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» fh . U KM NOVEMBER 1991 4 £1.65 RM EURO | CHAMPS REPORT | H A RIPPLE : . / \* soe iiB‘ Tomi YORKSHIREMAN Fl : wae De 4 ) 8 TEN Ls YORKSHIREMAN Build John Bone’s miniature sailing boat from our full-size plans – and discover the inexpensive delights of vane sailing In the Beginning often wonder what became of my very first model sailing boat. It was given to me on my eleventh birthday and so began a lifelong fascination. Over the years, despite divergences into other hobbies and interests, I have always returned to the small yacht for simple sailing pleasure. To sail a humble toy boat successfully on a large lake, with no power other than nature and one’s own ingenuity, is arguably one of the greatest challenges of our hobby. It has developed into a personal quest to find the ultimate small sailing machine and I have built countless models since that birthday present nearly thirty years ago. The commercial toy sailing boat has suffered complete neglect for a long time and it has never been able to rise above its ‘piece of string’ image. Given the archaic designs that most manufacturers cling to, there is little wonder that today’s ~ youngsters find them totally boring. The pleasures of simple sailing have been missed by a whole generation and the ultimate loss will be ours. In the light of school project. The overall length of sixteen inches has been established as the optimum, based partially upon the length of a sheet of balsa and the size of a plastic carrier bag. This boat is large enough to sail well, yet quick and simple to build, falling easily into the ‘miniature’ category. Ripple possesses no particular design surprises, her astonishing performance our present ‘green’ consciousness this coming about by close attention to detail hobby has much to offer and every effort should be made to encourage it. With a little thought the small yacht can be made to sail with considerable precision at speeds that are quite out of proportion to its modest size. That this can be achieved is worthy of recognition and an aimed at improving efficiency, the major failing of the toy boat. By a reduction of acknowledgement of the purest form of model boating. The model presented here has taken a long time to arrive, having been slowly refined and.developed to extract the maximum performance from the minimum of boat. She is a champion of her type, bringing the toy boat right up to date and on towards the next century. Ripple Ripple can be built for less than five pounds and on this alone represents excellent value. Whilst not entirely suitable for the novice to attempt, a little supervision from a more experienced modeller will help to develop the necessary skills and perhaps make an interesting 36 the scantling sizes to an absolute minimum, the cockleshell hull weighs less than half an ounce. A 75% ballast ratio has been achieved despite an all-up weight of only four ounces, putting the boat on a par with many high-tech Marbleheads. The ultralight displacement, high power and easily driven hull form is a sure-fire recipe for a fast boat, especially when propelled by an efficient rig. A simple, yet effective vane gear completes the set-up, making a miniature yacht with a superb sailing ability. The vane gear is an essential piece of equipment without which the model is virtually useless. The toy yacht will never be able to sail properly without one as it gives the boat an ability to think for itself, no other form of selfsteering system being able to match it. Once the difficulties of control have been overcome it is a great temptation to drive the boat very hard to see just how fast it can be made to go. This leads to a problem Ripple, moments after release, feeling her way through the dead patch at the windward end of the lake. that is also common in some of the larger classes — submarining and the pitchpole capsize. Due to the scale effect of the weather, the tiny model spends much of its time dealing with relatively extreme conditions. MODEL BOATS Heading, vane and sail trim for a beam reach. Note the apparent wind angle of the vane. The windward end of the lake may be an impossible area of doldrums, the short rig being unable to reach any high-level zephyrs that curl over the bank, whilst the steep broken waves at the leeward end are more akin to Cape Horn! The aircraftcarrier bow flares are therefore vital to give the boat a chance of survival, providing lift and buoyancy when the going gets tough. They are quite effective and when travelling fast, water can be seen squirting out horizontally from beneath them. The flares are added at the expense of windage and so their size and shape should be kept in moderation. Increasing the draught in the search for more power and speed should also be guarded against as, due to the short waterline length, the often violent changes in trim will conspire with a deep fin to trip the boat up, precipitating the pitchpole routine. Ripple has been observed in rough weather to submerge and perform a complete cartwheel before skating off a vertical centreline on both sides, is sprung into place and stitched with a spot of Superglue at each corner. The fairness of the hull is checked by laying it on a line drawn on the building board, ensuring that it passes through bow, stern and bulkhead centres. View the boat from ahead to check that it is not twisted at the stem and run a bead of Superglue into the joint from the inside, keeping it clear of the taped-up bow flares as these will be separated later. Superglue only sets quickly when used in small quantities or thin layers, so allow some time for this joint to fully harden. Cut and shape the stern bulkhead noting the chamfer at its sides and glue it in place, checking alignment again on the building board. Thé maximum beam of the boat is a shade below three inches and so the bottom panel can be fitted in one piece. Mark a centreline on the inside and stitch it in place with a spot of glue every inch or so. The offcuts at the bow are used later to sheet in the undersides of the flares and block and the hull shell is complete. At this stage it should be reasonably strong, yet will weigh next to nothing. The Dangly Bits 18 S.W.G. aluminium has just enough stiffness to support the lead with minimal thickness and frontal area, although a better fin can be made by filing and polishing a piece of 16 S.W.G. to an airfoil section. The amount of work that you are prepared to put into it is down to you. At this very small scale individual differences may be minor but the cumulative effect may add up to one boat being noticeably faster than another at the end of the day. Whether or not you are attempting to build an all-out speed machine or something a little more mundane is your decision but, personally, I have never been | satisfied with anything less than the very best that I can produce — probably the reason why I have continued for so long with this hobby! Improvements in the efficiency of a sailing boat do not come again on correct course with hardly a moment’s hesitation — a vivid demonstration of the control that a vane can exert to guide a boat downwind! Light air performance is surprisingly good and she will ghost with an unbroken meniscus all around, accelerating rapidly on the merest whisper. In a breeze she can whistle along under her spinnaker and a large lake will appear almost too small for a ‘normal’ sized model. This boat has given many hours of enjoyable sailing and her petite charm and delicacy makes her a firm favourite. Construction The hull can be built from two sheets of balsa, so she is not exactly going to break the bank. Choose light grades only, one sheet of %sin for the sides and another of xin for the deck and bottom panel. Construction follows along the lines of Akela, her radio-controlled cousin. they can either be trimmed off beforehand or removed after the panel has been fitted. A bead of glue is now run into the joints on the inside of the hull. Tip the boat up on its end and let it flow all around before finally trimming and sanding the bottom panel flush with the hull sides. A narrow strip is glued across the unsupported edge at the stern and carefully sanded to match the sloping transom sides. The remaining tape at the bow can now. be removed, allowing the flare sides to spring open. A short piece of balsa is glued vertically inside the stem joint to support the flare bulkhead at the nose. It can be The sides are cut out and sanded to shape whilst pinned together as a pair. Overlap them at the stern when marking left protruding above deck level, to be sanded down later. The bulkhead is glued to the flare sides first, then located centrally and joined to the vertical stem out, as most of the off-cuts are used for bulkheads and other bits and pieces. piece to prevent the whole lot from moving from side to side. Before separating the side panels, cut the flare-line at the bow. This must be carefully done with a hacksaw blade, ensuring that it is kept vertical. Tape up the sawcuts on the outside of each panel to prevent them from splitting during the next operation. The side panels are taped accurately together at bow and stern only, after first marking the position of the bulkheads on the inside faces. The main bulkhead, with NOVEMBER 1991 The thickness of the hacksaw-blade cuts allows the flare underside panels to be slipped into place, stiffening up the front end in the process. The sheeting may have to be notched to fit around the vertical stem piece. Glue the inside edges first, making sure that a fair curve is maintained in the lower part of the hull side panel. Once this has been done the bonding of the outside edges is easy. Clean everything up with a sanding Ripple heading in after a beat. easily once a certain level has been achieved and advancements only seem to happen a little at a time. This is an absorbing and fascinating pastime and I am quite content for it to remain that way. Boys and their toys! The fin should be perfectly true with an elliptical leading edge to promote laminar flow. Never make it too sharp or it will run the risk of a premature stall at high angles of attack. Although a very thin keel is theoretically less efficient than a thicker one for windward sailing, at the end of the day drag becomes the overriding factor and a compromise solution is always the best answer. In view of the way that the model is tossed around sometimes, it is too much to hope for that smooth, attached flow can always be maintained, however, this is what efficiency is all about and it cannot be obtained in any other way. No matter what size the boat is, the rules must always be obeyed! The lead ballast is made from a four ounce ‘bomb’ fishing weight, joined to the fin by means of a sawcut slot. By the time it has been reshaped to a more suitable profile, it should weigh in the region of three ounces. 37 Widespread practise in the Marblehead class these days is to use a square-cut trailing edge to the fin and lead. Whilst this may be beneficial, or at least, not detrimental at the higher speeds involved, the small model cannot tolerate such sources of drag and will happily remain in a laminar flow condition for long periods of time. For this reason the trailing edges of a small model must be sharp or‘pointed for the cleanest possible exit. Despite any advantages that may be considered by the use of a’flat-iron’ lead and its associated end-plate effect, the circular section type is to be preferred as it has greater tolerance to the many out-oftrim situations that are to be expected in a very small model. The proportions shown for the rudder should be adhered to for best effect, although its profile is largely a matter of taste. It may look fragile but it is well able to do its job. The slot is cut first and the stock glued in, before carefully sanding the blade to section. When completed, the whole item is coated in Superglue to stiffen it and fair in the joint between blade and stock. The narrower chord at the top of the fin and rudder is intended to reduce interface drag, the confusion brought about by air or water flow over two surfaces at right angles to each other. The broader base is given a chance to work in the relatively clean flow away from the hull, whilst the variation in chord ensures that a stall may only occur partially, before becoming total The simplest, quickest and most important, lightest method of finishing a small balsa hull is to use a cellulose system. As the hull is fragile it will not stand a tremendous amount of rubbing down and so a clear finish is desirable, hiding a multitude of sins that would otherwise show in a solid colour. Banana Oil, a type of non-shrinking cellulose lacquer, is the stuff to use as it resists yellowing and brittleness with age. Rub down lightly between each coat, taking care to avoid the edges where it is all too easy to cut right through. An advantage of this finishing system is that bumps and scratches can be easily repaired with Superglue. The flat panels lend themselves to go-faster stripes and graphics cut from Solarfilm, whilst the honey-coloured balsa stands out well on the lake. A simple finishing system can therefore be dressed up to create something quite special. Go easy with the iron when sealing the film, as the heat can blister the cellulose. straightforward manner adding mast, associated beams and supports. Check very carefully that they are all at their correct angles, using the fin as a datum for their alignment. As the hull has no inwhales it is important to ensure that beams and bulkheads are perfectly flush at deck level and not too tight a fit, causing distortion. This form of lightweight construction in a highly-stressed model demands accuracy, for a failed internal joint cannot be easily repaired. Pierce a couple of small holes in the converted into a more sophisticated moving carriage system, the extra complexity is of no great advantage for singlehanded sailing. When completed, the vane should be the hull with a short length of cotton thread, although the vane would probably drift ashore first, anyway! Propulsion Unit The power that can be generated by even a Vane and sail trim for a close reach. The vane gear will guide even the sraallest model safely across the largest of lakes. The Twiddly Bits A three-to-one reduction ratio is needed for the vane and Ripmax Nylon gears fit the bill perfectly. The vane gear used here is a slightly modified version of that first put forward by Geoff Draper on his Plane Jane model of the ‘sixties and subsequently used again by Vic Smeed with Splinter. It is built around %cin brass rod and tube-as used for the rudder assembly. Study the drawings to get the general idea. A plain nylon ten tooth pinion gear is a very tight fit on the tube and should be eased with a needle file to form the friction to describe just how tight it should be; too loose and it will slip, too tight and 38 mode only and, although it can be may perform, it is a good idea to tie it to a small hole cut in it, covered by a piece of sanding sealer and a test-float in the bath. Don’t lose it down the plug-hole. the angle at the top of its mounting tube in the hull serving to lock it centrally. Run some glue into this joint when finally set up, as movement of the pintle must be avoided. This vane operates in simple Although the vane will float quite grip, enabling the vane to be set without stitching will do the trick. The deck beams can be lightly coated in P.V.A. adhesive for greater integrity but keep it away from the edges, as the two glue types do not mix. Give the boat a couple of coats of Smooth meshing of the gears is obtained by adjusting the bends in the wire pintle, happily if unshipped and lost overboard during some of the antics that this boat bulkheads to allow air pressure to equalise inside the hull. The deck should also have tape and acting as a diaphragm. Never leave the model in a hot car as it may explode! The deck and transom panel can only be glued from the outside. Provided that they fit well, a bead of glue run all around after friction grip. feather must be lightly waterproofed and balanced with a small weight, I use a few turns of resin-cored solder secured with glue. Assembly and Fit-out vane and rudder tubes along with their helm available providing stops, against which the vane can be easily adjusted and preventing the pinion from running off the sector of main gear. The shape of the balsa feather is entirely optional but its relative proportions should be retained. The feather, vane body and counterweight arm are firmly glued together as a unit with the tube, the only moving part of this assembly being the pinion gear on its sensitive enough to respond when blown gently from a distance of a few feet. The in a severe case. The fin is slotted in from beneath the hull, using the previously marked centrelines as a guide. The slight forward rake angle is filled in with a small wedge between the leading edge and main bulkhead. Once tacked accurately in position, the fin is reinforced with bearers and doublers as shown in the sketches. These are all essential to spread the leverage stresses evenly into the fragile hull. Fitting-out continues in a Cocktail-stick pegs are inserted into small holes drilled in the gear to limit the lifting the gears out of mesh. It is difficult something will break when it is adjusted. However, it should never be too loose. The brass bush on the thirty tooth gear is filed away to an absolute minimum and is then sleeved with a short piece of tube to fit on the rudder stock. The steel grub screw should be replaced with a brass one as it will quickly rust and become impossible to remove. The gear is then sawn into a sector as shown, to reduce weight further. Count the number of teeth on the drawing. small rig is quite startling. Unfortunately, the unwanted effect of heeling means that only a small percentage of the available power can be converted into forward drive by the monohull yacht. Like the weightless glider or the kite that has cut its string, unless action and reaction can occur simultaneously between hull and rig, the thrust component will not be realised. We have done our best to produce a lightweight and powerful hull, so what can be done to drive it? The yacht’s sails represent a high lift/high drag airfoil; the lift being produced at the expense of drag due to the steep undercamber. If drag can be reduced by cleaning up the airfoil, a useful increase in efficiency and thrust will result, with proportionally less increase in the unwanted factors. The double-surface sail made from light gauge polythene is a simple answer to the requirements of a small yacht, many of the tasks associated with sailmaking being neatly side-stepped. The inspiration for this type of sail came from the Gerry Hoyt designed Freedom range of full-sized craft. By using a soldering iron and a metal straight edge to cut and weld the material in one operation, stitching or taping is avoided and seams made in this way are virtually as strong as the plastic itself. Give it a try to find the best cutting speed and then do a destruction test. A standard 25 watt iron is quite satisfactory and it is helpful to file the bit into a blunt knife shape. This type of sail solves the problem of luff attachment and is aerodynamically MODEL BOATS ‘cleaner’ than many of the other systems to be found. The use of ‘Invisible’ Sellotape for reinforcement, in conjunction with the welding technique described, enables the full potential to be obtained from this cheap and plentiful material. A ‘soft’ rig for Akela can also be made by these methods. The ‘noisy’ type of plastic, often used for frozen foods and bin liners, can also.be worked in this way and has the advantage of being stronger and lighter. Follow the sailmaking sequence shown in the sketches and you will have a serviceable suit of sails. The ‘cut’ of the mainsail depends largely on the characteristics of the mast as the upper portion becomes quite flexible when shaved down to a very small diameter. When the rig is tensioned, the curved luff of the mainsail bends the mast and tightens the leech of the sail whilst still maintaining a degree of fullness in its forward part. The degree of curvature is difficult to gauge on the cutting board but can easily be altered by re-welding the luff and tailoring the sail until it sets properly. Do not expect to get it right first time, sailmaking is difficult and generally best left to the experts. However, we have the advantage of working to a small scale with cheap, throwaway materials and practice will eventually make perfect — I’m still trying! A good book on the subject, containing much relevant information for models, is Jeremy Howard-William’s ‘Sails’. If you are serious about your sailmaking, read and digest. The difference between a good sail and a mediocre one can be very small indeed and the science is far too deep a subject to be covered here. The booms are made from split bamboo cane garden sticks, a most versatile material capable of being pared down to incredibly small dimensions whilst still retaining remarkable stiffness; nature’s own carbon fibre. The forward swing boom is extended well beyond the jib tack point and used for flying a spinnaker or masthead reacher. These sails should be used with caution as the boat can easily become overpowered, however, should you hit a good trim and conditions are favourable she will really fly. An elasticated lazy line is needed to prevent the rig from rotating when setting these large sails but you will have to be patient and wait for the boat to come ashore on its side, should they go aback! The small spinnaker gives some useful lift, helping to eliminate submarining and whisking the boat quickly onto the plane. In stronger winds a reduced rig is advised, dispensing with the spinnaker altogether. There is a limit to the speed at which she can be driven across the bumpy bits without a somersault, unless you are going for the triple! Finally I hope that you have found this article interesting and maybe, inspiring. Ripple is a super little boat and worthy of more than will be impressed by her performance. If the time taken to sail her own length is used as a measure, she must surely rate as one of the fastest yachts in the world. Russell Potts recently expressed concern about being a dinosaur and I understand just how he feels. If there are any other dinosaurs out there who enjoy experimenting with radical toy yachts, some correspondence and exchange of ideas would be welcome. For some, sailing with vane gear may be a mystery whilst others might enjoy the opportunity to put down their heavy transmitters and get some exercise again. With the Editor’s approval, I will prepare some notes on the almost forgotten art of walking. Next Month‘How to sail your Ripple successfully’ just a casual glance through these pages. Small she may be but I guarantee that you NOT FOR BEGINNER.NW…… ‘PRI VATEER’ HMS MORDAUNT 1681 This private commission for Lord Maudant was built by Captain Castle at Deptford Yard. After a chequered short career she was received into the Royal Navyin May 1683 — Lost with all hands off Cuba, November 1693. This beautiful model in kit form by Euro-Model of Como, Italy, captures the line and grace of this period. Contains double planking with pre-cut wooden parts and even machined mastings. Magnificent castings with superb high detailing. All fittings included Price inc. VAT £278 QUALITY COUNTS IN YOUR HOBBY – JUST LIFT THE BOX LID!! Full colour leaflet available – Send £1.00 in cheque or postal orders ONLY for leaflet. IN YOUR MODEL SHOPS NOW!! Freepost UK only. Overseas on application. If in difficulty obtaining your requirements Telephone 081-891 0342 (Ansaphone service) Mail Order. Fax: 081-744 2177 , 35 CROWN ROAD, ST. MARGARETS, TWICKENHAM TW1 3EJ %* ACCESS * BARCLAYCARD * HMS Mordaunt NOVEMBER 1991 1691. OAL 36″ UK Distributors for… AEROPICCOLA – MANTUA – AERONAUT AMATI – SERGAL- COREL – EUROMODEL (COMO) – RIVABO – HAWN – PANART – SOVEREIGN 39 : ‘|| | =E . : MINIATURE SAILING BOAT DESIGNE ..O:A; =46″. BEAM *=3″. BisPLAC) | Ep SAIL AREA = Q3saqr.ins. =A — RUDDER STOCK. I6S.W.G. BRASS OR S/S. RUDDER & VANE PINTLE TUBES 4g” BORE BRASS. -— RUDDER 1/16″ BALSA. MAIN BULKHEAD. \ \ | \
