Glossary - Part R

•  RACON: A radar beacon, which produces a coded response, or radar paint, when triggered by a radar signal.

•  Radius of Curvature: Every glass element in a Fresnel lens assembly has at least one surface with a curve that is designed to deflect and redirect the light coming from the source.

•  Range Lights: Two lights associated to form a range, which often, but not necessarily, indicates a channel centerline. The front range light is the lower of the two, and nearer to the mariner using the range. The rear range light is higher and further from the mariner. When the ship is in the proper channel, the lights will be in alignment.

•  Range Nominal: The maximum distance from its source at which an Aid to Navigation (AtoN or ATN) might be effectively utilized, based on a mathematical formula.

•  Red Sector: A portion of a light that is colored red so that a mariner sees a red light if he is approaching a dangerous obstacle.

•  Reflect: Return or throw back, light.

•  Reflector: A device used to reflect a point source of light back into the focus of the reflector (spherical reflector) or past the focus in a concentrated parallel beam (parabolic reflector).

•  Refract: Bend or slant rays of light.

•  Relocated Lighthouse: An authentic Lighthouse moved from its original location, except those moved a short distance due to erosion.

•  Replica Lighthouse: A structure built to carefully reproduce an authentic Lighthouse, faithfully utilizing historic documentation.

•  Revetment: A facing placed on a bank or bluff of stone to protect a slope, embankment, or shore structure against erosion by wave action or currents.

•  Revolving Light: One that produces a flash or characteristic due to the rotation of the Fresnel lens.

•  Rhythmic Light: A light showing intermittently with a regular periodicity.

•  Riprap: A loose arrangement of broken rocks or stone placed to help stem erosion.

•  Rock Lighthouse: A lighthouse surrounded by the sea.

•  Round Fiberglass: A round tapering tower made of fiberglass, utilizing lightweight prefabricated material which retains a traditional Lighthouse style.

•  Ruby Glass: Glass produced by adding gold to the molten glass mixture. Ruby glass was used in flat panels and molded into glass chimneys to produce a red character.