Application of ADCP to Ocean Current Measurement at Port Hanko

1. Introduction Where is Hanko Port?

Overview of Hanko Port

Hanko Port is located in Finland, on the southern tip of the country, facing the Baltic Sea. It is a medium - sized port with a unique position that provides it with good access to various shipping routes in the Baltic region. The port has a diverse range of activities and serves both domestic and international trade.

It handles a variety of cargo, including containers, bulk cargo like building materials and agricultural products; it also has facilities for passenger traffic in terms of scale and throughput. The management is efficient and focuses on maintaining smooth operation. Well-organized teams function in vessel traffic management, cargo handling, and customs operations.

Facilities of the Port

Berths: The port has a number of berths designed to handle different types of vessels. There are berths for medium - sized container ships and bulk carriers. These berths are equipped with modern mooring and docking facilities to ensure the safe arrival and departure of ships. The use of proper fenders and bollards helps in reducing the impact during the docking process.

Cargo-handling Equipment: There is a range of cargo-handling equipment along the quay. The gantry cranes for container handling are efficient in the loading and unloading of containers. Conveyor systems and grabs for the movement of bulk cargo from ships to storage areas can be installed. In the case of passenger ships, there are gangways and other facilities for smooth boarding and disembarking.

Storage Facilities: There are storage facilities for various kinds of cargo. For the containers, there is a container yard with a proper stacking and retrieving system. Bulk materials can be kept in stockpiles with proper drainage and containment systems. Then there are warehouses for storing other general cargo and provisions for perishable goods like agricultural products.

Channel and Navigation Aids: The port's channel is maintained to a suitable depth and width to ensure the safe passage of ships. Regular dredging operations are carried out to keep it navigable for vessels with different drafts. Navigation aids such as buoys, beacons, and radar systems are in place to guide ships into and out of the port. The radar systems provide real - time information about the position and movement of other vessels in the vicinity of the port.

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

Importance for Port Operation and Management

Measuring ocean currents in Hanko Port is of great importance. Firstly, for the safety of vessel navigation. The knowledge of the current speed and direction is quite crucial for ship captains while approaching berths or navigating through the channel. A strong cross-current near a berth can make the process of docking quite challenging and hazardous. For instance, a ship approaching a berth against a strong current may have to adjust its speed and angle of approach to ensure smooth and safe docking. The correct measurement of currents permits captains to make right decisions and minimizes the risk of collision and other accidents.

It is also crucial for the optimization of the port's operations. Current data helps in scheduling the arrival and departure of ships more efficiently. By understanding the tidal currents and other regular flow patterns, port authorities can better allocate berthing resources and plan loading and unloading activities. This leads to improved productivity as it enables more effective coordination of cargo - handling operations.

From an environmental point of view, the knowledge of ocean currents is useful in the case of an accidental spill of pollutants such as oil or chemicals. In fact, due to the nature of cargo handled in the port, a prediction of the spread of a spill is important. This current data can be used to quickly institute containment and mitigation measures so that there is less environmental damage.

3. How do ADCPs using the Doppler principle work?

Measurement Principle

ADCPs work on the principle of the Doppler effect. When an acoustic signal is emitted by the ADCP flow meter into the water, it scatters off the moving water particles. Since the water particles are in motion due to the ocean current, they produce a frequency shift in the reflected acoustic signal received back by the ADCP meter. As stated by the Doppler effect, this frequency shift depends on the velocity of the water flow.

Calculation of Current Speed and Direction

By analyzing the magnitude and direction of this frequency shift, the ADCP current profiler can calculate the speed and direction of the ocean current at different depths in the water column. By emitting signals at multiple angles and different depths, it can create a profile of the ocean current, showing how the current varies with depth.

ADCP Deployment in the Port

Shipborne ADCP

In the Hanko Port area, an ADCP current meter device is installed on ships operating within the area. The Acoustic Doppler Current Profiler (ADCP) sends acoustic signals into the water while the ship moves around the port area. In this way, the ship's movement enables the ADCP meter to scan over a large area and gather current data from various locations. For instance, during a routine survey of the port by a research or inspection ship equipped with a shipborne ADCP, it can gather data on the current patterns across various parts of the port, thus providing a comprehensive understanding of the water flow situation.

Fixed ADCP

Fixed ADCPs are installed at fixed, stationary locations within the port, on the seabed at places with high navigational importance or at the entrance/exit of the port. These ADCPs continuously monitor the ocean currents at their fixed positions over a long period. This data is helpful in analyzing the regular current patterns in certain areas of the port. For instance, a fixed ADCP installed near the port entrance can record the incoming and outgoing currents, helping to understand the tidal effects and other consistent flow characteristics in that region.

4. What’s needed for high - quality measurement of Hanko port currents?

Equipment Requirements

For high - quality measurement of the currents in Hanko port, some equipment characteristics are decisive. First of all, material reliability is the most important. It has to resist the effects of the marine environment. Seawater contains salts and other chemicals that can corrode materials over time. The equipment also needs to bear the pressure changes at various water depths and the mechanical forces from waves and currents.

Secondly, a smaller size, lighter weight, and lower power consumption are desirable. A compact size allows for easier installation in various locations within the port, whether on ships, on fixed structures like piers, or on the seabed. A lighter weight simplifies the installation and transportation processes. Lower power consumption means the equipment can operate continuously for long periods without the need for frequent battery replacements or excessive power supply, which is especially important for long-term monitoring applications.

Cost is another major factor: the lower the cost, the more measuring devices the port can deploy to achieve comprehensive current monitoring in different areas of the port.

The Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made of titanium alloy. The corrosion resistance of the titanium alloy is excellent, meaning that it can keep its structural integrity and functionality even when exposed to seawater for a long time. Its high strength-to-weight ratio allows for the construction of a durable yet relatively lightweight casing. For instance, in the deeper parts of the Hanko port where higher water pressures are experienced, an ADCP current profiler with a casing made of a titanium alloy can easily withstand such pressures and keep on delivering proper current measurements.

5. How to Choose the right equipment for current measurement?

Selection Based on Usage

Shipborne ADCP: If the objective is wide-area surveys of the port waters as the ship is in operation, then shipborne ADCP will be a good one for the purpose. While the ship is in operation and running in different sections of the port, it will gather substantial data over the area for overall current insight into the flow in the port. This will be useful for mapping the general flow patterns and variations across different areas of the port waters.

Sitting - bottom ADCP: The more suitable for long - term and fixed - point monitoring of any place in the port and those places near some important infrastructure or with complex current behavior, sitting - bottom ADCPs should be used. They could keep continuously recording the current at fixed positions, providing quite an insight into the local features of the current and changes in a given period of time.

Buoy-mounted ADCP: In cases when it is not feasible to install fixed equipment either on the seabed or on ships, buoy-mounted ADCPs can be used. They float on the water surface and can measure the currents in the upper layers of the water column. They are relatively easy to deploy and can also be relocated if needed. This makes them suitable for the monitoring of certain dynamic areas or areas difficult to reach inside the port.

Selection Based on Frequency This is based on the water depth in Hanko port. An area with a water depth of 70 meters or less would usually use an ADCP current meter frequency of 600 kHz, and this can provide current measurement with good accuracy in this comparatively shallow depth range. For deeper waters, up to about 110 meters, it is more advisable to use an ADCP profiler with a frequency of 300 kHz. In very deep parts of the port, where the water depth reaches up to 1000 meters, an ADCP flow meter with a frequency of 75 kHz is recommended to reliably profile the ocean currents at such great depths.

There are several well - known ADCP brands in the market, such as Teledyne RDI, Nortek, and Sontek. However, there is also an excellent Chinese ADCP brand - China Sonar PandaADCP. It is made entirely of titanium alloy material, which not only ensures its durability in the marine environment but also offers an excellent cost - performance ratio. For more information, you can visit its official website: (https://china-sonar.com/).

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