Radar Simulator

What each radar control does

Range:

How far the screen reaches. Each range has its own ring spacing, shown in the top-right corner. Use the shortest range that shows what matters, and range out regularly.

Gain:

Receiver sensitivity. Turn it up until a light speckle just shows, then back off slightly. Too low hides small targets; too high hides everything in noise.

Tune:

Matches the receiver to the transmitter. Adjust for the longest tune bar or the strongest echoes. Most sets do it automatically.

Sea clutter (STC):

Reduces the gain close to the boat, where waves return echoes. Use just enough to see targets through it: overdone, it wipes out small boats nearby.

Rain clutter (FTC):

Breaks up large, soft echoes such as rain to their leading edge, so hard targets inside a shower show. Turn it off again once the shower has passed.

EBL:

Electronic bearing line from the centre. Reads relative bearing in head-up and true bearing in north-up.

VRM:

Variable range marker: a ring you lay on the inner edge of an echo to read its range.

Head-up / north-up:

Head-up puts your heading at the top, like the view ahead. North-up puts north at the top, like the chart. The heading line shows which way the bow points.

Trails:

Show where each echo has been. In relative motion a trail pointing at the centre means a collision course.

Setting up a radar picture

1. Switch on, wait for the set to warm up, then transmit.
2. Choose a medium range, such as 3 or 6 miles.
3. Set the gain for a light background speckle, and check the tune.
4. Add sea clutter control until the waves near the centre thin out, but no further.
5. Use rain clutter control only while a shower is on the screen.
6. Check the heading line, orientation and ring spacing before you measure anything.

Collision avoidance by radar

COLREGs Rule 7 requires proper use of radar, including long-range scanning and systematic observation of detected objects. A steady bearing with a closing range means risk of collision. In restricted visibility (Rule 19), a vessel detected by radar alone forward of the beam calls for early, bold action, but avoid altering to port for it unless it is being overtaken, and avoid turning towards a vessel abeam or abaft the beam. Radar does not replace a lookout: small craft, wooden boats and targets in clutter may not show at all.

This simulator is a learning aid with simplified physics. Real sets differ in their controls and menus: read your own radar’s manual and take the RYA Radar course before relying on one at sea.