Hi Jackie.
Welcome to the show, by the way. The questions you raise are interesting, in retrospect. See if any of the following helps.
The bridge R/T you mention was probably either a short range (VHF) set, or a medium range (around a few hundred miles) R/T. The former was used by bridge officers for ship's purposes, in harbour, calling for tugs, etc., but could also be used easily when within range of one of the coast stations scattered about the coasts of Britain and Europe, for good quality 'link' calls, or phone calls, to you and me. You called on Ch 16 (the distress and calling frequency which was constantly monitored) and then were transferred to another, dedicated channel for working into that particular station. If they were busy, you were given a turn number and had to wait, obviously monitoring the channel for them to call you back. Once onto the subscriber ashore, it wasn't necessary to say "Over", as these channels were send/receive simultaneously, or duplex, same as if you were ashore using the normal landlines. In my experience, they were very good quality setups indeed. That VHF set came into its own many times in my time at sea. It was used around the U.S. coast a lot in the same way as around Britain. I even used it on an almost daily basis when at a grain berth outside the city of Seattle, Washington, many times for people who couldn't get ashore and needed to say "HI!" to their loved ones. Such a lovely and easy to use setup, that.
As for the Portisheadradio bit, well that was a bit more complicated. It allowed you to make R/T calls from just about anywhere in the world, if the radio gear on the ship was adequate (some weren't fitted with H/F R/T, only medium range and morse, but that was in the earlier days before much more modern equipment became the norm.) In the early days, when I first went to sea in 1969, and for one or two years afterwards, if you were using this service, you had to book the call ahead of time via the R/O, or radio officer, who would then send details of the ship's position, callsign, etc. to the long range station at Portishead via a service message in morse. At the appropriate time, with the prospective caller sitting in the radio room waiting, (and the subscriber sitting at home, having been advised beforehand that the ship would be calling at a set time), the link with the Post Office Centre at Baldock, in Hertfordshire would be made via Portishead, and the circuit set up for the forthcoming call to be made. They had directional transmitting and receiving aerials at Portishead, which could be turned in your direction for best results.
It worked well, if sometimes a little difficult technically. It could be either duplex (two way, interruptible) or simplex (one person only, able to speak at a time, using your favourite "Over" and releasing the button on the telephone handset in order to hear the response and stop the transmission).
Sounds a bit complicated? Nah, it was nothing to us heroes in the radio room. Scary, the first time you had to set it up, if you were just out of radio school, where you had no experience in these sorts of things. As for privacy, well I didn't know of any back then, so you were always aware that anyone could be listening and probably were, so if you had anything really sensitive to talk about you probably either waited until you could get to a landline or just simply put up with it. I for one, always found other peoples' phone calls incredibly boring after a while, and would imagine that to be the case with possible eavesdroppers. Most calls were inevitably about the usual family things, or even more boring: ship's business. The R/O wasn't allowed by law to mention anything either heard or sent, whether on the R/T or even a morse telegram.
I believe there were sometimes 'scrambler' facilities available, but I never saw or encountered that capability. So you were perfectly able to overhear anyone's conversations at any time, just by tuning in to the appropriate frequencies, which were often quite busy back in the day.
The shorter, or medium range R/T facilities were much simpler to use. You just called the coast station on either the distress and calling frequency (2182 kHz), or, if working into a British coast station, (and you were a British ship) the dedicated British ship-to-shore frequency of 2381 kHz and listen out for the coast station to give you a turn, or transfer you directly to the working channels if they weren't busy. The setup worked well enough, even if the quality wasn't always so good, what with interference and static and so on, and the service was often very busy, depending on the times of day or night, so it certainly wasn't always the case that you could just front up to the radio room and hope to get a line ashore straight away.
When the newer and more complex equipment came onto the market by the later '70's, some of the above got easier, and the long-range Portishead-via-Baldock thing was done away with, the operator at Portishead simply connecting to the landline there and then. The equipment was easier to use, more powerful and hence longer range capability, with usually somewhat better quality in the calls themselves due to the more powerful gear and differences in technical capabilities which came with that.
Hope all that was interesting. And also, all the best with your writing project. I'm doing a book myself, though not about the sea as such, though some of that will go in somewhere. How could it not!?
Best regards, Paul
Interesting to think of it from your point of view!
