPs emit a sound wave emitted from the transducer travels via water and gets reflected off particles suspended in water. These particles, moving with the flow of water. Due to the relative motion between the ADCP and the moving particles, the frequency of the reflected acoustic wave differs from the frequency of the emitted wave. The frequency shift-the so-called Doppler shift-is directly related to the velocity of the particles and thus the velocity of the water flow.

ADCP in Port Ocean Current Measurement - Specific Methods

Ship - borne ADCP

A ship-borne ADCP is installed on the hull of a moving ship. While the ship is underway, the ADCP is able to measure the water velocity at different depths relative to the ship. A ship-borne ADCP can give one continuous profile of the ocean current over a large area. This is useful for mapping the general current patterns in the port and its surrounding waters. For instance, an ADCP could record the current conditions for a routine passage of a ship through the port; such data may be used in analyzing long-term current trends.

Fixed ADCP

Fixed ADCPs are installed at fixed locations in the port, either on the seabed or attached to a fixed structure. These ADCPs can provide long-term, continuous measurements of ocean currents at a certain point. They come in handy when there is monitoring of current conditions at critical areas in the port, for instance, around berths or in shipping channels. Fixed ADCPs may record data over longer periods, which could be used to study the diurnal, seasonal, and long-term variations in ocean currents.

4. What is needed to measure the currents of Fremantle Port on a high level?

Reliability of Equipment

High-quality measurement of ocean currents in Fremantle Port requires highly reliable equipment. The harsh marine conditions, such as saltwater corrosion, strong waves, and variable water temperatures, may be challenging for the equipment. The materials used in the construction of the ADCP have to be able to bear such conditions. For example, the casing of the ADCP should be manufactured from materials that resist corrosion.

Size, Weight, and Power Consumption

The ADCP should be compact in size and lightweight, smaller in size and low in weight, which is of great concern in applications such as ship-borne or fixed-point installations. A lighter and compact ADCP has a number of advantages with regard to installation, maintenance, and possible shifting. Furthermore, small power consumption is of importance, especially for fixed-point or long-term monitoring. Low-power devices can keep operating for much longer without the need to constantly change batteries or be connected with a large power source.

Economical

The ADCP should be moderately inexpensive so that ocean currents in the port can be measured on a large scale. Too expensive equipment would allow the deployment of only a few units, hence making the data collection not as comprehensive. Cost-effective ADCPs can be installed in more places for more comprehensive current conditions within the port.

Titanium Alloy for ADCP Casing

The casing of the ADCP shall be fabricated from a Titanium alloy. A few of the added benefits for using a Titanium alloy are highlighted hereafter: being particularly resistant to corrosion in saltwater environments, this one would be critical for long-term operation in the port. Being lightweight contributes to fulfilling the requirement of ease of installation and portability. Besides, the high strength of the titanium alloy can protect the internal components of the ADCP from damage caused by impacts, such as those from waves or debris in the water.

5. How to Choose the Right Equipment for Current Measurement?

Based on Usage

Ship - borne ADCP

As mentioned previously, a ship-borne ADCP is fit to acquire a large-scale overview of the ocean currents. It is fitted for surveying the general patterns of the currents in the port and its adjacent waters. If a ship makes regular voyages through the port, it can mount a ship-borne ADCP to gather data along its route.

Bottom-mounted (Sitting-bottom) ADCP

A bottom-mounted ADCP is designed to be laid on the seabed. It is meant mainly for long-term, continuous monitoring of the currents at that location. This type of ADCP is useful in studying the local current condition at critical areas in the port, like near the entrance of a shipping channel or close to a berth.

Buoy-mounted ADCP

A buoy-mounted ADCP is attached to a floating buoy. It can move with the flow of the water, and thus deliver information on the surface-layer currents. Generally, buoy-mounted ADCPs serve useful purposes in monitoring current conditions at the surface level that may be of importance in studying the interaction of the atmosphere and the ocean near the port.

Based on Frequency

The frequency of an ADCP is selected according to the depth in which a measurement is expected to be taken. For example, a 600kHz ADCP should suffice in waters no greater than approximately 70m. Normally, this would be applied to relatively shallow water of the port near shore or areas of relatively flat sea floor. A 300 kHz ADCP might be utilized on depths up to about 110 m and would be applicable in some areas of the inner port or even in the port's approaches. For very deep waters, such as in the outermost areas of the port with a depth reaching 1000 meters, a 75 kHz ADCP is more suitable.

Some of the well-known ADCP brands in the market include Teledyne RDI, Nortek, and Sontek. However, for cost-effective and quality ADCPs, it is recommended to try products made by China Sonar ​PandaADCP, which is a Chinese brand. It is made of all-titanium alloy material, excellent in corrosion resistance and durability. With an excellent cost-performance ratio, it will be very well positioned for ocean current measurement in Fremantle Port and similar applications. You can visit their website at [​https://china-sonar.com] for further details.

Here is a table with some well known Acoustic Doppler Current Profiler(ADCP)  instrument brands and models.