1. Summary

The dredging development, since its beginning in 15^th century throughout further industrialization of the dredging market, has been directly allied to development of the monitoring capabilities of the water depths during the dredging operations. When concerning water transportation and safety of voyages, the maintenance and monitoring of waterways has always been a major issue. Providing a safe passage have had a direct relation to the size of the vessels and ultimately the development of the maritime transport industry. Over the years the dredging industry extended from simply controlling the waterways to other activities such as extraction of shellfish, underwater mining, civil engineering works, recreational activities, preserving flora and fauna and all sorts of other marine eco-system maintenance and control. Further expanded into protection of underwater structures and underwater construction support with rock dumping operations. All of these require real time monitoring, not just visual, but accurate measurement system to allow the dredging operations to efficiently function and develop for the current and future applications.

The monitoring of the dredging operation is indeed an elementary part of the dredging process. As early application, underwater acoustic play essential role as remote sensing method, replacing mechanical measurements. Recently, multibeams gave a real boost to the underwater dredging monitoring due to wide coverage and high efficiency. The intrinsic problem with multibeam dredging monitoring has been the complexity of system setup and sonar operation, which often required extensive experience in hydrographic surveying. It became a problem for smaller dredging setups where the operation is carried by single operator or a small number of personnel. They rely on sub-contracting of the hydrographic surveys to third party companies which reduces their revenue margins and sometimes makes impossible to achieve financially sound operation.

In 2018 NORBIT introduced a 3D sonar system, called STX360, for dredging applications allowing to observe the 3D bathymetry and imagery in real time during the dredging operation facilitated by the electronic scanning capabilities build into the transmitting antenna of the system. The STX360 scanning sonar has been used in bathymetry surveys and in dredging surveys but also in several adjacent applications like rock dumping and cable laying set-ups. In all cases the system offers excellent performance and efficient monitoring of the operation in real time. With the tightly integrated GNSS/INS system and the 360 deg titanium rotation system the iSTX360 system has become a dredge survey ready suite for any installations. In 2020 NORBIT has developed a software utility to facilitate the data collection and visualization for iSTX360 used for dredging monitoring and was given a name NORdredge. NORdredge is based on the NORBIT Open Hydrography Platform and continues the software solution simplifying the data acquisition initiated by the bathymetry data acquisition software – DCT.

NORdredge is a web-oriented utility which directly interfaces to NORBIT iSTX360 multibeam sonar system and is designed to monitor the dredging operation in real time with simple user interface and minimal installation efforts. It has been designed to facilitate three kinds of use case serving different users, needs and installations. These are:

1. Standalone operation supporting smaller installations and end users,
2. Used as a middleware as integrated part of in third-party (OEM) solution,
3. As monitoring tool adding an extra redundancy to large productions. That is to increase safety and efficiency of the operation.

This article details out the use first cases of NORdredge as a standalone utility and briefly discusses other use cases.

2. NORdredge and iSTX360 in a standalone operation

The first and main use of NORdredge is a standalone operation for dredging or rock dumping. The users connect to the data acquisition PC (via Wi-Fi, LAN or 4G network) using nothing else but the web browser. It is completely web based and any device with the web browser can be used to access and operate NORdredge.

Fig. 1 NORdredge operated via web browser on rugged tablet or PC

The dredger is equipped with the iSTX360 which is the integrated 3D sonar with INS system and robust titanium rotating mechanism. All in one consolidated lightweight device attaches to the pole or frame of the dredger or barge. The single pair of cables connect to the top side which connects the GNSS antennas for navigation as well as provides the power to the rest of the system. The industrial computer hosts the NORBIT software including NORdredge server and is responsible for all data acquisition.

The clients can connect in various ways to the NORdredge computer either directly, via mouse and keyboard, but more importantly with the remote clients utilizing the ruggedized tablets connected wirelessly.

Fig. 2 NORdredge split screen display with real time and differential depth

The wireless connection helps tremendously in limiting the network of cables and avoids expensive failures due to puncturing or destroying the cables. The wireless communication is facilitated by standard Wi-Fi or even mobile communication standards such as 3G/4G/5G and internet networking. The latter being useful when client is in remote location where standard Wi-Fi does not reach. The office personnel can take great advantage of that feature where the particular dredging station can be access from any location in the world.

All the users’ terminals, that is the operator and all remote users, share the same underlying data in the real time. Each user can take advantage of several displays offered by NORdredge such as real time bathymetry, differential grid, backscatter imagery and couple of QC tools such as standard deviation of the bathymetry soundings and their density.

Fig. 3 NORdredge differential, backscatter and depth displays

The users operate on the same underlying data and can use NORdredge to effectively manage the dredging monitoring by adjusting the coverage, setting up the run lines or planning the next step during the mission.

NORdredge natively supports split screen display with the real time depth display and differential depth display. The real time depth display shows the current measured depth while the operation progresses. The cursor informatics displays the current height with RTK aided navigation. All necessary navigation data are conveniently displayed on the screen and can be hidden with a mouse click.

The differential grid on the left-hand side provides immediate information on the area to be dredged by comparing the reference grid to the real time depth and showing in simple colors what and where to dredge. The reference grid can be prepared as a design template by importing the XYZ ASCII file outlining the desired channel or by using one of the previously collected bathymetry data. In that case the data could be any data collected with NORdredge or even imported from previous surveys performed with DCT as both are compatible.

With a single button click the user instructs the system to collect the data. The data is securely stored on the survey computer in NORBIT WBM format as well as in a popular s7k file. The WBM file is useful if user wants to replay the data or export it to another format using NORBIT GUI. The concurrently generated s7k files contain all bathymetry data and navigation data and can be used for future postprocessing if needed. At the same time the system collects the raw GNSS/INS observables which can be used to postprocess the navigation with PPK etc. which can be used for the final delivery of the bathymetric maps for PRE and POS surveys. That offers a possibility to avoid expensive pre- and post- surveys and use the data collected during the dredging as a final deliverable.

At any time during the operation the operator have access to QC displays. The real time display shows the mentioned real time depth and also standard deviation, sounding density and backscatter, all of which are updated at the same time and available for all connected clients.

All displays run concurrently on one or several clients, e.g. operator can view depth display and surveyor or QA remote assistant can view standard deviation and sounding density display. The backscatter display allows to differential between hard and soft bottom and avoid expensive mistakes when dropping the bucket on the boulder or submerged structures. The background maps (Google maps, satellite view or GeoTiff) can be selected according to user preferences differently on different clients. Zooming, panning and boat location/tracking options are available also on all displays.

The operator can take a decision in the real time on when to plan the next drop just simply by looking at the differential display. The immediate result from the scanning confirms the desired depth in the area of interest. When the entire area is confirmed and the operator is satisfied with the result the dredger moves to the next location and repeats the operation.

3. NORdredge in action

Some smaller operations tend to be very dynamic and the dredger moves from one area to another quickly. There is no time for extensive logistics or extra survey vessel to conduct the pre/post survey and the readings of the bathymetry needs to be done on spot to allow the operator to take an immediate decision to move the dredger to next location. NORBIT iSTX360 and NORdredge is designed for this kind of operations. The instantaneous measurement of the bathymetry and clear displays on a single screen is sufficient for operator to conclude the survey.

As an example of such dynamic survey a short dredging operation was conducted in December 2020 where couple of  buckets drop were needed to be performed in certain areas and move very quickly to another area along the shore of Columbia River in Portland, Oregon.

Fig. 4 NORdredge in real time dredging monitoring

With this type of operation NORdredge offers great advantage to the operator with the capability of quick measurement the bathymetry of dredged area and swiftly conclude the mission without any wait time for survey vessel to perform additional surveys. The raw data is securely stored on the industrial PC and can be further postprocessed for the final delivery without the need to perform the additional post survey.

4. Other uses of NORdredge

We will just mention two additional use cases in limited details due to the size of this article but more information is available on NORBIT web site and will be published in the future.

 

4.1. NorDREDGE use as middleware

The second use case for NORdredge is unique opportunity for OEM partnership for companies who provide their own offerings in the dredging industry. It allows the third-party solution provider to seamlessly integrate the bathymetry layer offered by NORBIT into their product without undertaking on the whole development of data acquisition and bathymetry maps generation. All that is already managed by the Open Hydrography Platform (OHP) architecture on which NORdredge is based on. That includes the well-known GIS platforms GeoServer, Postgres database and PostGIS which are used by NORBIT OHP and provides seamless access to the data as well as tiles of generated maps.

Fig. 5 NORdredge used as middleware in 3rd party solution

The governing software integrates the NORdredge layer into its user interface by simple http calls similarly to Google Maps calls. The API and integration instructions are part of NORdredge offerings from NORBIT and is based on standard map service used in other popular applications such as Uber app and similar.

This opens up the door for the companies who already provide services in dredging market and wish to expand their portfolio for professional bathymetry system and provide underwater monitoring capabilities to their clients. As OEM partner the companies can keep their feel and look of their products and concentrate on important drivers for their product while seamlessly expand onto the bathymetry monitoring capabilities.

 

4.2. NorDREDGE use as monitoring and planning tool

Large dredging production involve multiple sensors for their operation. There are specialized software (such as EIVA, Qinsy or Hypack and others) which consolidates all different sensors into one platform serving many users with many displays and features. This type of operation and logistics is beyond NORdredge intended use. However, the challenging production like this is surrounded with supporting functions which also requires access to the dredging data for progress monitoring and planning reasons. These supporting functions could be for example a party chief to watch the progress of the mission or a captain planning for the next vessel position. It also could be a next shift of the personnel who is curious what situation is awaiting his/her shift. In all of these cases the situation awareness can be provided by NORdredge, which can operate concurrently with large production dredging software. That adds the needed redundancy to the current main framework as the map generation is completely detached from the mainframe map generation and does not infringe any risk of disturbing the production logistics.

Fig. 6 NORdredge used as monitoring tool used concurrently with larger dredging operation

In this case the NORdredge function is simply monitoring function where redundant terminals are separated from the main production and can be freely used by all interested parties. That includes the vessel personnel but also the personnel in the office, which can access the same operational picture via internet. This immediate situation awareness improves the logistics and planning as well as efficiency as all interested parties have access to the same information without disturbing the main production team.

5. Conclusions

NORBIT iSTX360 solution along with NORdredge utility is simple and useful tool for various dredging operations. The web browser interface allows to conduct and monitor the dredging mission in efficient way. It is suitable for small dredgers and single person operations as well as the larger operations working as middleware or as monitoring tool supporting the main production. The iSTX360 and NORdredge through web-based displays allows to access the survey result and monitor the progress from any terminal in the network either local or remote.

6. References

1. Pawel Pocwiardowski, “NORBIT STX 360deg 4D Sonar for Dredging Applications”, WEDA, Pacific Chapter, 2019 Annual Meeting, October 29 to 31, 2019
2. Pawel Pocwiardowski, “NORBIT DCT Hydrographic Survey Made Easy”, MARINE TECHNOLOGY, June 2019 via internet.