This is the report from a study on the effectiveness of marine radar reflectors performed by Dick Honey, Stan Honey, Jim Corenman, and Chuck Hawley in September 1995. It was done with the generous cooperation of SRI International in Menlo Park who provided the use of their state-of-the-art radar cross-section measurement range which was normally used to precisely assess the design of aircraft that seek to minimize radar cross-section. Eldon Fernandes, the operator of the SRI RCS range and an employee of SRI, provided invaluable support. The study was originally published by Practical Sailor in September 1995. At the time, Dick Honey was a senior principal scientist at SRI, Stan Honey was a former research engineer at SRI and VP Technology at News Corporation, Chuck Hawley was the technical director for West Marine, and Jim Corenman was a electrical engineer and active cruising sailor.
The physics of electromagnetics remain the same and the conclusions of the report are still accurate today. Many of the radar reflectors tested are still popular. An octahedral radar reflector such as the Davis or Plastimo, in the double catch-rain position, remain a reasonable choice. The common Mobri radar reflectors are essentially invisible to radar on sailboats that heel. None of the passive radar reflectors are more than marginally useful offshore where ships might only be using S-band radars.
Finally, sailors should remember that the small boat is both better able and more highly motivated to detect and avoid a collision with a ship than vice versa. A small boat radar can detect a ship at 12 miles by radar whereas a ship’s radar can only see a sailboat at 3-4 miles.