Measuring The Range - Furuno FR-1500 MARK-3 Series User Manual

1.18 Measuring the Range

Use the fixed range rings to obtain a rough estimate of the range to a target. They are the
concentric solid circles about own ship, or the sweep origin. The number of rings is automatically
determined by the selected range scale and their interval is displayed at the upper-left position of
the screen.
1.18.1 Measuring range by the variable range marker (VRM)
Use the Variable Range Markers (VRMs) for more accurate measurement of the range to a target.
There are two VRMs, No.1 and No.2, which appear as dashed rings so that you can discriminate
them from the fixed range rings. The two VRMs can be distinguished from each other by different
lengths of dashes.
1. Press the [VRM ON] key to display either of the VRMs. Successive presses of the [VRM ON]
key toggles the active VRM between No.1 and No.2 and the currently active VRM readout is
circumscribed.
2. Rotate the VRM rotary control clockwise or counterclockwise to align the active VRM with the
inner edge of the target of interest and read its distance (unit: nm) at the lower-right corner of
the screen. Each VRM remains at the same geographical distance when you operate the
[RANGE+] or [RANGE-] key. This means that the apparent radius of the VRM ring changes in
proportion to the selected range scale.
3. Press the [VRM OFF] key to erase each VRM.
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