How to Plot a Radar Position Fix Using Range and Bearing (Step-by-Step), by Maritime Academia on YouTube. 4 min 28 s.
- Video length
- 4 min 28 s
- Time to do it
- 20 minutes
- Difficulty
- Medium
- Steps
- 9
What you need
Steps
Identify two or three charted objects that show clearly on the radar, such as a lighthouse, headland or buoy. Pick fixed objects, not other vessels.
Read the range to the chosen object with the Variable Range Marker. Turn the VRM knob until the marker circle touches the target, then note the distance in nautical miles.
Read the bearing with the Electronic Bearing Line. Rotate the EBL until it passes through the target and read the bearing from the radar display.
Write down the time, the object name, the range and the bearing for each target. Take all readings within a minute or two so the fix stays consistent.
Lay the parallel rulers on the chart and line them up with the bearing scale at the compass rose. Walk the rulers to the charted object without letting them slip.
Draw a line from the object along the bearing, then repeat for the second object. Where the two lines cross is your bearing fix.
Set the compass dividers to the measured range using the chart's latitude scale. Put one point on the object and draw a short arc across the bearing line.
Repeat the range arc for the second object. The point where the arcs and bearing lines meet is the radar position fix.
Mark the fix with a small circle and write the time beside it. Record the range, bearing and object names in the log.
Tips and common mistakes
Use objects with wide angles between them, ideally around 90 degrees, for a sharper fix.
Measure range on the latitude scale at the side of the chart, not the longitude scale.
Keep the radar on a steady range scale and check the heading marker is aligned before taking bearings.
Questions
Why use radar instead of GPS for a fix?
Radar fixing is a backup when GPS or ECDIS fails, and it is a required skill under STCW. It also confirms that the charted object matches what you actually see.
How many objects do I need for a fix?
Two objects give a workable fix. Three objects let you check for error, since the lines should meet at one point.
What is the difference between VRM and EBL?
The VRM measures distance to a target. The EBL measures its direction from your ship. You need both to plot a fix.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
