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

1. Overview of the Port of Greenore

The Port of Greenore is situated in County Louth, Ireland. It is a relatively small but important port with a history of maritime activities.

Port Scale and Throughput

• It has only small-scale port infrastructures. Throughputs are dominated by local and regional trade items such as building material, agriculture products, and light industrial items. Its other purpose also includes providing docking points to smaller vessels such as fishing boats or small-sized cargo vessels.
• There are a few berths with distinct characteristics to accommodate the vessels frequenting the port. The port capacity is built to move a limited volume of traffic, focusing on the demand of the local area and nearby regions.

Routes and Business

• Domestically, it is connected to other Irish ports, facilitating the movement of goods within the country. Regionally, it has some connections to ports in the UK and other nearby European countries. The main business activities involve cargo handling, fishing, and support for local industries.
• The port provides a base for fishing operations, with facilities for landing and storing fish. It also plays a role in the import and export of local products such as aggregates and food products.

Port Management and Operation

• The port operates through a management that coordinates in every aspect involved. In these aspects are arranging the berth of vessels, planning unloading and loading of ships' cargo, ensuring security, and all that in general involves a safe working area.
• The management also works with local fishermen, farmers, and other businesses to ensure smooth operations. They are responsible for maintaining the port's facilities and the channel to enable ships to enter and exit safely.

Port Facilities

• It has basic port facilities such as berths of appropriate depths for vessels, cargo-handling equipment like cranes and forklifts to assist in transferring goods from one vessel to another or to trucks for further transportation.
• Storage areas, including facilities for storing fish and building materials. This also offers refueling for ships that come into this port and basic maintenance services.
• It has a maintained channel so that the ships can safely enter and leave. Dredging is done according to the requirement to retain the depth for ships of variable drafts. Navigation aids like buoys and lights help in guiding the ships for both approach and departure in a way that vessels directly can navigate from different directions in the Irish Sea.

2. Importance of Measuring Ocean Currents in the Port of Greenore

Navigation Safety

• It is of great importance to measure the ocean currents at the Port of Greenore for ship safety. Current patterns are usually very unpredictable in the Irish Sea and may consequently affect the movement of small vessels. Knowledge of these currents helps captains to navigate more safely, especially during docking and undocking operations.
• A light fishing boat, for example, will be sent off course by any reasonable current. This may place a vessel in jeopardy of colliding with other vessels or even running aground. Good current information enables the captains to set a proper speed and course to avoid all of those risks.

Efficient Port Operations

• It helps in understanding the ocean currents for the smooth functioning of the port. Understanding the current patterns, the port authorities can schedule the arrival and departure of ships accordingly. The ships can thus avail the facility of favorable currents while consuming less fuel for docking and undocking.
• This also enables the optimization of port resources. For example, if the current is in a direction which assists the ship to be taken to a particular berth, then its loading and unloading operation can be more efficient.

Environmental Protection

• Currents play an important role in the distribution of pollutants in the port area. In the event of an oil spill or any other chemical release, the pattern of currents needs to be known to effectively take containment and clean-up operations.
• The port can also manage the discharge of wastewater and other substances more effectively by considering the current patterns, minimizing their impact on the marine environment.

Infrastructure Maintenance

• The forces exerted by ocean currents over time can affect the structural integrity of port infrastructure such as breakwaters and quay walls. Measuring the currents provides valuable data for the long-term planning and maintenance of these structures.
• For example, if the currents are consistently strong in a particular area, additional reinforcement may be needed to prevent erosion and damage to the quay walls. ADCP (Acoustic Doppler Current Profiler) provides a more advanced and convenient way to measure ocean currents compared to traditional methods.

3. How ADCPs Using the Doppler Principle Work

• The principle of operation of ADCPs is based on the Doppler principle. They send acoustic signals into the water. These acoustic waves scatter off the moving particles in the water, such as sediment, plankton, or other small organisms carried by the ocean current. When the waves bounce back, the frequency of the reflected waves changes.
• This frequency change, called the Doppler shift, is proportional to the velocity of the moving particles and thus proportional to the velocity of the ocean current. ADCPs are equipped with several transducers, which send and receive the acoustic signals in different directions. By measuring the Doppler shift from multiple directions-usually in a three-dimensional or two-dimensional configuration, the ADCP current meter calculates speed and direction of the ocean current at different depths.

ADCP in Port Ocean Current Measurement

Shipborne ADCP

• Shipborne ADCPs are mounted on vessels. Moving the vessel across the waters, the ADCP current profiler steadily sends acoustic signals downwards and sideways. As such, it provides data on current velocity whenever the ship traverses along different areas in the port.
• The advantage of this method is its mobility. It allows wide ranges of measurement within the port waters. It is only necessary to account for its own motion, which normally is done with calibration and compensation methods that account for the ship's movement.

Fixed ADCP

• Fixed ADCPs are deployed at specific locations within the port, either on the seabed or on fixed structures like piers or buoys, and monitor the ocean current continuously at that fixed point over a long period of time.
• This yields long-term and consistent data to understand the regular current patterns in a specific area of the port. The disadvantage they have is that they only cover a limited area around their installation location, but they are very useful in establishing reference current data for particular regions within the port.

4. Requirements for High-Quality Measurement of Currents in the Port of Greenore

Equipment Materials

• Materials that constitute equipment should be reliable for high-quality measurement of ocean currents in the Port of Greenore; in such a case, given the corrosive nature of seawater and possible impacts from floating debris, one is assured that a durable material shall be used.
• The equipment must be capable of withstanding the marine environment of the Irish Sea and maintaining its performance over time. The ADCPs may be suitably fitted in a casing made from a titanium alloy, which offers excellent corrosion resistance in seawater.

Compact and Lightweight Design

• The size of the equipment should be small to allow for easy installation, especially in areas with limited space such as on small buoys or in regions with complex underwater structures.
• A lightweight design is also beneficial as it simplifies the installation and maintenance processes. This is particularly important for equipment that may need to be deployed and retrieved frequently.

Low Power Consumption

• Low power consumption is essential, especially for long-term monitoring. Equipment with high power requirements may face difficulties in sustaining operation continuously due to the limited availability of power supply options in the port area or the need to replace batteries frequently.
• This is particularly important for fixed ADCPs that are intended for continuous operation over a long period.

Cost-Effectiveness

• It is also about cost-effectiveness. For the extensive current measurement in the port, which would be affordable equipment to provide more deployments, a thorough understanding of the current conditions in port waters.
• It's important for a port like Greenore to have that so it can best utilise its resources and make decisions on how best to perform current measurement.

5. How to Choose the Right Equipment for Current Measurement

Based on Usage Purpose

• Shipborne ADCP: If the objective is to obtain current data over a wide area of the port while the ship is in operation, for example, during regular port surveys or when collecting data for navigational chart updates, shipborne ADCPs are a good choice. They can cover different parts of the port as the ship moves around.
• Bottom-mounted (Sitting) ADCP: When long-term and fixed-point monitoring of specific locations within the port is called for, like near critical infrastructure such as breakwaters or at the entrance of the port channel, bottom-mounted ADCPs are suited. They can provide continuous data with much stability to understand the characteristics of the local current.
• Buoy - mounted ADCP: For areas where it is not convenient to install fixed equipment on the seabed or on structures, or when a floating monitoring point is needed to capture surface and near - surface current conditions, buoy - mounted ADCPs are the way to go.

Based on Different Frequencies

• A 600kHz ADCP may be a reasonable choice for water depths within 70m. It can yield relatively high-resolution current profiles in shallower areas. This would be appropriate in large parts of the port area where the water depth is not extremely deep, say near the quay walls and inner harbor.
• If the water depths are not more than 110m, a 300kHz ADCP is appropriate. It could effectively penetrate the water column of that depth and provide correct measurements for the current velocities.
• For much deeper areas, such as in the approach channel of the port where the water depth may be more than 1000m, a 75kHz ADCP is recommended; its lower frequency allows it to reach greater depths while still obtaining useful current information.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, for those looking for a cost-effective option with excellent quality, the China Sonar PandaADCP is worth considering. It is made of all-titanium alloy material, which combines durability and good performance. With its incredible cost-performance ratio, it provides a great choice for ocean current measurement in the Port of Greenore. You can learn more about it on its official website: (https://china-sonar.com/).

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