where is the white light located on a boat
Navigation light To avoid collisions, vessels mount navigation lights that permit other vessels to determine the type and relative angle of a vessel, and thus decide if there is a danger of collision. In general sailing vessels are required to carry a green light that shines from dead ahead to 2 points (​22 1⁄2°) abaft[note 1] the beam on the starboard side (the right side from the perspective of someone on board facing forward), a red light from dead ahead to two points abaft the beam on the port side (left side) and a white light that shines from astern to two points abaft the beam on both sides. Power driven vessels, in addition to these lights, must carry either one or two (depending on length) white masthead lights that shine from ahead to two points abaft the beam on both sides. If two masthead lights are carried then the aft one must be higher than the forward one.[2] Hovercraft at all times and some boats operating in crowded areas may also carry a yellow flashing beacon for added visibility during day or night.
Flannan Isles Lighthouse The first hint of anything untoward on the Flannan Isles came on 15 December 1900. The steamer Archtor on passage from Philadelphia to Leith passed the islands in poor weather and noted that the light was not operational. The ship suffered the misfortune to run aground on Carpie Rock in the Firth of Forth [9] some time after passing the lighthouse and after the struggle to save the ship, the fact of the lighthouse light being unlit was not reported on arrival at Oban for some time, the ship's master, Captain Holman, being distracted by the damage to his ship, and the procedures for dealing with her on arrival in port. The island lighthouse was manned by a three-man team (Thomas Marshall, James Ducat, and Donald MacArthur), with a rotating fourth man spending time on shore. The relief vessel, the lighthouse tender Hesperus, was unable to set out on a routine visit from Lewis planned for 20 December due to adverse weather and did not arrive until noon on Boxing Day (26 December).[7] On arrival, the crew and relief keeper found that the flagstaff was bare of its flag, none of the usual provision boxes had been left on the landing stage for re-stocking, and more ominously, none of the lighthouse keepers were there to welcome them ashore. Jim Harvie, captain of Hesperus, gave a strident blast on his whistle and set off a distress flare, but no reply was forthcoming.