Marine Models: Volume 11, Number 3 – June 1938

SSS YW“yli lifjve, SAMWQQ*y, W4 Y 4Z Z MMA DOO MWOW‘ WOKS ” Zz 4 7 SS f“Mtap <> %, CZ %, ZZ SVVTM1°~~»ooo Sess INCORPORATING Vol. XI, Z SIS gn WH S Cia WMS WYa <> Y“i Witlés Z MAG *°U°AAAA RARVAVQQQQO Ups,WL L, Wp, sod Y THE SANAARAARS AS SE SS Sass! MODEL YACHTSMAN Sevenpence JUNE, 1938. No. 3. \ Puen a) Bit YE. _| MARINE MODELS PUBLICATIONS LTD., ~ FETTER LANE, LONDON, E.C.4 EVERY JOB NEEDS A SKARSTEN my SCRAPER With Hook-shaped Renewable Scraping y FINEST SOFT PINE Specially selected for Model Boat Building. Edges. All thicknesses Hooks 4” to 3”, widths up to 24” extended for “Corner Scraping. SAVE TIME— SIMPLIFY WORK from ALSO Prime Honduras Mahogany Nothing better for superior smoothness and refinishing. FOR RE-SHARPENING CHETHAM TIMBER Co. Ltd., SKARSTEN SCRAPER FILE Sold at Ironmongers, Paint Shops, 70, FINSBURY Merchants, and Ships’ Chandlers, or write to : ” LONDON SKARSTEN MFG. CO. WELWYN GARDEN CITY -_ PAVEMENT, Builders’ METROPOLITAN HERTS. E.C.2 7418 “RYLARD” The Worlds Best Marine Varnish & Enamel LLEWELLYN RYLAND LIMITED, BIRMINGHAM, ENGLAND When replying to Advertisers please mention MARINE MODELS. THRTTUNAINIUDTISTID SDH BLD DEL) PPD 6 4 NY NS > yy NY\ Yh ‘n “i Pe, ‘ LI pa N Sy “J SIS ‘ x > = > a = 3 3 Vol. XI, No. 3. Published on the Seventh of each Month June, 1938 EDITORIAL A S our present issue is published the day after Whit-Monday, it will be impossible to include any reports of Whitsun racing, but we trust that all model yachtsmen and powerboat men have enjoyed a good holiday and exciting sport. Full reports will appear in our July number. About a fortnight ago a subscriber, Mr. P. E. Middleton, of Adlington, Lancs., very kindly sent us a copy of The Model Yachtsman of March, 1884. This little magazine was published by Thomas Grassam, 161 & 162, High Street, Hull. As a matter of fact, when we launched The Model Yachtsman in April, 1928, we were unaware that there had been a previous magazine of the same name. The late Mr. A. Littlejohn, Commodore of the M.Y.S.A., Kensington, however, subsequently informed us about our predecessor, and showed us one or two of the later numbers, and told us its history. Started as The Model Yachtsman, after a few numbers it was found necessary to enlarge its interests to increase the circulation, and it became The Model Yachtsman and Canoist. This, however, was not sufficient to save it from shipwreck, and it fizzled out after eight or nine numbers had appeared. In this magazine we were interested to read a history of the Kingston M.Y.C., Hull. It was founded in 1881, and by 1884 had grown to 180 members. We do not know the subsequent history of this club, but at that time it must have been one of the strongest. As a matter of fact, there are quite a few clubs in existence to-day that can trace _ their history back for 50 years or more. The enormous strides made by model yachting in the States during the last three or four years are undoubtedly due to the inception of the Marblehead class. It is now recognised in Britain by the M.Y.A., and has been adopted by quite a number of clubs. The class may possibly appeal less to many experienced skippers than the 6-m., but is certainly attractive to the novice. We hope it will bring recruits to the sport here also. A series of talks on Hobbies is being broadcast by the B.B.C. on Wednesday afternoons. On June Ist we had the honour of contributing a talk on Model Yachting to this series. One of the great advantages of Model Yachting (and this applies with equal force to Model Powerboating) is that it provides an indoor recreation as well as outdoor exercise. In our talk we particularly stressed this aspect of the matter, and pointed out that the indoor work of model-building is every whit as enjoyable as sailing. We hope to be on the air again on June 29 with a talk on Model Powerboating in the same series. Editors of magazines have to make their arrangements months ahead, and we are now making preparations for our Special September Number. Amongst the good things for readers will be a new A-class design by Mr. A. W. Littlejohn. Other features will be announced in due course. 54 MARINE SHIPS’ MODELS ANCHORS By A. P. IsaRD, A.M.I.Mech.E. (Continued from page 28.) i is improbable that any ship has been so extensively studied and made the subject of the model-maker’s art as the “* Queen Mary,” of the Cunard White Star Line, and often referred to as ‘“ The Wonder Ship of the Twentieth Century.” Readers of MARINE MODELS are surely very much indebted to the courtesy and kindness of Messrs. Samuel Taylor & Sons (Brierley Hill), Ltd., for supplying authentic data to the writer of “ Queen Mary’s” ground tackle as actually made and supplied by them. They are probably examples of the largest and heaviest cables and anchors ever made to date. In Fig. 21 we have a beautiful picture of these anchors reproduced from a photograph taken in the firm’s yard in Staffordshire. Some idea of their enormous size can be at once realised by comparison with the men standing by them, and in this connection the photograph is clear enough for the model maker to take at least proportionate dimensions— Fig. 21. pretty little gew-gaws to hang on the watchchain ! This beautiful ship has, nevertheless, quite a simple arrangement for her ground tackle: there are two sets of anchors and cable, a port and starboard bower only. Each of these anchors weighs no less than 16 tons, and is shackled to no less than 165 fathoms of enormous 44in. cable, about which more will be said later. These stockless anchors, known as “ Dreadnought,” are monster outsize anchors, very similar to the type of stockless gear already dealt with at some length in previous articles. The shape of the flukes, together with the formation of the correct angle with the stock, ensures a positive and quick “ nip” with efficient holding power. When the anchor or anchors are “ broken- out,” they are eventually hauled right up into their respective hawsepipes and the arms carrying the flukes tumble home correctly as THE *‘ QUEEN MARY’S ’”’ ANCHORS MARINE 55 MODELS the cable is hove-in and adjust themselves by fitting snugly and almost flush within the special recesses cut back into the ship’s either i which are a noticeable feature of this ship. When the anchors are “ let-go,” they fall quite freely to the sea-bed, the cables being simply dragged up from the chain lockers and overboard by their combined weights. Immediately the anchors begin to “ nip,” the cables are checked by means of powerful and specially-designed brakes, which are fitted to the base of the cable-holder barrels, these being arranged in such a manner that they grip the lower part of the barrels to which the snugs are fitted. The great importance of having rigidly fitted snugs and properly fitting and _ regularly pitched cable links and shackles is obvious. If they were not so carefully made, when running out the cable or cables would not lend themselves to the nicety of the light handbrake controls, so essential to the efficient and proper working of this specially designed gear. It is interesting to note that the shoes of these brakes are lined with a special high tensile brass alloy. Now a word about the “ Tayco” Chain Cables, which are electrically forged and are made from a high-grade steel with a breaking strength of from 31 to 35 tons per square inch. These also are made by Messrs. Samuel Taylor & Sons (Brierley Hill), Ltd., Staffs. Since this ship is so very large, special attention had to be given to the enormous strains likely to be sustained by her cables, and her equipment has attracted expert attention all over the world. In fact, it is stated to be the most efficient and effective complete ground tackle ever fitted in any ocean-going ship, naval or mercantile. As notes upon cables have appeared in MARINE MODELS in previous articles by the writer it is unnecessary to repeat them. The cables of *“* Queen Mary ” are, of course, ‘studded link,” but special notice should be taken that they are of steel and not of iron. Steel is quite a recent material for this purpose, iron bar having persisted and held its own up to very recent times, and even the latest and largest liners built abroad have cables of cable iron and not steel. The advent of drop-forging, or its equivalent, electrical resistance welding, together with British ability, has broken away from estab- lished ideas. The Cunard experts, therefore, after much full-scale experimental work, have Fig. 22. THE *‘ QUEEN MARY’S ’’ CABLE confirmed and accepted this new method of manufacture embodying the use of a special steel. The diameter of the actual round metal in the studded links is no less than 44in., bigger than a man’s forearm, and 10 complete links weigh approximately one ton. The manufacturers were faced with the problem of providing a cable of which every length would have to stand a proof test of about 300 tons; that is, a length consisting of three links cut from any part of each 9Oft. had to stand a load of 405 tons before definitely breaking. Actually on test the cable broke down at a load of not less than 693 tons, surely a proof of British workmanship, and consideration for the safety of the ship and her complement. For engineering experts it is of great interest to note that every length of completed cable is carefully normalised at 850 degrees C., this being obtained by scientifically and specially designed furnaces with temperature-recording apparatus, and an elaborate system for atmospheric maintenance inside the furnace. Considerable consideration has been given to the question of wear upon the cable itself, and specially designed hawsepipes, as already referred to, have been fitted. The speed of hauling-in is arranged at 90ft. per minute, but a speed of 50ft. per minute can be easily maintained when the load is 60 tons. All corners, 56 MARINE edges and projections are carefully rounded off, and the chain locker is tapered with a smooth interior, all rivet heads being smoothed off, to facilitate the easy stowage of the cable. There is also a special dished plate of heavy mild steel, fitted over the nose of the stem to avoid any chafe, which might happen if the cable should get across the bow, as not infrequently happens, and all horizontal hull shell-plate joints and rivet heads anywhere about the course of the cable are protected with triangular fillets. The shackles by which the lengths of cable are joined together are worthy of special notice. They are somewhat similar to an ordinary link, but the design permits the cable running out throughout its whole length smoothly around the snugs in the cabledrums without jarring. In this connection a studded cable is usually arranged to turn back upon itself, and at these turning points are situated vertical windlass MODELS drums, whose circumferences are very carefully made and fitted with snugs. These snugs must fit the cable exactly, and the shackles joining the lengths of cable must be of such a design that they also run over these snugs as smoothly as the cable itself without any jarring or grinding. These snugs play an important part, and it is easy to imagine the enormous strain that may beimposed upon them when the ship is riding to a gale. Fig. 22 is a reproduction of a photograph taken at the works during the process of manufacture of the cable, and the figure of a man standing on the control platform illustrates dramatically the size of ‘watch chain.” ‘ Queen Mary’s a For further information readers are aitined to obtain a copy of The Times Supplement for September 25, 1934, which contains a long article upon the subject. (To be continued.) B eo ee mS ‘ From an original sketch, by H. Hood Starter to Spectator: Do you mind standing back, sir, please You are preventing the wind getting to the boats MARINE MODELS 57 THE ed Shy gf Vines = B (Continued from page 32.) Me are a number of different wire in the tables given. The most usual gauge is the Imperial Standard (I.S.W.G.), and this is usually employed for sheet brass. In buying, however, it can do no harm to ascertain by inquiry that the vendor is speaking of the gauges in use, and, as these are not only used for wire but for sheet metal as well, it is useful to have a table giving the equivalent sizes in decimals of an inch. In the table given below, only the most important wire gauges have been included. Of these, the Birmingham (B.W.G.) is often used for sheet-iron. This is the same as Stubs’, but this must not be confused with Stubs’ steel wire gauge, which is not included COMPARISON OF same gauge as you are vient. One gauge not included in the table is the U.S. standard gauge, but this is not used in this country, and in the States mainly for steel plates. On examination of the tables it will be DIFFERENT WIRE GAUGES DIAMETERS IN DECIMAL PARTS OF AN INCH No. 7/0 6/0 5/0 4/0 Birmingham Imperial or Stubs’, Brown & Sharpe. || _ 500 454 -380 -348 -3648 — is! -464 -432 | -4096 |. 27 | 29 3/0 -425 -372 0 -340 -324 -3248 4 5 6 7 8 9 10 11 12 -300 -284 -259 -238 | -180 | -220 -203 165 -148 134 -120 -095 15 16 072 -065 17 18 19 20 21 22 | | | 104 092 -080 072 -064 -058 042 -035 032 028 | | | | 056 | -1285 a +1019 -0907 39 40 | | 42 | -036 032. 028 | 0641 | -0570 -(508 0403 040 0359 -0319 «| =~ 0284 | | 0808 0452 -048 36 +1144 «0719 0253 34 35 38 41 | | | 43 44 45 46 47 4 49 50 | | | | | CO | | | 025 | 016 | 33 | | | 1442 -128 116 | 28 or Stubs’. 022 -020 1819 1620 176 | 26 Birmingham | «| ae | ae -2043 144 | | | 30 i: 32 -232 -160 083 049 . -2893 -2576 -2294 -212 192 109 13 14 -300 :276 252 3. 24 eee -4600 1 2 3 No. aon ne -400 0 | | American or | Standard. | Imperial -0201 -0179 -0164 0142 -0136 01125 -018 014 | 0149 | -0124 -0116 -0108 -008 ‘007 005 | 0225 -022 -020 | 012 -010 -0C9 Brown & Sharpe. 024 018 -013 American or Standard. -0100 0159 01264 -01002 -00893 -00795 0092 0084 | om: -0068 | — _ 0052 -0048 a -0040 -004 -0076 = -0060 7 0044 ~y 0036 = — ay a — – — | | | | -00708 00630 00561 | -00500 | 00396 -00445 -00353 -00314 a _ ait 0032 -0028 = a -0020 am ‘0024 0016 0012 0010 = os ae zs 58 MARINE THE VICTORIA PARK MODELS MODEL STEAM YACHT CLUB The only Club in London devoted exclusively to Mechanically propelled Models Fitting on the deck after getting up steam THE ABOVE PHOTOGRAPHS Getting up steam with burns APPEARED seen that there is a big difference between the measurements of the numbers in the various gauges, so that it is essential to be sure which gauge is referred to. By the courtesy of Mr. F. H. Lambert, Hon. Secretary of the W.L.M.P.B.C., I am able to reproduce some pictures published in the Captain in 1904, showing members and craft of the Victoria Park Model Steam Yacht Club, the precursor of the present Victoria IN ** THE a blower charcoal CAPTAIN,” IN on a boat that 1904 Model Steamboat Club. It is interesting to add that some of the members are still in the club to-day. I admit to being greatly pleased with the picture of the owner getting up steam with a blower on his charcoal burning model! ‘I think readers will agree that the art of building prototype models has considerably improved during the past 34 years. I wonder if we shall look as old-fashioned in 1972. MARINE I recently had to make a number of ventilators of various sizes for a smallish model, and as ventilators often prove a stumbling-block to modellers, I will describe my way of making them. For each of the sizes required | made up a punch and hollow die, and, as comparatively few of each size were needed, I was able to use brass for the die. Either mild steel or silver steel can be used for the punch, and unless the worker is going in for mass production, there is no need to case-harden the punch, The die is recessed to the required shape for the cowl of the ventilator, but rather deeper, and the edge of the hole rounded off to take off the sharp edge, which would cut through the thin sheet brass used. The punch is given sufficient clearance in the die to allow for the thickness of metal being used. The sheet brass is first cut into squares of suitable size, as ascertained by experiment, and the corners cut off, making the shape octagonal. They are then cut approximately circular. The brass is next annealed by heating just red, and being allowed to cool. By way of starting the job, a slight dent is put in the middle of the brass disc. To do this, the disc is put on a block of lead, and the punch used, giving it a tap with a light hammer. The cowl is now pressed gradually into the mould, using the vyce jaws, the metal being annealed several times during this operation. It may be found necessary to ease off the edge of the hole in the die to facilitate drawing the metal into the mould, and it may also help matters if a little grease is used. When the die is withdrawn, the cowl should just cling to it. If the cowl remains in the die, the hole will have to be made a shade more tapered by easing round at the top. When the cowl is withdrawn on the end of the punch, the whole thing can be mounted in the lathe and almost parted off, but the metal must not be completely cut through. If the cowl will not hold on the die for this operation, it may be found to facilitate matters if an odd end of dowel rod is mounted in the tail stock and pushed up against the bell. The stems of the ventilators are made from tube and cut to length in the lathe with a parting tool. If a stop in the tail stock is used to feed up against, the lengths of tube can be parted off one after another. To take the cowl, the top of the tube has to be filed off at an angle, and if this is done with a MODELS 59 round file, it will fit the bell nicely. During filing I use a piece of wood with a groove on top asa steady. The cowl is then silversoldered onto the stem. The bead round the cowl is made from fine half-round wire sweated in position. The rough edge of the cowl can now be cleaned off. The hole from the cowl into the stem is drilled with a drill that exactly fits the tube, but a stop, made from a piece of tube, should be used to prevent the drill damaging the top of the ventilator. With a little practice the worker will find this method quite easy, and be able to make his ventilators quickly and easily. I have seen quite good models spoiled by poor ventilators, and I hope that any reader whose model is lacking in this respect will find the above help him to rectify this. There is a slightly different alternative to the method outlined above for making ventilators, and as a matter of fact, I used it for a few very small ventilators which I wanted for the same job. I made the hollow die with a stepped bit round the mouth so that the bead round the ventilator cowl is made in one piece with the cowl itself. The punch has a corresponding ridge to suit. For larger sized ventilators, however, the first method gives the best finish, but the second one is given for making very small ones, and also for the benefit of those who do not want to do too much silver-soldering, since when making this way the cowls can be sweated onto the stems instead of silver-soldering them. Just one final point that applies to both methods. Both the hollow die and the punch must be well polished, as this not only gives a smoother pressing, but also facilitates working. The above ventilators can be elaborated to any extent the modeller desires. For instance, a second bead can be put at the point where the cowl joins the stem. Again, trimming handles could be added, and the ventilator made to turn by using an internal sleeve fitted to the deck plate. Navigation lights are quite simple things to make. Take a piece of square brass of the appropriate size and drill a hole of a depth sufficient to bring the glass bead, which forms the light part, in the correct position. The hole should be as big as possible, as the real lamp is made of sheet metal. The front of . the lamp is filed to shape according to whether it isa sidelight or a masthead light. The light opening is easily filed out with a small round 60 MARINE file, as near as possible, to show over the correct arc. If filed straight across, it will open up the hole correctly. By B.O.T. regulations the sidelights show from right ahead to 2 points abaft the beam (ie., an angle of 1124 decies), the headlight from 2 points abaft the beam on one side to 2 points abaft the beam on the other (i.e., an angle of 225 degrees), forward, and the stern light from 2 points abaft the beam on one side to 2 points abaft the beam on the other side (1.e., an angle of 135 degrees) aft. The masthead light is carried 20ft. or the beam (whichever is greater) above the hull. When two masthead lights are carried (as they almost invariably are by all vessels of any size), the after one must be at least 15ft. above the forward one. Returning to making our lanterns, it is often difficult to get a plain round glass bead of the appropriate size, but a round glass ball can easily be made. Break off a bit of glass of the right size to make the required ball. Take a sheet of asbestos slate, choosing a smooth part, and cleaning it carefully. Put the bit of glass on this and melt up with the blowlamp, when the glass will run into a little ball. The ball will have a flat on the underside, but this does not matter. It only takes a minute or two to do this, and after a few “dummy runs,” the worker will soon get the hang of this. Some glass does not take kindly to this remelting and loses its colour, going a dirty tint, particularly clear glass for the headlight and sternlight. By the way, the flame should not be played full blast directly on the glass, and it should be warmed up gradually. Naval readers will recognise the expression “dummy run,” which means a_ practice attempt. It arises from practice torpedo exercises when torpedoes are run with a dummy head instead of a war head. The glass balls can be dropped into place, and the holein the top (or bottom, as the case may be) of the lantern plugged with a little brass disc made a tight push fit. If, owing to the shape of the lantern, the disc would be on the thin side, a thicker one can be used by recessing it to fit snugly over the top of the ball, using a drill. The ball should be a good fit for the hole, to prevent it getting out of position. It is, therefore, a good idea . to melt up, say, half a dozen of the glass balls to ensure getting one to fit nicely. The making of portholes has often been described, but I have never seen the following MODELS method given for making square windows, such as are found on yachts’ deck saloons, liners, etc. I started by making a former from a piece of bar metal the size and shape of the inside of the window frame. Round this I wrapped a piece of best sheet brass of the correct gauge to give me the scale size for the brass window framing. The sheet brass was cut so that when wrapped round my former the edges of the metal just butted, giving me a square tube the actual size of the window frame. When this was finished, all I had to do was to cut as many thin slices off the end as I wanted window frames. Having conveyed the idea in general terms, I will give a little more detail as to how it was done. The length of tube made up was considerably more than was needed for my window frames, but the odd piece left over came in very handy, as will be seen later. The width of metal needed to wrap round the former was very carefully marked off. The brass was annealed, and I started on one of the flat sides down the middle of which the joint was to come. Using a piece of flat metal, I clamped the brass in position in the vyce, and proceeded to make the first corner. The windows I was modelling were slightly domed top and bottom, so the top was then bent to follow the former to the next corner. In tapping the metal down to the former, | interposed a piece of metal to avoid bruising my brass. After wrapping, the brass tube was a little inclined to spring open along the joint, so had to be brought together gently in the vyce, taking care the two edges butted nicely and kept flat. The joint was then silversoldered, and being neatly made, this simply showed as a silver hair-line. As care had been taken in making the tube, it needed practically no finishing. When the tube was made it was again slipped onto the former, which was then mountedin the lathe and partially parted off for the number of thin slices required. The tool was not allowed to cut into the former as I had a second lot of windows to make. The flat sides were cut through with a piercing saw. The frames were cleaned up with that fine emery paper, knownin the jewellery trade as “‘ French” paper. I must leave the description of how these window-frames were glazed until next month, when I may have something more to say about deck fittings. (To be continued.) MARINE SOMETHING ABOUT MODEL MODELS CARBURETTORS 61 FOR SPEEDBOATS By KENNETH G. WILLIAMS (Concluded from page 34.) N the first part of my article, which appeared in last month’s number, I gave drawings of the carburettor I use on my own boat “Faro” (Fig. 1), together with enlarged drawings of the spraying tube and needle (Fig. la) and alternative types of primary chokes (Fig. 2). A main choke of 3in. diameter or more can only be used with advantage on an engine of 30 c.c. when the revolutions have been brought up to a really high figure. The estimated speed of my engine is not far short of 7,500 r.p.m. on load at present. A choke of 5/16in. diameter was used initially, and passed all the mixture the engine could deal with then. In my opinion this diameter is adequate until engine speeds of more than 4,000 r.p.m. are obtainable on load. Where smaller capacity engines are concerned, the cross-sectional areas should be reduced pro rata. None of the dimensions given here are rigidly fixed, but some are interdependent, and the best results are generally obtained by trial and error. The figures mentioned are quoted to give some idea of the proportions which have proved satisfactory. The drawing of this carburettor shows the attachment of the “ banjo” fitting of the float chamber. The screw over the primary choke closes a hole which is very useful for inspecting the setting of the jet in the primary choke when assembling, and the screw-end is faired off to the shape of the main choke. Originally, I used fibre washers above and below the “ banjo,” but, owing to the fibre shrinking during dry weather I had a good run spoiled at Farnborough M.P.B.A. regatta last year, when the assembly came loose and the engine stopped through all the mixture adjustments becoming upset. It is better to use metal-to-metal joints at these points, and grind the faces together with fine valvegrinding paste, finishing off with metal polish. LZ Ae R Fig. 3—Alternative Methods of Throttle Control. 62 MARINE Fig. 4—Rotating Barrel Throttle I have never attempted making floats, but always use the smallest “ Amal” pattern designed for bottom feeds—this costs 2/6. The matching needle is type 22/013, and costs lld. If you make your own float needles, keep the included angle of the valve head not greater than 30°—this will help to minimise flooding. The float mentioned has a diameter of I+in., and just fits nicely in a float chamber of 13in. diameter and 1in. high. Fig. 2 shows alternative types of spraying jet and primary choke, which will probably show interesting results. At A, the parallel arrangement overcomes the snag of primary choke area variation, which can occur when the fibre washers, if used to make the float chamber “ banjo” joint, alter their thickness with changes of temperature and moisture. At B is shown an arrangement which is used in the Bowden carburettor, and in this case the actual spraying orifice projects about 40 per cent. of the diameter into the main choke tube. Alternative methods of throttle control are shown in Figs. 3 and 4, neither of which uses an air shutter, but increase suction on the jet for starting by restricting the main choke area right over the primary choke. Both “a =o Fig. 5—Commonly known as the *‘ Rat Trap ”’ MODELS these types use the same form of jet and primary choke, as shown in Fig. 1. The rotating barrel throttle in Fig. 4 has a slot in the barrel at the delivery side, to allow the primary choke to enter the main choke. The type in Fig. 3 could also be adapted to usea variable tapered jet needle attached to the slide (C). In both these types extremely careful fitting of the moving parts is necessary to avoid air leaks, the slightest trace of which can upset the mixture completely. A further type (Fig. 5), which was very popular on sports motor cycle engines several years ago, was produced by the Binks Company, and was popularly known as the “ Rat Trap.” This pattern presents a most in- \ TNS ESN IN MWA an KN N Fig. 6—With Annular Spraying Device teresting type for experiment, for it enables an infinitely variable main choke size to be obtained at will, without introducing eddies from breaks in the smooth surface, and the maximum choke size may be increased simply by adjusting the limiting stop screw. The same feature of guarding against air leaks applies to this pattern, and the hinge is likely to be rather a teaser in making air-tight. Possibly a covering of oily felt or adhesive tape might help in this direction. Incidentally, the main choke is rectangular in cross-section, but this does not appear to be detrimental to the performance. The chief claim for it was the terrific acceleration obtainable by its use, and an interesting experiment would be to try one of this type on a hydroplane engine, with the throttle shutter operated by a delayed action dashpot. Still another type (Fig. 6) employs an annular spraying device. This has a very narrow slit, about .010in. wide, surrounding the choke throat, fed by a circular duct, which (Concluded on page 63.) MARINE MORE ABOUT MODELS BALANCED 63 BUOYANCY _ By YARDSTICK S INCE the appearance of my article on this subject last month, I have received a number of enquiries, both verbal and by letter, about this system of checking the balance of a yacht’s hull, so will endeavour to amplify my original article in order to clear up any misunderstandings. Now as to the whys and wherefores of the whole thing. Let us consider a single section in the after-part of a yacht’s hull. When upright, the C.B. is on the centreline, but as she heels the C.B. moves out to leeward. Suppose it moves a matter of 2in. The effect of the C.B. moving to leeward is to introduce a tendency for the section to move up to windward until the heeled C.B. has taken the position occupied originally by the upright C.B. (i.e., where the centreline is). As the movement is 2in., the heeled C.B. wants to move 2in. up to windward. The force with which it pushes up to windward cannot be calculated unless one also takes the heeled section area into account, so moments must be taken. If the area is 8 sq. in., then the slewing moment exercised by the section is 8 x 2=16. As this is an after-section and exercises a tendency to push the stern up to windward, this the C.B. Let us suppose this is |lin. Then our bolting moment of 16 is multiplied by 11, giving us the figure 167, representing the slewing tendency of the section in question. Every section is similarly treated, but while all the sections aft of the C.B. will have bolting moments, those forward of it will have griping moments. If the bolting moments and griping moments are equal, then they will balance each other, and have no tendency to slew the yacht, and, in consequence, her resolved axis of forward motion will remain parallel with the centreline. An alternative method which many will prefer to taking moments about the C.B. is to plot the slewing tendencies of the sections (using these as ordinates) with the centreline as base. The resulting figure is cut out and balanced on a pinpoint, as I mentioned in my previous article. Quite candidly, while I am certain that the basic idea of this system is correct and that one must take into account heeled section areas, distance of movement of C.B. and the distance section is forward or abaft C.B., my only doubt is whether the method of finding the fore-and-aft position of centre of slewing Next let us consider the effect of the bolting moment of this after-section in relation to the yacht as a whole. The pivotal point of the yacht is its C.B., and the yacht will turn about the fore-and-aft position of this. Now in considering the effect of this bolting moment, we have also to take into account the distance the section is abaft the yacht’s upright C.B., so moments are again taken, the individual section’s bolting moment being multiplied by the distance the section is abaft moment is correct. A horrid alternative, suggested by a reader, is that the area of each section should be multiplied by the square root of the sum of the square of the distance its C.B. has moved and the square of the distance it is forward or aft of the upright C.B. This would be fine for those who love figures for their own sake, but not so good for ordinary mortals! Anyhow, I have tried the simple way on a number of boats and results seem to tally with their known performances. By the way, the SOMETHING ABOUT CARBURET- have given quite good results in the past; can be considered as a is ead moment. TORS FOR MODEL SPEEDBOATS (Concluded from page 61.) draws mixture from the primary choke; a variation has a number of small holes instead of the slit, and one way of producing a large number of spraying points is to knurl the face of the inserted sleeve. An air shutter is used on this pattern, and the shutter can be arranged to retain the sleeve in place. All the types described are practical, and any one is well worth trying out and ex- perimenting with. Space restriction does not allow dealing with the large number of other types of car- burettor, including multi-jet, jetless and the S.U., which is self-regulating, controlled by inlet pipe suction. Please don’t rate me as a carburettor expert; I have only acquired a certain amount of practical knowledge through experience and experiment. ———— a 64 MARINE point of comparison is always the upright C.B. It should be added that the movement of the C.B. to leeward which I call the “ slewing arm ” of each section is not the same thing as is known as the “ righting arm”’ in stability calculations. Several correspondents point out that this system has much in common with others— notably the Volumetric and M/C Shelf Systems. As regards the first, the Volumetric System of balancing the upright and heeled Centres of Buoyancy, including a comparison of the two Curves of Areas, is by far the most satisfactory way of ensuring that a vessel neither stoops nor squats when heeled. As a.matter of fact, Goll anietsic Balance is em- bodied in all systems, Shelf method. including the M/C I pointed out in my previous article that the resolved longitudinal axis of a vessel must remain parallel with the original centreline at all angles of heel. There are two planes in which it must maintain this condition—the vertical and the horizontal—if no steering effects are to be introduced to divert the hull from its course. The Volumetric Balance takes care of the former but does not touch the latter. Since both this and the M/C Shelf System aim at revealing any lack of balance that will cause a boat’s axis to go out of parallel in a horizontal plane with the vessel’s original axis, it is not surprising that they have certain points in common. I may mention that I hit upon the present idea by accident when making some quite different investigations which, though they proved abortive in one respect, provided me with the present scheme. Many hold that absolutely ideal balance can only be obtained in an exact double-ender, where the stern is a duplicate of the bow. Let us imagine that we have designed a bow, and have nothing aft of the C.B. We can easily find the volume of the forward half and also the slewing tendency it will exert. Now, in order to get an equal volume and slewing tendency, it is not necessary for our stern to be an exact duplicate of the bow as the given volume can be arranged in an almost unlimited number of ways to produce the desired result. Nevertheless, there are other considerations to be taken into account which will mould our stern so that it matches the bow as well as balances, and our sections must maintain the character of the boat throughout its entire length. It will, therefore, be seen that a boat MODELS with an ordinary counter-stern can balance perfectly, though, of course, the two overhangs must match each other, and harmonise. Similarly, though I have not tried this system, yet on a square-sterned boat, I do not see any reason why a perfect balance cannot be obtained. I will admit, however, that under most systems of balance, including the present, the double-ender is the easiest method of drawing a balanced boat. Moreover, carefully designed, I see nothing to cavil at in this type, but, of course, | do not mean a boat whose stern is an exact duplicate of the bow. Bow and stern must each be designed for their own proper functions in relation to each other. Another correspondent enquires why the keel must be included in these calculations, and contends that as the keel is a constant factor in the hull, whether heeled or upright, it need not be taken into account. This is incorrect, since though the keel is there, whether the vessel is heeled or upright, it nevertheless alters its position in relation to the centreline, according to the angle of heel, and will thus make a considerable difference. There may be purists who cavil at my suggestion of tolerances, but, however obtained, even sectional areas contain a margin of error. As I stated, I am not at all certain what margin of tolerance is permissible, but I am hoping that readers will try the system over a number of designs of various types and help to determine this question. In doing so, they must remember that all yacht design is a matter of compromise. Nevertheless, for full-sized yacht or model, balance is most important. As far as models are concerned, balance is more important than speed, since a yacht that will not hold her course can never win, however fast she may be. On the other hand, even a slow, steady plodder, that will keep going on her course, is likely to pick up quite a few points. The ideal is, of course, to design a boat that has both. WANTED 36 in. in exchange 10-rater Phoenix design; cash difference Box No. G.666, ‘‘ Marine Models,” 52, Fetter Lane, London, E.C.4 _——— MARINE MODELS 65 “PICKED UP A TIDDLER!” By D. A. MACDONALD WONDER if the average model-yachtsman | ever pauses to consider his club’s sailing water otherwise than as a course to be sailed, or the other occupants of the water as anything but obstructions, inside or outside the meaning of the word as defined in the sailing rules. When his 10-rater picks up a small boat when half-way to winning a board, do his thoughts turn to the three points lost, to the possible damage to his paintwork, or to the small craft which has unwittingly thwarted his immediate intentions. Most probably to the first; in some cases, as In my own, to the second; but in how many cases to the third? Very rarely, I should think; and that is why I have written this small article, which might be termed the “ Saga of the Toy Boat.” We can make it a little bit of true history, if you like, by recounting the adventures of a fellow clubman who became involved, unwittingly, we believe, in the manufacture of these toy boats. We didn’t quite know how to take the news of our friend’s incursion into Big Business—** MassProduced Model Yachting,” as it were. We thought at first he was in a fair way to becoming Public Nuisance No. 1, by crowding our water with numerous identical small ‘obstructions ” to the detriment of our organised racing. But a happier aspect of the situation was revealed when someone suggested that the influence of a keen modelyachtsman on the toy boat industry would have the effect of so far improving the design and construction of the small “ Tiddlers,” that they would stimulate keen sailing among the youngsters and so provide in future years an influx of keener and more proficient members to the great benefit of our club and of the sport generally. We therefore awaited developments with some hopeful interest. Well, our friend seems to have lost no time in explaining to the directors of Blitz Bros. just where their toy yachts went wrong. It was rather difficult to convince them, we fear, as their sales of the little blue and red atrocities were definitely on the up-grade, their 5s. effort being quite half an inch longer than the best that their rivals, Schmitz & Co., could do for the price. But our friend is nothing if not tenacious, and he soon succeeded in arousing their interest in some boats he had built to reasonable lines. He finally persuaded the greybeard directors to witness a demonstration. Victory was, we thought, in sight, and one fine day a car driven by our friend arrived at: the pondside, loaded with toy boats (very small), and greybeard directors (very large), all of which it disgorged at the water’s edge. Following our friend’s example, each greybeard seized a toy boat; again following his example, all looked heavenwards and sniffed the wind; and again meekly following his example, each freed off the cord sheets of his little boat to a fair sailing angle. The whole performance, we are told, had a delightful ‘* Chorus ” effect, which would have delighted the heart of the great Ziegfeld himself. Then the sailing commenced. Board after board, greybeard against greybeard, with our friend as instructor, O.0.D., umpire, scorer and all. Small boats flitted to and fro across the pond in the fresh breeze—sometimes in the right direction, sometimes not—and the expressions on the faces of the ancients softened; one almost smiled—later, one gave vent to a queer little cackle. The old boy who admitted aloud that he was enjoying it, has since, we hear, been asked to resign. As each craft returned to its owner, he gravely picked it up, shook it close to his ear, satisfied himself there was no water in her, and returned her again to the pond. Finally, they were all gathered in, and returned to the car. The greybeards were hoisted aboard, and away they went. A great day, we all thought—a great and historic day for the sport, and a great moral triumph for our friend. He told us afterwards that the new models of “ Blitz Bros.’ Boats for Bright British Boys” would be something worth buying—boats which their small owners could sail, and race, and be proud to own. They seemed quite nice little boats, too, complete with everything necessary for ordinary sailing, and we at once decided that their success was assured. But we had reckoned without Messrs, Schmitz & Co. Their answer to the Blitz challenge was to produce toy boats of unparalleled size and of hitherto unsurpassed ugliness and general uselessness at a price which made the greybeard directors of Blitz (Concluded at foot of page 66.) 66 MARINE THE TWO BRIGS: MODELS “HOPE” AND “MARY” By G. W. Munro (Continued from page 37.) si: month we continue by starting on the inside work generally. At first glance it would seem that this is of very little interest to the model enthusiast, but nearly all the inside scantlings have some influence on the outside details. To take only one case, the keelson determines the amount of mast housing to be subtracted from the length of the mast to give that above deck. The keelson is to be of oak and in two heights, the lower piece to be 13in. sided and deep. The upper piece is to be 124in. sided, and 13in. deep. The keelsons are to be of sufficient length to bolt both to the stem and heel knee, and all the scarphs of the keelsons to be 6ft. 6in. long. The scarphs of the lower pieces are to be properly secured before the upper pieces are laid on. In these brigs, one of the uppermost pieces of the keelson must be of sufficient length, and so placed as to extend under the foot of both the fore and main masts; likewise all the scarphs must be placed clear of the keel scarphs and the scarphs of each other. The lower pieces to keelsons, every other floor and keel with 14in. copper bolts. The ceiling is to be all oak; to have one strake next to the limbers 3in. thick. This strake to be bolted down to every floor with 3in. bolts. The vessels to have four strakes —each llin. broad by 4in. thick. On each bilge are to be two strakes running from stem to stern. There are to be two strakes of thick stuff at the first futtock heads; the strake right on the joint is to be 10in. in breadth and 4in. thick, and the strake above or below is to be 34in. thick. There is to be one strake running from stem to stern. The other may be reduced in thickness to that of the ceiling plank at a distance of 6ft. from the stem and stern. All these strakes are to be bolted with 3in. bolts every two feet throughout the whole length. The ceiling from the last mentioned thick stuff to the clamps for the ’tween deck beams is to be 24in. thick. The clamps for the ‘tween deck beams are to be in one strake, llin. broad by 4in. thick. They are e be hook-scarphed with the scarphs 4ft. 6in. ong. be stopped down to the floors with a few small bolts, until the upper pieces are fitted; and the whole is to be bolted through both The clamps for the hold beams are to have their scarphs bolted edgeways with three 3in. bolts, and the clamps to be bolted to every “PICKED UP A TIDDLER!” with some 10 or 12 monstrosities, brightly painted and gay with coloured sails stamped in large print ‘Guaranteed to Sail.” He seized a few of the boats, read aloud the inscription, and with the words “ All right, then, go ahead and sail, you ugly little blighters,” he threw the lot in the pond, climbed aboard his car and drove away in disgust. We don’t think any of the fleet have come ashore yet; if not, there will be a few more “ obstructions” to argue about when our next race is held. (Concluded from page 64.) Bros. fairly gasp. Soon, the market was; to put it mildly, “ collared,” and the little Blitz boats lay forlorn on dealers’ shelves, unsaleable, while more and more “obstructions” of the most “ obstructive’ variety made their appearance on the pond. Things looked very black. Still more so when our friend told us his directors had decided that another design had to be produced, something so big and ugly as to outdo the Schmitz effort. Immaterial whether it would sail or not: it just had to be big or it wouldn’t sell. To say our friend was (and we were) disgusted, was no more than the truth; it was also true to say he was somewhat disillusioned. Ideals are fine things, especially in amateur modelyachting, but in big business they too often have to go by the board. We saw the latest Blitz boats when they came out for trial. Our friend drove up On the whole, then, I fear that my sympathy for the small toy boat was rather misplaced; it is generally little more than an obstruction, giving little pleasure to its youthful owner, who soon tires of its erratic sailing, and is not likely to be encouraged ‘by it to aspire to model yacht racing proper. It succeeds only in giving annoyance to the racing model-yachtsman whose sailing so often suffers by its presence on the pond. | : MARINE timber with 3in. bolts. There are to be six breast hooks in all; the upper one to be 14ft.; the one under the main deck to be the same length. The former is to be Qin. sided and 10in. moulded. The latter is to be 12in. sided and 13in. moulded. All the other hooks to be 14ft. long, 1 lin. sided and 12in. moulded and fastened with eight jin. bolts. And each to have one bolt in the throat to go through and be clenched on the stem. The throat bolt, and one in each arm of the main deck hook, to pass through the length direction of a carling, and be clenched on the aftermost side of the fore-beam. The hooks below the main wales are to be bolted with copper bolts, in diameter as stated above. The principal hold or ‘tween deck beams are to be of oak, and in number as per plans, with one or two more, if found necessary. The largest, seven in number, are to be 1lin. square in the middle, and moulded at the ends to 7%in. The others to be diminished in scantling, in proportion to their length and situation. All the hold beams to be double kneed as far as can be managed; the midship knees to be 7in. sided, and moulded on the arms not less than 8in., and to be bolted through every timber with {in. bolts, three bolts to be in each beam arm, 3in. diameter. The lower deck planks are to be 24in. thick and double nailed. There are to be two strong carlings on each side of the ‘tween deck main hatch, 7in. sided and 7in. moulded. These are to be secured to the side and partners of the hatch with iron knees at each end. The clamps for the upper deck beams are to be of the same size, and worked in the same manner as those for the hold beams. The main deck beams are to be of English oak, six in number, and situated as shown on the plans. There are to be six midship beams, 94in. sided, and 9in. moulded at the middle. The others are to diminish in proportion to their length and situation, and the whole are to be double kneed as far as can be managed. The midship knees are to be 6in. sided, and bolted through every timber in the side with 3in. diameter bolts. There are to be three bolts in each beam arm. The whole deck frame is to be completely warped with ledges and carlings, and not more than 2ft. apart; the carlings are to be Sin. sided, and moulded. The ledges are to be 34in. square. The mast partners of the main and fore masts are to be 10in. broad and 8in. deep. The stepping pieces for the capstan are to be MODELS 67 114in. sided. Their depth is to be the same as the beams to which they are fixed; the ends to be let lin. into the beams, and fastened with two angular bolts through the beam at each end. The main deck plank is to be 3in. Danzig or Memel fir, and not to be more than Qin, in breadth, nor under 61n.; and all to be double nailed. The hatch coamings for the main hatch are to be Qin. in height above the deck at the side, and 6in. thick. All the other coamings in depth and thickness as may be required for the intended trade. All the coamings to be of English oak, and to be let down to the beams; the side carlings of the hatches to be properly checked into each other, and fastened down with in. bolts. The waterways are to be 9in. broad by 5in. thick English oak. There is to be an oak plank, two strakes, inside the waterways on each side, 8in. broad by 3in. thick. These strakes of plank are to be fixed down to the beams with two 3in. copper bolts in each strake and beam. The waterways are to be fastened down in the same manner. These strakes and the waterway to be bolted with #in. bolts through every other timber to the side, where it can be done. The said water- ways are to go all round the vessel, both bow and stern. The iron hanging and staple standard knees are to have iron hanging keys, 16 in number, for the hold beams. The iron hanging knees are to be 4ft. on the side arm, 3ft. 6in. on the beam arm, and 34in. in breadth, and 3in. thick at the throat, and 3in. at the points. There are to be four bolts in the side arm— the two uppermost being lin. in diameter. There are to be three bolts in the beam arm —the two next the throat being lin. in diameter. The diameter of the bolts at the ends is to be 3in. The staple standard iron knees are to be eight in number with 3ft. 6in. beam arms, 3in. thick at the throat, 3in. at the points, and 34in. broad. These knees to be bolted with the same size of iron, and same proportional number of bolts as the hanging keys mentioned above. The other oak plank is the main deck. The vessels are to have an oak plank on each side of the main hatchway, for fixing ring bolts, etc. These planks should be 34in. thick. There are also to be proper oak chocks and oak plank for fixing the windlass and the winch. We shall now deal with particulars of the 68 MARINE main deck. The pawl bitt is to be made from good oak, 112in. sided, and 123in. moulded. The windlass is to be 16in, diameter, and of oak, and have 5Zin. sided and 16in. broad windlass bitts. The spindles are to be 3in. diameter in the round. The windlass is to be fitted with patent cast-iron wheel and pawls, with cross-rail and belfry. The winch bitts are to be 5in. sided. The catheads are to be of sufficient length and strength, as shown on the plans. The capstan, of sufficient size, must be fitted with all necessary parts. The stanchions for the main rail are to be 6in. in breadth at the gunwale, and 54in. at the rail. They are to be 4in. thick at the gunwale, and 3in. at the rail. The stanchions, where intended to serve as timber heads, are to be as large as necessary. The main covering board is to be of English oak 4in. thick, and bolted down to the waterways and plank sheer with Zin. iron bolts, clenched, and to have a bolt 3in. diameter, passing through every timber head and stanchion. The main rail is to be of American elm, 84in. broad and 44in. thick, and have mouldings on both edges. The taffrail is to be of oak, 12in. in breadth at the middle, 10in. at the side rail, and to be 34in. thick throughout. As it will be difficult to procure plank of the breadth specified above, a piece of a proportional size may be bolted on the after edge to make up the round of the rails according to the round aft of the stern. The height of all the rails to be the same as represented on the plan. All the taffrails are to be kneed to the side-rails. The vessel must be completed with channel wales and chain work, with all other eyebolts, plate-rings, and ironwork of every description that is attached to the hull of the vessels, and which is connected with the carpentry work necessary for the completion of the vessels, whether herein mentioned or not. The rudder is to be made after the most approved manner, copper bolted, and fitted with copper on composition rudder bands of the best quality. There are to be three bands below the counter. The diameter of the lower pintle is to be 23in.; that of the second pintle, 24in.; that of the third pintle, 23in. The cabin and fo’c’sle deck is to be of 2in. American yellow pine. The cabin deck is to extend from the seat of the transoms to the main bulkhead. The fo’c’sle deck and steerage deck is to extend from the stem to the MODELS hold bulkhead. The coamings for the cabin skylights are to be either elliptical, circular, or square, as required. The main channels are to be of oak, 15ft. long, 34in. thick at the inner edge, and 24in. at the outer edge. The breadth is to be lft. 4in., or broader, if required to clear the shrouds from the rails. They are to be bolted down with six Zin. diameter bolts. The fore channels are to be the same size and specification as given for the main. All channels are to be supported with three iron knees or straps with sufficient bolts in each. The projection of the cutwater from the underside of the bowsprit, at the front of the main stem, to the shoulders of the figure, is to be carried out as per plan. The rails of the head are to be of oak, as also the knees and timbers; to be moulded, and neatly finished with carved work. The lead for the fore part of the cutwater is to be 10 lb. per square foot. (To be concluded.) CORRESPONDENCE THE FLAW IN THE A-CLASS RULE Sir,—The correspondence resulting from the publication of my paper ‘* Twenty-foot Sloop Rates as International A-class Model,’’ has been quite interesting. C. O. Brook went so far as to challenge me to a race with one of the Behemoths. I accepted Mr. Brook’s challenge with pleasure, but not with a Behemoth. I do not intend to build one of the big boats to the ** flaw in the A-class rule ’’ for obvious reasons. Such a boat would be too large for convenient portability, and it would so hopelessly outclass other A-class models as to remove the zest from competition. My purpose in *‘-delving for flaws ’ in the rule was at first the same as that of any other designer: ? to produce the largest and fastest boat possible in the class. The flaw was discovered by accident. Since it would be poor sportsmanship to build such a model, it was deemed advisable to expose the flaw, not to encourage building to it, but to effect a strengthening of the rule through the action of the authorities governing the A-class formule. In accepting C. O. Brook’s challenge, I assumed the privilege of naming the weapons and the field. I wagered the finest lobster dinner in San Francisco that my Marblehead ‘* Bobby ’’ made a better showing in the national championship at Berkeley, California, than his boat. M. A. C.’s poem gave me much laughter. It would please him to know that, properly rigged, the “Queen Mary ”’ would really rate as an A-class. Mr. Pike, Col. Holden and *‘Amateur’’ made a careful analysis of the paper, and I appreciate their intelligent criticism of it. Col. Holden’s suggestion for stopping the leak in the rule is quite logical and would adequately handle the situation. Yours, T. W. Houk. 8053, Bothell Way, Seattle, Wash. MARINE MODELS 69 SPECULATION ABOUT SAIL PLANS By AN AMATEUR DESIGNER Be ye is no doubt that during recent years great advances have been made sheet lets the top of the sail off far more than is intended. Battens present another problem. Was the batten originally introduced to obviate an ugly hollow leach? or to get unmeasured sail area? or because a battened sail is more efficient? in the design of sail plans, but has finality been reached? Years ago we had low-peaked gaff sails. Then, gradually it was found that the highpeaked gunter was more efficient, and from that we graduated to the Bermuda. The first Bermudan sails were low in aspect ratio (ratio of height to breadth), and a sail with a 2 to | ratio was daringly high, but by degrees one learnt the truth of the old saying : ‘An inch in the luff is worth two in the leach.” Sails became higher and narrower, to an extent that appeared ridiculous in the eyes of old hands. With the great increase of height all sorts of problems as to staying of masts had to be faced. Aeroplane wind tunnel experiments proved that an aspect ratio of 9 to | was probably the most efficient for windward work theoretically, while down wind | to | was best. It_ therefore became obvious that the most suitable aspect ratio for all-round purposes was presumably about half-way between, say, The Chinese junk with a sort of battened lug is a highly efficient craft to windward, but her battens go right across the sail, which has a very heavy roach. Our battens are limited in length to prevent too much unmeasured sail area being obtained by their use. If we had a sail area measurement in any class that measured any outward bow and had no batten limits, we might have a chance to learn something about this part of the subject. Fore triangle measurement again forces us to use our sail area ahead of the mast in a certain way. The old theory was that a good gap between the headsail and mainsail prevented the former backwinding the latter. Then we learnt that an overlap increased efficiency. Did it, or was it simply that under modern rules that way we got ‘owt for 5 to l. But 5 to | is a terribly tall, narrow sail, and the higher and narrower a sail is, the more difficult it becomes to set properly. A sail nowt.” The old-fashioned, long-based jib on a long bowsprit certainly pulled like steam, and many of the old deep, narrow-bodied boats pointed very high indeed. Possibly these huge jibs only pulled as they did on account of their area, but they seemed to be full when modern types of flattish jibs were too close for effectiveness. The old-type sailor used to insist that the jib must be a lifting sail, but our high, narrow jibs, hard-sheeted, are the is not a rigid aerofoil like an a — SAILS— <> CHAS. DROWN & SON Model Yacht Sail Makers A World-wide Reputation for nearly a Quarter of a Century 8, ULLSWATER RD., WEST NORWOOD, LONDON, S.E.27 When replying to Advertisers please mention MARINE MODELS.