ADCP's Application to Ocean Current Measurement in the Port of Youghal

1. Where is Youghal port?

Youghal is a port city in County Cork, Ireland. The port of Youghal is a small but significant coastal port.

In terms of its scale and throughput, it serves local fishing fleets and also welcomes a number of small to medium-sized commercial vessels. Annual throughput includes a significant amount of fish and seafood products because of the strong catching industry in the vicinity. It also handles small amounts of general cargo associated with the local economy and tourist traffic.

The main routes of transport in this port are focused on local and regional trade only. The port undertakes the movement of goods that is there between the nearby coastal areas and has also acts as a fishing base with vessels operating along the Irish Sea. Handling at the port is done without any obstacles regarding fishing as well as cargo shipment. Overall, management of the port takes place concerning safety to docking and other facilities as well so as to manage the maritime business locally operating.

The port facilities include a quay with berthing space for fishing boats and small cargo vessels. There are fish - handling areas with cold storage facilities to keep the catch fresh. In addition, there are basic amenities for the crews of the vessels.

The channel in Youghal port is maintained to allow for safe passage of local fishing boats and small trading vessels. Navigation aids are in place to assist ships in entering and leaving the port, ensuring direct and safe navigation for the vessels frequenting the port.

2. Why should we measure the ocean currents in the Youghal port?

Measurement of ocean currents in the Youghal port is important for various reasons. First, regarding the fishing industry, understanding the ocean currents will enable fishermen to locate fish with much more effectiveness. Most fish species would come together in areas where currents carry nutrients. Understanding current patterns thus enables fishermen to take a better route for fishing and hence increase their catch.

From the point of view of port operations, the precise current data would facilitate the safe docking and undocking of vessels. Currents can affect the maneuverability of ships, especially small and medium-sized ones. In this respect, having current measurements in high resolution enables the port authorities to better advise vessel captains and hence reduces the risk of accidents during these operations.

Moreover, the knowledge of ocean currents is crucial for the long - term maintenance of the port infrastructure. The impact of currents on the quay walls and other structures can be significant over time. By monitoring the currents, preventive measures can be taken to protect the port facilities from erosion and other forms of damage.

With Acoustic Doppler Current Profiler (ADCP), there is a far more refined and effective method for these measurements. They can, in very quick time and with a high degree of accuracy, provide substantial detail of the current speed and direction at varied depth, much more so than traditional methods of measurement.

3. How do Doppler principle ADCPs work?

ADCPs work on the principle of the Doppler effect. They send acoustic pulses into the water. As a result of the interaction with the particles which are moving with the ocean currents (such as plankton, suspended sediments), the frequency of the reflected signals changes. This change in frequency is proportional to the velocity of the moving particles.

By using sophisticated algorithms, the ADCP current meter analyzes the difference between the emitted and received frequencies to calculate the speed and direction of the ocean currents. In the case of Youghal port, two common deployment methods of ADCPs are:

Ship-borne ADCP: The ADCP current profiler is installed on a fishing boat or a small survey vessel. While the boat is moving around the port area and its adjacent waters, the ADCP continuously measures the ocean currents. It can cover a relatively wide area and give a good understanding of the current pattern in different parts of the port and the nearby sea.

Fixed ADCP: A fixed ADCP is placed on the seabed near the port entrance or at other critical locations and continuously monitors the current conditions of a point. This has been useful for long-term and stable current measurement and provides valuable data for the understanding of the regular flow of currents and any sudden changes that might occur.

4. What are the requirements for good measurement of Youghal port currents?

For high-quality current measurement in Youghal Port, the equipment requires reliable materials. Considering seawater is corrosive, and the environmental conditions change most of the time, equipment should be in a way that it could bear it. Compact size is important because some areas of the port have very limited space, and smaller-sized ADCP can be installed easily either on a vessel or on a fixed installation.

Light weight is another advantage. For ship-borne ADCPs, lighter weight means less impact on the stability and handling of the vessel. Low power consumption is crucial for fixed ADCPs operating continuously. It reduces the cost and complexity of power supply systems.

For the casing material, the best choice would be the titanium alloy. The properties of corrosion-resistance for titanium alloy are very strong, which is important in bearing the harsh marine environment. It also has a relatively high strength-to-weight ratio, enabling a durable yet lightweight design. This material can bear the pressures and impacts that the equipment may face in the port waters.

5. Selection of Equipment for Current Measurement?

The usage scenario stands out as one of the main factors when choosing current measurement equipment in Youghal port.

Ship-borne ADCP: When the intention is to carry out surveys of a greater area of the port and surrounding waters, a ship-borne ADCP is a good option. It can be used during fishing trips or routine port surveys to gather current data over a wide range.

Bottom-mounted (sit-on-bottom) ADCP: For long-term and stable current monitoring at specific locations such as the entrance of the port or near important berths, a bottom - mounted ADCP is suitable. It provides a continuous stream of data about the local current conditions.

Buoy-mounted ADCP: When a more flexible and movable measurement point is required, a buoy-mounted ADCP can be considered. It can be deployed in different areas of the port waters depending on the specific requirements.

Different frequencies are suitable for different water depths in terms of frequency selection. A 600kHz ADCP often works quite well for water depths up to 70m, while a 300kHz ADCP is more appropriate for depths up to 110m. A 75kHz ADCP would be suitable for deeper waters, measuring up to 1000m.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, a Chinese brand, China Sonar PandaADCP, is also worth considering. It is made of all-titanium alloy material, ensuring its durability and performance in the marine environment. It also offers a great cost-performance ratio. You can find more information on its website: (https://china-sonar.com/).

Here is a table with some well known ADCP instrument brands and models.