A new resolution on energy-efficiency regulation of ships was adopted at the 65th session of the Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO),...
Sectors may be only a few degrees in width or extend in a wide arc from deep water toward shore. Bearings referring to sectors are expressed in degrees true as observed from a vessel.
In most cases, areas covered by red sectors should be avoided. The nature of the danger can be determined from the chart. In some cases a narrow sector may mark the best water across a shoal, or a turning point in a channel.
Sectors generated by shadow-casting filters do not have precise boundaries as directional sector lights do.Therefore, the transition from one color to another is not abrupt. The colors change through an arc of uncertainty of 2° or greater, depending on the optical design of the light. Therefore determining bearings by observing the color change is less accurate than obtaining a bearing with an azimuth circle.