Ships were fitted with all the frequencies you quote; all with dedicated crystals, in the case of the Oceanspan transmitter, say, until the later transmitters with synthesised drives came along. That gave you a bit of leeway. If you were working Nitonradio/GNI, for instance, you would probably go for 468, his working frequency being 464, or Landsendradio/GLD, who was on 438 and would often use 425 from the ship. It got a bit congested in European waters (Scheveningen/PCH was on 461, so you would use 468 or maybe 454 with him. Hopefully the relative distances between stations would lessen problems with interference). That's how I used to work, anyway. Somehow it worked out alright.
Last edited by Paul Braxton; 7th August 2019 at 23:57..