ADCP's Application to Ocean Current Measurement in Tallinn Port

1. Where is Tallinn Port?

The Tallinn Port is located at the southern coastline of the Gulf of Finland in the Estonian capital - Tallinn and is considered a major hub, as far as a maritime base is concerned in the region of the Baltic Sea.

Scale of the port and its throughput

This is among those large-scale-sized ports in the Baltic Sea region. It is characterized by a vast port area with highly developed quays that could serve large numbers of vessels. It has a high annual throughput, handling all kinds of cargo, such as containers, bulk goods, liquid cargo in various forms. The container traffic is also the significant part of its work, with a considerable number of TEUs being processed. It occupies a strategic position in providing a critical link for trade not only within the two but also in countries further afield within the Baltic Sea region. It is a gateway into transporting goods to and from the Estonian hinterland through its efficiently interconnecting road and rail networks.

Routes and Business

The port is connected with different international shipping routes, mainly in the Baltic Sea and connecting to the North Sea and other European ports. It is an important regional shipping hub, with numerous shipping lines having it as a regular call port. Business activities range from shipping services, freight forwarding, to logistics. It includes the importation and exportation of goods like machinery, electronics, foodstuffs, and forestry products.

Yet another fast-growing segment in which Tallinn Port is involved includes cruise liners shipping, attracting tourists willing to explore the rich historic and architectural beauty of the city.

Port Management and Operation

The port is managed through both public and private entities. Infrastructure development, maintenance, and overall operations are controlled by the Port of Tallinn Authority. It coordinates with terminal operators, shipping companies, and other service providers to ensure smooth and efficient port operations.

The operation entails complicated processes that involve vessel traffic management, cargo handling, and customs procedures. Advanced technologies are used in the optimization of goods and vessel flow to increase productivity and safety in the port.

Port Facilities

Tallinn Port is a modern facility with good infrastructure. It has container terminals that are well-designed, each having high-capacity cranes for loading and unloading containers. Besides, there are specialized terminals to handle various bulk cargo types, including storage silos and tanks. The port offers warehousing and distribution services, while for cruise ships, it has dedicated terminals with facilities for passenger services such as embarkation and disembarkation.

Channels and Direct Navigation

The channels are in good condition, being dredged at the proper depths that allow vessels of different kinds to pass through them. The Gulf of Finland and the Baltic Sea can be reached directly from there, providing access for ships to connect to other major regional ports. Good navigation conditions for ships going along the Estonian coast.

2. Why do we want to measure ocean currents in the Tallinn port?

Navigation Safety

Such measurements help protect ships from accidents. The Gulf of Finland is known to have complicated currents due to tides, winds, and local topography. Understanding the velocities and directions of such currents could better help a ship captain plan in arriving or leaving the port.

Currents play an important role in the handling characteristics of a vessel, mainly in critical operations of berthing and un-berthing. In view of congestion here due to cargo vessels and cruise ships, the information is vital for the avoidance of collisions and all other accidents.

Port Operations and Efficiency

Knowledge of present patterns is necessary for the proper working of the port. The direction of currents might affect the process of docking and undocking. If not appropriately taken into consideration, the flow of currents would create a lot of problems with the alignment of the ship to the berth, causing undue delays in the cargo handling as well as in the passenger services.

Currents also, to a great extent, regulate the movement of tugs and other support vessels within the port area. Measuring the currents will thus enable the port authorities to optimally schedule these operations and therefore enhance the overall productivity of the facilities. ADCP current meter provides a more advanced and convenient means of measuring currents compared to traditional methods since it can provide current data in real time for better decision-making during port operations.

3. How do ADCPs using the principle of Doppler work?

ADCPs work on the principle of Doppler. They emit acoustic pulses into the water column. When these pulses interact with particles or objects in the water which are moving with the current, the frequency of the reflected sound waves changes.

Ship-borne ADCP

A ship-borne ADCP is usually installed on the hull of a vessel.

Because the ADCP measures the relative velocity of the current with respect to the motion of the ship, it is ready to go through the water. It continuously records the Doppler-shifted frequencies of the reflected acoustic signals. With the help of advanced signal-processing algorithms, the relative velocity of the current is determined. Then it is able to combine that information with knowledge of the ship's own speed-an input directly received from other navigation systems-to compute the absolute current velocity in that location.

Fixed ADCP

Fixed ADCP on other hand is stationed at fixed locations within the port structure. A seabed or a pier can mount them. They constantly broadcast acoustic pulses through the water and measure the change in frequency of that pulse as it echoes back to its transducer. They give a stationary view of the current velocity at one point.

This information is highly useful for long-term monitoring of current patterns, for example, in order to understand how the currents vary with tidal cycles or seasons.

4. What's needed for high-quality measurement of Tallinn port currents?

Equipment Characteristics

Materials must be reliable to give high-quality current measurement in Tallinn Port. The equipment has to be able to resist the corrosion effect of saltwater and other harsh conditions of the sea. Smaller size and weight are advantageous because it would make the equipment easier to install and maintain, especially in places like buoys or cramped spaces on ships. The equipment has to have low power consumption, mainly for long deployments where access to power sources may be limited. It has to be cost-effective so that more numbers of such equipment can be deployed for comprehensive current measurement across the port.

The Advantage of Titanium Alloy Casing

The casing of ADCP current profiler is preferably made of titanium alloy.

Properties of excellent corrosion resistance are of great importance in this port-the reason being that this equipment would have quickly deteriorated, since seawater is not only rich in salinity but also other corrosive agents. The good mechanical properties of the titanium alloy are very good, strong, and durable; it could bear the pressure imposed by the water and any possible mechanical impacts.

5. Selection of Correct Equipment for Measurement of Current

Application Based on Installation Type

Ship-borne ADCP: This type is suitable for vessels that need to measure currents during their transit in and around the port. It provides a mobile way of obtaining current data and is useful for ships such as container vessels and tankers that are always on the move.

Sitting-bottom ADCP: Good for fixed-point monitoring of the current at a certain place, like the entrance of a channel or near a berth; it gives a stable and continuous measurement of the current at that particular point.

Buoy-type ADCP: It can be mounted in areas where a floating platform becomes more suitable, such as open water areas within the port or in areas that are less defined. Buoy-type ADCPs are important for monitoring larger areas and may be very helpful in defining wider current patterns in the port.

Based on Frequency

• Normally, for water of up to 70m, a 600kHz ADCP can be chosen. Due to the higher frequency, it can give a better resolution in the case of shallower water current measurements.
• For depths around 110m, a 300kHz ADCP is more appropriate since there is an increased depth penetration but still provides reasonable resolution.
• The recommended ADCP for waters as deep as 1000m should be a 75kHz. With the lower frequency, deeper penetrations into the water column can be realized to measure current at greater depth.

There are well-known ADCP brands such as Teledyne RDI, Nortek, and Sontek. However, the Chinese brand China Sonar PandaADCP is also a great option. It is made of all-titanium alloy material, providing excellent durability and corrosion resistance. It also offers an incredible cost-performance ratio. You can find more information about it on their website: (https://china-sonar.com/).

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