The use of navigational lights on state aids to navigation, including regulatory markers, is discretionary. When used, lights on solid colored buoys shall be regularly flashing, regularly occulting, or equal interval lights. For ordinary purposes the frequency of flashes may not be more than thirty flashes per minute (slow flashing). When it is desired that lights have a distinct cautionary significance, as at sharp turns or sudden constrictions in the channel or to mark wrecks or other artificial or natural obstructions, the frequency or flashes may not be less than sixty flashes per minute (quick flashing). When a light is used on a cardinal system buoy or a vertically striped white and red buoy it shall always be quick flashing. The colors of the lights shall be the same as for reflectors; a red light only on a solid colored red buoy; a green light only on a solid colored black buoy; a white light only for all other buoys including regulatory markers.