Detecting Buoy Lights: Effects of Motion and Lantern Divergence

摘要

The motion of a buoy may affect the probability that a navigational light signalis detected. Buoy motion is studied to quantify the effect it has on the detection range of a buoy's light signal. Buoy motion data were taken from video recordings of standard USCG buoys in a variety of sea conditions. It became evident during the study that buoy motion is a combination of both list and roll. Properties of a buoy signal light were mathematically combined with the buoy motion data to calculate detection ranges under various conditions. The detection ranges used in the analyses correspond to the distance at which a mariner has an 80% probability of detecting the buoy signal. Results show that buoy motion is a problem. The present buoy lanterns provide an 80% probability of detection range which is only about half of the commonly accepted and published nominal range. This is true for most combinations of weather, buoy size, and flash characteristic. The effect of list alone contributed substantially to buoy signal degradation. Further calculations showed that increasing the vertical divergence of a lens from the currently used 4.2 deg to between 8.3 and 10.0 deg (full-width, half maximum) will increase the detection range by approximately 40%. Keywords: Buoy motion, Signal effectiveness, Lantern divergence, Probability of detection. (JHD)