Raymarine DS400 & DS500 User Manual

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Chapter 3: Getting Started
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The shape of the arch is also affected by the speed of the boat. If the boat is 
moving slowly, the arches tend to be longer; if the boat is moving more 
quickly, the arches are short and peaked. If the boat is moving very fast, a fish 
may be indicated by vertical lines.
3.9 Using the Variable Range Marker (VRM)
The VRM (variable range marker) key is used to determine the distance 
behind the boat of an object on the display. The VRM function is available on 
the scrolling sonar display and zoom windows, if your transducer is equipped 
with a paddlewheel for measuring speed and distance.
To display the VRM, press ENTER from the main fishfinder page. The VRM 
is displayed as a vertical line running the entire height of the display. You can 
use the < and > keys of the trackpad to move the VRM over a particular object 
to reference it from the boat.
Distance behind the boat is displayed next to the vertical line. The VRM 
distance units correspond to the depth units assigned in the system set up 
parameters you have assigned for your unit. However, when set to fathoms, 
the VRM is displayed in feet.
The vertical line does not scroll with the scrolling sonar image. If the display 
range changes, the VRM retains its position. When you switch on the VRM, 
it is displayed at its last position.
Press QUIT to remove VRM from the screen.
If the sounder is in split frequency display mode, the VRM is shown in only 
one window at a time.
QUIT