Features November 2007 Issue

Marine Myth Buster: Can sun-reflective tapes also reflect ship’s radar?

Practical Sailor determines that the shiny tape on life vests and other products can also act as a radar reflector, but we wouldn’t bet our lives on it.

Three common adhesive, light-reflective materials were examined: 3M Scotchlite SOLAS-A reflective tape, ACR’s Res-Q reflective patches, and 3M’s Scotch-brand reflective adhesive tape. Kitchen aluminum foil was also tested. But being a good reflector of light does not necessarily mean that a material is a good reflector of radar. What makes a good reflector of radar? First, the object must be made of something that is a good conductor of electricity, aluminum for example. Second, the object should be flat. Curved surfaces such as spheres do not reflect radar nearly as well as fl at plates. Third, the surface must be smooth. Surface ripples as small as 1 millimeter can reduce radar reflectivity by as much as 50 percent. And, the dimensions of the object must be at least as long as the radar wavelength. (The wavelength of X-band marine radar is about 1¼ inches.) It is likely that any light-reflective tape that is relatively stiff, looks metallic, and has no visibly noticeable pattern would be a good choice, but that cannot be guaranteed.

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