ONLY REQUIRED UNDER CERTAIN CONDITIONS: Although radar reflectors are required for boats under 20m and boats that are built of mostly non-metallic materials, there are some exceptions where a radar reflector is not required
If you are operating your vessel in limited traffic conditions, daylight hours and in favourable environmental conditions, a radar reflector is not needed because it isn’t essential to the boat’s safety. The small size of your boat and/or its operation away from radar navigation and large shipping lanes might make having a radar reflector impracticable and, therefore, is not needed.
Radar reflectors are used to help larger vessels spot smaller vessels on their radar screens to help avoid collisions on the water, as well as to facilitate search and rescue operations if necessary. There are different radar reflector models that can be used.
A radar reflector can enhance your safety on the water, but only if it’s big enough and well placed on your boat. When buying a reflector, there is no substitute for size, so buy the biggest one that is practicable for your boat. This being said, when navigating in busy seaways, at night or far from land, a radar reflector is a rather cheap device to have and one that is easy to rig up. It should be installed in an area where it is a minimum 4m (13.1 ft) above the waterline and higher than all the surrounding superstructures to insure that you’ll be seen on the radar screen of large ships and fishing boats. Height is also very important.
There are all kinds of reflectors of varying quality on the market, so make sure you look carefully before buying.