The potential effects of propeller-induced velocities (propeller wash or propwash) on the erosion, transport, and re-suspension of contaminated sediments can be significant.  EEMS uses an integrated propeller wash sub-module that can utilize the automated information system (AIS) telemetry from vessels regarding their position and orientation every few minutes or any user-defined ship track information. 

Propeller Wash Setting in EE Forms.

The Propeller Wash module has been developed to simulate the impact of ship propeller jet on bed erosion and suspended solids. It is an important element in the development of plans for improvement and optimum utilization of waterways. It should be noted that the propeller wash does not have an impact on the model hydrodynamics by default. When simulating sediment this module will affect the movement of sediment, but propeller momentum must be turned on by the user to impact the model hydrodynamics.  

To activate this module, RMC on Modules from the Model Control form, then check on the box of Propeller Wash as shown in the Figure 1. RMC on the Propeller Wash module under the Modules option in the Model Control as shown in the Figure 2. The Propeller Wash form will be displayed as shown in the Figure 3. This shows the total number of ships, tracks, and ship track points. The Propeller Wash form has three tabs consisting of: General, Ships, and Tracks tabs.

Figure 1. Activate Propeller Wash Module.

Figure 2. Edit Propeller Wash Module.

Figure 3. Propeller Wash Form: General tab.

Import AIS Data

The high-resolution, real-time AIS (Automatic Identification System ) ship traffic data collected by the U.S. Coast Guard for large vessels in the U.S. and international waters and is provided free on websites such as MarineCadastre.gov; Shipfinder.com and Vesselfinder.com. The ship track data in a specific time and location can be downloaded from websites and prepared in advance. The file can be imported to Propeller Wash form by using the Import AIS Data button as shown in Figure 4. Once clicking the Import AIS Data button, the Import AIS Ship Tracking Data window will pop up, as shown in Figure 5. Click on the Browse button to browse the data file. The example AIS ship track data file in CSV format is shown Figure 6. EE can search keywords in the column name of the data file to match the prop wash parameters. Once the AIS data is loaded, the Import Ship Tracks interface will update the Track Field Settings fields and display all available data values as shown in Figure 7. The user should pay attention to the ship speed unit (i.e., column 4 in this case) in the data file because EFDC+ uses the meter per second unit for ship speeds for model simulations. Time Shift is used to convert the AIS data time from Universal Time Coordinated (UTC) to Pacific Daylight Time. Check on the box Clear Current Track Data Before Importing to erase all the existing ship tracks. Click OK button to start importing ship tracks, and when the process is complete the total ships and total tracks will be updated as shown in Figure 8.

Figure 4. Import AIS Data.

Figure 5. Import AIS Ship Tracking Data.

Figure 6. AIS Ship Track Data File (CSV Format).

Figure 7. Import Ship Tracks Interface After Loading AIS Data.

Figure 8. Ship Information After Importing AIS Data. 

General tab

The General tab consists of four frames: Propeller Momentum Linkage to EFDC+ Hydrodynamics, "Mass" Erosion Options for Cohesive Sediments, Jet Velocity Regions (based on Propeller Diameter), and Sub-Grid Setting frames as shown in Figure 9. Each of these frames is described below:

1. Propeller Momentum Linkage to EFDC+ Hydrodynamics

• If the Propeller Momentum Factor is set to 0 the model will neglect the momentum effect. If it is >0 the model will add propeller momentum to the EDFC+ flow field

2. "Mass Erosion Options for Cohesive Sediments

• Fraction Eroded as Mass Erosion: will split the mass into the base and "mass" eroded material of the total mass of the cohesive class eroded
• Multiplier for "Fast" Settling of Eroded Mass: is a multiplier to increase the source cohesive settling velocity

3. Jet Velocity Regions (based on Propeller Diameter)

• Efflux Zone: the efflux zone multiplier
• Zone of Flow Establishment: the flow establishment zone

4. Sub-Grid Setting

• Number of Axial Elements
• Number of Radial Elements
• Sub-Grid Length Multiplier
• Sub-Grid Width Multiplier

Figure 9. Propeller Wash Form: General Tab.

Ship tab

The ship tab is shown in Figure 10. The list of ships is displayed on the left of the tab. The Add button below the list of ships is used to create a new ship and and Delete button will remove a ship from the list. Search for a ship by entering the ship name in the search box, then the ship will be highlighted in the list. 

Figure 10. Propeller Wash Form: Ships Tab.

When you right-mouse click (RMC) on a ship, there are a number of options provided, including:

• Remove Selected Ship(s): LMC on a ship (or press the Ctrl + LMC to select multiple ships) then RMC to select Remove Selected Ship(s) to delete the selected ships from the ship list
• Remove All Ships: will delete all ships in the list
• Move Up: LMC on a ship to select then use this option to move up the selected ship up in the list
• Move Down: is the opposite to the Move Up option
• Sort Ship Names in Ascending Order:  will sort ship names from the smallest to largest, 0 to 9, and/or A to Z
• Sort Ship Names in Descending Order:  will sort ship names from the largest to smallest, 9 to 0, and/or Z to A
• Add New Ship: adds a new ship to the list

Figure 12. RMC's Ship Options.

The missing ship information can be filled in based on the MMSI code by using open-source online data or the EEMS Ship Database. Clicking Update button as shown in Figure 13 .The online downloading process will apply to each ship in a step-wise manner. After updating a pop-up message will appear to inform the download process is completed as shown in Figure 14.

Figure 13. Update Ship Info.

Figure 14. Complete Update Ship Info.

EEMS also supports importing of ships from EEMS ship information database by clicking the Import Ships button. The EEMS ship information database will pop up as shown in Figure 15. Search either by name or ship information such as length, gross tonnage, deadweight tonnage, or year built. After checking the number of ships that meet the requirement will be listed as shown in Figure 16. Select the checkbox and then import to the ship list or close to exit the form. When the result of searching returns, if we check on the checkbox Clear Existing Ship Data Before Importing then, click the Import button, the old ship data will be deleted. If the checkbox Clear Existing Ship Data Before Importing is not checked. The new ship will be added, even though the new ship has the same name as the existing one. It means that overwrite is not happened.

When there are two ships with the same name, we can check their information and extract information from them to update to only one ship and remain it, and we should remove the other one.

Figure 15. Import Ships from EEMS Ship Information Database Form (1).

Figure 16. Import Ships from EEMS Ship Information Database (2).

 After selecting a ship, the information for the selected ship will be presented in the Ship Info, Propeller Info, and Edit Parameter sub-tabs, as shown in Figure 17.

Figure 17. Propeller Wash Form: Ships Sub-Tabs.

Figure 18 and Figure 19 illustrate terminologies and dimensions which relate to the propeller of a ship. These dimensions are used in EE forms shown in Figure 20 and Figure 21.

Figure 18. Propellers with Side View of a Tugboat.

Figure 19. Propellers with Back View of a Tugboat.

Ship Info

Figure 20 displays general information for the selected ship such as MSSI Code, ship name, ship dimensions, number of tracks, etc.If the ship name is missing, the MMSI code will be displayed. Ships are distinguished by MMSI Code. From EEMS 11.7 onwards, users can select Use Horsepower or Use Revolutions option. The bold inputs fields are required to be filled first because those fields are essential indices. 

Figure 20. Ships Tab: Ship Info.

Propeller Info

Propeller information for the selected ship such as the number of propellers, number of propeller blades, propeller diameter, etc are shown in Figure 21. Please note that all fields are required to be filled. 

Figure 21. Ships Tab: Propeller Info.

Edit Parameter

In the Edit Parameter tab (Figure 22) select ships based on criteria in the Ship Selection frame by selecting a parameter from the drop-down list then select Comparison and Target Value. After selecting the criteria, click the Select button to proceed. The result is that ships that meet the selection criteria will be highlighted on the list of ships.

Figure 22. Ships Tab: Edit Parameter.

Tracks tab

The tracks tab of the propeller wash module is shown in Figure 23. The first frame is the information on all tracks for the selected ship and the second frame is the information on a specific track for the selected ship. The tracks of the selected ship are listed with the number of tracks, the number of points, data begin and end in Julian date, a maximum time gap in hours, maximum distance gap in meters, invalid data points, and missing data points. 

Figure 23. Tracks Tab.

Edit Track Table

Modify individual ship tracks by clicking Edit Track Table button in Figure 23. The Edit/Modify Individual Ship Tracks form pops up as shown in Figure 24. Select the ship from the drop-down list then the number of tracks and points are listed at the top. All detailed track points are presented in the table. 

Figure 24. Edit/ Modify Individual Ship Tracks.

Refine Global Tracks

Click the Refine Global Tracks button shown in Figure 23. The Refine Global Tracks for All Ships form will be displayed as shown in Figure 25. From this form, there are different options for processing ship tracks as follows:

• Delete Track Points Outside Simulation Period: enter the beginning and end times and then click the Delete button. This will remove tracks outside of the simulation period.
• Delete Track Points Outside Domain Extent: imagine that a rectangle covers the model domain and four corners of the rectangle are controlled by values of the West, East, South and North. These values are updated automatically in the model domain. However, the user can change these values by entering new values into the box and then clicking the Delete button to remove tracks outside the domain. Note that in case the track has two points, one point is inside the domain and the other is outside of the domain, then the two points of the track will remain.
• Delete Track Points by Selection:  using criteria, the criteria can be selected from the drop-down list as Speed (m/s), Course (degree), Draft(m) etc, next select the operator then enter the value, finally click the Delete button.
• Select by Polygons: this option is similar to the function to remove tracks outside the domain extents, this option allows the user to remove tracks inside or outside of existing polygons prepared in advance by browsing to the polygons file and then clicking the Delete button.
• Split Tracks: splitting tracks can be based on two options, the user can select eitherSplit using Time Duration (hours) or Split using Track Point Distance (m) check box or select both options at the same time and click theSplit  Tracks button.
• Delete Tracks: this feature allows deleting tracks based on the following two conditions, the user needs to define the values to enter the two conditions:

     Deleting Using Minimum Track Duration (minutes)

     Deleting Using Minimum Track Points

Click OK to close the form.

Figure 25. Refine Global Tracks for All Ships.

Fill Missing Values

After clicking the Fill Missing Values button in Figure 23, the Fill Missing Data Values for Global Ship Tracks Points form will be displayed as shown in Figure 26. From this form, fill of missing data can be requested:

• Compute Speed:  will fill in data for the speed of the track points
• Compute Heading: will fill in data for the heading of the track points
• Compute Course: will fill in data for the course of the track points
• Set Value:  will assign a value to a field (the field can be selected from the drop-down list) with criteria as shown in Figure 27

Fill Tracks Point Values by Selection: using this option, the criteria can be selected from the drop-down list such as Speed (m/s), Course (degree), Draft(m) etc. Select the operator then enter the value

Select by Ship Tracks

• All Ship Tracks: fill data applies to all tracks of all ships.
• Specific Ship: fill data only applies to all tracks of a specific ship.
• Specific Track: fill data only applies to a specific track of a specific ship.

Select by Polygon: under this feature there are three options as Don't use Polygon, Tracks Inside Polygon, Tracks Outside Polygon. This feature allows the user to fill ship tracks points that are inside or outside of existing polygons prepared in advance by browsing the polygons file 

Click the Process button to start filling in missing data values. If not check the Overwrite Existing Values box, the process will only update when the data values of the specified parameter are missing. 

Figure 26. Fill Ship Tracks Points form.

Figure 27. Fill Ship Tracks Points: Set Value.

Propeller Wash in the 2DH View

To display the Propwash in the 2DH View, open a new 2DH View from the 2DH View menu or the 2DH View button from the main toolbar of EE main form. There are nine parameters that belong to the Propwash. It includes Max. Course Difference, Max. Ship Speed, Max. Speed Difference Fraction, Mean Course Difference, Mean Ship Speed, Mean Speed Difference Fraction, Propwash Mesh, Ship Count, Ship Track.

The following steps show how to add a parameter of propwash shown in Figure 28 and Figure 29

1. Click the Add New Layer in the Layer Control.
2. Select PropWash for Primary Group in the 2DH View Option.
3. Select Ship Track for Parameter
4. Select a ship from the drop-down list (e.g. BERING SEA). In case, checked on the All check-box then all ships will be selected.
5. Click the Apply button. In case the All box is checked then all ships will be selected.

Figure 30 shows the ship track layers added to the 2DH View.

Figure 28. 2DH View: Adding a parameter of PropWash (1).

Figure 29. 2DH View: Adding a parameter of PropWash (2).

Figure 30. 2DH View: Ship Track Layer.

To edit ship tracks in the 2DH View, select the ship track layer in the Layer Control and enable the pen. Next, LMC on a track point, and the general information of the selected track point will be displayed on the yellow board. We can move the track point by holding the left mouse button on that point and moving to another place then releasing the mouse. When right mouse click, a number of options will appear as shown in Figure 31. 

• Ship Properties: Select this option, the Vessel form appears to show all information belonging to the ship as shown in Figure 32
• Set Focusing Object: When selecting this option, the animation of the ship moving just focus on the ship.
• Insert Single Track Point: Move the mouse to a place in the selected track then select this option, a new track point will be inserted.
• Insert Multiple Track Points: adds multiple track points. When this option is selected the Insert Multiple Track Points as shown in Figure 33. The user enters the number of points and then click OK button. The default value in the form is 2.
• Delete Selected Track Point: deletes the selected track point.
• Break Selected Track Point: breaks the ship track into two tracks at the selected track point.
• Delete Selected Ship Track:  deletes the selected ship track.
• Delete Selected Ship and Tracks: deletes the ship and all tracks belonging to that ship.
• Undo and Redo options can be used after using some options like insert or delete options above then the Undo and Redo option will appear from RMC options as shown in Figure 34.

Figure 31. 2DH View: Edit Ship Track.

Figure 32. Ship Properties.

Figure 33. Insert Multiple Track Points.

Figure 34. Undo and Redo Options.

RMC on the ship track layer in the Layer Control, options are shown in Figure 35. They include the following:

• Properties: when this is selected, the Ship Track Layer form will be displayed as shown in Figure 36. From this form, the user can set line style, color, and width for the tracks. The user can also show the current ship track only or all ship tracks by using two check-boxes Hide All Ships Except Active One and Hide All Tracks Except Active One.
  
• Edit: when this option is selected, the 2DH View Option form is displayed, allowing the user to change from the current layer to another parameter layer.
  
• Zoom to Layer: zooms to the ship track layer
  
• Remove Outside Points:  allows the user to browse a defined polygon and then remove track points outside the polygon.
• Export:  exports the ship track to a JSON file format (*.json)
  
• Remove:  deletes this layer from the Layer Control.

Figure 35. RMC Options for Ship Track Layer.

Figure 36. Ship Track Layer Properties Form.

Input File Format for Propeller Wash

There are three input files for the propeller wash module. The files are in *.jnp format, including propwash_config.jnp, propwash_ships.jnp and propwash_tracks.jnp. These files are generated automatically by EE when the user saves the model.

The propwash_config.jnp file contains information on mesh settings and model parameters as shown in Figure 37. These fields are in the General tab of the Propeller Wash form.

The propwash_ships.jnp file contains information on ships and propellers shown in Figure 38. These fields are in the Ships tab of the Propeller Wash form.

The propwash_tracks.jnp file contains information on tracks for ships shown in Figure 39.

Figure 37. Propwash Configuration File.

Figure 38. Propwash Ship Input File.

Figure 39. Propwash Tracks Input File.

Hotkeys list for overviewing different ships in the 2DH View are shown in Table 1.

Table 1. Hotkey to Overview Different Ships

References

https://www.navcen.uscg.gov/?pageName=AISMessagesA