Model Yacht Designing, Whilst Not Everyone will Ever Aspire to Designing Their Own Yacht These Notes Will Provide a Background to Enable the Average Skipper to Appreciate What Lies Behind Any New Yacht Plan He is Offered. By John Lewis.A Yacht Query, Which M to Build? .
VOLUME 4 NUMBER 4 APRIL 1954 Model Railway Number with Beal on TT Railroading, Carter on Railway Structures, “Crested Goods” 0 Gauge “Ella” Contest, Prize {£10 Steam Learner’s 3} Gauge Passenger Hauler, Radio Also: Collection. Overhead Control Model Parker-Bell Fourteen Six Launch, Model Yacht Design, Model Cars for Novices, Supercharged !0c.c., Model Motorcycles, Reader’s Letters. We APRIL,
= beautiful DECK LINE ‘A’ shape of stem is produced by the combination of two curves with a distinct “chin” be- tween them. This is made clear in dia- gram 5. The effect tiers MAX. BEAM 115″ = ae ee \ ; 3 TE STERN 4 : } 4 SECTIO! a ~ , 227 – FOR ‘M PR AEE La cx 763 soo” ; \ Se oa ee “Le: FoR 8 Fi ft Sy ae ae at por ‘c’ * fact | i et MAX. BEAM 12°07 COMPARISON OF ; | rane ae ———————— Tea ate = olr ete 55° LW. AREA OF PROFILE 18! SQ. INS. DECK bow overhangs of 10 iy ac Eane ; 8″ DECK LINE LINE ‘C’ Fé, 2 6 t $5.0″ i hg Ve) / —-“=— 7 6 5 * LWL. AREA OF PROFILE. 190-0 $O.1NS Se Seen 8s = re and length of the most uw 4 3 2 r) po about the profile, class yachts. The © me Be “A sesae 50-0″ j Fia I (5) word 10-raters and “A” 50° LWL_ aa j ee poe r < boee ward at a slightly fs greater angle than 10 ex ti ag Te AREAeeOF PROFILE: 201-5 SQ.: INS. Fig /(@) of to Sees Cae eee en Sie is not very much [* po <= Gr re can be done that about it from an i 50:0" 10-0” | have MnEnanA RADWS OF CURVE A t ° Sal um. Fig 2 i EEE transom is the result. This 1954 MODEL MAKER) Sketch 1. File the shanks of the buffers so that they do not protrude from the rear face of the beams and glue them in position. Assemble and fit the couplings; it will be easier now than when the main decking is in place. If you are using an acro springing unit, be taken to mate the five pieces by cutting them to the correct angles or to adjust them by filing after cutting. Glue into position on the underframing. If you are using outside bearings for the wheels, drop them in position in their slots, or a similar home-made job, now is the time to fit the wheels. The Acro Unit should be cut in half across its centre line hole, and the two halves glued and screwed to the top side of the false floor, using tiny wood screws and washers, so that the axle coincides with the marked position of the axle on your side frames. Do not worry at the moment about getting the correct axle bright—this can be achieved by judicious bending when the and glue keepers across the bottom of the slots, made of 1 mm. strips of well-shellacked card. No strain falls on these keepers, and they are merely to stop the wheels dropping out each time the truck is lifted from the rails. You will also have to file a vertical groove in the back face of the axle guards to clear the axle ends. Glue the axle guards in place with Durofix. Now cut the 12 triangular thrust plates which extend from the edge of the decking to the bottom of the sides—6 for each side. Glue them in place. Drill holes in the deck to take the load anchoring rings, and fit the rings. These are made of fine wire, and the “split pins” which hold them in place ate made of the same material. The buffer hoods are cut from shellacked card, and stuck in place. Paint the wagon with one coat of primer, and finish in standard wagon grey. Loads for your wagon ?—why not a Dinky toy steam roller, or a small ship’s propeller in suitable stripwood cradling ? wagon is complete. With a wood built model. I think it wiser put a lead or brass block in the centre division under the floor well to give the finished to wagon extra stability—it is inclined to be light otherwise. Glue this in position between the two centre crossmembers. Cut the 5 pieces of ply to form the decking of the wagon, and scribe to represent the planking. You could use good quality card for the deck, but I think, all things considered, that ply is better material, as a certain amount of strength is required here. Care will have to > es detailed the steps taken to ensure the boat’s balance and freedom from vice. Her plans include her Curves of Areas which indicate a well-balanced and easily driven hull. 3 In L-W.L. article on “Tonga Belle”, Mn. Lewis and his drawings do not include her Curves of Areas.- Appearances in the small reproduction in the magazine may be deceptive. but shoulders and quarters do not appear to match exactly, and [ should not be surprised to find a quite considerable amount of movement aft in the C.B. on heeling. With Mr. Lewis’s permission, I would like to examine the AK YACHT interesting theory which leads him to rake his rudderpost forward. Mr. Lewis tells us that this saves a few square inches of wetted surface, and gives “ maxi- QUERY W HEN the Editor of this magazine decided to appoint Technical Consultants for various branches of modelling, he honoured me by asking me to assist on the model yachting side, and in particular to neply to readers’ questions. QUERY:—As a beginner, wishing to build an Mclass yacht, which design would you recommend— “Saida” (D. A. Macdonald) or “Tonga Belle’ (J. A. Lewis)? And why? ANSWER:—A first boat should not present unnecessary difficulty in building, and when complete, she should be easy to handle and dependable. Therefore, I unhes:tatingly plump for “Saida.” In the article which accompanied the design, Mr. Macdonald his ignores the important matter of balance completely, mum blade area for a given skeg and rudder combination.” TI fail to see how this can be, or any advantage in wetted surface or blade area can be gained by raking the rudderpost in this fashion. The enclosed rough sketch shows a skeg and rudder, approximating to “Tonga Belle”. On this I have indicated a normal vertical rudderpost by the broken line. Comparing the two rudders, the one with the upright post has lost a small triangle at the top and gained one at the bottom. I cannot see that there is any material difference in the areas, non is the total wetted surface area affected. On the other hand, by straightening the rudderpost, the blade area is increased at the bottom where it is most efficient because it is less masked by the hull. It has also been found by experience that steering gears (Braine or Vane) function best with a vertical tudderpost, as it makes a better mechanical coupling with the steering gear. H. B. TUCKER. 234
