Originally Posted by gwzm
(b) send, in addition, class A1 and A2 emissions on at least two working frequencies;
(c) receive, in addition, class A1 and A2 emissions on all the other frequencies necessary for their service.
The provisions of (b) and (c) do not apply to apparatus provided solely for distress, urgency and safety purposes."
The ITU Radio Regulations and the UK Radio Rules did not specify the maximum number of frequencies that had to be available for transmission, only the minimum provision. However as standard the UK GPO only licensed two MF working frequencies in the 1950s and 1960s. I assume that additional frequencies were obtainable if the owners applied for them, because I sailed on and encountered vessels that had all 4 of the listed frequencies. One was a Shell tanker and I suspect that, being major company with its own radio superintendent, they had some clout in getting their way. I also sailed with ships of smaller companies that did not have that advantage (or couldn't be bothered to ask).
I sailed with the Oceanspan I, which had variable MF oscillator tuning using a miniature 'starting handle' to wind up the frequency required. That was no problem when working any station - whatever they asked for you could give them.
I also sailed on vessels that had crystals fitted for all 4 working frequencies but only 2 of which appeared on the Ship Radio Licence (one of which instances caused me some hassle with the Aussie radio surveyor in Melbourne).
Para. c) above really has no relevance since it applies to provision on the ship for reception, not transmission.
As I said, as time passed and technology moved on, such small matters faded into the background and the GPO Radio Surveyors found something else with which to torment us shore technicians.