Raymarine SL72 Owner's Handbook Manual page 193

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Ensure the display unit is in Radar mode.
To switch to transmit mode, press and release the POWER key. The antenna
sweep should start to build up the radar picture.
Run through the operations described in Chapter 3 and check that all the
expected data is displayed.
Bearing Alignment
When the system is correctly installed, you must check the bearing alignment
to ensure that targets appear at their correct bearing relative to the ship's bow,
and adjust the alignment if necessary.
To adjust the alignment, you need to select a visible target of known bearing
that is displayed on the radar, and then use the setup options to adjust the radar
until the correct bearing reading is obtained.
➤ To determine the alignment error, use one of the methods detailed below.
1. Visually identify a suitable target, such as a buoy that can be seen towards
the edge of the radar screen. Typically, this will be on the 1.5 nm range.
2. If the vessel is moored:
i. Determine the accurate bearing of the target relative to the ship's bow
Example 1
Visual bearing= 065 °M
Ship's head= 021°M
Relative bearing= 044°R
Example 2
Visual bearing = 030°M
Ship's head= 042°M
Relative bearing= -012°(+360) = 348°R
ii. Measure the relative bearing of the target on the radar using an EBL.
iii. If there is a difference in the two bearings (alignment error), adjust the
If the vessel is under way (in reasonably calm conditions):
i. Align the vessel's bow to the target.
ii. Note the position of the target relative to the Heading marker.
iii. If the target is not under the Heading marker, there is an alignment error
SL72 & SL72RC PLUS Pathfinder Radar & Radar/Chartplotter
with the aid of a hand bearing compass. i.e. Subtract the ship's head
bearing from the target visual bearing.
radar as detailed below.
and the radar can be adjusted as detailed below.