Optimize your radar to get the best line of sight.

You don’t need to know the exact science of mounting a radar, however, understanding the basic principles of the line of sight will enable you to decide on the best place for your radar.

The basics:

If you are sitting in the cockpit and your eye line is 2m (6ft) above the waterline you could, in theory, condition-dependent, see 2.7 nautical miles (nm).

Your radar at the same height will be able to see approximately 3.2nm (radar line of sight). Therefore, if the object you were looking at was 2m high, the distance you and the radar first see would double (6.4nm).

The total-line-of-sight visual:

The total visual line-of-sight distance is your line of sight to the horizon added to the object’s line of sight.

A radar mounted 3.5m above the waterline would have a radar line-of-sight of approximately 4.2nm

If you were looking at some cliffs 150m high and your eyes were 2m above the waterline, you should start seeing them when you’re 26nm away (23.6nm + 2.7nm).

Likewise, if a ship is 30m high, the furthest you could to see it from would be 13.3nm (10.6nm + 2.7nm).

If that ship is traveling towards you at 25 knots, the maximum time you’ll have to assess the possibility of a collision is just over half an hour (31 minutes), and less than that if you’re sailing towards it and don’t spot it for a while...

Difference in locations:

So, if a 30m high ship was heading for you at 25 knots, assuming you have your radar alert set at 18nm and noticed the ship straight away, you would have 44 mins with the radar 8m above the waterline.

With the radar at 3.5m above the waterline, you would have 39 minutes.

Final thoughts:

• As you may have realized, a slight change in height can have an advantageous effect on your radar's vision range.
• Understanding where restricted visibility is on board is key to improving your radar vision.
• Want to see more radar options? Check out our offerings here!