normally be on the frequency that is paired with the frequency on which the call was made. The station that is called should either confirm the frequency for'the follow-up traffic or indicate another frequency.

On receiving a DSC call that gives no indication of follow-up frequency to use, the receiving ship should indicate a suitable frequency in its acknowledgement.

4.10.4.2Routine communications using radio telephony

Before commencing any transmission, check whether the frequency is already occupied.

A simplex call in which both stations use the same frequency involves listening on that frequency. A duplex call in which separate frequencies are used involves listening on the ship's transmit frequency; when the channel is free the receiver should be retuned to the coast station reply frequency and the call made in the normal way.

When calling, speak clearly. First give the name of the station being called followed by own ship's name (and call sign if necessary). If it is necessary to spell the name of the ship the phonetic alphabet should be used. Give the other station time to answer; it may have heard you but be unable to reply immediately.

4.10.4.3Routine communications using radio telex

Before transmitting to a coast station, listen on its answering frequency for the 'channel free' signal. This is interspersed with the coast station call sign in morse.

4.11Emergency navigation lights and signalling equipment

The OOW is responsible for ensuring that the emergency navigation lights and signalling equipment are in working order and ready for immediate use at all times.

The condition of flags and shapes should be checked at regular intervals.

Sound signalling equipment must be checked daily and maintained in an operational condition. Where roller guides and wires operate the whistle, these should be examined frequently to ensure easy operation. Electric and automatic whistles should be maintained according to manufacturers' instructions.