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Author Topic:   RADAR Visibility
jimh posted 12-26-2011 08:27 AM ET (US)   Profile for jimh   Send Email to jimh  
I don't have any hands-on experience with modern ship RADAR units. From reading a lot of Tom Clancy books, I know that modern warfare tactics tend to rely on being stealthy. Not only doesn't a combatant want to give an opposing RADAR system a good target by providing a strong return signal, being stealthy means not emitting any RADAR signals yourself.

Small boat navigation is, of course, the antithesis. You want your boat to be visible to the RADAR of other boats. Unfortunately the RADAR profile of a small boat with a low profile and made of fiberglass is probably not very visible. In practice, many small boats will employ RADAR reflectors to increase their visibility of the RADAR of other vessels. This leads to my question:

Does having an operating RADAR on your small boat have any effect on the ability of other vessels to see your boat on their RADAR? Particularly with these newer marine RADAR sets that use a low-power frequency modulated continuous wave technique rather than a high-power burst method, will having your boat RADAR operating cause a strong signal on other ship RADAR sets?

I know in the Tom Clancy fictional word, emitting a RADAR signal will give away your position to the other combatants, but in the real world of present practice in small boat RADAR, does operating your set help other sets to see you?

Peter posted 12-26-2011 09:30 AM ET (US)     Profile for Peter  Send Email to Peter     
The short answer is a simple and inexpensive radar reflector will provide a much more distinct target at a greater distance on the radar screen than any crosstalk from another active radar will. Navigation aids that have the perpendicular planes or the radar reflectors similarly constructed produce distinct radar signatures on the screen.
jimh posted 12-26-2011 01:06 PM ET (US)     Profile for jimh  Send Email to jimh     
Peter's thinking is akin to mine. I think typical small boat marine RADAR sets are not the sort of "threat receiver" that Tom Clancy novels feature in their combatants vehicles, planes, or ships.

Regarding RADAR reflectors, there is a good report about the general ineffectiveness of many commonly sold devices from the United Kingdom, contained in a follow-up investigation to a nasty big-boat/small-boat collision at sea between the sailboat OUZO and the ferry PRIDE OF BILBOA. See

and in particular the section 2.6.5 RADAR REFLECTORS, where the radar cross section (RCS) of some commonly used reflectors is discussed.

For more details see the separate report on the RCS of many devices sold as reflectors:

Performance investigation of marine radar reflectors on the market Radar%20reflectors%20report.pdf

For all reports and annexes related to the OUZO incident see

David Pendleton posted 12-28-2011 09:55 AM ET (US)     Profile for David Pendleton    
From my RADAR display's manual:

Mutual radar interference is likely when two or more radar-equipped vessels are operating within range of each other. This usually appears as a series of small dots moving to and from the display center in a straight line or a long, sweeping curve. This type of interference is most noticeable at long ranges.

There is a setting on my display that filters this sort of interference. When this setting is disabled, it is possible to determine if another RADAR is operating in range, but it is not possible to determine where the other RADAR is.

bluewaterpirate posted 12-28-2011 01:01 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
All US Navy ships are equipped with the AN/SLQ 32 shipboard electronic warfare system. This system can/will detect commercial surface radars in the I/J bands.

To my knowledge there is no commercial application for the use of electronic warfare equipment on merchants and small craft.


David Pendleton posted 12-28-2011 05:28 PM ET (US)     Profile for David Pendleton    
I can also tell you that small, fiberglass boats like ours do not make particularly good RADAR targets. If you want to be seen, a reflector or transponder is the best way to go.
jimh posted 12-29-2011 10:13 AM ET (US)     Profile for jimh  Send Email to jimh     
Perhaps reflective of a U.K. bias, the investigation report (linked above) mentions active marine RADAR transponders made by SEE-ME:

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