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SEPTEMBER 1969 TWO SHILLINGS AND SIXPENCE ” U.S.A. & CANADA [uis> HOBBY MAGAZINE MUU MODEL BOATS Sail Efficiency NEW RIG 64″ Some experiments discussed by R.R. Cole displacement. The +J in sail area calculations in the A-class rule. We are also allowed a larger spinnaker for better downwind performance. More of this later. Having begun model yacht racing in 1962 at the age of 15, I only had the experience of two and a half seasons before I left my boat behind and moved away start my college career. It was at college, start my interest in sail efficiency as, although I had also had some dinghy racing experience, whatever class boats we raced in, Stewart could always seem to get that little fraction more speed out of his boat! This was really illustrated at a sailing camp that we attended in the summer of 1968 at Chichester, Sussex. Here, we had several Graduate class racing dinghies at our disposal, and some half dozen or so of us used to hold single-handed races. No matter how we swapped and changed boats, the finishing order seldom deviated from Keech-first, Cole-second, and then the rest. My own relative success was largely due to the fact that having had more racing experience than most of the others, I could usually Dambuster areas and displacements of the two boats in purely maximum power from any given number of square to however, that I met Stewart Keech, a young and successful dinghy helmsman. This friendship was to drawings by Roger Stollery show a boat of 56 in. W.L. displacing only 52 Ib., slightly less than the minimum in the rule. She thus accepts a small displacement penalty and ends up with a rather small sail area of 1,400 sq. in. This is some 57 sq. in. less than the Lewis monster, but if we compare the sail mechanical terms as a power/weight ratio, we find that Kubernetes has 144 sq. in. of sail to drive each pound of her displacement through the water, whereas Dambuster has 26} sq. in. per pound. Other designs have gone even further in this direction. Chris Dicks’ boat Projectile is only about 46 lb. These boats have shown that small sail areas can successfully be made to drive light boats in light weather, Dambuster notching 2nd place in the 1968 Nationals, in light to moderate weather under Roger Stollery’s excellent handling. The trend both ways, then, seems to indicate a reduction in sail area. My good friend Fred Shepherd, so successful with Marbleheads and 10-raters, has drawn out an ‘A’ boat with only about 1,200 sq. in.! Other dimensions I must keep quiet about, but suffice it to say that she is very unconventional. With this reduction of sail, the need to obtain the aes inches becomes more and more urgent. Very little work seems to have been done on ‘A’ class sails since Admiral Turner pioneered the present larger type of jib, bringing the J measurement up to about seveneighths of the B measurement. This gives the average ‘A’ with, say, 1,570 sq. in. sail area, and sails of the following dimensions: Main Luff (A) … 80in. Foot(B) … 24 in. Jib Foretriangle height (I) … 64 in. Foot (J)… 22in. By increasing the size of the foretriangle, we gain more free area because of the 15 per cent that is always subtracted from the total of I multiplied by I feel that, good as some of these designs may be, they cannot yet fully overcome the penalty of the reduced sail areas they have to accept within the rule. Most of these designs tend to push the overall size and displacement up from the average, and the sail area, in order to comply with the rating formulae, has to be reduced quite substantially. Lewis has done this with his Moby Dick and Kubernetes designs. These boats have tremendous potential in winds of about 8 knots and upwards, but with present-day sailplans, 1,457 sq. in. of sail is not really sufficient to drive a boat of nearly 80 Ib. displacement in any calmer conditions. (1,457 sq. in. is the sail area of the Kubernetes design.) Some designers have favoured the opposite apreducing TT neti somehow, from the sails of these models, very little improvement in their performance can take place. With the present, almost universal use of the conventional sailplan within this class, we are still seeing boats to twelve-year-old designs at the top of the lists. It is true that several new designs have appeared over the last few years with several attempts to break out of the ‘dimensional rut’, as John Lewis calls it, of the 52-62 lb., 54-56 in. W.L. yacht. of . RIG eo (VER the last few years, it has become very clear to many people who sail International ‘A’ class yachts that unless more power can be obtained proach OLD out-manoeuvre them, but Stewart simply went through the water faster. This led to lengthy discussions about sails and sail power. Stewart’s own boat (he had at the time, an Enterprise), had a very comprehensive sail wardrobe and he is also a great believer in bendy rigs, so, without delay, he began to design a great number of weird and wonderful rigs for my ‘A’ Scheherazade II. Some of these were hastily made up and the boat taken to Chichester. The rigs involving a bendy mast (a converted fibreglass fishing rod) were soon abandoned. Even if a wholly satisfactory mast could be made up (the fibreglass was really too heavy), it was difficult in the extreme to get the boat to point very high to windward unless the mainsail was fully battened, and this is not allowed in the ‘A’ class. Her speed at all times was impressive and her performance on a reach was 378 SEPTEMBER 1969 phenomenal. All the usual tendencies to luff in gusts J. were completely overcome but, without the ability to point, her fate in the type of race one more than 15 per cent foretriangle Ans. 1S. per; cent -foretriangle (free Downwind, with her massive balloon spinnaker, she was faster under all conditions. Things looked good. The championship arrived and brought a whole week of fickle, light to moderate, reaching winds. Under these conditions the biggest basic fault of the new rig was revealed. Off the wind a spinnaker is essential. When reaching with these boats, it is impractical to carry a spinnaker as one would on a full-size yacht or dinghy, and the ordinary sailplan, in this case designed specificaily for beating to windward, has to be used. Scheherazade II’s giant jib had to be eased a long way out to prevent it pulling her bow off the wind, and so was not driving the boat much at all, and her mainsail, being so small, could not alone give her much speed. When the wind crept round on a couple of occasions to give a long, closehauled plug through the lake, she showed much promise, beating several high placed boats, including Dambuster, from the leeward berth. Her very low decided to make a start with an all-rigid rig, but with the J increased to about 14 times B. Now Scheherazade II carries 1,565.5 sq. in. of sail and her old rig had the following dimensions: A… 804 in. Brest 4 24am: By aah 64> an. 22in. 22 area) equals 1274 sq. in. By doing this, over 20 sq. in. of free sail area were gained. It is amazing how valuable 20 in. can be when one is having to cut down one’s sail! The only question was, would this sail plan work? She was tuned up in June and July, ready for the championship. Throughout this tuning she was sailed in beat and run conditions, and proved quite satisfactory. To windward she seemed a fraction faster in light weather than she was in her conventional sails, and was certainly no worse in a blow. often has to compete in, with 3 points for a beat to weather, would have been sealed. Her speed had been so good, however (it was often impossible to keep pace with her in the canoes we were using as chase boats), that it was decided to modify the ‘all-bend’ rig to a ‘booms-only-bend’ one. The mast was replaced with a rigid alloy version, but the bendy booms remained. At last! Speed and the ability to point reasonably high. Not as high as a well-tuned conventionally rigged boat, but the extra speed gained seemed to overcome any small disadvantages. Scheherazade II was raced three times with this rig at Gosport, and gained two firsts and a second. She was then taken home for a refit, while I concerned myself with designing and building a new boat. So to the Easter of 1968, when my college career ended and I was again able to devote a reasonable amount of time to model yacht racing. I mentioned earlier, Admiral Turner’s enlargement of the foretriangle to increase the free area gained by the method of sail measurement in this class. The next experiment called for was a continuation of this line of thought. How far can one go? At present, most “A’ boats are carrying rigs where the J measurement is about seven-eighths of the B measurement. It was J… ue, place in this championship indicates that the sails she was carrying had no suitability for the prevailing conditions, but it is intended to persevere with this sail arrangement during the course of this season. The main reason for this is the improvement of her running. Having a 27 in. J, her spinnaker is 5 ft. wide! Various small improvements have been introduced over the past few years, such as double luff sails. These do, probably, add to the efficiency of sails, but their advantages are slight. I believe that it is a more dramatic change in sail design which will give us the power we are looking for. I hope we find it! (free area) equals 127} sq. in. This rig was changed to: 80+ in. Acs’ Bosse Qtr, Dteye HOSA: M.S. PRIAM A 42 in Blue Funnel cargo liner built by W. L. Maxwell I HAD been seeking a plan of a ship for some time. I wanted something that had an attractive appear- ance but was basically simple in design, so that a model could be built which looked like a ship but without any fiddly detail. This was due to the fact that all my previous models had been highly detailed and were always damaged during operation. On receiving the January 1968 copy of Model Boats I was very attracted by the simplified plan produced by R. Carpenter in his series of Simplified Merchantmen. I decided to build the ship of length 42 in. so as to be fairly seaworthy and, at the same time, not too difficult to transport. Obviously the plan provided was unsuitable for building a ship model of this size. As a result a search was conducted through the merchant marine periodicals and a detailed plan of M.S. Priam found in one of them. This was used to give detailed information of the structure of the ship. The model was built using ply to give a strong but light hull. The keel and fifteen bulkheads were drawn onto 3/16 in. ply and cut out. The position of the stringers were marked and cut out. Stringers of 4 in. X 3/16 in. obechi were glued along the hull, glueing both sides of the hull at the same time so as not to distort it. The extreme ends of the hull were filled with roughly shaped balsa blocks. The framework was then diagonally planked with strips of 1/32 in. ply, narrow strips at the bow and stern with wider strips amidships. Two layers of planking were 379 SEPTEMBER 1969 NHE containerisation of deep sea cargoes is now well under way, and more and more services are being introduced as the months go by. Japanese and German shipyards have secured the lion’s share of contracts for these ships and it is now clear that there will be little variety of layout. Size varies considerably and in one class of ship the bridge is set well forward in the style of the Great Lakes cargo ships. Otherwise, engines and superstructures are either right aft or with one hold abaft the engine room. The Hakone Maru, the first Japanese cellular ship, is typical of several already in service or being built and is employed between Japan and the West Coast of the U.S.A. She has a service speed of about 22.5 knots, and carries a crew of 30, plus two apprentices. READERS WRITE The largest container ships carry well over 1,000 containers, the Endeavour Bay being one of the largest cargo ships ever built. The latest development is the proposal of an American line to build super container ships with a speed of 26 knots. These will be second generation ships and may well cause existing container ships to become obsolescent as soon as they enter service. model monohulls sailing, and for this reason they are not (to some) as pleasing in appearance as one would like. After all, ‘Beauty is in the eye of the beholder’. OFF-SHORE ir, As a raw novice to model boat racing but an aeromodeller of some twenty ears’ standing, may I give my uniased impression of my first attempt at competitive boating, and offer some constructive criticism of the Folkestone Off Shore Model Power Boat Race which may help to avoid such a wonderful event in the future being spoilt by ending in such a manner that the result was, for most competitors, an anticlimax. A draw being given for first place was, | feel, an error of judgment, with one finalist being given the opportunity to run, and retiring halfway round the course, the other being told that owing to the level of the water in the harbour being so low, he would be unable to attempt the course, as the chase boats had to be withdrawn from the water. It would seem that a much fairer result would have been arrived at if the judges had awarded first place to the boat with the fastest average time for all three runs. In addition it should be paintes out that had the starting rule een enforced and the racing on the Sunday commenced at the proper time, the final would have been completed in plenty of time. In conclusion, | would hasten to point out that these matters did little to mar our otherwise wonderful week-end’s hee se and in my view, the satisfac- tion of running a boat in this type of event far exceeds that which | have encountered in any other branch of our hobby. My thanks to Mr. D. Perry and his other hard working officials, the cheerful and alert chase boat drivers, and all others concerned in the organisation of this event, for without their efforts we modellers would have nothpi gripe about — Roll on Folkestone Walton-on-Thames. The deadweight tonnage is 16,306 tons, this being equivalent to 752 I.S.O. units, each 20 feet in length. The containers are stowed on deck as shown on the plans; in the hold there are 6 tiers in the main holds, the after hold and the forecastle loading varying between three and five tiers. R. W. Abbot NEW YACHT CLASS? ir, | read with interest Mr. G. S. Gould’s article on Chinook (June M.B.), as do all articles on sailing yachts. To answer your question, we are not members of secret societies, Mr. Gould, and | am glad that one of the persons whom you would term an expert has an article in the same issue as_ your Chinook. You say that rule bending is being introduced, but can you say exactly what it is you mean? The ‘M’ class is a restricted class of boat, so how can one boost performance by bending the rules? The formula is 50/800, as simple as that. The latest Marbleheads are probably length for length the most efficient : To be competitive in today’s racing, one has to have one of these machines, or get sadly left behind by the wayside, ya which no-one wants to keep oing. Pot hunting? one uses this Generally, expression, when it is some- a case of sour grapes, and the least said the better. The new class suggested in_ the article has some strange restrictions. Fully battened mainsail. Wooden construction only. The sail area mentioned hardly seems sufficient for a 54°’ LWL boat, when one considers an average Marblehead has at least this in its working rig of about 64” hoist. The Eastern District M.Y.A. put forward a proposal at the 1968 A.G.M. for a new class similar to Mr. Gould’s, but it hardly had a vote in its favour. At the moment, there does not seem to be the need for an additional class. Chiddingfold. F. Shepherd 30 v. 100 Dear Sir, Although | know that Philip Connolly is an expert modeller, | cannot agree with some of his remarks in his article in your June issue. | do not agree with a 100 watt class; in my opinion the 30 watt class is the one in which to start modellers off in R/C boats. The equipment needed is low in price, only small amounts of balsa are required, and even if the best accumulators (silver zinc) are bought, only a few are necessary. Rough water can be a problem with small boats, but the right hull design is the answer to this. For any country where materials are expensive, 30 watts is the class. | do agree, however, that 500 watts is only for modellers with a deep ocket, and | think this class should e reduced to an actual 250 or 300 watts. Yugoslavia. P. Burkeljc (Philip’s reference to 100 watts applied principally to Britain, but in most countries we believe that good results could be obtained cheaper with a 100 watt limit than with 30 watts. Radio small enough for a 30 watt model is one of the major stumbling blocks for beginners.—Ed.) oe WHEN YOU’RE THERE ir, With reference to ‘Improve Your Performance’ by Mr. Harris, in your June issue, | feel that dinghy sailors can offer some views on the subject of masts and rigging in models. Mr. Harris states that to accommodate the sail shape, the mast should only bend a little, otherwise the sail needs recutting. In dinghies, however, it is well 393 MO known that while a full sail is very good for reaching and running, it is desirable to flatten it for beating. Instead of having two different suits for beating and running, one suit will suffice, providing the mast and sail are made to work together. To do this, the amount of bend in the mast must be known beforehand, and the sail cut accordingly. Another point mentioned by Mr. Harris is that of rigging. He states that ‘if the mast is of adequate section, large amounts of rigging are not required’. Here again, dinghy sailors can offer something, for it is well known among sailors, International 14 ft. dinghy sailors particularly, that windage can be reduced by having a small sectioned mast with jumper struts and diamond stays. The windage removed by using a small section mast is more that that added by the extra rigging. The rigging also serves the purpose of adjusting the mast bend for different conditions — in relation to what | have said above. | would suggest that the rigging be as follows: —forestay and backstay, shrouds, just one each side; jumper struts at the hounds and diamond stays below. For further information Paul Elvstrom’s book on dinghy oe keelboat racing should prove useul. | hope that the above information is of some interest to model sailors and that performances may improve as a result. Reading. Sir, T. Lewis : | should like to comment on the article by M. J. Harris, ‘Improve Your Performance’, which appeared in the June issue of Mode/ Boats. It is devoted to model yachts of the racing type, and begins by saying that it is intended for the benefit of beginners who have been sailing for a season or so, and wish to do a little better now that they have gained some experience. As | am in just this position myself, | read the article with a great deal of interest, and must now tell you | am more mystified than ever. What is a Cunningham, Wilcock, Richey, Corbey, Jones, or Sykes type steering gear, and what is a Stollery, Shepherd, Sykes, etc., type boom please? Why should it be assumed that beginners with only a season’s experience should have ac- quired this knowledge? At least you could have added a note, recommending books which would explain these terms. Whilst writing, should | like to applaud Mr. C. S. Gould, when he says, in his article, Chinook, in the same issue, that one almost gets the impression that apart from your coverage of regattas, members of the sailing fraternity appear to belong to secret societies, especially when it comes to fittings and rigging. Kidderminster. J.C. R. Newman
