I have known Roy for very many years since about 1956 when I lived in North London and sailed my boat on the Round Pond in Kensington Gardens on Sunday mornings.
However one needs to go back in time a little, because I was a member of the London Group of Radio Controlled Model Society since 1946 shortly after it was formed, as it was then, that I built my first radio controlled model boat, which I still have. I was at school at Pangbourne and won a prize so I got a book on “High-Speed Small Craft, by Peter du Cane. In there was a photograph of the Royal Barge so I wrote to Peter du Cane at Vospers to ask if they would send me a set of drawings of this boat. I still have the drawings dated January 1953, directly from Vospers. So I built a 12th scale model of this boat and fitted it with radio control.
It was this boat that I took to the Round Pond every Sunday morning, and it was Roy who had an interest in same, however he also sailed an “A” class yacht. As far as I can remember he also had a small cabin cruiser so I suggested that he should fit it with radio control, which he did with my help. At that time he worked for the Great Western Railway at Paddington. In 1961 I came to Switzerland however we still kept in contact with each other.
When he retired he moved to Otterton in Devon, so I visited him quite often, as I also went to Camelford to visit Peter Cummins, whom I had known since 1946 through the R.C.M.S.. In 1951 this became the International RCMS.
It was here in Devon during one of my visits that Roy said he would like to build a Fairmile “D” MTB, and asked for some help. The hull of the boat was built as almost a copy of the oridinal, with frames and longitudinal stringers. When making the frames he asked me to make him a jig so that he could make all the cutouts for the stringers identical, which I naturally did almost by return so as not to delay the building of the hull. So the next problem was that of the motors, propulsion and steering gear. It seemed that the best offer for motors was from a company selling motors under the name or “Motors Direct”. I was also interested to purchase some myself so we ordered 8 of one type. The label placed on the motors was that they were for 6, 12, 18, 24 volts. This is of course incorrect as such DC motors are made for one voltage only.
When we tried one of the motors on 12 volts it did not seem to deliver very much torque or speed. I took all eight of these motors back to Switzerland and found under one of the labels that they were manufactured by Bühler of Germany, so I obtained a data sheet from Germany and saw that the windings on the armature were for about 19 volts. So the next job was to remove the windings on one of the armatures, carefully counting the number of turns for each of the 7 individual windings, also the thickness of the wire.
After some careful calculation I decided how many turns were neded for a supply of 12 volts and the thus increased wire size. I then rewound this armature and carried out comparison with this new version against the original type. I made up a long drive shaft on a piece of wood taking measurements of the applied voltage and current, also the RPM of the shaft with the propeller running in air as well as in water. I then rewound the remaining severn motors, each being tested as the first one.
The next problem was to control the motor in the boat so a speed controller was designed and built. I made a small series of these as I wanted to rebuild the control system in one of my boats as well. As the build of the “681” progressed I made several other parts as Roy only had an “EMCO 1” lathe and even with the many extras that I had bought him for this lathe, so my machine shop could solve the problem, which has four precision lathes, two precision milling machines and five vertical drilling machines apart from very other machines.
As a result of meeting with Hilary Breeze in Germany, we competed a little to see which was the faster of our two “D” boats. This meant that there were three such boats in the SWA, so between the three of us there was a competition to see who was the first to achieve an air cooled “ASDIC” under the bows.
Philip T. Bellamy