NaviPac and Helmsman Troubleshooting and FAQ

Owned by jr_mateo
Last updated: Dec 20, 2022
6 min read

 

1. NaviPac-Online indicates that it cannot calculate current position.

Possible causes (1) A GPS has poor signal; (2) The estimated position is way off from the actual. NaviPac-Online > Edit> Estimated Position; in the window that appears, manually enter the coordinates from the GPs console in the A/LO Office, and click the GPS Pos button (which should update the estimated position).

 

2. I changed the geodesy of my project, and now the waypoints and runlines are not plotting properly.

Re-import the waypoints (drag-and drop the file into the map view). For runlines, you may have to digitize them again, or convert the coordinates using GEOCalc (NaviPac > Tools > GEOCalc)

 

3. In Helmsman, I changed the units in Project Settings, but the units in the graph and data views are still different.

In the Data View table, click on the particular parameter/item and change the property to change the display unit. In most cases, like the speed, graphs default to Metric unit and cannot be changed to knots. A ticket has been submitted to EIVA and this problem has been flagged as a bug, to be fixed in future versions.

 

4. In Data View, the coordinates are only in decimal degree (DDD.dddd) and DD MM SS formats. How do I change that to degree decimal minutes format (DD MM.mmm)?

At present, Helmsman is not able to display coordinate formats in degree decimal minute (DDD MM.mmmm). A Feature Request has been submitted to EIVA (Ticket #41709)

RESOLVED, as of version 4.6. During Exp. 398, the data view displayed latitude and longitude in DDD MM.mmmm format, as used by Ops and the Bridge

 

5. What is a Filtered vessel position?

Automatically generated when Kalman filtering is applied to the vessel motion in NaviPac (Vehicle > Properties). The filtered vessel position will appear as an "object" that can be selected for navigation and display in Helmsman, and as an item that can be recorded in NaviPac-Online Custom Log file.

"Kalman filtering, also known as linear quadratic estimation (LQE), is an algorithm that uses a series of measurements observed over time, including statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probabbility distributionover the variables for each timeframe" (https://en.wikipedia.org/wiki/Kalman_filter)

The plot below shows the moonpool position, which is undulating, and the Kalman Filtered vessel position, which is more linear. For the JOIDES Resolution, the moonpool is regarded as the origin of the Common Reference Point (CRP), and is therefore equivalent to the Filtered vessel position. The difference is negligible (about 0.1% error or about 0.6 m)

 

6. Unlike waypoint files, why is my shapefile not displaying properly or appears missing when i drag-and-drop it into the map view?

Well...it appears that the drag-and-drop does not work all the time, especially in version 4.5.4. For shapefiles (e.g. EEZ boundaries), you may have to deliberately import it: Helmsman > View > Import new files > shapefile.

In version 4.5.5, the issue has been resolved: Draggin-and-dropping of shapefiles into a map view now works!

 

7. How can I remove or display the map scale?

The map scale are green vertical and red horizontal lines in the middle of the map view. It is referred to as "Target" in the Map View Properties > Screen Overlay. To hide, simply change the value to "False".

 

8. The calculated speed and distance are are not accurate.

Possible reasons:

  1. Check the map projection: UTM projections are more accurate in measuring distances, but distorts the outlines outside of the designated zone. Also, one needs to manually adjust the zone number in the Helmsman Geodesy pop-out window. However, any active navigation and data logging in NaviPac should be stopped. Also, all map elements (e.g., waypoints, EEZ outlines, etc.) should be re-imported.

  2. A waypoint file from a previous map projection or UTM zone may still exist in the Helmsman project, and navigation in the Vehicle Control is pointed to that older waypoint.

    1. With the correct UTM zone entered, re-import the waypoints. You may need to append/suffix the name of the waypoint list with the zone number (e.g. 393_waypoints_27S.wpt). Do not remove or delete the old waypoint list because you may need it again for the return transit.

    2. In the Vehicle Control panel, select the specific waypoint from the newly imported list (look for the appended UTM zone name).

 

9. In Helmsman, the background map adjusts to the geodesy setting from NaviPac, but not the toppings (e.g. EEZ shapefile). This happens when the UTM zone is updated.

Just like the waypoints file, you need to RE-IMPORT THE ORIGINAL SHAPEFILE (C:\ExpNAVdata\World_EEZ_v11_20191118), and NOT the shapefile from the Helmsman folder > Project>Toppings.

For any shapefile that is imported into a helmsman map view, make sure that the dbf (and shf and prj) files are also in the same folder, so that the polyline attributes will also show up in Helmsman.

 

10. How can I update the UTM zone in Helmsman?

Helmsman's Settings>Geodesy is only for setting the project when NaviPac is offline, otherwise, Helmsman will follow the geodesy settings in NaviPac. Therefore, to update the UTM zone (or other map settings in Helmsman, simply

  1. Go back to the NaviPac window (see figure above).

  2. If NaviPac is running, stop the data acquisition first.

  3. Select Geodesy in the Project Tree (panel to the left), and

  4. In the Properties panel (to the right), select the ellipsis (...) button next to the Projection.

  5. A Reference System Selector window will appear.

  6. Change the UTM zone at the bottom row.

  7. Click the OK button.

  8. Start NaviPac again and remember to customize items to record and start recording in NaviPac Online.

This should automatically adjust the background map and the EEZ shapefile. If the shapefile does not re-plot to the new zone, re-import the original shapefile (NOT the one from Helmsman project>Toppings folder, which has already been projected), together with the waypoints.

 

11. How do I know that an instrument is fully and correctly integrated into NaviPac?

A connection to an instrument does not always guarantee that NaviPac is parsing the relayed information correctly. For example, an MRU connection can be established and shown to be streaming data via the NaviPac Online > Instrument Spy window. However, to check that the information is being parsed correctly:

  1. NaviPacOnline > View > Attitudes. This will bring out a GUI that shows the gyroscope and MRU readings.

  2. NaviPacOnline > View > Raw Data. This will bring out a window where you can select the port number of the instrument. Incoming data will be shown in the two panels: Raw Data and parsed data below.

If the expected data is not streaming, stop NaviPac data acquisition and edit the instrument properties. In the case of the MRU, a user defined format was selected, instead of a pre-defined format. After editing, save the NaviPac configuration and re-Start again. Remember to customize items to record and start recording in NaviPac Online.

 

12. How does NaviPac calculate GPS Tide?

Source: https://eiva.freshdesk.com/support/solutions/articles/43000621882-gps-tide-calculation

  1. RAW GPS Height received from GPS

  2. This is compensated for antenna offsets (3D roll/pitch) -> CRP height

  3. Based on position a geoidal separation (e.g. VORF or DNN) is found and subtracted from the tide

  4. If a heave sensor exists then the heave is taken out of the value.

e.g. An Octans MRU is giving vessel HPR and gyro with XYZ of 0,0,0. Does this MRU require lever arms set for CRP XYZ? 

Yes that is needed as NaviPac needs to calculate the heave value in CRP – and to do so it need the offsets from MRU to CRP.

  5. We have now CRP height where short terms waves are taken away – this is GPS tide

  6. If there is defined a draught sensor then,

  1.  

    1. Use the pressure value (has to be in dB)

    2. Subtract pressure from surface.
      The pressure comes from the NaviPac Global settings Depth calculation parameters.

    3. Convert to depth. NP estimates the depth from pressure based on the Saunders and Fofonoff - Simple method.

    4. Compensate for offset of draught sensor

    5. Now we have draught in CRP

    6. Subtract that from the tide

 

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