shown on approaching, or on being approached by, another vessel in sufficient time to prevent collision.
Art. 10. A vessel which is being overtaken by another shall show from her stern to such last-mentioned vessel a white light or a flare-up light.
The white light required to be shown by this Article may be fixed and carried in a lantern, but in such case the lantern shall be so constructed, fitted, and screened that it shall throw an unbroken light over an arc of the horizon of twelve points of the compass, viz. from six points from right aft on each side of the vessel, so as to be visible at a distance of at least one mile. Such light shall be carried as nearly as practicable on the same level as the side-lights.
Art. 11. A vessel under 150 feet in length, when at anchor, shall carry forward where it can best be seen, but at a height not exceeding 20 feet above the hull, a white light in a lantern so constructed as to show a clear, uniform, and unbroken light, visible all round the horizon at the distance of at least one mile.
A vessel of 150 feet or upwards in length, when at anchor, shall carry in the forward part of the vessel, at a height of not less than 20, and not exceeding 40, feet above the hull, one such light, and at or near the stern of the vessel, and at such a height that it shall be not less than 15 feet lower than the forward light, another such light.
The length of a vessel shall be deemed to be the length appearing in her certificate of registry.
A vessel aground in or near a fairway shall carry the above light or lights, and the two red lights prescribed by Article 4 (a).
Art. 12. Every vessel may, if necessary, in order to attract attention, in addition to the lights which she is by these rules required to carry, show a flare-up light, or use any detonating signal that cannot be mistaken for a distress signal.
