Art. 13. Nothing in these rules shall interfere with the
operation of any special rules made by the Government of
any nation with respect to additional station and signal
lights for two or more ships of war, or for vessels sailing
under convoy, or with the exhibition of recognition signals
adopted by shipowners, which have been authorised by
their respective Governments, and duly registered and
published.
Art. 14. A steam vessel proceeding under sail only, but having her funnel up, shall carry in daytime, forward, where it can best be seen, one black ball or shape two feet in diameter.
SOUND SIGNALS FOR FOG, ETC.
Art. 15. All signals prescribed by this Article for vessels under way shall be given:
1. By 'steam vessels' on the whistle or siren.
2. By 'sailing vessels and vessels towed' on the foghorn.
The words 'prolonged blast' used in this Article shall mean a blast of from four to six minutes' duration.
A steam vessel shall be provided with an efficient whistle or siren, sounded by steam or some substitute for steam, so placed that the sound may not be intercepted by any obstruction, and with an efficient fog-horn, to be sounded by mechanical means, and also with an efficient bell. A sailing vessel of 20 tons gross tonnage or upwards shall be provided with a similar fog-horn and bell.
In fog, mist, falling snow, or heavy rain-storms, whether by day or night, the signals described in this Article shall be used as follows, viz.:—
(a) A steam vessel having way upon her shall sound, at intervals of not more than two minutes, a prolonged blast.
(b) A steam vessel under way, but stopped and having no way upon her, shall sound, at intervals of not more
