Inserting the ship origin and dimensions

When you have several different sensors and transducers on your vessel, and you wish each of them to provide accurate data, you need to know their relative physical positions. To do this, you must establish one or more common reference points. This reference point is also used to position the sonar echoes relative to the ship symbol on the display presentation.

The ST90 system has been set up with its hardware units connected as specified in the Installation Manual.

  • The ST90 system is turned on and operates normally.
  • The ST90 system is in Normal mode, but TX Power is set to Off to prevent transmissions.
  • The vessel is berthed or at sea.
  • Neither tools nor instruments are required.

For accurate ship dimensions you need the detailed vessel drawings.

Use the Ship page with the ship's physical dimensions to create a virtual reference point (the Ship Origin) in a dedicated coordinate system for the ST90 system. The Ship Origin is normally located in the following position:

  • X position: Half the ship's length
  • Y position: Half the ship's width
  • Z position: On the waterline

If you want to change the location of the Ship Origin, you can do this by providing offset values in the X, Y and/or Z directions. To do this you will need the ship drawings.

Tip:

It is common practice to place the Ship Origin at the same position as the motion reference unit (MRU). This will minimize the vectors when your vessel is moving. Use the vessel drawings to establish the offset values between the basic position of the Ship Origin and the MRU location.

If you do not have a motion sensor you can place the Ship Origin at any location on the vessel. We suggest that you place the origin under the captain’s seat on the bridge. All sensors will then be referenced to this position. Whenever a sonar is used with short ranges, this will provide a more precise presentation.

Procedure

  1. Open the Setup menu.
  2. On the Setup menu, select Installation.

    Observe that the Installation dialog box opens. This dialog box contains a number of pages selected from the menu on the left side.

  3. On the left side of the Installation dialog box, select the small white triangle next to Installation Parameters.

    Observe that a menu opens with access to all the individual pages.

  4. Open the Ship page.
  5. Insert the physical dimensions of your vessel (length and width).

    Do this as accurately as possible. This information is used to create a new origin in the vessel coordinate system.

  6. Offset:
    1. If you want to keep the default reference point (origin), leave all offset values to 0 (zero).
    2. If you want to move the reference point to another location, use the necessary offset values.

      To find these offset values, consult the vessel drawings. Do this as accurately as possible.

  7. At the bottom of the page, select Apply to save your settings.
  8. Continue your work in the Installation dialog box, or select OK to close it.

A common reference point for the sensors and transducer has now been established.

You must proceed by defining the locations of the navigation system antenna, the motion reference sensor, and the transducer. These locations are all referenced to the same reference point.