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i MARBLEHEAD CHAMPIONSHIP Details extracted from the official report, photographs by W. A. Smeed Wwe only three points dividing the first five, this year’s Championship (Birkenhead, Whitsun) provided one of the closest finishes yet seen in a National event. Winds generally over the two and a half days favoured the light-weather boats. and were mainly from N.E. to N., giving semi-reach conditions for much of the race. Many re-sails were necessary because of the conditions, but nevertheless 30 ‘heats were sailed before the pre-arranged deadline was reached. Priest-designed Witches and Witchcrafts were numerous (at least eight) and did extremely well; Sue and Anne were Witchcrafts. Duck and Mithras designs (Gannet, Luvaduck, and Girl Pat, Trump, and Mithras) fared badly in the light wind conditions, Trump’s position being due solely to outstanding skippering. The Ballantine (U.S.A.)-designed Bacchus was one of three sliding rigs racing, and other competitors looked thoughtful about the effectiveness of this controversial rig. Only one sharpie appeared, Blue Mist, and this boat finished higher than two previous winners, Floreana and Tweedledee, both of whom like more wind. Once again the 1953 winner Foxtrot was well up in the hands of her designer, as was the well-known Gretel; seven the points Scottish behind boat the pleased the keen Scots. a race which the conditions, out on proved top. Yacht “Sur’’ “‘GRETEL’’ ‘‘FoxTrRoT’’ ‘“ANNE’’ “TRuMpP’’ 7 8 9 10 11 12 13, 14 15 16 17 18 19 20 21 I) 23 24 25 26 27 28 29 30 31 32 33. 34 “YACHABEL’? “SUSAN J’’ “‘ESTRELLE’’ “BAcCHUuS’’ “Ecuo IT’’ “SpERO’’ “Gicr’ “BLue Mist’’ “‘FLOREANA’’ ‘“BoLERO’’ “TWEEDLEDEE’? ‘‘CANASTA’’ “BLUE Boy’? “BLACK AJAx’’ ‘‘WeREWOLrF’’ ““GANNET’’ “LuvApUCK’’ “TaNntivy’’ “CrusaDER’’ “LewarRa’’ ‘“EcHo’’ ‘‘ATom’’ “Aricra’’ “Davey’’ “EpNa’”’ “Girt Pat’ “URsuLa’’ ‘‘MiTHRAs’’ 6 631 KS.2 319 763 955 1015 968 1187. 1182 564 1195 726 972 668 884 1166 947 935 1034 1173 1092 1013 1035 214 1162 1100 1117 1112 906 ‘“Comer’’ did which well, only must have matter what Altogether a fair result from again the best Posn. No. 1 1197 2 654 3 927 4 937 5S 1090 Yachabel winner, Heading picture shows Lewara leading from Girl Pat; above, Foxtrot and Susan ¥#. manage to keep full spinnakers despite a tricky wind. Below, highest placed heavyweight was Trump, here shown in company with Canasta that boats Skipper D. McIntyre R. Harris W.L. Grint R. Mackarel J. Pemberton P. Mustill no and skippers come Club Total Score Fleetwood 103 Bournville 101 Norfolk & Nwch. 101 Fleetwood 101 Birkenhead 100 Birkenhead T. Todd Glasgow D. Watts Birkenhead R. J. Burton Clapham K. Jones Birkenhead J. Graham Clapham K. Roberts —_ Birkenhead L. Maskell Bradford C. Dicks Clapham W.H. Jones Birkenhead G. Reeves Bournville M. Widdows Bournville R. Bonthrone Clapham S. Camm Birkenhead D. Britton Bournville G. Stobbs Doncaster J. Gorst Clapham J. Sixsmith Birkenhead R. Dunning Bury P. Hughes Llandudno D. Pearson Birkenhead W. Whittle Nth. Liverpool E. J. Blackshaw Birkenhead C.H.Elsom Clapham J. Elliott Bournville F. Hunsperger Nth. Liverpool G. Kelly Llandudno J. Whittle Nth. Liverpool L.G. Nason Clapham » 97 96 94 91 91 89 88 82 79 784 75 744 73 71 71 71 70 65 64 64 62 60 54 53 50 49 45 42 38 386 MODEL MAKER) RADIO2+ CONTROLLED YACHES | J. C.HOGG CONCLUDES A THREEPART ON SERIES THIS GROWING SPORT ae control system gives proportional steering and progressive (non-sequential) sail control. It has two relays only—one a normal type, the other a “‘Rotorelay”’. It needs no intergear batteries or relays. Fig. 4 is the circuit, which shows that both relays A and B are operated from the anode circuit of the last valve, one directly and one via the transistor “‘T’’. Before describing the action reference is made to the Rotorelay A, used for controlling the rudder servo. This operates rather in the same way.as a milliammeter, but instead of a pointer it has a contact arm. The contact arm will move strictly in accordance with the mark space signals being received (as would a milliammeter) and therefore in accordance with the “‘tiller’’ at the transmitter. The Rotorelay contacts are set close together and are electrically connected to the rudder servo motor and are also mechanically connected by means of a light rod to the lever or crank which operates the rudder itself, to give a feed back action to the contacts. So the rudder accurately and quickly follows the contact arm to whatever position it is moved by the tiller. The Rotorelay comprises a cylindrical magnet mounted on a vertical spindle which carries the contact arm. This turns inside a coil system. The relay can best be made out of a small Desyn indicator by adding a contact platform, contacts and contact arm. Only two of the three wires from the base of the Desyn are used— found by trial. Care should be taken to avoid sparking at the contacts by bridging them with a condenser and resistance in the usual way. I find that a small 25 mf electrolytic condenser and 10 ohms resistor is a suitable combination for this purpose. The other relay contacts have changes in polarity so that an electrolytic cannot be used. In this case they should be bridged with a 0-1 mfd and 40 ohms. Properly protected the contacts will go the whole season with cleaning. Without protection they will soon stick. This applies to most sensitive relays. While mark/space signals are being received the second relay B (a polarised E.D. type or similar) is held in, being fed via the condenser C and the transistor. If these pulses cease, either due to a full space or a full mark being sent, the relay drops out and feeds current to the winch servo S. A mark lets out the sheets and a space winds them in, the amount depending on how long the signal is held. For close trimming the winch can be “inched” in or out by short prods on the mark or space buttons. It will be seen that with the centre connected servo batteries the usual limit switch wiring cannot be used. However, two small rectifiers, G.P.O. type, fitted (and forgotten) as shown provide the answer. They only come into use at the beginning of the return journey after a limit switch has opened. As soon as it closes the rectifiers are shorted out—hence they can be of small size. Limit switches for the rudder are not necessary to limit the swing of the Rotorelay contact arm with stops. Usually, however, it is wise to fit a small friction clutch on the rudder servo, set to a value above the maximum pull required. This protects the gears in the event of a rudder being knocked in handling. The clutch comprises two #-inch discs, one fixed on the servo final shaft, the other carrying the crank for the rudder rod. The two discs are pressed together by a compression spring on the shaft and have a fibre disc between them. The clutch is fitted before the mechanical feedback linkage so that if accidentally knocked the rudder will immediately return to its original position. Fig. 5. Batteries and Weights Radio yacht sailing differs from other radio control boats in that being windpowered the models are frequently sailed for long periods at a time, and two hours at a stretch is not unusual in a day’s intermittent sailing. The 7$ volt AD38 are quite suitable for the above gear. The extra voltage allows for loss in circuit and contacts and the initial voltage drop of the battery. It is better to be rather higher in nominal voltage than lower, when using dry batteries. It does not pay to save weight on H.T. batteries, and a B109 or its equivalent should be used. The total battery weight for the equip- ment described above is 12 1b. The total weight of the equipment including these batteries is under 5 Ib. I stress this because figures sometimes quoted are very mis- leading. Total weights will vary according to the type of boxes, gear trains, motors, etc., used, but certainly should be about this figure. Trends and Developments The development of equipment for radio control has reached a stage which, though by no means final, can enable boats to be designed specially for this type of 396 SEPTEMBER, 1959 RUDDER DIAGRAMMATIC SUDDER SERVO GEAR Heading picture on opposite page shows the Author’s ex. A Class yacht Sundial, which has been extensively used for radio experiments. Bottom photograph shows the control gear for a Marblehead consisting of a rotorelay, sail winch and rudder servo receiver and batteries fit between these and switches at top of frame Top photograph this page shows right, a Desyn indicator and a converted rotorelay. Photograph at right, shows the parts added to the Desyn to make the conversion in mind that with national tournament racing, every boat in a contest races each other so that the chances of a clash are greatly increased. As the sport grows these chances will become very likely. I suggest that one solution would be to develop the technique of making VALVE ANODE “RECEIVER — S0ut ROTORELAY (A) 3 c anc =)nt W zed Ps3 8200 3 Fig4 each receiver capable of being switched to operate on T — 8 b, NORMAL ewig sw. UMIT SWITCHES sas HT- CIRCUIT FOR YACHT CONTRO!. w+ sport. The formulation of a set of Racing Rules based on full-sized I.Y.R.U. rules has given definition to the movement. There is no doubt of the interest aroused in the sight of two or more yachts racing together under radio. This has immediately raised the question of the means whereby such yachts can race without mutual radio interference. The present day super-regenerative receivers, though excellent in performance, are not sufficiently selective to allow two to operate in the allotted band. The superhet receiver has, therefore, been brought in and for the present is unsurpassed for reliability and selectivity, although it involves the use of a crystal-controlled transmitter—which is desirable from other aspects. With properly chosen crystal frequencies some 10 yachts can go on together. With the present number of boats it is unlikely that crystal frequencies will clash at a regatta, but it must be borne either of two frequencies, one near the top of the allotted band, and one near the bottom (rather like the Light and Home programmes, though the two frequencies should not be the same for every boat). In superhets this would involve crystal switching. By this means any two com- petitors when brought together could be certain of avoiding each other’s frequency. If, as I hope to see, three boat racing becomes standard practice, it is almost certain that this method would allow three boats to meet since between them they would have a choice of six frequencies. I realise that this calls for a little bit more thought and effort with the radio gear, but it would widen the scope of contest immensely. Many possibilities lie in the near future for R/C yacht equipment. The improvement of transistors, though they often are very temperature-conscious, is already having its effect. Servo motors have reached a high standard of efficiency, and it is already possible to drive them direct from power transistors. The new DEAC chargeable dry cells are proving to be excellent for R/C use. Our aim should be to have small, light economical equipment with portable transmitter, and a high degree of reliability. The equipment will then become a means to an end—the improvement in yacht performance, and the practice of hard and enjoyable model sailing. FORTHCOMING EVENTS M.P.B.A. REGATTAS sen Lindlow Common, Wilmslow, Cheshire wa Mee nahi … Rushmere, Wimbledon … Se Princess of Wales Pond, Blackheath … ste. rae Round Pond, Kensington … Hackney Park, Victoria Walthamstow M.P B.C. ay September 27 RC SR SR ne … ~ Canoe Lake, Southsea… …. Portsmouth M.P.B.C._.. RC Sp 4 October Note alteration of date of Portsmouth event to October 4. SR—Straight Running ; RC—Radio Control. Sp—Speed; etc. Other Meetings, Exhibitions, ( R/C boats will be running during the afternoon.) London Ham Rally, Festival Gardens, Battersea. September 6 September 6 September 13 September 20 SR Sp SR RC SR Sp SR nee ie Altrincham M.P.B.C. Kinzsmz2re M.P.B.C. B. Blackheath M.P.B.C. W. London M.P.B
