ADCP's Application for Measuring Ocean Currents in the Port of Vaasa

1. Where is Vaasa Port?

Overview of Vaasa Port

Vaasa Port is located in the city of Vaasa, Finland. The port is of a considerable scale and throughput. It serves as an important transportation node in Finland, connecting to many countries by different shipping routes. It handles a diverse range of cargo including containers, forest products like timber and pulp, and industrial goods.

The management of the port is very efficient and operation-oriented. Well-organized teams manage vessel traffic, cargo handling, and other functions related to the port. Besides, the port is much concerned with the promotion of regional trade and economic development.

Port Facilities

Berths: There is more than one berth at this port, each serving different functions for vessels. These are facilities for medium-sized cargo ships or container ships. The facilities offer modern mooring and docking mechanisms to ensure the safe approach and departure of vessels. The fenders and bollards used are of a high quality to avoid the slightest damage to the ships and the berths during the docking and undocking process.

Cargo-handling Equipment: On the quay, there is a line of cargo-handling equipment. These include gantry cranes that efficiently load and unload containers in the case of container handling, while in the case of forest products, the same is facilitated through cranes and conveyor systems that move logs and pulp. Other handling equipment also exist for other general cargo.

Storage Facilities: There are storage facilities for various types of cargo. For containers, there are container yards with a systematic way of storing and retrieving. For forest products, there are stockpiles with adequate protection from the weather. For other general cargo, there are warehouses.

Channel and Navigation Aids: The channel is dredged to an appropriate depth and width to enable ships to pass through safely. 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 guiding ships into and from the port. The radar systems give real - time information of the position and movement of other vessels in the vicinity of the port.

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

Importance for Port Operation and Management

The measurement of ocean currents is very important for the Vaasa Port. Firstly, for vessel navigation safety. The knowledge of current speed and direction is 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 even hazardous. For instance, when a ship approaches a berth against a strong current, its speed and angle of approach may have to be adjusted accordingly to ensure smooth and safe docking. Precise current measurements enable captains to make informed decisions and reduce the risk of collisions and other accidents.

The reason being, it helps optimize the port's operations. Current data aids in efficient scheduling of arrival and departure of ships. Understanding tidal currents and other periodic flow features will allow the port authorities to plan the utilization of berthing resources more effectively, apart from planning loading and unloading activities. Productivity increases because this would facilitate the coordination of cargo-handling operations with much more effectiveness.

From an environmental point of view, the knowledge of ocean currents is quite useful in case of any accidental spill of pollutants like oil or chemicals. The nature of the cargo handled in the port provides the relevant background for predicting a spill spread. The current data can be used to quickly implement measures of containment and mitigation of environmental damage.

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

Principle of Measurement

The principle behind the operation of ADCPs is the Doppler principle. If an acoustic signal is projected by the ADCP profiler in the water, it results in the interaction of the water particles with the moving sound wave. Since the water particles are in motion due to the ocean current, they change the frequency of the reflected acoustic sound wave that is received back by the ADCP meter. By the principle of the Doppler effect, this frequency shift is proportional to the velocity of the water flow.

Current Speed and Direction Calculation

By knowing the magnitude and direction of this frequency shift, the ADCP flow meter can then compute the speed and direction of the ocean current at various levels within the water column. With signals transmitted at multiple angles and different depths, a profile of the ocean current can be obtained as the variation of the current with depth.

Deployment of ADCP in the Port

Shipborne ADCP

The shipborne ADCP will be installed on ships operating within the Vaasa Port area. By movement of the ship in this port area, the ADCP current meter sends acoustic signals into the water all the time and makes one general scanning over wide areas. For instance, in a normal survey of the port by a research or inspection ship with a shipborne ADCP, it can collect data on the current patterns across various parts of the port, thus giving a comprehensive understanding of the water flow situation.

Fixed ADCP

Fixed ADCPs are deployed at fixed positions in the port, like on the seabed near areas of significant navigational interests or at the entrance and exit. They will continuously measure the ocean currents while stationed at these fixed positions over a long period. The information obtained from them is useful for analyzing regular current patterns in certain areas of the port. For example, an ADCP profiler fixed at the port entrance would be able to measure currents coming in and out, which would provide a record needed to understand tidal effects and other consistent flow characteristics in that area.

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

Equipment Requirements

The following equipment characteristics are important for high-quality measurements of currents in Vaasa port: First of all, reliability of the material is the biggest factor. The equipment should withstand the harsh marine environment. The sea water contains salts and several other chemicals that cause corrosion in materials over time. Changes in pressure at various depths of water and also the mechanical forces due to waves and currents must be withstood by the equipment.

Second, it is desirable to achieve a smaller size, lighter weight, and lower power consumption. The compact size will enable the system to be installed at any place in the port, whether on ships, on fixed structures like piers, or on the seabed. A lighter weight makes the installation and transportation processes easier. This contributes to lower power consumption, ensuring that the equipment can operate continuously for long periods without frequent battery replacements or excessive power supply, especially in the case of long-term monitoring applications.

Cost is another significant factor. A lower-cost option enables a port to deploy a larger number of measuring devices for more comprehensive current monitoring across different areas of the port.

The Advantage of Titanium Alloy for ADCP Casing

The casing of ADCPs is preferably made of titanium alloy. It has excellent corrosion resistance; that is, it will not lose its structural integrity or 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 example, in the deeper parts of the Vaasa port where higher water pressures are present, an ADCP current profiler with a titanium alloy casing can effectively withstand these pressures and continue to provide accurate current measurements.

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

Selection Based on Usage

Shipborne ADCP: Where the objective is to undertake extensive area surveys of the port waters during vessel operation, shipborne ADCPs would be appropriate. It could cover various parts of a port as the ship moves to different areas, collecting vast amounts of data to give an overview of the general current situation at the port. This acts as a guide in mapping the general flow patterns and variations across the different areas of port waters.

Sitting-bottom ADCP: For long-term and fixed-point monitoring of specific locations within the port, such as near important infrastructure or areas with complex current behaviors, sitting-bottom ADCPs are more appropriate. They can continuously record the current data at those fixed positions, providing valuable insights into the local current characteristics and any changes over time.

Buoy-mounted ADCP: When it is not convenient to install fixed equipment 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 be relocated if needed, making them suitable for monitoring certain dynamic or hard-to-reach areas within the port.

Selection Based on Frequency

The choice of frequency for ADCPs depends on the water depth in Vaasa port. An area with a water depth up to 70 m would normally require an ADCP with a frequency of 600 kHz, as it can accurately measure currents at this relatively low depth. For deeper waters, with a depth of up to approximately 110 m, an ADCP of a frequency of 300 kHz will be more advisable. Where the bottom topography includes very deep sections in this port, with water depths of up to 1000 m, an ADCP of 75 kHz is advisable if reliable profiling of the ocean currents at such great depth should be ensured.

There are several well-known ADCP flow meter 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.