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JANUARY 1970 THREE SHILLINGS U.S.A. & CANADA SEVENTY CENTS JANUARY 1970 ing, therefore, we suggest that 60-65 watts for the Sea Wasp 12, and 55-60 watts for the Sea Wasp 6 would seem safe limits. For speed work, i.e., fairly short high power runs, the 12v. limit is 240 watts, and the 6yv. 120 watts (l6v. 15a. and 8v. 15a. respectively). a 100 90 IE go Different propellers would affect the water flow, EFFICIENCY| 10} * and the boat’s own motion through the water would : ie 995 7° certainly increase it. This is where practice must supplant calculation—water scoop drag could well be worth several watts, and a scoopless uncooled E08} 60 Sor] 4 |,° 50 despite a slightly lower input, in the marginal con- *%)2 : ditions for continuous running around 50 watts. An air fan mounted on the coupling could well be less 5.04 30 £03}, 99 even though its cooling would be at the opposite end to the hottest part, the brushes, it could still show a oe 10 ie Se ae Pim more valuable, as anyone who has touched a motor after a speed run will appreciate! : An obvious application for these motors is fast electric steering, where 80-100 watts seems the ideal sort of power input, and where electric boats can at least equal i.c. models. They are two or three ounces heavier than their nearest equivalent, but a very long 16} 1600 ¢ ial 1400 and trouble-free life can be expected. The very high 2 equivalent data on similar size motors, this will only = 10) 1009 interest, especially as we are promised an article on will be of interest and help to all users of electrics. Modellers wishing to purchase a Sea Wasp can get in touch direct with the makers, Kroker Engineering & Development Company, 10616 Moon Valley Ct. N.E., Albuquerque, New Mexico 87111, U.S.A. Readers course demands not only a superb boat/engine/operator combination but also a hull that is very stable when turning at speed and also when crossing its own wash. No doubt the present course is breeding hulls that are stable when turning at speed, and this is reflected in the greatly improved performance of some competitors in the last three years both at home and abroad. Perusal of the suggested new Naviga course brings one immediate point to light; how many clubs have a parallel bank 394 ft. to lay this new course beside? My guess is not many. It is also apparent that this new layout must become an even greater test of eyesight, as the turn buoys are farther away from the operator than the furthest buoy on the present course. No doubt the proposed course would be simple to lay, but so is the present one. A triangular bridle tethered at each CONT. DUTY — || — | Th An ae YE | 3 2 3 4 TORQUE ~ INCH – OUNCES 5 attractive wallet of wie i corner suspended to about the one nearest foot bank beneath and the worst conditions and usually takes far less time than this; also, regardless of water depth, it is accurate in length, the most essential factor in comparison of performance. Finally, why the need to convert to KPH or MPH, surely we are recording the times in seconds and parts thereof and | for one certainly know when my times are not fast enough, without unsheathing the sliderule to convert to KPH or MPH. After that, all power to your elbow for airing the subject and may we hope that this is the beginning of more speed discussion in Model Boats. Lyndhurst. (The Editor has D. A. G. Naylor. been to Continental regattas and does realise what the present course demands; it is true, if immodest, to point out that probably 90 per cent of the Continental speed models running are bred from his Pirana concept. While he has always been a protagonist of the Naviga triangle, Ss it 6 chrome-vanadium 7 span- it is still a fact that the limits of this course are being approached and concentration on it will lead eventually to a falling off of interest, though possibly 15 Speed in k.p.h. or m.p.h. is better pub- licity for boating -— seconds mean little to the uninformed from whom recruits must come — Ed.) EFFICIENT SAILS Dear Sir, The article by R. R. Cole on Sail Efficiency, contained in the September issue of Model Boats, was interesting and thought provoking. The search for more efficient sail proportions will continue and |, personally, believe Mr. Cole to be on the right track. It is to some of the remarks he makes to advance his theories that | am addressing this letter in rebuttal. As your excellent magazine has world-wide _ influence among modellers, two of Mr. Cole’s statements stand correcting or modi- assertion that ia ‘I not for two or three more years. The suggested course was kite-flying to induce discussion; no one has come up with a convincing rebuttal or an alternative, though discussion has been hot. fication. (1) The | A aaa UTY earned by letters published on interesting matters water by the buoys has been used for some time by the Southampton and Portsmouth Clubs; we know from experience that this can be laid by three people in about 20 minutes under the it ia. ce| 8 Ts Sen Siar —— MAX. Ee —~— ei => VOLTSDC eee | SPEED 4VDC FS 8 1O4CG REM TAX 75% EFFRei —SH0GD | oe : 8 _INT.DUTY | DC ners in the hard-to-get small B.A. sizes is a ee 7 }—6VOLTS prreep2voc| 1 es 5 : {a = ine 6.2000); > 9 Write Dear Sir, Concerning your editorial in the September issue suggesting a_ revised Naviga speed course. First | must take you to task for suggesting that the fastest 10cc. boats in Europe are rather in the position of fluking home due to their lack of stability; whilst no doubt this inference was not intended, had you witnessed the FIV-10 event at Russe you would realise that the present 2 ol 5 nana INPUT CURRENT — cage lo 474000 electric motor performance, from the makers, which 5 | SPEED 6YDC g909.c?–—— 3 5 & 2600 — ee ay ae INCH/ OUNCES eh sony | £ 8! a 4VvDC 2 SEED BOC a = 12| 12000of/——— be seen by practical tests with models fitted with 3 =e a] efficiency could well mean an edge in performance, these and other motors. As soon as any results have been achieved, we will pass them on as being of eat = TORQUE— eo = ~sS ages a —a & despite the small extra weight; in the absence of evoe ee Le SP as i 2020000 184 18000 < a pe yea = evog POWER CL ee costly in power absorption than a water scoop, and S o! 2 profit. At higher wattages, the water-cooling becomes 4v00 [ATO voc motor could well give a slightly better performance, 3° 3 40 8V the not allow the mainsail of an boat to be fully battened is rules do ‘A’ Class incorrect. Under Sect. 6 (Calculation of areas), ‘Sails bounded by curved edges’, this is allowed. (2) His hypothesis that a disproportionate increase in sail area can be gained through increasing the size of (continued on page 21) 8 JANUARY 1970 R/C YACHTS - WHAT ABOUT THE DX CLASS ? DX CLASS HERE is discussion going on currently about the possibility of a recognised smaller R/C yacht class —smaller, that is, than the Q class, which is likely to average 7 ft. or so in length, and 50-60 Ib. or more displacement. The well intentioned R class rule has now been written off; possibly it was rather too broad in its approach in an endeavour to bring in existing hulls. Unfortunately most existing boats required slight hull modifications — snubbing of 10R’s or lengthening of M’s—and, of course, the rule involved waterline measurement which, while leading to nice-looking models, is difficult to apply in that it requires a measuring tank, etc. for checking. A suggestion that radio Marbleheads would be popular has been made, though these are not the nicest looking of models and can be very wet. Another suggestion is the American X class, where the sail area limit of 1,000 sq. in. is virtually the only rule. This, however, produces boats of at least 10R size (6 ft. or so long, around 30 Ib.-plus displacement) JIB - 6 CEE I + What else should be mentioned? Well, Naviga recognises one national body per country, and for England it is the M.P.B.A., which does not have much to do with yachting. However, many clubs are affiliated to both the M.P.B.A. and the M.Y.A., and under the wing of the M.P.B.A., though an autono- Sq. ins. ever been. It is not beyond the bounds of possibility that something similar could happen in yachting. in the view of many of my correspon- | refer to your publication of my letter in your October issue concerning my suggestion of a smaller class for R/C Yachts. From the replies | have received, the results are somewhat inand are worth comment. performing at Poole. boat that we have seen 4. Although no correspondent has mentioned it, the American ‘X’ class might fill the need. This rule covers a wide range of boats and dimensions. The main rules are for a sail area not more than 1,000 square inches, and a conventional design that does not in- clude multi-hulls or similar unconventional hulls. 5. The London Radio Controlled Model Society seems hurt at my suggestion that the ‘Q’ class is a failure. I, personally, have sailed this class for about seven years, so can speak from authority that it is an eminently suitable class, but we cannot all run ‘Rolls Royces’ and the time has come to consider a smaller, more popular size that will receive better support. Perhaps that august body that did a lot in the formation of the ‘Q’ sponsor the smaller class. Highcliffe-on-Sea. class might C. Robert Jeffries. 19 = large boat. 2. The Model Yachting Association shows no interest in R/C yachting, and Sq. ins. 775:2 M.P.B.A. veterans), interest in this branch of boating has more than doubled, and is higher now than it has dents, the future control of this sport should be in the hands of a more competent and enthusiastic body. 3. The demand for a smaller class is definite, but from replies received, there is a wide variety of assorted boats ranging from 10 raters, down to 18in. TOTAL airscrew class (always previously anathema to many field tiny 3 Sq. ins. 2 = These notes are included, not to grind any par- mous entity. A great opportunity for international participation in R/C yachting, is going by the board, and with the next European Championships in 1971 in Belgium, it would be nice if some of our yachting enthusiasts could enter. We are certain that one visit to such a meeting would spark off a tremendous wave of enthusiasm, and this is one aspect of international participation in which we should be able to lead the a vi 2! ticular axe, but because, if there is a move towards an acceptable smaller class, what is being done by a dozen or so other nations seems relevant to the consideration of what possible move this country may make. In this we are perhaps influenced by what has happened in tethered hydroplanes, where, following the recognition of the Naviga classes, including the body might be necessary to look after R/C yachting; there is no reason why such a body should not be 1. There is nothing wrong with the present ‘Q’ class. It is a most satisfactory yacht for those that have the space and facilities to handle such a 2 3 + Caen 775.2 sq. in. is the smallest. in any event it has been suggested that a separate conclusive, but several facts stand out BAL Cxb Besides the DX class there are classes for R/C Marbleheads, 10-raters, and International 10/40 class; details of the latter, which is not very familiar to British yachtsmen, were given in September 1967 Model Boats. At 1 metre long, it is perhaps rather smaller than present R/C sailors feel desirable. Based on sail area, of the other three classes, the DX at temptation! Dear Sir, = oO De s AxB and more efficient boats would gradually supersede them. The free hand for designers is a tremendous READERS WRITE = MAIN > There is, however, a European X class, or, with radio, the DX class, under Naviga rules, and we feel that this could be an answer. The rule is just as simple —sail area limited to 5,000 sq. cm., measured as our diagram, and there is no other restriction at all. Any hull can be used, provided sails complying with the rule are fitted. Now. if it is pointed out that the Marblehead sail limit is 5,160 sq. cm., it becomes obvious that many M hulls could be used, though with the design ability in this country, more attractive oO and this could well be too big. JANUARY 1970 cause of her side area, she cannot sail to windward in anything more than a gentle breeze; but on a calm day she makes a very stately picture as she chugs then be split in two and each half scraped and sanded down to the finished rail size, just over 1/16 in. wide and just over 1/32 in. thick. Approximately another 8 in. of straight rail stock will be needed for the rail sections at the fore and aft ends of the upper deck. Assemble the rails with epoxy directly on top of thus incorporating another ‘scale’ feature, the possibility of catching fire! However, since she is nearly all straight lines and sharp corners, she could easily to prevent the rail from sticking to the deck. The outer edge of the rail is even with the upper deck edge, to just behind the stack, aft of which the rail outer edge follows the roof plan view. With the or similar-sized small pond. She runs about 12 minutes on half of a fat ‘birthday cake’ candle, and almost 40 minutes on a ‘food warmer candle. Be- the upper deck, with a sheet of plastic film in between dauntlessly along. My own model Alki was made mostly from balsa, assembled rail firmly taped down on to the upper deck, the stanchion holes can be marked and then drilled through both rail and deck. Then the roof outer sections can be taped down atop the rails, and the 6 holes in each side can be drilled, upwards, through deck and rail into the roof underside. This method assures the proper alignment of all the holes, so that accurate assembly is guaranteed. The superstructure needs no elaborate attachments to the hull. My prototype merely had a short bit of + in. i.d. aluminium tube cemented into each bottom corner of the superstructure, and dowel pegs were let into the hull to match the tubes. A snug friction fit be made in tinplate. Construction should begin with the ‘engine’. This requires 2 ft. of 3/16 in. o.d. dead soft copper tubing. If the inside diameter is no larger than ¢ in., the tube can be bent without a ‘filler’ inside. It will flatten slightly but not excessively. If the tube has a thinner wall than 1/32 in., it will have to be stiffened before bending. One good way of doing this is to close off one end of the tube with a drop of solder. Then pack the tube full of fine sand or common salt. Solder the open end of the tube closed, after which it can be bent without any tendency to collapse. Then, when it is fully formed, the soldered-up ends can be cut off —NOT melted out —and the filler material shaken is all that is required. It proved impossible for me to determine for certain the colour scheme of the original Alki. My best guess is that the stack was a light (and somewhat streaky) slate grey with a narrow black stripe at the top rim. The roofs and ventilator were probably a dull brick red (i.e. red lead); and the pilothouse and upper cabin walls a slightly yellowed white; as was also used for the boat’s name. The rails, stanchions, and main deck structure were probably a light yellow ochre, out of the tube. The only practical way of bending the ‘boiler’ correctly at first attempt is to do it with a ‘jig’. This can be made from a scrap piece of # in. plywood, as shown in the sketch. The bending procedure is also explained in the sketch. Next, the plywood keel can be made and the ‘engine’ attached to it with epoxy. The hull proper is made in two halves, one on each side of the keel, and cut away as necessary to fit around the tubing. A tapered wedge of wood atop the bow provides the upslope of the forward deck. After this is attached the 1/16 in. thick fore and aft deck pieces are added, and then the } in. square ‘gunwale’ all around. The upper works are made as a single assembly, which lifts off the hull for access to the ‘engine’. The construction is straightforward except perhaps for the rails and stanchions. The rails can be readily made from bamboo, by heat forming (around a light bulb) a piece roughly 3/32 in. x ¢ in. x 8 in. to fit the shape shown on the plan view. This piece can READERS WRITE (continued from page ae e discounted the foretriangle can somewhat by the following illustration. |, personally, carry a 29in. x 64in. foretriangle on my ‘A’ boat, with actual jib dimensions of 26in. x 60in. My foretriangle area as used in the formula comes to 789 sq. ins.; my actual jib area comes to 780 sq. ins., or 9 sq. ins. less than used in the formula. Using the above as a basis, if we increase the J dimension by 4ins., to 33ins., we get a calculated foretriangle of 898 sq. ins. and by increasing the foot of the jib by a like amount (4ins.), we get an actual area of 900 sq. ins., or slightly more than calculated. This theoretical advance hardly warrants the development of a thesis. It is more likely, | believe, that an increase in propulsive power is obtained through the use of a larger jib simply because it is larger and not through any increase in sail area of the one sail plan over the other. If it is allowed that a jib, inch for inch or sq. ft. for sq. ft., is more efficient than a mainsail, then the sheer increase of size in the jib may account for an increase in overall efficiency and thus an increase in power. with the decks and ‘gunwales’ somewhat darker (or dirtier). The hull itself was possibly a charcoal grey, or maybe a dark, dull maroon. The cleats seem to have been natural wood, also the forward flagstaff, while the capstan was doubtless the colour of a blacksmith’s anvil. In sailing the AJ/ki there is only one important point to keep in mind. Before lighting the candle, be certain that the ‘engine’ tube is completely full of water. This is best achieved by suction via a long length of transparent plastic tubing whilst the boat is floating in the water. The whole concept certainly is intriguing and should provide the model yachting fraternity endless opportunity for further experimentation. Detroit, U.S.A. G. Muller. PERFORMANCE IMPROVEMENT Dear Sir, With reference to Messrs. Gould and Newman’s letters which have appeared in these pages during the past few months. | have finally calmed down enough to compose a reply. My first reactions on seeing their criticisms were to find the two gentlemen and rend them limb from limb, in the case of Mr. Newman this being particularly easy as he is a member of my own Club. The cause of my annoyance was not because | had been criticised in print but the fact that both of them had not read and interpreted the first lines of my article correctly. These read: ‘This article has been written to try and help those skippers who have been sailing for a season or two and would like to try and do better’. First, Mr. Newman, as | know him personally. He has been sailing for racing experihis months; ten about 21 = S65 = Se ee ence is based on four Club races and Marblehead District Midland one Championship. He did not attend the National at Birkenhead from which he could have gained much experience. As to his allegation that | am a member of a Secret Society, | should like to know who the person was who | helped him tune his Marblehead. could have sworn it was me. However, now, from seasons few a in | trust that Mr. Newman will be helping novice skippers to get started in our fascina- ting hobby. Now to Mr. Gould. He seems to be the most non-competitive competitor | have come across. He criticises M.Y.A. Classes, sails, fittings, rule bending, pot hunting, and G.R.P. construction. Fantastic for a non-racing man. He dabbles with classless R/C yachts and then advises on free sailing. By the way, Mr. Gould, if you are using 40 degrees of helm to keep your M and 10r on the wind, as an expert member of a Secret Society | advise you to push the mast forward about a quarter of an inch. My motto is: don’t knock it. If you haven’t tried it, M. J. Harris. (Schhhhhhh.) Birmingham 9. JANUARY 1370 METROPOLITAN & SOUTHERN DISTRICT -W TEAM RACE but dropped to tall rig strength at around 4 pm. These conditions gave a three-tack beat to windward. and a spinnaker run. Heats were being sailed in approx. twenty-five minutes, and at lunch, 1.15 pm. the half-way stage had been reached, with seven heats completed. At this stage, Clapham, with 54 points, had a two- point lead over Hove, with last year’s winners, Guildford, pursued closely by Portsmouth and Bournville, following with 38 points. The individual scores were Clive Colsell 30, Clem Fallows 29, Chris Dicks 28, Mick Harris 27, Dick Seager 26, the rest of the field being some way behind. Left, Fantasy Impromptu below, left to right, Narang, Zaza, and Sweet Sixteen. HIS was the third Marblehead team race held in the Southern district and, as last year’s winner, Guildford was host club. The Hove and Brighton club kindly agreed that the race be staged at the Lagoon, and all facilities were at Guilford’s disposal for the racing on the Sth October. H. Godfrey, OOD, and E. Hunt, of Hove, Assistant OOD, were aided by members of the Guildford club with umpiring, judg- ing and keeping a large score board up to date. The Met. and Southern District invited four clubs from other districts to compete, and Bournville accepted on behalf of the Midland district. Sixteen boats from eight clubs came to the start at 10.30 a.m. in perfect sailing conditions, clear and sunny with a fresh, top suit wind, 8-10 m.p.h. from the E.S.E. The wind increased slightly at midday, Racing started at 2.00 p.m., and during the afternoon Clapham gradually drew ahead of Hove. A dramatic change took place in Heat 13, with Hove, who had scored 86 up to this point, dropping all ten points, and Guildford, who had trailed with 65 and 6 resails outstanding, gaining the full 10 points. The full programme of heats was completed at 5.20 p.m. and Clapham were clear winners with 111 points. Hove had 91 with 5 resails, Guildford 84 and a possible 16 in resails. After six resails, second place was decided, this going to Guildford with 953, Hove being third with 93, and Portsmouth fourth with 68. With superb sailing conditions, good organisation and an excellent spirit between skippers and officials throughout, the competition provided racing at its best, and was enjoyed by all those taking part. The fleet represented a very wide cross-section of the Class, from Martini and Wayfarer, both vee’d, displacement type boats, designed for windward work, to Zaza, Sweet Sixteen, and Fantasy Impromptu, planing hulls, and at their best when sailing offwind. No one design or designer stood out. Of the 16 boats present, thirteen were to different designs, and four of these were sailed by their designers. Glass fibre reinforced plastic accounted for ten of (continued on opposite page) an MODEL BOATS spacing between guns. eleven destroyers were lost in an incomplete condition, most of them being broken up on their slips by the Germans. The characteristics of the three classes were follows: NAVIGATORI DARDO Built: 1927-1931 1929-1932 Pre-war colours were pale grey with black water- line. Decks were either hull colour or painted a dark grey. Deck fittings and hawse holes were black. as During the war, numerous camouflage schemes were used. Large identification letters were carried on the bows of all destroyers, and these are shown in brackets against the name of the ship in the following Displacement: 1,943/2,580 tons 1,220/2,100 tons Machinery: 50,000 SHP=38 knots 44,000 SHP=38 list: NAVIGATORI knots Armament: 6-—4.7 inch; 4-37 mm. 4—4.7 inch; 4—37 4-21 inch TT mm. 6-21 inch 185 Complement: 225 SOLDATI (1st series) SOLDATI (2nd Series) Built : 1937-1939 1940-1942 1,846 /2,550 tons Displacement: 1,830/2,459 tons 50,000 SHP=39 knots 50,000 SHP=39 Armament: 4-4.7 in. (1); 12-20 mm; 6-2linch TT Lanzerotto Malocello Nicoloso Da Recco (DR) Emanuele Pessagno (PS) Leone Pancaldo (PN) Antoniotto Usodimare Luca Tarigo (TA) Giovanni Da Verazzano Ugolino Vivaldi (V1) Nicolo Zeno (ZE) Antonio Da Noli (DN) TT Machinery : Alvis Da Mosta (DM) Antonio Pigafetta (P1) (DV) DARDO knots 5S-4.7 in. (2); 1220mm; 6-21 inch TT Complement: 219 218 (1) 5-4.7 inch on Camicia Nera, Carabiniere, Geniere and Lanciere. (2) 44.7 inch on Velite. There were numerous modifications to all three classes, either before or during the war. The Navigatoris, with only two exceptions (Da Recco and Usodimare) were fitted with heightened bows, a change which somewhat marred their handsome appearance, prior to the war. All ships were subject to wartime changes, usually to augment anti-aircraft armament, and in some cases one set of tubes was removed. Ships of the Soldati Classes carried either four or five 4.7 inch guns, the extra single gun being mounted on a bandstand between the tubes as shown on the plan. The twin 4.7 inch were remarkable for the narrow the boats, eight of these being two-part mouldings with plastic decks. The remaining six were either carved or planked in timber, and fifteen of the boats were bulb keelers. Today, a Marblehead without a bulb keel is something of a stranger in any open event, although steering gears were equally split between the moving carriage, and the pin and slot type, there being eight of each. Sail material used on 12 of the 16 boats was woven terylene of the type used for Dardo (DR)* (MO) (US) Saetta (SA) Strale (ST) Freccia (FR) *Changed to DA during war. SOLDATI (Ast Series) Alpino (AP) Artigliere (AR) Ascari (Al) Aviere (AV) Carabiniere (CB) Corazziere (CB) Fuciliere (FC) Geniere (GE) Granatiere (GN) Bersagliere (BG) Lanciere (LN) Camicia Nera (CN)* *Renamed Artigliere (AR) in July 1943. SOLDATI (2nd Series) Bombadiere (BR) Carrista (CR)* Corsaro (CA) Legionario (LG) Mitragliere (MT) Squadrista (SQ)* Velite (VL) *These two ships were not completed. Squadrista was renamed Corsaro in July, 1943 after loss of her sister. NEXT MONTH: Modern Soviet warships including the new helicopter carrier Moskva. making full-size yacht sails. This material seems now to be much more popular than the varnished terylene used a few years back. It can be seen from the sail numbers in the results list that all the boats are quite new, March Hare, the 1968 Champion, being the oldest in the fleet. This indicates the healthy state that exists within the M Class at present, with new ideas constantly being put into practice. RESULTS Points Boat Position 1st Club Clapham Scored 57 Number 1597 Skipper C. Dicks Designer Own Design 54 1608 R. Seager Own Design 2nd Guildford 523 1676 F. Shepherd Own Design 43 1692 G. Austin Shepherd 41 1674 D. Daly Stollery March Hare 53 1661 C. Colsell Shepherd 3rd Hove & Brighton 4th Portsmouth 5th Bournville ne / 6th MYSA Danson 24 7th 8th _ Southgate 48 1536 C. Fallows Stollery March Hare 20 1629 1697 B. Welch G. Reeves Stollery White Rabbit 49 1686 M. Harris Own Design 32 1659 P. Dunkling 323 1604 F. Shattock 28 1631 1653 C. Griffin G. Clark 7 1625 C. Daniels 5 1654 B. Woods Modified Duck Stollery Mad Hatter Stollery Mad Hatter Witty Golden Archer Witty Modified Wasp Witty China Boy
