Model Maker: Volume 3, Issue 28 – March 1953

t MARCH 1953 _ VOLUME 3 NUMBER 28 IN ‘THIS ISSUE : A (New for Fabricated Vertical Slide for the Lathe : A Close up Frame Finder : “Harlequin” 36 in. Rest. Class Duck-style Yacht : Lassel S. T. Vane : Radio Controlled Ambulance : Novel Racing Car : Making a Freelance Tanker in 00 Gauge : Terminal Station Track Finish : A New Vane Gear : The Locomotive Family—Humour in Models : Speedway J.A.P. Model : Radio Control Rally Ford Zephyr = Carloe—Monte Model Yachts : Trade Review : M.C.A. News : Prototyp ail Track Cor ence : Gerry — 0 Gauge Steam Loco : “A” Class Design MODEL MAKER A BY PART OF MAIN FRAME SCREW. (68.A) MIDDLE DISC— 13/4’DIA. GYBING LUG_Z Fe ALL DISCS – 1/4’THICK. CUT R Vane A. Gear WILCOCK Introduction S O far as the author is aware the gear to be described is novel. It embodies features of balance detailed in previous articles and a novel infinitely variable and easily adjustable guy. A particularly novel feature is the ability to use the same scale for fixed and self tack settings of the gear brought about by the feather being “Lung” about the pintle of the gear as a whole. Principles Fig. 1 gives a simplified sketch showing the basic arrangement of the mechanism from which the following description will be clear. The vane pintle (A) is relatively tall and pointed at the top so that the whole gear is balanced about it. The gear is built about tube ‘B), which should have adequate clearance about the pintle (A). The tube (B) is threaded on the outside (4 in. tube with a model engineer’s thread of 40 per inch is most suitable 3/16 in. with similar thread tends towards a weak pintle). The feather and counterweight are each attached to U shaped brackets (C) and (D) that have threaded holes for them to swing on the tube. The self tack motion is obtained by the bellcrank (E) mounted to one side on post (F) and linked to (C) and (D) by links (G) and (H). A counterweight (J) is mounted on post (K) on the opposite side to maintain balance. A lever (L) enables the motion to be locked and unlocked relative to the main frame. With the gear in the locked position its angle in relation to the rudder is by the friction clutch (M) (shown in Fig. 2A), which also carries the scale. The degree of grip in the clutch can be varied by screw (N). The adjustable guy motion comprises details (O), (P) and (Q). (O) is a plain rod mounted over the top of the gear immediately over the main pintle, (P) is a friction slider on the rod, while (Q) is a semiadjustable fixing on the feather arm. (P) and (Q) are connected by a spring or rubber band and also a limiting cord. The action will be explained later. Constructional Details Note the same lettering is used throughout. Fig. 2 shows the components and dimensions of the basic framework. These are three perspex discs, the bottom one (M) forming the friction disc and having three lugs, one for the link pin to the tiller and the other two for attaching TACK ADJUSTING BOTTOM 21/4’DIA. New LINK PIN TO TILLER ARM. 68.A) MAKE FROM 1/8 OR 20 SWG BRASS SHEET. 132 March 1953 Assembly gybing lines. The guying attachment is also shown on this figure. The end brackets are fixed to the top disc on the vertical side rods and the lugs turned down to engage in holes in the disc. Fig. 3 shows the feather and counter weight assemblies and the bellcrank and dimensions, while Fig. 4 shows the geometric construction used to determine the lengths of the links and arms for any particular diameter. If dimensions other than those shown are used, adequate difference must be allowed between the lengths of the bellcrank arms to give suffi- The method of assembling should be as follows: (1) Make the vane and counterweight brackets in position on the central tube—this ensures that the threads top and bottom mate at (2) Remove brackets from the same time. central tube and fit tube to the middle disc, screwing tight against the blank piece of the tube. (3) Refit brackets to the tube, leaving equal clearances top and bottom and screwing down to a 1/16 in. clearance to the middle disc. (4) Fit top disc. (5) Fit tack adjusting screws to top disc. (6) Fit side vertical screws. screwing through the top dise and fitting bellcrank, to which the links have already been fitted. and bellcrank counterweight on the opposite side, in the process. (7) Fit guying bar and locking cient clearance between the links at the vane and counterweight bracket ends throughout the full tacking motion. The length of the arm set at 45° is determined by the construction shown in Fig. 4, therefore clearance is given by adjustment of the length of the other arm. Threaded bearings have been used throughout in the construction. It is possible by this means to have as little or less backlash than one gets with good meshing gears without the nuts to the centre tube and side rods. (8) Fit base friction disc, spring washer and locking nut. The surfaces forming the friction clutch should have been well rubbed with fine glass paper before assembly to give a smooth friction grip without undue pressure. If this is not done the pressure required to grip is excessive and movement is jerky. With the dimensions given it is recommended that the vane pintle be 34 in. from the rudder pintle with a tether arm of disadvantage that a bit of grit in the teeth can be very inconvenient. The links are probably best made in one of the two ways shown in Fig. 5. The ends of the links surrounding the nuts on the vane and counterweight brackets are best soldered after assembly, this enables the heights of both the bellcrank and the nuts to be adjusted after the main assembly has been put together—this 34 in. The more advanced worker with facilities and experience for more precise work can with advantage make the two links from brass strip. both holes being drilled and tapped at the precise design distances. The assembly required is then as shown in Figs. 6. This is rather like assembling a chain. The first link is fitted to the vane assemblv. and the other end of it to the bellecrank. The second link is secured to the other arm of the bellcrank and avoids many assembly problems. The tack adjusting screws may be as shown or alternatively the vertical side screws mounting the bellcrank and counterweight may be made of 3/16 in. tube threaded with the model engineer thread of 40 t.p.i. and be drilled near the top to take the tack adjusting screws. ee 133 ee e e MODEL MAKER 68.4. NUT ON VANE OR COUNTER WEIGHTASSY. the screw projection in the top disc and the gear turned relative to the friction disc to the 7 required angle. On tack and tack without guying, the guying slider on the top bar is left in the central position, the gear is lined up by the scale to the fore and aft position, and lever is FILED TO SUIT—& ua ASIN WIRE TYPE unlocked. The tack adjusting screws are adjusted according to the requirements of the UICIRCLES STRIKE BISECT A. OD boat—start with 45° and close up. For guying the slider is moved to one side or the other, the REQUIRED: 45° ANGLES. INTERSECTION POINTS GIVE LENGTHS OF ARMS & LINK. 1. OFF 3/4°CENTRES. 1. OFF. O!53 CENTRES. FIG.4 FIGS) amount from centre determining the length of aus, FIG. the guy. The strength and extension of the spring or rubber band, however, affects the degree of adjustment obtainable by the slider movement. its other to the counterweight assembly, taking care that the links and assemblies are at the correct relative heights. The “chain” can then be closed up and the central tube, already secured to the middle perspex disc, screwed through vane and counterweight assemblies held in their relative positions. The completion of the gear will then be apparent from what has already been said for the other method of assembly. This method produces a neater the gear is locked and that all the bearings are “free.” Adjustments conditions On fixed tack the locking lever is engaged in YACHT It is expected that a date in the first half of July will be chosen for the event, to be sailed on the club’s Barnby Dun water, final date and rules will be published in our next issue. The organisers, however, intend to make the contest Isles, rather than to restrict it to their own distri ct — which should arouse to TROPHY fail to guy FOR is most 1953 will be eligible, and the normal contest rules of sailing will be operative. We would remind new readers that. this MopeL Maker trophy is intended to encour age novice skippers, who may be broadly define d as those who have not previously been in winnin g brackets at a National event. In addition to holding the Trophy for a year, prizes to the value of Five Guineas will be presen ted by MopEL Maker. As a special gesture MODEL MAKER will award a further prize of Five Guineas to the winner should he win sailin g any 36 in. Class Restricted Yacht built from Model Maker Plans Service drawings, and a Special Encouragement award to the competitor travelling farthest to take part, distance being Yachts. amount of interest. when exasperating. As previously announced the MODEL MAKER Model Yacht Trophy for 1953 will be organised by the Doncaster M.Y. and P.B.C.. and will be open tc 36 in. Restricted Class British limiting cord through the the gear in correct adjustment for when the boat is turned. This prevents the tack motion crossing the centre line but leaves the gear in correct adjustment for when the boat comes around and gives that most certain guy quickly under the vane and counterweight arms are in line when open to entrants throughout the tageous to have a spring of such length that with the slider full to either side the angular movement of the vane to the opposite side is limited to say 10° less than the setting of the tacking screws. Finally, when the occasion arises for a certain quick guy to cross the finishing line the lever G is thrown up before the boat is turned. This prevents the tack motion crossing the centre line but leaves linkage but calls for appreciably more precision in the making and assembly to ensure that the OUR MODEL Thus it will be found for light winds the course adjusting screw on the vane lever must be set well in so that the tension is light. In heavy weather appreciably more tension must be given by setting this screw well out. In addition under these conditions it is advan- a considerably greater In general, the contest will be run strictly in accordance with M.Y.A . regulations, that is to say only registered boats measured in normal railway miles. 134 il MODEL J MAKER Radio Controlled Model Yachtin« ‘THE description or radio racing around a article, those who are radio enthusiasts rather than radio users, will want to race all manner of craft fitted with their own pet radio brain child. There is only one solution for such racing. It will have to be Handicap Racing and it cannot race two boats together. triangular course, between Mr. Honnest Redlich and myself,-has drawn some interesting letters, indicating the interest already created by the possibilities of this new form of model yacht racing like the real thing, with tactical battles between two or three helmsmen sailing together in the same heat, using the In view of the interest, and opposition too, stirred up by this radio racing together, | am also fitting out my old Marblehead yacht of 50 in. in length with similar three reed radio to that used last season in larger boats. The Marblehead is so. easy to transport compared with the A or 10 Rater boats. It is cheaper to build, whilst its bulk in the home is more acceptable to the mistress of the house! No wonder this Class yacht has become so popular in Britain. Now that the three reed receiver is being produced with the tiny hard valves like deaf aid instruments, the battery weight can be reduced more compatible with the bouyancy factor of the Marblehead. In this article I am showing photographs of the radio box I am fitting to my Marblehead. When the installation is complete and the model tested ready for racing, I will give a description of how the boat sails under radio, and whether there are any unforeseen snags. As a Marblehead has little freeboard compared to my 10 Rater, and it is a short boat, it is a “wet” boat. Therefore the radio box waterproofing must be particularly good. This is particularly evident in my case as I sail on salt water at Poole. Incidentally, our lake at Poole Park will be one of the finest, if not the finest, model sailing water in Great Britain next year, for the new catwalk for model sailing is nearly complete, and has been built by the Poole Town Council at a figure that would keep most of us in luxury for a year or more. The catwalk will break up the rough water in bad weather, but leave us clean sailing air, and we shall have round the pole racing facilities all built in for the power speed fans, with a radio platform for launching our radio craft. Our Radio Regatta will be held on June 6 and 7.- legal 27 megacycles band. From letters it appears that some people have not quite grasped what I was attempting to explain in my first article. One point that seems to worry some people— why pick on Reed receivers and not one of the other principles for radio racing? The answer is simple: We must have two or three or maybe more boats RACING TOGETHER. Sailing around in single file is no fun at all. It doesn’t provide tactical battles and that spirit of helmsman competition at close quarters. At the moment of writing the reed system 1s the only one that gives us this sailing together. If we use other systems that are commercially obtainable, the only way would be to sail one boat on the legal 27 megacycles band, whilst the other boat would be off tune—the Post Office would probably stop our sailing! Now if some individual will come forward with an alternative system to the reed, that will give us two or more boats sailing in the legal manner, and will make the system available to the public, and can keep the cost down, we shall receive him with open arms as a public benefactor. As far as I know the Americans are not yet sailing two or more boats together on one band. They are experimenting with all sorts of controls, however. Let us keep at it, too! I will quote two letters that seem to affect the problems of quite a lot of people interested in radio sailing, and I will try to answer each problem. Readers will remember that Mr. Redlich sails an “A” Class yacht, and { sail a “10 Rater.” The “A” yacht is naturally a little faster on certain points of sailing because of its greater length along the waterline when heeled, but we can get some quite good racing together at this stage, although it is obviously better to match two boats of One Design together to get the best racing. It is certainly very necessary for good racing for all to use the same type of radio system, so that everyone in a class has equal control. As I mentioned in my first I might mention here that since I last wrote, and as a result of our last year’s racing together, Mr. Redlich has produced the promised single transmitter with two control boxes, so that it is now possible for a club to own one transmitter with two receivers to fit into Class boats. Last year we used sevarate transmitters when racing two boats together. 138 March 1953: A NEW REGULAR FEATURE BY LT.-COL. C. E. BOWDEN Extracts from Readers’ Letters, with replies Mr. D. T. Byron expresses the point of view of many people who are not radio “experts” but who, like myself, want to use radio to improve the sport and fun of their craft, and in his case, racing does not come into the considerations — are expense but picture, important. Let us see what the commercially obtainable model radio has to offer to suit his purposes. The views that I express are from the user’s angle and of course are only personal choice. Nevertheless, a user is often the man who finds the faults as well as the good points. Mr. Byron says: “I was very interested in Col. Bowden’s article on radio control for model yachts, which I feel may well revolutionize this fine sport. I see that you invite readers to send in any queries they may have, and I would very much like to avail myself of this offer. I want to build a yacht in which it would be possible to instal radio, and although I would not call myself a raw beginner, I am far from expert and feel that maybe this is a little too ambitious. Anyway ‘faint heart never won fair lady,’ and I am determined to try. Would even the smallest yacht capable of carrying radio be too expensive and difficult to build? I am essentially a ‘sailor’ at heart (1 race a 12 ft. dinghy) and I am sure I would get more fun with a yacht than a power cruiser model. Could you inform me of the approximate price of a suitable radio set, and the cost of building a yacht. I want to keep the cost as low as possible.” Well, Mr. Byron’s cry is a very normal one, and perhaps rather lengthy to answer. It depends so much on what a lone man wants to spend, who cannot share the thing with a club. It is evident that he wants a small boat with cheap radio, and I would add that this is only worth having if it is reliable and does not require constant tuning and fiddling with. As Mr. Byron does not want to race, and he does not want to spend the larger sum on radio to get sail control for racing, I consider he will be quite happy, for a while at least, to build a little 36 in. Class hull or a 50 in. Marblehead. The Marblehead will probably be better, as later he can fit more exnensive radio and race if he wishes to do so. There are several good designs published by the model journals. and he won’t go far wrong if he chooses a Littlejohn’s The author’s Marblehead is now being fitted out with three reed radio control similar to the 10 Rater, to give “‘sheet’’ operation and inching of the rudder. Two Marbleheads will be able to race together in a heat if trials prove satisfactory. Note radio box, hatch, and box cover (Below) This photograph shows the box in position with cover on steering radio, sailing with sheets a little free from “close hauled.” He will then be- able to steer by push button control in sequence. Thus one push gives full left rudder, followed by the next press for full right rudder, as most people fly model radio aircraft. No press is centralised rudder. He can give a left pulse, hold until the model bears away far enough, give a quick pulse through right sequence, and return to left, or vice versa. In this way one soon steers quite a good course, but naturally nothing like the accuracy of reed control. It is possible to rig up the sheets to a ““Vane” power operation, but not essential. (To be continued) The E.D. miniature three valve single channel receiver is mounted in the author’s balsa box, which can be dropped into aeroplane or boat, where single channel radio is deemed sufficient. Note batteries forward, and receiver aft, with white tuning lever visible design, and he then fits it with a single channel A March 1953 FoR far too long has the 36 in. Yacht—the smallest of the rating classes—been regarded as the Cinderella of the sport by the model racing fraternity, and as such has probably received less consideration with regard to improvement in design than her larger sisters. I am pleased, however, to see that this state of affairs seems to have come to an end, and more and more clubs appear to be catering for this class. Designers are realising that this lusty infant is growing up, not in stature, but in performance, and are applying more scientific principles based upon the findings of wind tunnel and testing tank data. In presenting Harlequin to model yachtsmen readers of MopEL MAKER | wish to emphasise that this is not just another 36 in. model yacht, but a boat embodying the latest ideas on hyrodynamics within the limitations of my own interpretation of these findings. While there is nothing freakish in this design to those who have made a close study of the . trend of modern design, the lines may appear somewhat unorthodox and at variance 36 in.RESTRICTED CLASS As the keel appendage is a totally submerged body its forward edge has to deal with undisturbed water in a similar way to the entry of the canoe body and its most efficient shape is, therefore, the blunt ended fine tail form. Some designers have a preference for the elongation of the keel appendage to form a skeg, but in Harlequin this has been omitted in favour of a separate skeg placed well aft; this skeg has the same streamlined form as the keel with previously accepted ideas. I refer in particular to the rounded bow and the full sections of the entry. For many years it was thought that the fine entry was the fastest section, and some of the early designers drew out these fore sections to extremely fine limits, but tank experiments have proved conclusively that this is not so. The fine bow exposes the forward sections to considerable wetted surface skin friction for some distance along the canoe body, whereas the rounded bow, while requiring less energy to propel, also overcomes the initial inertia of the still water ahead of the bow by pushing it forward, thus retarding the rapid closing in of the water at the point of entry, with resultant lessening of wetted skin friction, which more than compensates for the effort expended by the full bow in parting the water ahead of it. Whereas the bow entry has to deal with static water the after sections are dealing with water already in motion, and at this point fine lines are essential to obviate the creation of undesirable eddies and their serious retarding effects. We must, therefore, draw out the lines of the after sections of the canoe body to allow the water to flow smoothly and naturally. We come next to the keel appendage whose angle of entry must be in the region of 40 degrees to the vertical, certainly not more than 45 degrees, for maximum efficiency. appendage and this streamlining has been: con- tinued right through the rudder whose after edge is fined right out. The reason for the separate skeg is as follows:—All sailing yachts make a certain amount of lee-way and a lot of pressure builds up in the garboards on the lee side of the keel appendage. If, therefore, we arrange for a few inches of exposed canoe body immediately abaft the keel this pressure is minimised before it reaches the rudder. This tends to make the modei more lively, calls for less weather helm and helps gyeing performance, all of which are desirable features when designing a hull for maximum efficiency and speed. It will thus be seen that Harlequin embodies all those features which I hope will make her a fast well behaved little vessel able to give a good account of herself in the best company. In point of fact the rounded bow is not such a new innovation as some may imagine. Let me digress for a moment to supplement this statement by recalling the races for the America’s Cup of 1934 and 1937. In the former year Endeavour was superior to the American defender Rainbow and the 143 MODEL MAKER QObechi being more opaque has not this desirable characteristic so other means must be latter won on a protest which is still subject to much controversy in yachting circles. In 1937 that master designer Charles Nicholson built for Mr. Sopwith Endeavour I] which proved far superior to the first found to determine how far we can go. The accepted method is to cut a Vee groove just touching the plotted inner finishing line—the actual cutting line is } in. under this as will be explained later. Small Vee chisels are obtainable from most tool shops and I do advocate its use as a time saver. Mr. W. J. Daniels goes further than this by suggesting that the wood between the inside edge of this Endeavour and hopes ran high in the British camp. In the intervening years, however, the Americans had been busy with a model of Endeavour I and the experimental tank with the result that the “ fastest fore and after ever ” was evolved. She was the Ranger and when Charles Nicholson saw her hauled up at Herreshoff’s Yard he remarked, “ This is the biggest advance in yacht design for fifty years.” Why! because Ranger had a_ well-rounded entry and flat stern; and what was the result of groove and the inside of the plank be cut away also, thus allowing the pressure of the clamps to come on the actual glued joint. This sounds an excellent idea, but as I have never tried I give it here for the benefit of those who wish to do so. Each plank has a 45 degree chamfer planed on the outside of each layer right up to the outside cutting line, thus acting as a further guide when shaping the outside. Some constructors may query the use of ? in. planks instead of the more usual 1 in. widths. Admittedly this gives more glued joints but this departure? Ranger won all four races by 17 min. 5 sec., 18 min. 32 sec., 4 min. 27 sec. and 3 min. 37 sec. respectively. A decisive victory indeed and proved the theory of the rounded bow in no uncertain manner. Having disposed of the theory let us now turn to the practical and, to most constructors, the most interesting side of the pastime. this slight disadvantage is more than outweighed by the increased accuracy gained when shaping the Timber for Hull As it is still practically impossible to obtain yellow pine for layer hulls I have selected obechi which is in good supply, and now hull. A list of timber sizes is given below which familiar to all model ship constructors. From the table of weights or the lines plan it includes will be seen that the hull must not weigh more than 1 lb. 12 ozs. and to reduce a hull to this weight if carved from yellow pine would mean that the sides must not exceed 1/5th of an inch in thickness. Using obechi we can increase this to at least 3 of an inch as obechi weighs 21 lb. per cubic foot as against 32 lb. for yellow pine. This is all to the good as obechi although a tough wood is rather prone to splitting so that any increase in wall thickness is an all the wood necessary for the com- plete hull and spars and arrangements have been made for a parcel to be available for constructor readers from the follow- | OF 2 SHEET 36 MY.A RESTRICTED CLASS RACING YAC Street, Liver- pool, i Southern Supplier : Arthur Mullett, 16 Meeting House Lane, Brighton, Sussex When you receive your hull timber it will be planed, but you may find it has been left a little proud to allow for sanding down to a dead 3 in. To check this, clamp up the four main planks, measure their total thick- 144 (91 Mo CLARENOON RO WATFORD. PERT % etch Pe, wie Te _ a \ \ \ ie cis VOZErFAC-TOAMMoO>Y Paradise Some constructors may not be aware that obechi has a rather obstinate grain which is liable to rough up when sanded in one direction. To overcome this it is advisable when setting out the various layers to arrange them with the grain running in the same direction for the whole pack, a pencilled arrow on each plank can be used to mark the run of grain; if this is done there will be no difficulty in obtaining a perfectly smooth finish in the final sanding, a most desirable feature. With yellow pine it is easy to gauge the thickness of the hull during carving by holding the model up to strong sunlight which shows – through the wood in an orange coloured glow. DESIGNED BY ag ye ing:— Northern | Supplier: The Precision Model Engineering Co. 61 advantage. “H ARLE QUIN’ a) See ae pear ge Aae Sing GUNWALE EYES FOR LIVERPOOL BOV Fi MAST SLIDE. JIB RACK HATCHWAY SPINNAKER SHEET STEERING PULLEYS HOOKS P&S P&S EYE FOR RUBBER TENSION CORD EYES FOR BEATING SHEET SLIDER. & SPINNAKE MAIN HORSE. STEERING QUADRANT. TRANSOM PIECE ANCHORAGE FOR RUBBER TENSION COs wiz 2 oe @” X BEAMS. Y CARLING 2 DECK COAMING. March 1953 ness which must be 3 in. If every plank from A to N was only 1/64 in. over size you would have an accumulative error of nearly } in.— enough to put the finished model out of rating for her class; so please make sure of this important point. ‘Timber Pack (3 in.-thick obechi) Plank S, 16 in. long by 9 in. wide. Planks A, B, C and D, all 37 in. long by 93 in. wide. sin. Mahogany for Stem and Transom pieces, 6 in. x 14 in. }in. Mahogany for Beams and Cabins, 9 in. x 4 in. 4 in.x 4 in. Mahogany strip for Deck Coamings, two off each, 36 in. long. Spruce for Spars Main Boom, } in. thick by 4 in. wide by 21 in. long. Bowsprit, 4in. x }in. square. Spinnaker Boom, 12 in. long by } in. square. Jib Booms, all in. square—Ist 15 in. long, 2nd 14 in. long, 3rd 12 in. long. ae 37 in. x 94 in. x 1/16 in. Resin Bonded Ply. Setting Out So much has been written by so many designers upon this subject that it would appear invidious to go over the ground once again. I propose to do so, however, as Harlequin, apart from her advanced design, is also an excellent model for the novice skipper / builder who may need a refresher on the building of layer hulls. The old hands will dismiss this part of my article with a shrug. The first procedure is to mark out planks A, B, C, D and S by drawing a centre line on both top and bottom faces, then form the profile or sheer plan, using a try square, accurately plot the transverse section lines and draw them in. Now turn to the body plan and with a pair of dividers measure off from the centre line the distance from this line to the edge of each water line. Reference to the drawing will be helpful when doing this. For example, plank A will have on its top face the lines of W.L.14 and on its bottom face the lines of W.L.13 whereas plank B will have on its (Continued on page 148) TABLE PROFILE HALF BREADTHS & DECK PLAN LOA 36:0 OEPTH 11-0 SCALE-FULL SIZE __ OF DIMENSIONS DISPLACEMENT IILBS. | HULL (LB & WEIGHTS 1407S. LEAD 12075. SECTIONS SPACED 3°6| PAINT & VARNISH 12 07S. BUTTOCKS 1-00″ _| DECK & OTHER FITTINGS 8 O7S. 7L8S 8 O7S. .|DECK BEAMS HATCH 12 07S WATERLINES -75|MAST, SPARS, & SAILS 10 02S APPROX POSITION OF 3 MAST a4 DATUM Ld 5 — ‘ : __LINE é 7 se ik J ! s ners pee eae KEEL | BOLT BUTTOCK A == aokeee a H LEAD 9 ] L~ SG wor | eet | i Z| ij ——— ae Wud gt -+——_| | Leg eee, Pe 7 i e P| ROE SIT Sos ; eee |__ mas = 8 ft aay oe ee ee or DECK AT GUNWALE mal r 3] San | \ Ei } WLIO SS s al Se 3 ES L~ 1 —| wis BODY iS & 5) out. KGa) —a en ||| 8 16 wu? WL6 PLAN ( SUNKISS — PT. II CONTINUING A. R. “GUS” LASSEL’S \ SLIDING RIG & GEAR | S.T. VANE N the middle of the Seattle bar, there is a screw adjustment that actuates the Plunger. The purpose of it is a means of controlling the angular scope in the to and fro movement of the feather frame. At its widest amplitude, the angle is a bit less than 45 degrees on each side of centre. Since the apparent wind over the deck has a lesser angle of incidence, the wide amplitude set produces weather helm normally. That’s how it should be, for the need of weather helm means that the centre of effort is aft enough to allow the yacht to coast through a dead spot with a reduced chance of yawing (wandering off to leeward). In this situation: no wind and, therefore, no torque on the tiller; none needed since the centre of effort takes over the steering. In order to produce less weather helm, neutral—and, finally, lee-helm, the plunger is moved out by backing up on the adjustment screw. If the winds over our ponds were as constant as the South-East Tradewinds, neutral helm would be the thing, and lee helm sailing would have the additional charm of a way of cheating the sail-area limitation, for the feather, then, would be acting as an unmeasured mizzen sail. When the centre of effort is too far forward, lee helm must be used to make the yacht head up. In the absence of steerage way, the yacht can’t head up; the misplaced centre of effort takes charge, and she yaws. The vane given control again, she slams into the wind and completes the cycle of aberration by losing steerage way once more. Not much is known of a recommendable minimum angle of setting the vane in closehauled sailing. However, one certain yacht, using lee helm at a 30 degree vane setting, always lost her race as she paid off in an updraught, while her competitor held her course. Another one, with extreme lee helm (11 degrees) in similar situation, failed to get back on her course for lack of space. Prudence, therefore, would suggest a 3-point (33 degrees) minimum. The symmetry adjustment is provided as a means of making the yacht point equally on both tacks. The sure way of gauging this equality is by observing the lifting of the jib. “ Lifting” is the sea-going expression for the deflation mentioned before. The procedure is: if she is sailing low in the wind while on the starboard tack, as compared with lying on port, turn the adjustment screw left-handedly; low on port, right-handedly. Two turns, if the difference is obvious. After we have achieved symmetry, occasion might arise when a lopsidedness is desirable. Ability to point higher on one tack than the other is brought about by means of the proper Cam, on the plunger, being rotated so as to restrict the amplitude of the oscillator to leeward of the outbound tack. Used for gying; particularly, in slowing up the quick gye. Its efficacy, limited. The Tension Slide on the oscillator functions as a means of attaching one end of one or more rubber bands and of adjusting the tension of these so that, when the inertia of the counterweight becomes disturbed, the elasticity of the rubber swings the counterweight over, which act causes the yacht to heave about. A heading puff, a wave, or a “dead spot” can be the triggering agent. In the use of this “long gye,” there is always an element of suspense, and the skipper who “converts ” 100 per cent. is a wizard, But such wizardry is not dependent on the skipper alone; the yacht has to be designed for it, but MYRAA does not permit recessive leading edges of keels. We assume now that the windward passage has been made. The return trip will be done with the latch straddling the locking lug, and with the resulting locked complex rotated so that the leading edge of the feather looks into the wind’s eye 180 degrees from the position that brought the yacht to windward. That generalisation does not pertain if the yacht has been tacked, for the new position would be 180 degrees from the medium of the tacking positions namely, directly or nearly above the vane-arm. Neither does it pertain to exactitude of any course to be steered, for an “ overtrim ” is needed, and this depends on the yacht’s behaviour characteristics in variations of the wind strength. As-a rule, the stronger the wind, the more overtrim. The vane-disc is calibrated like a compass card. The total number of marks or points is 32; eight to a quadrant. For our purpose, the quadrants must be named, and the designations might just as well be derived from the general = Eee LASSEL SELF TACKING VANE GEAR ° [REVISED OCT. 1952] DESIGNED BY A. R. ‘GUS’ LASSEL COPYRIGHT OF / MODEL MAKER PLANS SERVICE 38. CLARENDON RD | “| WATFORD. HERTS. -—28 DRILL= 6-32 SCREW fousAPPROX. POSITION OF FEATHER ENGAGES WHEN NOT GYING GEAR BODY LOCKING LATCH POINT GYE HOOK ADJ’T BOWSER ENGAGES HERE WHEN GYING ~ RIVET& SOLDER TO BODY 2 VANE FEATHER. MAKE FROM LIGHT BALSA. NEEDLE POINT FITS FIG’R’ weicur ADJ. BAL.WEIG shen i TILLER LENGTH & DISC ARM “Ht LOSKRING \\| CENTRE TUBE ‘° te bony weeds IF GROOVE —~, |} – CENTERING CATCH ate ; AVE 4-40 ADJ. SCREW aS < ne At ij| at Pampas 4 2 HH| LENGTH ARE DETERMINED OD.X 2¥2z" LONG 4. “FOR ADJ. SYMMETRY ap 4 40) fs See OS ate : s NUT- SOLDER TO SCREW AT ASSEM. DISC 16 DIA. PINTLE !/s" DIA. BY: 3” LONG. DECK PLATE | ve" DIA.- "x" DIA. HOLE FOR TILLER LOCK PIN a ‘ i 7) VANE HARD OVER & HELM IRREVERSIBLE Bee ARMS NOTE MATERIAL-'/32 SHEET BRASS OR STAINLESS STEEL-WIRE "1c" & '/s DIA. BRASS OR STAINLESS FIXED JOINTS SS MAX. RUDDER ANGLE STEEL- BEARINGS & TUBE BRASS- SOLDER ee af ° \ 2 3 ABSCISSA:| DIST, BETWEEN CENTRES OF4ROTATION | /; = 4 4 5 6 7 8 37% _RATIO ELEMENTS OF LINKAGE, VANE STEERING GEAR. 147 MP 9 10 l ee ee MODEL MAKER course sailed when the latch is over the quadThus, the latch over the port forward quadrant would be: Port Broad Reach. To this should be added the number of points, counted from the forward centre of the disc. As an mental courses like full and by, wind abeam, the reverse of lying close, and directly before the wind. rant. For instance, he can expect to have to set the vane at 64 points, close reach, to sail wind abeam in light airs, while 8 points would be example: Five points, port broad reach. Under certain wind conditions, that would be the set- indicated in a 20-mile wind. Directly before the wind, if the boom is out on starboard side, one ting for a return trip after the yacht had fetched the turning line while lying close on port tack and without having tacked. Four of these points represent the ideal 180 degrees, and the fifth, the overtrim. The term “on port tack” means that, if the mainsail were a square sail, it would be necessary to hold down the lower weather corner by means of a tackle at the port bulwarks, when the wind was coming over the port bow. In our specific situation, the boom would be over the starboard counter, and the latch of the vane, theoretically or actually, over “ Starboard Close Reach” quadrant. A theoretical 34 points for close hauled, if the latch were down or two points on port broad reach would be the setting. In this case, the kicking strap on the boom should be hooked over to starboard to prevent unauthorised jibbing. In order to correct the steering on the lee- 8 points for close reach, with the ward board, “ Squeeze her to you” is a simple latch up. The sailing at certain angles with the wind, other than lying close, we shall call “ sailing courses,” and forget that the term connotes compass courses. For the she How are the sheets to be set? So that the sails don’t spill the wind, on the yacht getting two points off her course. That, on broad reaching and running. If the skipper must gamble, a full spinnaker gives him that opportunity, otherwise, a flat one is suggested, for it is easier to keep filled. in the recess; actual 4 points for full and by, and 4 to Should jib, her new course would be at least three points off the attempted course. rule to follow. “ Her” refers to the feather-bar complex, and “ squeeze ” to its rotation toward the lee shore and “to you,” in an assumed position abaft the vane. A squeeze amounting to one point is rarely enough, even if the angle of approach was sharp; it is supposed to be a result of the venturi-effect. sake of preserving his poise, the skipper should know howto sail, both in light and heavy going, certain funda- ss — HARLEQUIN — 36 in. REST CLASS top face the lines of W.L.13 and on its bottom centre of plank A. once again will make this clear. When dealing with the slightly different procedure The centre is cut out but a be left at the after end to when the clamp is applied. the outside to shape 1/16 in. outside the plotted line, and cut out the inside on the inner cutting DRAWINGS PLANS OF SERVICE, HARLEQUIN 38 ON CLARENDON Treat planks E, F and G in the same way as you did A, B, C and’D by plotting the outside and inside lines, allowing for the cutting out of centres of planks E and F. Plank G is solid and reference to the drawing outer line. Both the outer hull line, the hull thickness line and the inner cutting lines are, so far, only a series of dots. These must be joined up with a fair curve by means of a batten passing through all points. By means of a coping saw, or better still a power fret saw if you have access to one, cut FULL-SIZE (Continued from page 145) line. You will now have four additional planks, and these are used as follows :— Plank E comes from the centre portion of plank B. Plank F comes from the centre portion of plank C. Plank G comes from the centre portion cf plank D. All keel layers H to N are obtained from the face the lines of W.L.12 and so on for planks C and D. So much for the outside lines. To obtain the inside lines plot a line 2in. inside the outer line—this gives the hull thickness when finished but at stem and stern a thickness of 14 in. should be allowed for. So far we have only dealt with the four main planks and to obtain the other layers we must cut out the centre portions of the main planks, and this cutting line will be 4in. inside the MAKER YACHT TWO SHEETS ROAD, 148 ARE WATFORD AVAILABLE HERTS, sheer plank S a must be followed. bridge piece must prevent distortion DIRECT PRICE 9s. FROM MODEL 6d. POST FREE March 1953 Designing to the ‘A’ Class Rule PART .THREE -OF A - SERIES BY ig did not take Mr. Daniels and Company long to win the first “Yachting Monthly” Cup outright. It was then that the second cup was also donated by the “ Yachting Monthly.” 1929 saw the rule well under way and that year saw the advent of the very famous British Champion Albion, designed, of course, by Mr. W.. J. Daniels, L.O.A., 75.5 in. L.W.L., 47.5 in. L.W.L., beam 13.6 in., displacement 40.4 Ib. and 1,821 square inches of sail. The “A” boat fleet of this period were nice handy sized boats. In those days, however, hull balance as we know it was not known, most of the boats having weak shoulders and full quarters. Their water line was as a rule for finer forward than is usual to-day. Many of the models must have been pigs to sail, with alarming griping qualities. At this time, too, there was a very hot debate in progress between full keel and fin and skeg. All in, Champion in 1929 and 1930 was of the former type. By 1931 things had not altered a great deal and Hermione designed by Mr. L. H. Willey was L.O.A., 73.85 in. L.W.L., 47.6 in. L.W.L., beam 13.9in., displacement 41.21b. and sail B. H. PRIEST, MIMAR.E. the height of rig is limited to 85.3 in. above deck, is a very inefficient sail plan. To increase efficiency the height width ratio must be increased but, of course, as the height was limited it meant less square inches. So it became natural to make a larger boat to use the full rating. Turner again led the way and to Fleetwood in 1933 came his first battle squadron. Three to the new Flash design, L.O.A., 75.1 in. L.W.L., 53.3 in. L.W.L., beam 15.15 in., displacement up to 54.6 1b. and only 1.645 square inches. Large Metacentroids with a weak Wine Glass Section with a maximum beam of 16.9in. And the more radical Hemera of still newer design, L.O.A., 76.6 in. L.W.L., 53.7 in. L.W.L., beam 13.9 in,, displacement 52 Ib. and 1,610 square inches of sail. This fleet burst upon the British Championship, which was sailed in two fleets in a fullblooded four days of gale. Their weight and power put them up to the top of the lists, but pitted against them was a very remarkable ship. Daniels had pulled one out of the bag. He also was cutting down sail but by another method. He used a small water line length with its small displacement but a long sailing length, by taking quarter beam penalty. The result was the famous Glengarry—the only other boat to win the British Championship two years running. L.O.A., 76in. L.W.L., 48in. L.W.L., beam 15.6in., quarter beam area 1,796 square inches. All seemed calm outwardly, the class seemed to have settled down into boats like the above two and with skimming dish tendencies, but behind the scenes a storm was brewing. Admiral Turner, a far-sighted engineer, had been perfecting a system of hull balance which he called “ Turner’s Metacentric Shelf Theory.” Not only this but he perceived that we were too small for the rule. The advent of Cressett with a Metacentroid hull and balanced on his theory was probably the biggest jump model yachting has ever taken. In one bound he went to L.O.A., 71 in. L.W.L., 50in. L.W.L., beam 15.12in., displacement 501b. and sail area 1,840 square inches. And wonders! the penalty almost two inches. Displacement 42 lb. and sail area 1,760 square inches. Now a 48in. L.W.L. boat has a permitted Q.B.L. of 45.6 In other words 2.4 in. less than the L.W.L. If Glengarry has a penalty of 2 in. then her actual Q.B.L. is 45.6+2 x 2 in. or 49.6in. In other words when heeled she sails almost at 50 in. L.W.L. boat. Not only this but she has a very long bearing surface. It is not weight which dictates how well sail can be carried but beam and section. The flatfloored boat will be stiffer until over pressed than a vee sectioned boat of similar beam and monster was a marvel in light airs and could keep a steady course to windward no matter how light the conditions when some unbalanced boats would have needed a three inch aft movement of the mast to get them to face not even 12 or 14 pounds extra in the lead will up to the wind. Parallel to this, development was taking place in sail plans where the Ten Raters were showing the way. It was beginning to dawn upon designers that 1,800 - 1,900 square inches on an “A” boat model, where assist the latter. . Not only did Glengarry outsail the heavies in the blow but in a moderate breeze in the final was an easy winner. Had the race been sailed in light breezes the heavies would have won 163 HIN MODEL MAKER for all their weight and less sail, for here Glengarry’s shallow wave and stiffness would have been of no value but her very large wetted surface would have made her as dead as Dawn and Lady Nell, the latter winning the British Championship in 1936. She was L.O.A. 77.75 in., L.W.L. 48.75 in., L.W.L.° beam 14.2 in., displacement 50 Ib. and sail area 1,796 square inches. The Alexanders embarked on a series of experiments in all directions and the results mutton. Admiral Turner evidently realised that his Flash tribe were too weak in their section and Hemera had not enough sail. So the former design was dropped and the latter scaled up to the 56 lb. Hisporos design to get more sail. He also seemed to realise that he had a poor airfoil on his keel which consisted of a lead bulb low down, the leading edge of which was a were White Heather I to VI. Most of these excelled in a breeze but probably due to unbalance were poor windward boats in light airs. Sail plan was still slowly improving but jibs were a great deal smaller than they are now, circle 4 in. in diameter and commenced a policy of violently slimming his lead. So drastic was this operation that the top of the lead was the base of the fore triangle being around 18 in. Spinnakers being flat and carried inside the jib. Balance began to make great strides. “ Turner’s theory ” had been hotly debated by the Institute of Naval Architects who disposed of it on the grounds that one cannot apply Static ideas to Kinetic problems. The author however, believes the theory to be correct for, actually taken into the garboard of the hull. The Hemera design was a good one and vast numbers of good and bad variations were made off the original lines. Even to-day Black Empress is an original Hemera design. The 1935 Champion Niaad was a variation as so was Brig. Ingles’ well-known Actinia. In this period the south had Mr. Daniels, Mr. Feltwell and Mr. Nash all hard at work designing lovely creations, for none of these three could have designed an ugly boat. All were most sweet lined and famous. argue as one likes, practice proves it so. From Mr. Daniels’ board cameAnglican and Da Shetland Lass and Fusilier all between 40 and 50 Ib. Mr. Feltwell had produced a design from which came Mersey, Conquest, Concord, Comet and Quest well-known boats all, with three or four British Championship seconds to their credit. They were rather lean-shouldered boats of 75 in. L.O.A., 48in. L.W.L., L.W.L. beam 14 in., displacement 42 1b. and sail area 1,737 square inches. Mr. Nash produced the very beautiful Fantasy and it is a tribute to how far ahead of the times he was that Fantasy is still sailing and still without a doubt one of the best boats in the country. L.O.A. 80in., L.W.L. 51 in., L.W.L. beam 14.5 in., displacement 50 lb. and sail area 1,736 square inches These designers added to Admiral Turner gave the south an overwhelming advantage over the north, who only had Mr. Davey and the Alexanders in serious competition. This is well exampled by monster from the Daniels’ lightweight Janet. 1933 final 6 Southern, 2 Northern designers 7 6 6 4 29 ° 6 29 ella final final final final This win gave the Turner boats a great boost and the following year he produced the well- known Seri design to which Burika and Whisp were built. Se 1934 1935 1936 1937 No boats either manned up or model designed to balance on this theory have ever been unbalanced, whilst those which fail, when the theory is applied to them, exhibit the faults predicted by the Turner theory. A couple of our best known designers have never subscribed to the idea and used a system of volumetric balance. Even so some of their designs even to the present day have shown distinct signs of unbalance as various alterations, to keel positions and profiles necessitated after building, prove only too well. We will show in a later edition, when we get down to getting all our information put into a design, how easy it is to prove the balance of a ship by “ Turner’s System.” 1937 and 1938 were definitely Admiral Turner’s years. 1937 saw the advent of a new Turner monster Arktis, L.O.A. 77 in., L.W.L. 53 in., L.W.L. beam 16 in., displacement 60 Ib. and sail area 1,700 square inches. (It should be noted here that in YM. 6M.O.A. there was an idea that carried a great deal of weight in the south, that whatever was the ideal sail area it was not to be found under 1,700 square inches). The final was sailed under light conditions and was won by 11 clear points by the 60 Ib. Mr. Davey’s best efforts at this period were (To be continued) 164