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On marina piers it is not rare to come across some occasional, sailing-inexperienced bystanders pointing at somewhere on a sailboat mast and asking “what’s that tube over there?”. Well, in most of cases they are pointing at a radar reflector, i.e. a transparent “tube” (the most popular ones, but also available in different models and shapes) that peeps out from the crosstree. 

What is a radar reflector used for on a boat? It’s simple. It helps a boat to show up on other boats’ radar. It is a so-called “passive” device, as it does not require energy to operate (except for specific, sophisticated models). It is very light, cheap, easy to install (just a small rope or two plastic clamps are needed) and it significantly improves the safety of small boats. It is highly recommended in areas crowded with ships, ferries or maxi yachts or in case of poor visibility or when sailing by night. The most widespread models on sailboats are cylindrically-shaped, about 40-cm long, 5 or 6-cm Ø. Essentially, tube-type radar reflectors consists of a plastic tube containing 90° oriented crossed aluminium plates, like e.g. Supercompact radar reflector (

Manufacturers ensure radar reflectors make a boat be visible within 2-3 miles or even farther in case of bigger models, like e.g. Professional radar reflector ( Remember that for a radar reflector to be as effective as possible, it has to be installed high up. It is very affordable in price. It is mandatory for boats allowed to navigate beyond 12 miles (in this case specific technical characteristics are required) but highly recommended also when sailing closer to the shore.

The operating principle is simple: due to the aluminium plates a “reflective surface” is created to echo the radar signal to the surrounding area. In fact, a radar emits electromagnetic waves at a certain frequency that are transmitted to and reflected from the reflecting object. The radar reflector acts as a reflecting target able to enhance your boat’s signal on the area radars. As normally many sport boats are made of fiberglass or wood, the surface area required to generate a sufficient radar signal is usually lacking.

As already mentioned, tube-type radar reflectors are the most widespread models, however there are also rhomboidal-shaped versions, like e.g. Radar Reflector (, foldable and with aluminium panels. Similarly to the tube-type versions, they are easy to install, have to be mounted on the mast top and, as they do not emit any signal, no electrical connection is required.

Last but not least “active” radar reflectors are also available. They amplify and retransmit radar signals through a transmitter antenna. Radar visibility is significantly improved and the risk of collision highly reduced. They are of course quite expensive (up to 1,000 Euros), which makes perhaps more cost-effective to provide your boat with a complete radar set.

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