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

1. An Overview of the Port of Howth

The Port of Howth is located on the east coast of Ireland, near Dublin. It is a picturesque and active port with a rich maritime history.

Port Scale and Throughput

• The scale of this port is relatively smaller when compared to major international ports like Dublin. Its throughput mainly consists of fishing-related activities because it is a big fishing port. It also handles small general cargo, including supplies to local businesses and small imports and exports.
• The facility is designed to handle a combination of fishing, small cargo vessels, as well as pleasure craft. Several berths accommodate various-sized boats and ships.

Routes and Business

• Domestically, it is connected with other Irish ports; it allows the local goods and fish to be transported. Internationally, it has some trade links mainly for exporting local fish and seafood products, while it imports fishing equipment and other necessities.
• The major business dealt with at Howth port is fishing. It gives a base to the local fishing fleet besides the facilities of landing, processing, and storing fish. There is also some related business of tourism due to its scenic location of the port and restaurants/ cafes that serve fresh seafood.

Port Management and Operation

• The port is managed by a team that oversees its day-to-day operations. This includes berthing arrangements for vessels, ensuring the safety of fishing and other maritime activities, and coordinating with local businesses such as fishmongers and restaurateurs.
• The management also focuses on maintenance of the port facilities regarding the upkeep of the quay walls, berths, and other infrastructure. They are also working with local and national bodies for regulatory compliance in order to keep up with safety and environmental standards.

Port Facilities

• It has facilities befitting fishing and small cargo handling. The port has berths with depths suited for different vessels. There is basic cargo-handling equipment in the port, like small cranes and forklifts for unloading fish and other goods.
• Facilities include cold - storage facilities for fish and other perishable items. Amenities for fishermen and visitors include a fish market, restaurants, and cafes. There are also facilities for refueling and basic maintenance of vessels.

Channel and Direct Navigation

• It has a well-maintained channel that ensures safe ship entry and exit. Dredging is always done whenever the need arises to have the right depth of the vessels passing through it. There are buoys and lights on for navigation during the approach of ships and their departure. This allows for direct navigation for vessels coming from different directions along the Irish Sea.

2. Importance of the Measurement of Ocean Currents in the Port of Howth

Navigation Safety

• Measuring ocean currents in the Port of Howth holds great importance in relation to the safety of the ships passing through it. Currents in the Irish Sea can become very unpredictable, affecting even the movements of small-sized fishing vessels. Understanding of these currents will provide considerable assistance to captains while navigating much more safely into and out of the port.
• For instance, a fishing boat can be swept off course by a strong current while trying to dock. Precise current data enables captains to make the necessary adjustments in speed and course to avoid hitting other vessels or running into shoals.

Efficient Port Operations

• It helps in the working of this port effectively: The study of ocean currents, therefore, helps in developing a better scheduling of arrivals and departures of fishing vessels. The fishing boats may then use currents to their advantage to have better consumption during their trips.
• This also helps optimize the port resources. For example, if the current is in a direction that favors the ships' movement towards a certain berth, then the unloading could be done much faster.

Environmental Protection

• Currents are important in the spreading of pollutants in the port area. In the case of an oil spill or any other chemical release, it requires proper knowledge of the pattern of currents for effective containment and clean - up operations.
• The port will be able to handle the effluent discharge and other disposals in a better way, keeping in mind the current patterns so that minimal impact is caused to the marine environment.

Infrastructure Maintenance

• Currents exert certain forces on the structure during its lifetime, which would modify the structural integrity of such port infrastructures as breakwater and quay walls. Measurement offers much useful data for the long-term planning and maintenance of the structure.
• The actual recorded currents at a place being strong enough may even necessitate additional reinforcement as a precautionary measure in that particular area to prevent erosion of soil and damage to the quay walls. The Acoustic Doppler Current Profiler (ADCP) therefore gives a more advanced, easier way of measuring the currents in the ocean than by manual methods.

3. How ADCPs Using the Doppler Principle Work

ADCPs work on the Doppler principle. They emit an acoustic signal into the water. These acoustic waves become interacted with moving particles in the water, such as sediment, plankton, or any other small organisms, carried by the ocean currents. When the waves bounce back, the frequency of the reflected waves changes.

This shift in frequency, the so-called Doppler shift, is directly proportional to the velocity of the moving particles and hence the velocity of the ocean current. ADCPs have multiple transducers that emit and receive these 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 can calculate the speed and direction of the ocean current at different depths.

ADCP in Port Ocean Current Measurement

Shipborne ADCP

• The shipborne ADCPs are installed on vessels. During the movement of a ship, the ADCP flow meter continuously emits acoustic signals downward and around. In this process, it gathers data regarding the current velocity while the ship traverses different areas of the port.
• Advantages of this technique are its mobility. A wide range of measurements is possible within the port waters. However, the ship's own motion needs to be accounted for in order to obtain correct results. Methods of calibration and compensation will be used to correct errors caused by the movement of the ship.

Fixed ADCP

• Fixed ADCPs are placed at specific locations in the port, such as on the seabed or on fixed structures like piers or buoys. They continuously monitor the ocean current at that fixed point over an extended period.
• This will give long-term and continuous data on the normal current conditions of a particular area of the port. The drawback is that they cover only a limited area from where they are installed, but they are quite helpful in establishing reference current data for certain areas of the port.

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

Equipment Materials

• The equipment materials should also be reliable for high measurements of ocean currents in the Port of Howth. With seawater being corrosive and the potential impacts from floating debris, a durable material should be used.
• The equipment should be capable of withstanding the marine environment of the Irish Sea and maintaining performance over time. A casing made of titanium alloy is a good option for ADCPs as it has excellent corrosion resistance in seawater.

Compact and Lightweight Design

• The size of the equipment should be small to facilitate 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 consumption may not be continuously operable due to limited power supply options in the port area or the need for frequent replacement of batteries.
• This is particularly important for fixed ADCPs that are supposed to run continuously over a long period.

Cost-Effectiveness

• The cost-effectiveness is another aspect. For comprehensive current measurement in the port, with inexpensive equipment, one can make more deployments for wider coverage of current conditions across the waters in the port.
• This becomes vital for a port like Howth for effective exploitation and making proper decisions regarding the strategy for current measurement.

5. How to Choose the Right Equipment for Current Measurement

Based on Usage Purpose

• Shipborne ADCP: In cases where the goal 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 good options. 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 required, such as near critical infrastructure like breakwaters or at the entrance of the port channel, bottom-mounted ADCPs are suitable. They provide stable and continuous data for understanding the local current characteristics.
• 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

• The latter two are usually chosen for application in water depths within 70m, where good profiling resolution is desired. More concretely, a 600kHz ADCP can perform quite well, yielding high-resolution current profiles in slightly shallower areas, quite suitable for most parts of the port, except possibly a few very deep areas located far from the quay walls or inner harbor.
• A 300kHz ADCP would be more in place in the case of water depth up to 110m. It would sufficiently penetrate the water column at this depth with a very good accurate current velocity measurement.
• For much deeper areas, such as in the approach channel of the port where the water depth may be in excess of 1000m, a 75kHz ADCP is recommended; its lower frequency allows it to reach greater depths and still obtain 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 Howth. 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.