Inserting the installation parameters for the transducer
The physical location and the installation angles of the transducer are critical for the echo data accuracy. Incorrect angles will greatly reduce the data accuracy. A hull unit may be provided as an option. It allows you to lower and hoist the transducer. When the installation trunk is mounted, it may not be positioned with the mounting holes perfectly aligned to the centre line of the vessel. When the hull unit is placed on the trunk, the "forward" mark on the transducer shaft sleeve - and thus also "forward" on the transducer - may not point forward at all, but several degrees off the centre line. To obtain accurate echo presentations, this misalignment must be adjusted by changing the installation parameters. Providing the correct value for this rotation is crucial for the sonar performance. An inaccurate or incorrect value will cause the sonar echoes to be presented at the wrong bearing.
Prerequisites
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With hull unit:
A Bow
B This is the alignment angle (±180°)
C 0° transducer mark
The SN90 system has been set up with its hardware units connected as specified in the Installation Manual.
•  The SN90 system is turned on and operates normally.
•  The SN90 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 location of the transducer, you need the detailed vessel drawings. You also need the installation angles that were recorded when the transducer was installed.
Context
The physical location of the transducer is important for the echo data accuracy.
Without hull unit
Use the centre of the transducer face as reference, and define the offset values related to the Ship Origin. The installation angles relevant for the transducer must also be defined. These values were recorded during the installation, and they define the direction of the transducer face.
Note
It is very important that the transducer installation angles are measured and recorded accurately during the installation. Incorrect angles will greatly reduce the data accuracy.
In order to visualize the process of finding the installation angles, observe these three examples.
For trawl and navigation use, the transducer must be pointed straight forward with the indicator arrow pointing up.To set the angles correctly, observe this exercise. Use your cellphone to visualize the transducer movements.
1 Start with the transducer in its default position: The transducer face is horizontal facing down, and the indicator arrow is pointing straight forward.
2 If the transducer is properly installed without unintentional skew, the Rotation Around X can also be set to 0 (zero).
3 Lift the front end of the transducer up, so that the indicator arrow moves up.
4 Proceed until the requested angle has been reached.
Example: If a 30-degree Y angle is requested, the Rotation Around Y must be set to 60 degrees (that is the angle from the default position).
5 Since the transducer is pointing straight forward, the Rotation Around Z value is 0 (zero).
For purse seine with the gear on the starboard side, the transducer must be pointed approximately 90 degrees towards starboard with the indicator arrow pointing up. To set the angles correctly, observe this exercise. Use your cellphone to visualize the transducer movements.
1 Start with the transducer in its default position: The transducer face is horizontal facing down, and the indicator arrow is pointing straight forward.
2 If the transducer is properly installed without unintentional skew, the Rotation Around X can also be set to 0 (zero).
3 Lift the front end of the transducer up, so that the indicator arrow moves up. This is a Rotation Around Y.
4 Proceed until the requested angle has been reached.
Example: If a 15-degree Y angle is requested, the Rotation Around Y must be set to 75 degrees (that is the angle from the default position).
5 From this raised position, turn the transducer towards starboard. The indicator arrow is still pointing up. This is a Rotation Around Z.
6 Proceed until the requested angle has been reached.
Example: If a 90-degree Z angle is requested, the Rotation Around Z must be set to 90 degrees (that is the angle from the forward position).
Used for purse seine with the gear on the port side, the transducer must be pointed approximately -90 degrees towards port (or 270 degrees towards starboard which puts you in the same direction) with the indicator arrow pointing up. To set the angles correctly, observe this exercise. Use your cellphone to visualize the transducer movements.
1 Start with the transducer in its default position: The transducer face is horizontal facing down, and the indicator arrow is pointing straight forward.
2 If the transducer is properly installed without unintentional skew, the Rotation Around X can also be set to 0 (zero).
3 Lift the front end of the transducer up, so that the indicator arrow moves up.
4 Proceed until the requested angle has been reached.
Example: If a 20-degree Y angle is requested, the Rotation Around Y must be set to 70 degrees (that is the angle from the default position).
5 From this raised position, turn the transducer towards port. The indicator arrow is still pointing up. This is a Rotation Around Z.
6 Proceed until the requested angle has been reached.
Example: If a -100-degree Z angle is requested, the Rotation Around Z must be set to -100 degrees (that is the angle from the forward position). Setting it to +260 degrees will also work.
With hull unit
A hull unit may be provided as an option. It allows you to lower and hoist the transducer. When this option is selected, the transducer is delivered readily mounted at the lower end of the transducer shaft. Since the transducer is pointing straight forward, the Rotation Around Z value is 0 (zero). However, if the hull unit has been installed with an unintentional rotation referred to the centre line, the Rotation Around Z must be adjusted to compensate for this.
Independent of the hull unit orientation, the alignment is always defined as:
The angle measured from the bow to the 0° transducer mark.
The 0° transducer mark is located outermost on the mounting flange, and it is marked as a red "0". Depending on the transducer mounting, it can be located at any angle on the mounting flange, not necessarily as shown in the illustration.
On the Transducer page, define this angle as rotation around Z.
•  If the 0° transducer mark points to the starboard (right) side of the vessel’s centre line, insert the alignment as a number between 0 and +180 degrees.
•  If the 0° transducer mark points to the port (left) side of the vessel’s centre line (as shown in the illustration), insert the alignment as a number between 0 and –180 degrees.
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Illustration:
A Rotation around the x-axis: In the positive horizontal direction (forward), a positive rotation is clockwise.
B Rotation around the y-axis: In the positive horizontal direction (starboard), a positive rotation is clockwise.
C Rotation around the z-axis: In the positive vertical direction (down), a positive rotation is clockwise.
D Reference point (Ship Origin)
Procedure
1 Open the Setup menu.
2 On the Setup menu, select Installation.
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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 Select Transducer to open the page.
5 Insert the relevant offset values.
a X Offset: Insert the horizontal distance on the x-axis (fore-and-aft direction) between the transducer and the Ship Origin.
b Y Offset: Insert the horizontal distance on the y-axis (athwartship direction) between the transducer and the Ship Origin.
c Z Offset: Insert the vertical distance on the Z axis between the transducer and the Ship Origin.
6 Without hull unit: Obtain the rotation (angle) information from the personnel that installed the transducer.
Insert the values. Do this as accurately as possible.
7 With hull unit: Obtain the rotation (angle) information from the personnel that installed the hull unit.
Insert the values. Do this as accurately as possible.
a Rotation Around X: Specify an angle (in degrees) to compensate for any deviation from the X axis (fore-and-aft direction) in the vessel coordinate system. If the transducer is properly installed without unintentional skew, this angle can be set to 0 degrees.
b Rotation Around Y: Specify an angle (in degrees) to compensate for any deviation from the Y axis (athwartship direction) in the vessel coordinate system. If the transducer is properly installed without unintentional skew, this angle can be set to 0 degrees.
c Rotation Around Z: Specify an angle (in degrees) to compensate for any deviation from the Z axis (vertical direction) in the vessel coordinate system. This is the alignment angle.
•  If the 0° transducer mark points to the starboard (right) side of the vessel’s centre line, insert the alignment as a number between 0 and +180 degrees.
•  If the 0° transducer mark points to the port (left) side of the vessel’s centre line (as shown in the illustration), insert the alignment as a number between 0 and –180 degrees.
Examples:
•  If the alignment angle is 295 degrees, insert -65 degrees.
•  If the alignment angle is 15 degrees, insert 15 degrees.
8 At the bottom of the page, select Apply to save your settings.
9 Continue your work in the Installation dialog box, or select OK to close it.