The master of every ship arriving at any port shall show, until the ship has received pratique under these Rules, whichever of the following signals is appropriate.(a)by day, during the whole of the time between sunrise and sunset, when the ship is within three miles of the coast(i)the Flag Signal Q: meaning-"my ship is healthy and I request free pratique.(ii)the Two Flag Signal QQ: meaning-"my ship is suspected" (vide rules 20, 24, 29, 41 and 45), or(iii)the Two Flag Signal QL : meaning -"my ship is infected" (vide rules 20,24,29,35,41 and 45), the signal being shown also when a person suffering from typhus or relapsing fever is on board.(b)by night, during the whole of the time between sunset and sunrise but only when the ship is within three miles of the coast, a signal which shall be shown at the peak or other conspicuous place where it can best be seen, comprising a red light over a white light the lights being not more than six feet apart, and meaning "have not free pratique":Provided that the authorities at a port may, with the previous approval of the Central Government, notify alternative signals, not conflicting with the International Code, for use by ships visiting the port frequently.
