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

1. Where is Naissaare port?

Naissaare port is located in Estonia. Being a relatively smaller port, the port serves certain regional needs.

Port Scale and Throughput

The port of Naissaare is rather small in scale compared to several large international ports. Nevertheless, it has a very important meaning for the local economy. It mainly handles cargo related to local industries and agricultural activities. There are many types of cargo passing through this port, such as building materials, agricultural produce, and fishing equipment. Local demand and the fishing season determine the annual cargo volume.

Routes and Business It is connected with other Estonian ports and partly with the Baltic Sea ports that are located nearby. The main businesses include exporting of local products like fish and timber and importing of necessary products such as machinery for fishing and agriculture. Shipping routes serve local fishing fleets and small cargo vessels carrying goods to and from the surrounding area.

Port Management and Operation

The port management ensures that the best use of its limited resources is made. The port authority manages the vessel berthing, cargo handling activities, and the port facilities. They ensure that all the operations go smoothly without any problem considering the specific needs of the local fishing and goods carrying businesses.

Port Facilities The port has basic, very important facilities. It provides berth facilities appropriate for small to medium vessels. Loading and unloading equipment in the form of cranes and forklifts facilitate cargo. Besides this, storage areas accommodate different types of goods. Also, facilities related to fishing boats and small vessel repair works are available.

Channels and Direct Routes Channels in the Naissaare port are dredged for the safe navigation of local vessels. It is connected to other important ports in the Baltic Sea region with direct routes, which play a major role in the transportation of goods and the economic well-being of the local community. Regular monitoring and dredging of the channels are carried out to maintain the depth required by vessels using the port.

2. Why should we measure the sea currents in the Naissaare port?

Measuring ocean currents in the Naissaare port is very important. Firstly, it is very important from the point of view of safety for the fishing vessels and small cargo ships. The local fishermen rely on the precise knowledge of the current patterns to ensure safe return to the port. Unfavorable currents may threaten the vessels, and by measuring the currents, the port is able to issue timely warnings.

Understanding the present pattern aids in optimizing the docking and undocking operations that occur for the smooth functioning of the port, thereby reducing the time and effort required to do so, quite considerable in the light of small-scale operations.

Data obtained by measuring ocean currents is highly relevant for understanding sediment transport processes around the harbor area; this can help in identifying programs for dredging and access channel maintenance. ADCPs will offer a more sophisticated and efficient means of measuring such currents than has been available with prior technology.

3. How do ADCPs using the Doppler principle work?

ADPs work on the principle of the Doppler effect. They send acoustic signals into the water. These signals are reflected back by particles in the water that move with the current; their frequency is different from the original because of the flow of the water body that has scattered the acoustic waves. From these frequency changes, or Doppler shifts, the velocity of the current is determined.

Ship - borne ADCP

When a ship-borne ADCP is used in the Naissaare port, it is installed on a vessel, which may be a fishing boat or even a small cargo ship. The Acoustic Doppler Current Profiler (ADCP) would emit acoustic pulses as the ship moves through the water in either a generally downward-looking or side-looking aspect. The reflected signals from the water column are received and analyzed. The Doppler shift in these signals provides information about the current velocity at different depths. This allows for a detailed profile of the current as the ship travels through the water.

Fixed ADCP

Fixed ADCPs can be installed on structures such as piers or small buoys in the Naissaare port. They emit acoustic signals in a specific direction, usually downwards. The reflected signals are then analyzed for the Doppler shift. With the continuous recording of these signals, the fixed ADCP allows for the recording of long - term records of current velocity and direction at one location. Therefore, this could be used by monitoring current conditions near the entrance of the port or around essential infrastructure.

4. What is needed for the good quality measurement of the current in the Naissaar port?

For high-quality current measurement, the equipment used in the Naissaare port should include reliable materials. The size and compactness of the equipment have to be light due to its use in a relatively small size port and vessels operating in these ports. This also allows installation and deployment with much ease, especially on smaller fishing boats and other vessels employed at a small scale.

Also important is low power consumption. During fixed-point measurements, it would prevent the need for equipment to always run continuously without changing the battery or maintenance of the power source. Cost-effectiveness, from an economic scale perspective in ports, requires the devices to be deployed on a wide scale. The preferred material for the casing in the ADCP is titanium alloy. It has excellent corrosion resistance, which is very important in the marine environment. The waters of the Baltic Sea, for example, are salt-laden and can give many other materials a severe corrosion attack. This is resisted by the titanium alloy, ensuring the long-term performance of the equipment. It also has a very high strength-to-weight ratio that helps reduce the overall weight of the device while maintaining the structural integrity of the device.

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

Based on Usage

Ship-borne ADCP: This is right for the measurement of currents during the movement of a vessel. In relation to Naissaare port, it is applied to fishing boats and small cargo ships for measuring currents along the routes taken. It provides information on the profile of the currents and helps with navigation and operational decision-making.

Sedimentation ADCP - Sit - on - bottom ADCP: Suitable for long-term and fixed-point monitoring of currents near the seabed. In the port, it can be used to monitor the current behavior at specific locations such as near the berths or in areas with important underwater structures.

Buoy-based ADCP: If the objective is to monitor currents in an area over a longer period, and some flexibility in location can be allowed, a buoy-based ADCP will suffice. In Naissaare, it could also be placed in places that might not be frequented by ships but are relevant for the general pattern of currents.

Based on Frequency

For waters up to 70m deep, an ADCP with a 600kHz frequency is usually appropriate. In cases of depths around 110m, a 300kHz frequency is more suitable. For very deep waters of up to 1000m, a 75kHz ADCP is the better option.

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

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