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

1. Where is the Port of Sligo?

The Port of Sligo is situated on the northwest coast of Ireland, and it forms one of the major ports on the region as it serves local and regional maritime needs.

Port Scale and Throughput: The port is of average size, and its throughput consists of cargo like agricultural products, building materials, and fishing catches. There is a number of fishing vessels that use the port. Imports and exports related to the small business and industry are also processed at the port. With the given scale, the port could support the economic activities in the Sligo area and its hinterland.

Routes and Business: Sligo port is connected through shipping routes to other Irish ports and has some links to international destinations. The main business activities include fishing, with the port serving as a base for the local fishing fleet. It is also involved in the transportation of goods such as grains, livestock, and construction materials. Tourism-related activities, such as ferry services for sightseeing and access to nearby islands, contribute to the port's business as well.

Port Management and Operation: Port management focuses on efficient operations. Berthing facilities are made available for the fishing boats and other vessels. Safety measures are required in the vessels and for the personnel who work at the port facility. The port authority is in charge of cargo handling, starting from the arrival of the ship up to its departure after unloading and loading cargo. Similarly, there is also infrastructure and facility management that maintains the infrastructure so that the port can continuously operate.

Port Facilities: The port is equipped with facilities that support its functions. There are berths for different-sized vessels, including those for fishing boats and small- to medium-sized cargo ships. There are storage areas for fish, agricultural products, and other goods. Equipment such as cranes and forklifts are available for loading and unloading operations. There are also fish-handling and cold-storage facilities to preserve the quality of the catches for fishing.

Channel and Direct Shipping: The channel of the port is kept intact for safe vessel passage. The dredging of the water bed is regularly done to keep the water depth suitable for the ships visiting the port. There are direct shipping links that offer the possibility of transporting goods and people from and to other ports. These are vital connections for trading and tourism in the role of the port.

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

Measuring of Ocean currents in the Port of Sligo is quite vital. Due to safe vessel navigation, there are indeed a lot of accurate data on current that is absolutely necessary. The fishing boats as well as several other vessels need to operate safely in and out of the port. These vessels are susceptible to such currents, especially in loaded conditions and bad weather. Accurate current measurements will, therefore, enable the port to give better navigational guidelines to the vessels, thus reducing the chances of an accident.

Secondly, for efficient port operations, current measurements are valuable. Currents can affect the docking and loading/unloading processes. For example, a strong current can make it difficult to position a vessel accurately during docking. With accurate current data, the port can optimize these operations, reduce waiting times, and make the best use of its berthing facilities.

Additionally, it will be helpful from an ecological point of view to understand ocean currents for monitoring the health of the local marine ecosystem. Currents contribute to the distribution of nutrients, fish larvae, and other biological elements. By measuring the currents, the port can help to better understand and conserve the surrounding marine environment. The ADCP current meter provides a more advanced and convenient way to measure these currents compared to traditional methods.

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

The working of ADCPs is based on the Doppler principle. A sonic signal, generally at some ultrasonic frequency, is transmitted by an ADCP current profiler into the water. The signal produced by the ADCP interacts with moving particles in the water, such as suspended sediments or small organisms. Due to the Doppler effect, there will be a frequency shift if the acoustic signal is reflected back to the ADCP profiler. This frequency shift is measured by the ADCP, which then computes the velocity of the water particles-the ocean current velocity.

Ship-borne ADCP

Ship-borne ADCPs can be installed on the fishing boats or other vessels. While the vessel cruises around the port and nearby waters, the ADCP flow meter sends acoustic pulses in various directions, usually downwards and sideways. The device measures the current velocity at multiple depths as the vessel travels. This gives a high-resolution profile of the present conditions across the vessel's track, thus giving an accurate understanding of the current patterns in the areas the vessel covers.

Fixed ADCP

The fixed ADCPs can be deployed in the port at some points: seabed at the berths, at the entrance of the channel, among others. These continuously recorded current measurements from a single point over long periods of time. Long-term measurement of these types is very important to understand long-term current characteristics in some key areas of the port, such as the channel entrance or near the berths.

4. What is required for high-quality measurement of the currents in Sligo port?

High-quality measurement of ocean currents in the Port of Sligo requires equipment made of reliable materials. The device must be able to resist the corrosive nature of seawater and possible physical damage from the marine environment. The size should be small, weight lightweight, and power consumption low. A compact and lightweight ADCP is easier to install and operate, whether on a boat or at a fixed location. Low power consumption allows for continuous operation without frequent battery replacement or high energy demands. Cost-effectiveness is also an important factor in enabling wide-scale deployment in the port.

The casing of ADCP meter is preferably made of titanium alloy. Titanium alloy has excellent corrosion resistance in seawater, which will guarantee the integrity of the device over a long period of time. Besides this, it has a high strength-to-weight ratio, which makes it strong and durable at relatively low weight. Furthermore, titanium alloy is biocompatible, hence reducing adverse effects on the marine environment.

5. Selection of Correct Equipment for current measurement?

The selection of the correct equipment in the Port of Sligo would depend on the specific requirement.

Ship-borne ADCP

This is suitable when an overview of the current conditions over a large area in different parts of the port is needed. The ship -borne ADCP may gather data from various locations as the vessel sails around the port. Thus, it provides a wide-range view of current patterns in the port waters.

Bottom-mounted (Sitting on the seabed) ADCP

This type of ADCP is ideal for long-term and fixed-point monitoring. It can be installed at strategic points in the port, such as at the entrance of the channel or near the berths, to continuously monitor the current conditions in those specific areas.

Buoy-mounted ADCP

Buoy-mounted ADCPs are used in places where the installation of a fixed device either on the seabed or on a boat is not practical. They can be deployed in open water areas within the port to measure currents at different depths.

In the selection of the frequency, different frequencies suit different water depths. A 600 kHz ADCP would be appropriate for water depths up to 70 meters, a 300 kHz ADCP for water up to 110 meters deep, and a 75 kHz ADCP for much deeper waters at up to 1000 meters.

There are well-known ADCP brands like Teledyne RDI, Nortek, and Sontek. However, there is also a Chinese ADCP brand, China Sonar PandaADCP. It is made of all-titanium alloy material, which ensures its durability in the marine environment and offers an excellent 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.