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INTRODUCES “MONA” 0-6-2 IN THI Poole],RADIO REGATTA A. Wilson of Bournville with his M.T.B., whose guns swivelled, depth charges dropped, lights flashed, signals passed, and finally brought its armament to bear on the judges’ table and sunk Chas. Read with Peter Sellers’ Boat Called Fred, which played its part valiantly in the regatta at Poole. them with a devastating round of blank shot. Peter Cummins gave a polished exhibition with HE annual Po ole Radio Regatta, regarded by many radio boat siasts control —enthuas the ee ls eae ech ) Mt Dealt eal cl cet a 2 premier meeting of the year, enjoyed its usual strong support from nearly everybody who is anybody, with fine weather to match, until a thunderstorm broke over the prizegiving—which was hastily adjourned to the clubhouse. Event I was a two-lap race for diesel, petrol or steam powered r./c. craft, and brought out the cream of the models. Max Coote won easily with the maiden competition run of his new Seine fireboat Lutece, clocking a time of 1 min. 384 secs., which must have been close to the upper limit of 15 m.p.h. for the course. Lutece is a truly elegant craft and will shortly be the subject of a full length article, meanwhile we would only say that she is powered with George Nurthen’s latest 30 c.c. o.h.v. G.A.N. Gannet marine engine. As a a fireboat it provided a comedy turn after completing its run when Max’s transmitter went up in smoke! Alas its monitors had not been connected to provide the water! Second place resulted in tie, so that Mike Taplin and Bill Warne had to re-run. Altogether a most exciting start. Steering event for electric boats attracted only two entrants—not surprising as the large open water of Poole is not really ideal for electric propulsion, a remark which is of course immediately belied by the efforts put on in other events by electric boats over the years. Novelty event brought out Mr. Jennings’ historic model of P.S. Devonia, the paddle ship which aroused so much interest at the National Boat Show, but nothing could stand against the superlative performance put on by his “test-bed” Trixie for second place. Open steering event attracted twenty-three entrants with Mr. Curwin of Shaftesbury the winner, followed home by Mr. Batten of Barnstaple, whose Veron Police Launch carried a Model Maker receiver. This boat has been developed over several years by Mr. Batten and probably contains more apparatus per cubic inch of carrying capacity than any other boat except Trixie, which incidently took third place in this event. Most notable development of the regatta must, however, be the terrific interest shown in radio controlled yachts. Instead of a scant two or three, we counted over a dozen in as many different ownerships, so that at least it may be said to be coming into its own, with a really widespread band of experimenters. Col. Bowden, as usual had some interesting novelty on display, in the shape of his fully battened sail which performed very well, but has yet to convince the experts that it enjoys advantages over conventional sails, though in model size it would certainly appear to benefit. We were glad to see one enterprising entrant, Mr. A. Robinson, had installed a r./c. vane gear, a method of control we have long advocated. This has now been on test some considerable time, and we hope to have an article on its use from his pen shortly. Veteran of the meeting was a yacht which we can only describe as a “pseudo-Marblehead” of circa 1907 (Since the class was not then invented, this was presumably intelligent anticipation on someone’s part?). One disappointment was the absence of Peter Sellers—of the Goons—who did however send along his Boat Called Fred in charge of Max Coote’s a.d.c. Chas. Read. As usual the Dolphin Hotel had grown bigger and better since the previous meeting, and Councillor Miller put on a most enjoyable luncheon party there at short notice for judges, officials, and friends. Finally, mention must be made of Mr. Miller’s inspired commentaries on the contests, which must have made events doubly enjoyable to the large crowd of spectators in attendance most of the time. 396 AUGUST, On the right: Max Coote’s French fireboat, Lutece, an elegant scale model with working monitors and a great turn of speed Next: George Honnest-Redlich had this new craft to try out. All being well it should be amongst H.M.M.’s new designs in the near future Lower right: A. Wilson of Bournville with his winning M.T.B. and interesting control box. EVENT RESULTS EVENT I—TWO LAP RACE 19 Competitors Ist Name Max Coote Town London Boat Lutece Time I min. 38} sec. 3rd 4th Wm. Warne D.J. Taplin London Birchington Amazon — I min. 56 sec. 2 min. 21 sec. 2nd M. Taplin Birchington — I min. 50 sec. EVENT II—STEERING EVENT FOR ELECTRIC BOATS Ist Name J. Merrick Two Competitors Town Boat Birmingham Rosmic Points EVENT III—NOVELTY COMPETITION Five Competitors ’ Name Town Boat Ist A. Wilson Bournevilie M.T.B. 2nd P.Cummins Byfleet Trixie 3rd F. Jennings West London P. S. Devonia EVENT IV—BRAVERY CHALLENGE CUP Handicap Sailing Race Nine Competitors Name Town Ist J. Tamplin Birdham 2nd V. Gascoigne Twickenham 3rd J. Aldridge Bristol Boat Kit Antoinette Painted Lady EVENT V—FREEMAN CHALLENGE CUP Steering Competition 23 Competitors Name Town Boat Ist P. Curwin Shaftsbury _ 2nd —. Batten 3rd 4th P. Cummins —. Mogg Barnstaple Byfleet Wells — Trixie Puck EVENT VI—HOGG CHALLENGE CUP Sailing Race up to 50 in. Four Com: etitors Name Town Boat Ist V. Gascoigne Twickenham “M” Class EVENT VII—TAPLIN CHALLENGE CUP Ist Sailing Race “A” Class Five Competitors Name Town Boat G. Honnest-Redlich “A” Class Below: Col. Bowden’s fully battened sail in operation on his 10-rater. Centre: Messrs. Aldridge and Robinson’s “A” Class yachts go over the starting line together about two seconds after the gun (or klaxon horn in this case). Radio controlled vane gear – Mr. Robinson’s “A” Class yacht 397 1956 MODEL MAHER) i eee —— In answer to several requests, Model Maker presents a full-size Shiff for anne Water Sailine Designed by H. B. Tucker in the same sense throughout. Thus, when I refer to the “bottom of the keel,” I mean the actual bottom as it will be when the boat is right side up. In order to bring the work to a convenient height, the stem and frames are carried some distance above the gunwale to form “horns” (or legs) on which she At one time, owing to lack of suitable ponds, much American model yacht sailing was on rivers, lakes and the sea. It was found that ordinary rowing boats are unsuitable for handling models as they are too long to turn rapidly and also lack the requisite stability. On the other hand, yacht dinghies are too short and have too much freeboard. In consequence, a special type of skiff was evolved that is stands during construction. When the outside of the hull is complete, the boat is turned right side up, and these horns,cut off at gunwale level. Two battens are screwed to the after side of the transom to serve as horns. It should be mentioned that the horns shown in the drawings are of a length to suit a man of medium height, but their length can be varied to suit the builder, or his material. almost, but not quite, a “flattie.” of An excellent example, designed by Mr. A. E. Bull, New York, was published in the “Model It will “Model Sailing Craft” in 1932. Although all serious model racing in this country is on ponds and lakes, the new sport of Radio Controlled sailing has been found to demand larger waters than ordinary model yachting. As a result, R.C. model sailers are taking to sailing their yachts from boats on open water. Hence, there is a need for skiffs suitable for the purpose. The present skiff is of a similar type to those referred to above, but specially designed to permit the use of modern materials and methods of building. Incidentally, this little boat should be a very versatile craft. In addition to her primary function from the plans that the frames Frame No. 1 owing to the rather steeper floor. Ties likewise serve as a tender to be left on a yacht’s moorings, and many other purposes. She can be as shown should be put across the horns. These are simply screwed in place. The first step is to make up the frames complete with gussets and ties. The transom is then cut out to the shape of its rowed, or sculled with an oar in the transom notch, or propelled by a small power outboard motor. In shallow water, she could be punted with a pole. forward face. Two battens are then screwed to its after side to form horns. The fashion pieces are made and glued in position on the forward side. These have slots, or notches, for keelson, seat stringers, chines and inwales. The stem consists of two parts—the inner stem being pine, and the outer stem oak. At the moment we are dealing solely with the former. With a marking gauge run a centre line right round the stem. Then mark parallel lines down the foreside of the stem on either side of the centre-line for the depth of the “rabbet”. Similarly, lines are gauged up the sides for the “bearding” line. The “rabbet” is the groove down the stem which houses the The estimated weight is 90/100 Ib. so she will be easily handled by two persons. It takes approximately 140 lb. to put her down an inch, so she should carry three normal people comfortably in reasonably sheltered waters. There are two thwarts and sternsheets, but the forward thwart and the sternsheets can easily be unshipped to make extra space in the bottom of the boat for model yachts, etc. Thus she could carry not only the model yacht and skipper, but his R.C. Transmitter as well. She would also be suitable for handling R.C. power-driven models. In designing this boat, there were three points that euided me. Firstly, she must be suitable for ber purpose; secondly, she must be cheap to build; . end thirdly the construction must be within the pewers of anybody, whether a skilled woodworker Briefly. the modus operandi is as follows:— ow the boat is being built upside Gown. for the sake of clarity, I have used the terms “top” and “bottom”, “upper” and “lower”, etc.. seen angle jig should be made up to hold the floor and the frame proper in their correct respective positions while the gussett is being glued and screwed into place. The chine angle on the transom varies slightly owing to the rake of the transom. It also varies in as a model yachting skiff, she could be used for fishing, or as a punt for duck shooting. She would built upside down on any reasonably be consist of the upper parts (or “frames” proper) and floors stretching from chine to chine. The floors and the frames proper butt against the chines and are held together by chine angle ties, usually known as “gussets.” The open space at the chine angle permits water to flow along when the boat is tipped on her side to rid her of bilge. The boat is a constant chine-angle sharpie, so an : —— ee Yachtsman” (which subsequently became “Marine Models”) in 1928. Another good skiff, designed by Mr. W. J. Daniels, appeared in the Ist Edition of forward end of the skin. The rabbet line is its forward extent, and in this boat is formed by the joint between the inner and outer stem. The “bearding” line is the after end of this groove where the planking comes to the surface and leaves the stem. The two forward corners of the stem are planed off to the gauged lines. Care must be taken to cut off the end of the stem horn to the correct angle for the rake of the stem. The stem knee has now to be made and glued in position at the bottom of the inner stem. 408 In cutting this 4 AUGUST, out the grain-of the wood should run parallel with the longest side. The breast hook, which fits in between the forward ends of the inwales has also to be made and glued into position at the top of the inner stem. In erecting the frames, please note that for reasons that will be apparent as the work proceeds, Frames Nos. 1, 2 and 3 have their after faces set on the station lines, while Nos. 4 and 5 have their forward faces on the station lines. Erection Start the erection in the centre of the boat, holding the frames in position with a couple of battens “tacked” to each side. Stem and transom follow. The notches in the floors for the keelson (or hogpiece) should have been cut out before erection, as also the “Limber” holes. The object of “limber” holes is to let bilge water drain through instead of being trapped between floors. The notches in the frames for thwart stringers and inwales should also have been cut out. The keelson can now be prepared. Gauge a line along both upper and lower faces. Next two further lines parallel with the centre line ing the position of the keel proper, which also the keel rabbet line. Gauge lines on each side centre gauge showforms of the keelson the Plane line. bearding keel the keelson for down accordingly so that the skin of the bottom will lie snugly in position. The keelson should be a little long at the forward end. The after end butts against the transom and is lodged in a slot in the fashion piece. The keelson is now offered frames. It will be found that frames it touches only at the notch, the reverse is the case to the grooves in the while on the forward forward edge of the on the after frames. The notches must be bevelled off accordingly until the keelson takes fairly right across the frames. At the after end, it fits into a notch in the bottom of the: lower fashion piece and this notch has also to be bevelled. Glue into place and “tack” to hold in The expression “tack” place until the glue sets. means to nail temporarily, leaving the nailheads standing well above the wood to permit their being pulled out when the glue is hard. Panel pins about 2 inches long will be very suitable to use for tacking. For gluing, use one of the cold setting, gap-filling Separate resin glues with a suitable hardener. application glues (with which the resin is applied to one of the surfaces to be joined and the hardener to the other) are the most suitable for boat work, and Aerolite 300 can be strongly recommended. The Start at the transom and work forward. forward end is glued to the bottom of the stem. The panel pins may not by themselves be sufficient to hold the keelson, but a lashing here and there round the floor will make all secure. It is necessary to give the glue time to set, so we turn to another part of the boat. In any case, however, it would not be advisable to put the inner keel member in place until some of the other longitudinal parts of the framework are in place. We next fix the thwart stringers. These are plain battens 3in. square so require no bevelling. On the other hand, the forward end has to be chamfered off at an angle to fit against the stem. The extreme forward edge falls on the stem immediately abaft the bearding line, so that the stringer will be against the skin and support it. For the moment, leave the battens a few inches over length, and offer to the 1956 boat. It will be noticed that in order to make the stringers take properly across the full thickness of the frames, the notches have to be adjusted in the same way as those for the keelson. Having attended to this on both sides of the boat, chamfer the forward ends as mentioned above. In connection with the above instructions, two points should be mentioned. For these stringers as well as for the keelson, and in fact all longitudinal frame members that fit into notches in the fashion-pieces and butt against the transom, the notches in the fashion-pieces must be adjusted in the same way as those in the floors and frames. When fitting, even temporarily, these stringers, also chines and inwales, care has to be taken not to distort the framework of the boat So, particularly when dealing with athwartships. the first of a pair, pull the frame member in question down into position gently but firmly, using two Spanish windlasses. No doubt most readers know what a Spanish windlass is, but for the benefit of anyone who has not met this useful device before, I will explain matters. A Spanish windlass consists of a loop (or loops) of line carried right round the two parts which are to be brought closer together, with a piece of stick inserted in the loop (or loops). As the stick is turned round, the loop is shortened and the parts drawn together. In order to equalise the strain between the two sides, one end of the loop is round the stringer being bent into place, and the other round a convenient part on the opposite side of the boat. In this case a frame would be selected. When the fore end of the stringer has been chamfered off, the stringer is again offered to the boat, and its after end marked for cutting off to butt against the transom. It is now ready for fixing. Get both stringers ready and fix the pair in one sittting. Now one caution on the use of resin glue may not be out of place. Aerolite 300 and similar glues are all gap-filling glues. This means they will fill gaps up to 1/20in. wide, but it also means they are very stiff and liable to make a thick glue-line. Now a thick glue-line is likely to make our longitudinal frame members stand proud instead of settling nicely into their notches. The solution is to add about 10 per cent. more water if the glue is being made up from the powder form. In any case, the resin should only be the thinnest coat possible to cover. Apply the resin to the notch and the hardener to the stringer. Bring as much pressure to bear as you can using cramps and/or Spanish windlasses to settle the stringer right into its notch. Our keelson should have set hard by now, so we can fit the inner keel. In order to obviate a difficult bit of bending, instead of using an oak keel 24 in. wide by 1in. thick, we are using an inner keel of pine 4in. thick and an outer keel of oak +in. thick. Unlike the keelson, the keel is carried across the transom. The inner keel is not only glued into position, but screwed right through the keelson to the frames, using in. brass screws. It should be left temporarily a little long at each end, Since the inner keel is screwed as well as glued into position, the oak outer keel can _ be fixed right away. This is glued but not screwed in position. It will therefore, need tacking and lashing into place, or cramps, if available, can be used with advantage. (To 409 be continued) mooeU MAKER Top left: A fine scale model of the Will Everard, built by . R. A. Brown Centre: Start to the race for square rig and fore and aft rig craft. In the foreground is Mr. A. K. Williams’ 52 in. model of the barque Star of the South ‘THE annual Rally of Sailing Ship Models was held recently on the Round Pond, organised by the Thames Shiplovers and Ship Model Society. Dull weather with strong gusty winds proved unkind to these scale models of fore and aft rig, square rig, and Thames barge prototypes, making some adjustment programme of events necessary. in the However, in spite of everything, a variety of sailing ship models performed very well during the day, with perhaps the main interest focussed—as in past years—on the race for model sailing barges built to a scale of half an inch to the foot. First boat home was Mr. FitzGerald’s Mavourneen, who thus repeated her last year’s victory. ) : Rallies of this kind are more of a get together : than a stern competitive occasion, but a Rally of Sailing Ship Models generous vee – = ane =P Sse sean oo SSSEker = ai pont a ST a earn See ae Oe Saree & of trophies, medals and Bottom left: A good start to the 1956 Model Barge Race, won by Mavourneen : Bottom right: The Cutty Sark drying out, with the Diana in the background. This shot gives some idea of additional keel area and weight needed to enable such scale models to give of their best ror en ee 2 SMa et — petit, array diplomas gave a wide selection of enthusiasts something material by which to remember the meeting. Principal awards were as follows :— Square Rig: Thames Trophy—P. Gould’s Cutty Sark; Medal—N. A. Ough’s Deliverance; Diploma—wW. Hill’s Diana. Class Il, Fore and Aft Rig: Medal—D. S. Paterson’s Valerian; Diploma—J. B. Jenkinson’s S. A. Elines. Class Ill, Native: Diploma—W. Gay’s Gay-Bao (1867). Class IV, Thames Barges: Medals— J… J… Starkey’s Janice,» G? “°R. ‘Sinelair’s Youngarth, R. A. Brown’s Will Everard. Diploma—C. B. Maycock’s Irene. A412 MODEL MAKER tiller. angle STARTING ON THE RIGHT TACK way acts as a form of servo established now proceed vane steering simple gear. (though, as to our the Let we mast position, process us first shall of of see all we setting a not. gear can the that if the yacht hull is now turned towards the wind, the tiller will take up a new position such as helm. If the linkage ratio were 1:1 (i.e. linkage pin halfway between vane pintle and rudder post), ten degrees devia tion from the original course would more common apply ten degrees linkage ratio of of 2:1 helm. (i.e. With the short linkage arm and long tiller arm) the amount of helm correc tion would be 5 degree s. If the yacht is turned 10 degrees off the wind, the gear will similarly provide 5 degrees of lee helm, assuming the linkage ratio is still 2:1. This linkage ratio is one which we shall have to experiment with, until we find the best value for the particular yacht. I suggest that for the start of the tuning-up operation it be set at 2:1, with the intermediate size of feathe r (as described in a previous chapter). _This simple conception of how the gear works gives us an equally simple rule-of-thum b method for setting the follows:— vane angle for any desired course, as (1) hold the yacht on the desire d course. (2) hold the tiller arm central. (3) rotate the bar of the gear so that the tail edge of the feather is pointing away from the wind. Then assuming that the wind stayed in that direction and the yacht stayed on the selected course, the tiller would remain central. If, however, the yacht tended to deviate from course, the vane would still remain at the same angle to the wind, and the deviation from course will thus result in the application of a correcting angle of helm applied to the BOW TILLER ARM ANE: — ANNU\\\ (o} gee SWSe WIND WIND SSIsAVANT A Fig| has, without understanding sail The any object at particular this stage is not course accurately to or attempt to the represented by the resultant line of force OA, which It is on this apparent wind (which comes from a source more ahead than the true wind) that the yacht will an ACTUAL Fig 2 sail, and the vane gear will operate. This accounts for the fact that when the gear is set for the true wind, the yacht sails rather more free than anticipated. if the wind force increased, and the yacht did not increase speed, the new line of force (OT’) would be greater and the apparent wind (OA’) would be nearer in direction to the true wind. If, however. the increase in wind force produced a corresponding increase in the speed of the yacht, the line of force OC would also increase, and the direction of the 420 oo he differs in direction from the true wind (OT). MOTION FEATHER if speed of this extra “wind” is the same as the speed of movement of the yacht, so that the force acting on the feather increases with forward speed. (See Fig. II). The feather is now controlled by two wind forces simultaneously, i.e. the true wind, represented by the line of force OT in Fig III, and the “created” wind, represented by the line OC. The result of this combination is the “appare nt” wind, CREATED 4 (or best advantage, but to familiarise the skipper with the general handling of the gear. Some practice at retriming on shore will also help in this direction. One effect which should soon become apparent (assuming the gear is working even reasonably well) is that the yacht sails on courses appreciably freer than the courses for which the vane gear was set. For example, with the gear set to give zero helm with the vane athwartships the yacht will sail not at 90 degrees to the wind, but at a greater angle— 100 degrees or more. A few practice runs will show how to correct vane setting for an accurate course does, in fact, differ from that “gue – timated” ss by the foregoing simple rule. For running dead before the wind the simple rule gives nearly the right answer, but the error becomes greater on courses with the wind more abeam, and is still apparent as the yacht is close-hauled, for a wind more ahead. There are, therefore, certain factors to be studied, which complicate the process of setting the gear for an accurate course in relation to the direction of the wind. We must now attempt to understand these factors so that we can assess, and allow for them when we attempt more precise course-setting. Reverting to our first illustration (Fig. 1), the yacht is stationary, on a course with the wind exactly abeam, the vane feather at 90 degrees, and the tiller central. The yacht now begins to move forward on its course. In doing so, it creates, by its own motion. the effect of a wind from dead ahead, and_ this “created” wind will affect the vane feather. The the wind, the tiller is centr al (as in Fig. 1), we can see weather before courses. to a position such that, with the feather lying away from give the tion non-critical. The sails are, of course, trimmed for each course being sailed, and trial runs should be made on beating, reaching, quartering and running very If the yacht is held on a course beam-on to the wind, and the bar of the vane gear is turned on the rotor to to of much about it), I suggest that he now proceeds to sail a few trial courses, using this simple technique of vane angle setting, and note the results. This should be done in a light to moderate wind, to ensure that the gear is at no time overpowered, but at the same time has enough windpower to make its opera- strictly accurate) conception of how the gear works . applying a If the skipper has never sailed a yacht with vane up adopt later, mechanism, proportion (dependent on linkage ratio) deviation angle as a correction to the tiller. PART FOUR—TUNING UP (Contd.) BY D. A. MACDONALD H4VING This tiller angle would be equal to half the of deviation from course. 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This brought her exactly to her designed L.W.L., and she has since proved quite a successful yacht. This owner is an advocate of the heavier type of boat, and she was intended to be almost ton displacement for her L.W.L. The boat was specially designed to his require ments by el alae arto -2S—— 3: one of our leading designers, and built by an excellent builder. The designed dimensions were: L.W.L. 55.0in., Disnlacement 63 Ib., S.A. 1620 sq. in. When she was put into the measuri ng tank, however, she was found to float much below her marks, and was about 5in. too long on the L.W.L. With 7lb. removed from her keel, the L.W.L. was reduced to 56 in,. but with reduced Displac ement and increased L.W.L. the S.A. had to be cut down — —s rwemeienre etreewer” a ree aa to 1460 sq. in. It remains to be seen how she will perform with her canvas reduced in this drastic fashion. She is a pretty boat with sweet, easy lines, so she may do quite well. Yet the fact remains that she is entirely different from what her designer intended, and it leaves one wondering how an experienced designer came to make an error of this magnitude. Possibly his nlanimeter was out. of adjustment. Now busy designers, whether of full-sized yachts or models, almost invariably use a planimet er to measure section areas for the calculation of displace- ment. For the benefit of those who have never seen one of these instruments, I may mention that. this is an extremely ingenious instrument invented by J. Amsler, a Swiss. It is rather like a vair of compasses, but one leg has a pointer. This pointer is run round measured, the and nerivhery the area of can the then figure be read to be off the gm ents ieee 2 by, | a, we Te ” dials. There are several ways in which a planimeter reading can be checked. One way is to set the dials at zero before running the pointer round the figure clockwise. After the dials have been read, the pointer is again run round the figure, but this time anticlockwise, when the dials should be exactly back at zero. Nevertheless, however carefully readings are taken, there is often a slight variation. Hence another method of getting a reliable measurement is to run the pointer several times round the figure, and take an average of the readings. After much use, the friction wheel gets worn smooth, and this will throw the readings out. Likewise, the other moving parts may get out of adjustment. About a year ago, I found that my own instrument was running fast and over-measuring. In consequence, floated a below model her from designed one of my own L.W.L. built exactly to the calculated weight. I was puzzled about this, and re-measured her lines several times, besides t. pee we: {f tracing paper. With this, I got an entirely conclusion my plani- impossible to weigh a yacht, or to know exactly what any part of her weighs, except perhaps the ballast. Of course, with experience, a pretty close estimate can be made, but the weights of woods vary even when they are of the same kind. With a model we can weigh the boat at every stage of construct ion, and the finished yacht goes on the Measurement. Hence with models at accuracy in displacement scales for all events, calculations is all- important. How far these calculations can be out on a fullsized yacht is shown by the fact that after she was launched, one of the British Challengers for the “America’s” Cup was found to be below her marks. To rectify the matter, no less than 5 tons of lead had to be removed from her keel. This error was roughly an error of about 4 per cent. In the case of my own model to which I referred above, the error was between 4 and 5 wer cent., but in the case of my friend’s A-Class, it was an overmeasurement of 124 per cent. * * * Many model yachtsmen will remember Mr. J. P. de Freitas of Portugal. Recently he wrote to the M.Y.A. and said that he did not think he would ever be able to attend a Regatta here again, and as a memento of the happy times he had passed, he enclosed a cheque, and requested the Association to purchase a cup with it. This is a very charming gesture for which we all thank Mr. de Freitas very warmly. In donating this cup, our friend stipulated that it was to be named the “Little Portugal’ Cup, and was to be a perpetual Challenge Cup, which was to be used as a Consolation Cup for A-Class skippers. An annual race will be held, commencing in 1957. Skippers and boats, that have never won either the British A-Class Championship or the “Yachting Monthly” Cup, will be eligible to enter. The race can be held on any U.K. water, except the two (Gosport and Fleetwood) which are used for the two major events. Districts, or individual Clubs which wish to stage this race, can apply to the M.Y.A. Council, stating convenient dates, etc. The idea is that as far as possible this cup will circulate * * Since the A-Class formula was drafted in 1922, model yachtsmen and designers have tried to solve the problem of what type is most advantageous under it. The 1955 Fleetwood Regatta gave us no information on this point owing to the long spell body plan yet again, but this time used a sheet of different result, so I came to the ‘planimeter was in need of overhaul. took since these instruments are nowadays very expensive , the cheapest model costing over £20. Of course, in the case of a full-sized yacht, I am somewhat doubtful whether meticulous accuracy in displacement calculations is of any great value. It is * most carefully checking my calculations, but always got the same result. In the end, I measured the squared I round the country, and not to be associated with any particular water (or waters). To avoid this, it will not be allocated two years running to the same water or district. designs though But when is a costly business. However, it is well worth while, rey FRIEND of mine recently took deliver y of a A-Class yacht. confirmed, and its overhaul cost me rather over £5. The repair and adjustment of planimeters is a job for a very skilled specialist, so an overhaul oi, new little meter to the instrument makers, my suspicion s were PLANIMETERS, PORTUGAL & PROBLEMS NS As a result we took some weight out of the boat, reducing her displacement to the figure obtained with my 426 AUGUST, of fluky winds, which introduced such an element of chance. On the other hand, the results proved the value of good handling, and the importance to a 1956 displacement gives the highest S.A. : Displacement ratio, so theoretically, the lighter boat should have the advantage, especially in light winds.. Yet this does not always work out in practice, as some heavyweights put up remarkable performances in light breezes. It is, of course, possible that up to a certain L.W.L. length, it may pay to take maximum displacement and thus get maximum S.A., but once skipper of knowing his boat intimately. It remains to be seen whether the 1956 Regatta at Gosport will prove more enlightening. The questions to be answered are:— (a) What is the maximum L.W.L. length for an all-round boat? (b) Should Displacement be the maximum allowed for the given L.W.L., or the minimum, or somewhere about the mean of these extremes? In this connection, we know that the minimum this is exceeded, the designer must fine his lines and reduce wetted surface area, even at the expense of being lighter and sacrificing S.A. In any case, I think it can be assumed that extremes do not pay if we want an all-round boat. _ i THE RIGHT TACK (continued from page 42!) unnecessarily long and even erratic course. What tends to happen is that a change of wind direction causes the vane gear to move auickly, and “overshoot”, i.e. swing beyond the optimum point, oversteering the yacht, and then swing violently back, when the yacht has gone too far off course. This “hunting” action is characteristic of all servo systems. In elaborate equipment, devices are used to damp out or cancel the tendency to over-swing, but on a simple device like the vane gear, we have to suffer this defect, and minimise it as far as possible by simple means. If all the parts of the gear are heavy, such overswings are likely to be greater than on a lightweight gear, and this emphasises the need for reducing weight as much as possible. A “sticky” pintle or tiller movement wil cause similar effects. The centring tension line can be used to provide “damping” to the vane action, and this, used in moderation, with a slight additional helm imparted by vane angle adiustment, should enable a reasonable course to be sailed. A large feather and small linkage ratio would lead to trouble on these variable winds, so this test is also a cross-check on the decisions made in the previous feather size and linkage ratio. one, in respect heavy gusts, we are indeed fortunate—most probably, however, she will luff considerably in the squalls and fall away whenever the wind force drops. If so, the tensioner should now be brought into operation, and the vane feather removed a few degrees forward. This means that between gusts, the tension will overcome the additional helm resulting from the change in vane angle. In squalls however, the extra wind pressure on the vane feather will overcome the tension and apply additional helm. in feather size will be necessary. Note that this test and the previous one are concerned mainly with feather size rather than linkage ratio; the previous test might indicate a need for a smaller feather, and this test might suggest a larger one. The conclusion may be reached that an overall compromise is impossible, and alternative feathers for extreme conditions may become necessary. It is worth repeat- ing some of the previous tests to obtain an overall compromise, but with some yachts it may not be possible. I know of at least one very successful yacht in this category, and although capable of performing satisfactorily under all conditions it needs a choice of three feathers to do so. Having carried out as thoroughly and systematically as possible all the foregoing tests we of If a reasonable course can be sailed, with the vane feather moving gently but positively with each change of wind direction, the yacht can be passed for the next test. For this check we need a strong, preferably gusty, quartering wind. This is the most difficult point of sailing with the vane gear, and the one where the tension line can be of great value. The course-holding qualities of yachts (apart from their steering gears) vary widely under these conditions. In general, the shallow beamy type performs well, and craft with their keel deadwood centred well shall end un with either of the follow- ing two sets of conditions:— (1) We have a feather size and linkage ratio which give an adequate performance under all normal conditions, and, with care in setting and in use of the tension aft, also steer better under these conditions. The deep narrow hull, however, tends to heel excessively, and the yacht dips its mainboom in gusts. As a line, we can do all we need without altering either. (2) We have certain conditions which need an_ alternative feather, result it tends to broach easily. So it would appear that this test is one concerning the hull rather than the steering gear, but the fact remains that whatever and/or a change in linkage ratio. we have learned from our tests the natural tendencies of the craft, we still have to make the best use of the steering gear under these conditions. As a first trial, the yacht should be set up with its sails trimmed to sail with a wind on the quarter (i.e. a “true” wind 135 degrees or so from the yacht’s course). Both booms will be set at about 145 degrees, and the vane feather at about 50 degrees to its forward centre position (see Fig. VI). The behaviour of the yacht, as she sails, should now be noted carefully. If she holds her course well in If we can easily secure a trim in this way which will enable us to sail the course satisfactorily, we can consider the gear to have passed this test. If it fails, an increase what those conditions are, and what changes when they arise. are mecessary the onwards, this point From tuning-up operations comprise attention to finer points of sail trimming and vane adjustments, and the acquiring of greater familiarity with the behaviour of the yacht under varying conditions. : 427 ee ON
