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iviodel Boats Gunboat ‘Foxhound’ Watercooling engines @ R.A.F. ‘Miami’ Air/Sea Rescue Launch @ Radio Yachts e@ Engine Starter MAY 1976 30p U.S.A. & CANADA $1-50 HOBBY MAGAZINE MAY R/C YACHT TACTICS = BY CHARLES REYNOLDS Charles Reynolds admits to being relatively new to radio yacht racing. However, he represented UK in the International Dragon class from 1965 to 1968, and in the International Soling class 19691972, including the Olympics at Acapulco in 1968 and Kiel in 1972, not to mention the Admiral’s Cup in 1975. Is now a member of \ | | | \ \ 45°-6|_ 45°+ Ohi); \ On model yachts in particular, I certainly claim no expertise, being a comparative newcomer to the game, and so the following comments are based more generally ae Given the prerequisite of a responsive yacht, and one that is capable of good acceleration after a manoeuvre, the aim must be to be in a position after the start whereby one can control the fleet. The control attitude is important — leading as such at this stage is not. As Messrs Goodrich pointed out, a preparatory look at the course is vital, principally to get a feel of the frequency of wind shifts. We all know that wind speed and direction are never constant, but the point that is often missed is that a frequency pattern can be detected, particularly in what a meteorologist will call ‘unstable air’ conditions. Relating this frequency pattern to the anticipated start time can not only influence whether one starts to leeward or to windward of the fleet, but also which side of the windward leg to work. Let us first consider the start line itself and the approach to it. It may not be immediately apparent from the shore whether the starboard or port end of the line is biased— hence which is the paying tack at the start. A simple check is to reach down the line on one tack with sails eased to the point where they are just lifting. Having ascertained this setting, reverse your course and come back down the line on the opposite tack without adjusting the sails. You will invariably find that the sails will lift more on one tack than the other, so demonstrating which end of the line to aim for, provided an opposite wind shift is not due. In other words, if your sails lift more on port tack, then you want to be at the starboard end of the line and vice versa. (Figure 1). The fixed wind bends which your trial sail up the lake will have shown, together with any frequency wind shifts your initial observations will suggest, must both be considered in assessing which side of the beat to work. For instance, if you expect a veer halfway up the beat, you may not be able to work it if you adopt the safe leeward position at the starboard end of the line on starboard tack. A progressive veer away from the line will allow those boats on your starboard quarter to sail the shorter arc inside you, irrespective of the fact that they may have been late on the line, and so climb up on to your wind. (Figure 2). This illustrates what I said earlier about being able to control the opposition after the start, rather than lead it off the line, hell bent for the middle distance. Of course in the case I have just described, the safe leeward berth would be ideal if the wind was tending to back on the windward leg. | ly 1 / \ | \ corners. on full size practice, partly adapted. The start / Sey / N the December 1975 issue, Larry and Niel Goodrich covered some very interesting aspects of windward technique. Perhaps it would be helpful before going on to reaching and running work to fill in one or two odd a = | | | STBD Gosport MYC, and a welcome contributor to MB! | oh 1976 | \ | \ —_ op = ‘X’- START = —Ea gee START LINE THIS END The windward leg In a covering battle, the covered yacht is in some ways at a greater advantage than may at first seem apparent. The covered yacht can in fact control the covering yacht by deciding when he is going to tack. If one can lure the covering yacht into consistently tacking into headers, there is a chance that one will slowly break through the wind shadow to leeward and work out ahead into a safe leeward position. Provided the distances allow it, the previously covered yacht is then in a position to initiate a port/starboard incident and reverse the tables. For a covering yacht, the counter-ploy to this strategy is to progressively delay the covering tack, so spending longer on the favoured tack, and then to try to tack dead ahead of the covered yacht either to slow him down further in his break tack or to force him to take the header and fall into your direct blanket. I’m not sure I agree with the Goodrichs’ feeling that you should cover closely at the beginning of the windward leg, especially away from the start. My own preference is to get away as fast as possible and to establish clear air, and freedom of movement as early as I can, then to try and work into a control position relative to the wind A START | NEWWIND—VEERING FIG. 2. : | | | | | | POSITIONS AFTER WINDSHIFT A2. 3) 253 I B12 C2 ae A B Cc BOATS AT START MODEL BOATS WINDWARD A a MARK WIND.1 Considering for the moment big boat practice, it used to be common in days gone by for the off-wind legs to be regarded as heaven sent opportunities to take a breather after the rigours of a thrash to windward. Cigarettes and beer appeared, and pictures of calm serenity appeared on the crews’ faces. Alas, those days are no more. The offwind legs are now, if anything, even more action packed, requiring a high workload to produce success. In heavy, gusty winds, it is necessary to be supremely alert, having a keen eye on the water upwind of your yacht, in order that you can pull her off a point or two a fraction before the gust strikes. This will ensure maximum acceleration in the desired direction rather than a screaming broach — or ‘uncontrolled luff’, as our more self-conscious colleagues might term it. When leading the pack on a reach, and if the opposition is close on your heels, it will of course be necessary to hold up to weather early on to avoid somebody climbing on to your wind and hence through you. If, however, you feel yourself further back in the bunch, you should force yourself to keep down on the rhumb line. This allows you to sail a shorter course, possibly faster overall since those ahead of you who have pushed each other higher and higher to keep wind free wil!l eventually have to bear off onto a slower point of sailing in order to round the mark. At best, you may find you have succeeded in establishing an inside overlap on the gybe mark, and can reassert yourself on the next leg. WIND. 2 | | | COURSE.1. ’ py! (f\COURSE! BOAT B a Q) Boar / / Hal | | | ge | §) COURSE 2 /(OR GYBE) | | | | | | COURSE 2 7 FIG.3. | | | | | LEEWARD MARK pattern and fleet distribution. Covering closely when approaching the windward mark is particularly useful in extending the gap between you and the opposition, thereby allowing you to sail unhindered the fastest course to the gybe mark, and on running legs, removing yourself as far as possible from a pursuer’s blanket. The reach Trans-ocean ships sail the ‘great circle’ route as the most rapid transit line. Given a constant wind over a model yacht course, the fastest route returns to the more familiar ‘shortest distance between two points’. This basic philosophy has to be modified to take care not only of backs and veers, but gusts and lulls — vital consideration when we consider the percentage increase in speed of a model yacht when sailing free. Bearing away in the gusts or luffing up in the lulls can produce extensive gains in distance over the ‘fixed sheet and rudder’ brigade. WINDWARD FIG.5. 4 Y] GYBE MARK ay ACK psc WIND AVERAGE WIND MARK \ / 4 LEEWARD MARK | A- ROUNDS MARK FIRST GYBES TO SHADOW 8’S STBD GYBE LEG,COVERS EACH GYBE THEREAFTER | | | | | | | | pe LEEWARD MARK The run Not unnaturally, this leg should be sailed in the opposite way to the beat, though this reversal of discipline does take some getting used to. Whereas on the beat, one is normally searching for freers, on the run we need to go looking for headers in order that we may continue to sail as close to the rhumb line as we can on the fastest point of sailing. As with tacking, gybing also slows a boat, so we want to try for the most direct, trouble free course. (Figure 3). Covering on the run is a two way attack ploy. A leading yacht must aim to always stay between the opposition and the leeward mark. In this way, he will always sail the shorter course, and also be inside the boat at the turn. (Figure 4). For pursuing yachts, covering is aimed at slowing the yacht ahead by blanketing him, and if possible luring him into an unfavourable wind streak, or indeed to a position where he is blanketed by other yachts, leaving you free to break off and follow your preferred course in the hope of breaking through. The leeward mark, to be rounded from a reach (or run) to a beat, is probably the one that can contribute more to 254 MAY | FIG.6. 7yelled ga Pare AT oor UU JOU I ar | FINISH THIS END | “Arnis 25 START THIS END | | | | | | | | | | i LEEWARD MARK success or failure than any other. If the leading boat of a pair (‘A’ in Figure 5) takes the mark too close while still on her reaching course, the action of rounding on to the same windward tack leaves a large and inviting gap just waiting to be filled by the eager pursuer (‘B’ in Figure 5). The correct action for the leader is to take a low course immediately prior to the mark, and then to harden up in a firm steady are such that she will in fact be closest to the mark when on, or nearly on, her closehauled course, as did ‘B’ in Figure 5. In this way, the gap is plugged, her pursuer has to go the long way round into dirty air, and she herself is free to tack or carry on as the spirit moves 1976 away a race. While it may suit your tactics very well to stick a tight lee bow on a yacht just astern of you, it will negate everything if that yacht can hold on long enough to carry you past the lay line and then tack for it himself. (It is much better in this sort of situation to bear off round his stern, luff up firmly and then tack to the lay line, so carrying him away from the line instead. (Figure 7)). General In average conditions, model yacht races are short in duration. If you hit a mark, you’ve had it — time taken in re-rounding is virtually impossible to recoup. Similarly it is very important to keep out of trouble, not only to the obvious extent of avoiding collisions, but also of keeping clear of situations which risk the necessity for violent and/or substantial alterations of course. These slow the boat and cause delays which are ill afforded. The man who wins is the one who concentrates first and foremost on keeping his boat moving fastest for longest, who keeps out of trouble, avoids problem areas and keeps his wind clear. The rules are there primarily to avoid collisions, and while they can certainly be used to advantage on occasion, they should not become the be-all and end-all of yacht racing. While on the subject of rules, is there any chance of revising rule 38.4 ‘Curtailing a Luff’? It would allow a much more accurate reflection of the situation if the big boat ‘Mast Abeam’ rule could be brought in — perhaps modified for model yachts into a Mast to Stem limit. It does seem rather absurd to allow a situation where a luffing yacht can carry on above her proper course for ever and a day until the overlap is broken or the bank reached, irrespective of the fact that the windward yacht is to all intents and purposes past her. 7 AVERAGE PREFERRED Aaa WIND Ree opie \ er. The finish While the finish should be at right angles to the last leg of the course, it will in all probability have a wind bias on it in the same way as a starting line would have. When coming up to the finish, the object is to cross the line as soon as possible, and it doesn’t matter in the slightest how far up to weather one is on the line. It therefore follows that, for a line having the same wind bias on as at the start, you should aim to finish at the opposite end to that at which you would have started. (Figure 6). It is important when working towards the line to try and establish which end is best, and of course we can’t afford the luxury of sailing beam reaches to assess the bias. Of course the need to cover the opposition will often remove the need for too close a scrutiny of options open, but in a tight battle it is critical to know at which stage to break off and charge for the line. Of course we must also be careful to avoid getting into a situation where another boat can prevent you from tacking for the line, as this is the surest way to throw \ yg N AS ike rn eae REN Ve \84 sy B3 B2 \ \ Za Yyors Vv / / PORT VY / 7 TACK LAY RINE ie / VA f / / / ale / / 7 FIG.Z \. STBD TACK \ \ LAY LINE \ \ \ \ \ 25/30 boats — 6-boat races. MYA Radio Control Racing Schedules Some Clubs may not be aware that for the past two years, standard sets of Racing Schedules, prepared by Frank Walker of Poole MYC, have been available on application to the R/C Secretary, Norman Hatfield, 26 Shanklin Drive, Westcliff-on-Sea, Essex, SSO 9XU. The standard set provides for: 6 & 7 boats — 3-boat races. 8/13 boats — 4-boat races. 14/17 boats — 5-boat races. 18/24 boats — 6-boat races. Cost of a standard set is 90p including postage. In addition, new sets have been prepared and are available as follows: 14/17 boats — 6-boat races. 25p per set including postage. 35p per set including postage. Also, master computer printouts are available on loan for 31/35 boats, 6-boat races. However, a deposit of £5 per master copy is required, plus postage, to ensure safe return. The Association is greatly indebted to Mr David Robinson, Secretary of the New Forest R/C MYC, for having prepared these new schedules free of charge on an IBM 360/50 Computer. Attached to each schedule is a printout showing the number of times boats race against each other. The cost of having these schedules prepared by a commercial firm would have amounted to hundreds of pounds and the Association is most grateful to David for having programmed the schedules in his spare time and arranged for the free use of the Computer. 255 INI MODEL BOATS All of the above classes up to and includi ng Centaur were scrapped in the twenties and thirties, so that in 1939 only the three surviving Caledons and the Ceres and Carlisle Classes remained from the original 28 C’s. In 1935 Coventry and Curlew of the Ceres Class were converted to Anti-Aircraft Cruisers: the 6 inch guns and the torpedo tubes were suppressed and they were re-armed with ten 4 inch AA guns. A drawing of Coventr y as an AA Cruiser will appear next month. Later Curacoa was similarly converted, as were Cairo, Calcutt a, Carlisle and Colombo, although AA armament varied between ships. World War 2 losses were as follows : Curlew was lost in the Norwegian campaign, being bombe d by German aircraft on 26 May 1940. On 12 June 1940 Calypso, of the Caledon Class, was torpedoed and sunk by the Italian submarine Bagnolini south of Crete, the first British warship to be sunk by the Italians. The Mediter ranean was also the scene of two further sinking s; the Calcutta was bombed by Axis aircraft off the Egyptian coast on 1 June 1941, and Cairo fell victim to yet another Italian submarine, Axum, off Tunisia on 12 August 1942. The greatest tragedy to befall a British warship in the war was probably the sinking of the Curacoa in the Irish Sea on 2 October 1942. She had been detailed to escort the liner Queen Mary en route to Liverpool carrying a large number of American troops. The giant liner was steerin g a zig-zag course and her escort was required to conform to her movements. Something, however, went terribly wrong for, as the Queen Mary swung on to a new course the cruiser, instead of swinging on to the same course, veered across the Mary’s bows. The liner hit Curacoa eleven feet from the stern, spun her round, and then plough ed right through her. Cut in half, the cruiser sank within five minutes, taking 338 of her crew with her. To add to the tragedy the Queen Mary was unable to stop and pick up survivors: her precious cargo of 10,000 troops require d that she continue with all speed. She was, in fact, little damage d, and had only a crumpled bow foot to show for her encounter. The surviving ships were all scrapped in the period 1946-1949. In 1942-43 Caledon was extensi vely modified Pacemaker by the redesign of the bridge and rearmin g with twin 4 inch AA guns. The clumsy ‘B’ gun position aft of the bridge disappeared as the bridge was moved back and she emerged with two pairs of guns forward , one pair in the superfiring position. This gave her a profile very similar to the Ceres Class. The design provided the basis for the Japanese cruisers Tenryu and Tatsuta, the forerunners of the 5,500 ton light cruisers of the Nagara, Oi and Sendai Classes, and also for the Spanish cruisers Mendez Nunez and Blas de Lezo. The particulars of the three ships illustra ted were as follows: FORWARD ARETHUSA Built: Fairfield, 1903-05 Displacement: 2,860 tons Machinery: 16,500 HP=25 Armament: knots 14-12 pdr; 2 — 18 inch TT Complement: 268 CERES Built: Chatham DY, 1912 -14 3,520 tons 30,000 HP=30 knots 2-6 inch; 6 -—4 inch; 4-21 inch TT 318 Clydebank, 1916-17 Displacement: 4,190 tons Machinery: 40,000 HP=29 knots Armament: 5-6 inch; 2 —3 inch AA; 8 — 21 inch TT Complement: 400 Up to and including the early part of WW 1, ships in Home waters were painted dark grey (Humbr ol HN 2). During the war this was changed to a light grey (four parts white to one part black). Betwee n the wars Ceres served extensively in the Mediterranean when she would have been painted the very pale grey of the Mediterranean Fleet (six parts white to one part black). In Home waters a dark blue-grey was used and the best approxi mation is Humbrol Number 27. Waterline in all cases was black. Weather decks were planked and others covered with brown corticene (Humbrol Number 29). Next month: Part 2, AA Conversions and the ‘D’ Class. certain that any advantage can be gained. If the adhesive cracks, a properly made joint would prevent the beam from dropping, but the chances of any of the normal epoxies failing are very slight. Stage one is to fit the fore and aft centre beam, which we notched into the ply stem piece and ran across the top of the fin box. It was decided to make a slightly cambered deck and this centre fore and aft member represents the Continuing the construction of Nylet’s 10-rater kit for radio control. Part four. CAUTION is in order at this stage, passed on by Nylet Limited. The hull is still flexible and can be easily distorted, so that care is needed if the rudder hole is to be drilled to ensure that the hull itself is not twisted in any way. It is essential that the rudder lines up accurately with the fin, and we elected to leave drilling a hole for the rudder tube till at least the deck beams were in place. Fitting beams is in fact the next job, and here we ran into slight difficulty in that there was slight shortage of material, possibly due to our having continu ed the main centre plank along over the top of the keel box instead of butting against its fore edge. It was possible to obtain ramin (to match the timber provided) in every shape and size but the one needed, and we therefor e used planed deal laths of about by lin. section for several of the beams. Normal model yachting practice is to halve the end of the deck beam into the inwale, but nowaday s it is not 268 high point of the camber, which at its maxim um is only tin., just enough to take off the flatness of the deck. The deck beams proper can be slipped underne ath with a shallow groove locating on the centre plank, the actual camber being produced at a later stage by slipping in small fillet strips and sanding them to shape. It is, of course, quite possible to shape the camber into the deck beams, but we think it easier to use something a little softer to produce the actual curved shape, as our model is being built in the office with a minimum of tools, etc, and ramin is a fairly hard timber to deal with. One point that gave us a small amount of puzzlement was that the beam of the hull was given in the instructions as an accurate measurement at one point only, and it is quite possible for the beam over the rest of the hull to vary by ¢ or even tin., by Squeezing the sides in and out. This would probably make very little differen ce to the performance of the boat, but it could have a small effect on the water line length, since obviously if the hull is squeezed in slightly the boat will float lower in the water. At the same weight it would mean a longer water line and there- fore a smaller permitted sail area. However, in this case MAY 1976 Deck beams in place; the side hatch and short centre strip have yet to be added. Right, the position of the check screw in the deck moulding with, beneath, the hatches cut out for beam alignment. since the boat’s weight has to be adjusted to match its marked waterline, this should not mean an alteration in the sails, but it could well mean that some yachts built from the kit would weigh say 23lbs and others perhaps 25lbs; since the additional weight would be in the lead this could mean that some apparently identical boats could be slightly stiffer than others. We have no answer to suggest other than perhaps one or two additional beam dimensions to be given at various points along the hull, but we felt that the point should be brought up for the benefit of builders who might be puzzled. The position of the deck beams towards the stern of the boat are related to the hatches moulded into the deck, and it is feasible to cut out these hatches at this stage. A fine screw can then be passed through the deck at the fore end of the raised deck moulding, at the point where the fore stay will ultimately be attached, and this screw can be fitted into a hole drilled in the centre member. This ensures that the raised moulding on the deck is central at the bow and that the deck can always be replaced in the same position. It then becomes possible to mark on the inwales the positions for the deck beams which support the fore and aft edges of the hatch openings. These beams can be fitted in place, together with the two short fore and aft pieces, and when dry, the deck can be repositioned and the points for the side hatch members marked on the beams. These side members can be slotted and glued into the deck beams; now when it is time to fit the deck perfectly, its fore and aft position and its centralisation at the bow are secured by the temporary screw, while at the stern the hatches can be aligned with the frame members: this means that it is possible to secure the deck temporarily in place and then by inverting the hull to mark round it with a pencil and remove some of the surplus area before the deck is epoxied in place. This in turn makes it easier to hold the deck in place with rubber bands or tape while the epoxy sets. It should be mentioned that the side members of the hatches will require to be flush with the top of the beams, so that if fillet strips are to be included to give a rounded deck, this must either be allowed for in slotting the hatch side pieces in, or these pieces fitted in after the camber fillets have been completed. The instructions recommend that before fitting the deck a dummy run is made with the radio installation, and it is therefore reasonable to drill for the rudder tube at this stage. The inclusion of the deck beams makes the hull It is suggested that the radio is fitted in a box secured to a ply plate in the bottom of the hull and that the winch should also be secured to the ply plate. We believe that it is correct to say that no winch on the market is absolutely waterproof, and since there is the chance of water sloshing about inside the hull it may be wise either to raise the winch slightly above the bilge or to take some measures to protect it from loose water. This could range from taping it all over with waterproof tape to encasing it in its own box. In any case, the manufacturers’ seal round the winch drum output shaft has to be relied upon, unless the drum is also encased with the winch and the sheets fitted to it through grommets mounted in the side of the case. Individual opinions on the necessity or degree of waterproofing vary, as do installation details for different equipment. Itis however desirable to note exactly how the gear is to be laid out before the deck is secured in place. much more rigid and less liable to twist, so insert the fin into its slot and use this as an alignment guide for the drill. Many builders prefer to put a pilot hole through first and insert a wire, etc, in this hole to check alignment: the finish size drill can then either follow the pilot hole or be biased during drilling to correct any slight error. It is assumed that most builders will fit their tiller below the deck, but if it is desired to bring the rudder post right through the deck and have external linkage, a block should be fitted to fill in the area through which the tube will pass, between the existing block and the centre beam above, and drilling the hole can be left until after the deck is fitted. In such a case, it would be unnecessary to cut out the rearmost hatch area of the deck. The disadvantages of an external rudder link are that the servo has to be mounted at deck height with consequent exposure to water, or an intermediate linkage using bell-cranks above and below deck is required. There is also the chance that a loose sheet could snag the above-deck linkage. The keel box with sides extended up to lock with centre strip, and the principal deck beam. Fillets for deck camber to be added, and the keel box still has to be reinforced with glass mat and resin. 269 ee TT
