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Vviodel HOBBY MAGAZINE U.S A & Canada Seventy-f ive cents Ee, PRICE 15p JANUARY 1972 Pe:“Pp co} af MODEL BOATS STAR-C ‘MODEL BOATS’ NEW 42” ONE-DESIGN R/C YACHT CLASS PART TWO – BUILDING BY VIC SMEED (obviously more if you have to send away to a metal merchant), sO we are somewhere between £10-£11, plus sails and fittings; final prices are awaited on these, but in total the entire boat, less radio, should come out at under £20 and require only a week of evenings to complete. Money can be saved by using scrap lead, ex-aerial tubing for mast and booms, and making one’s own fittings, on the Starlet style. If you wish to make your own sails, two articles showing how have appeared in the last year, so that it would be possible to have the boat on the water, less radio, for about £10, which is pretty moderate for a new FNHE aims of this relatively small class for R/C yachts are to produce (a) a boat satisfying the general opinion of what constitutes a nice-looking model; (b) a conveniently portable model which is still large enough to sail well and not look like a cork out on the water; (c) a relatively low initial cost and a minimum of frills to keep sailing costs low; (d) a model capable of accommodating any reasonable R/C outfit; (e) one capable of being processed by simply putting it on scales and checking the head-tack-clew dimensions of the sails; (f) one which can, if preferred, be sailed by vane steering gear; (g) one which yacht of this size. Some people feel that they can economise still further by using single channel radio. Certainly, by using rudder only and setting the sails at about 40 degrees, the boat can be sailed on any course, but inevitably it is going to sail far less efficiently. Endeavouring to arrange sail setting by quick-blip secondary actuators is possible; one would be best advised to use a four-position two neutral secondary actuator, closing circuits on the two active positions to drive the sheet motor one way or the other, but this is rather gimmicky, and would lose too much time in racing to make the boat competitive. Obviously, superhet radio is necessary to sail races, and interchangeable crystals are desirable so that the chances of avoiding frequency clashes in tournaments are at a maximum. While proportional radio is valuable, reed radio is perfectly acceptable and can be bought second-hand in good condition for, often, the price of new single-channel superhet gear. We will be discussing the installation at a later stage; in the meantime, let’s consider the assembly of the hull. There is a relatively small amount of woodwork to be dealt with, the first stage of which is to cut and fit fashion pieces in the bow and stern. A detail sheet for fitting out is available, and the shapes of the fashion pieces can be seen. They are cut from in. obeche or a similar light but close-grained timber, chamfered to be a reasonable fit, and glued into the hull with epoxy resin or Plastic Padding. It is always advisable when gluing to cured g.r.p. to scratch up the surface with a fragment of hacksaw blade or some similar tool (even coarse glasspaper) to ensure a better key for the adhesive. The size of the fashion pieces is such that 36 in. lengths of spruce or obeche will fit neatly between them, allowing a shade for trimming. These are 3/16in. x in. and are glued inside the top edge of the hull shell, clamping with clothes pegs while the adhesive sets. The hull comes trimmed to the sheer line, but the inwale strips can be used to check that the line is fair and any high spots sanded off flush to the timber after setting. Deck beam positions can now be marked and small involves no special expertise in construction; (h) reasonable performance — good enough to make it interesting to sail. Not necessarily in that order of priority! With regard to (a), this is largely a matter of personal taste. We tend to have rather a jaundiced eye, especially with regard to our own creations, but certainly we feel that this boat is pleasing, having lived with two or three hulls in the office for a spell. At a cost of a few ounces, a scale-type coachhouse and cockpit could be built on for those who prefer semi-scale appearance, and we will sketch a suitable lay-out in a later article. Size-wise, (b), 42 in. l.o.a. is a compromise between a current model yachtsman’s idea of small (about 60 in.) and a newcomer’s idea of big. It has been said by experts that nothing under three feet can be made to sail consistently and well, and although this is arguable, at 42in., 33 in. on the waterline, we are not down to ‘toy boat’ size. Derigged, with a mast length only a bit over four feet, portability, even on a bus, is no problem. Cost is, of course, a relative factor. Radio is inevitably the biggest item; the average power boat without radio but including engine costs £20 or so, and this has proved no bar to popularity. If the cost of a yacht can be kept below this, with most of the work taken out of construction, there can surely be little objection on grounds of price. We have arranged for glass-fibre hulls to be available (they are now) and the price of a hull plus two half fin mouldings is £6.70. Packing and carriage, about which little can be done, costs 80p. The standard ex-stock hull is white, but colours can be produced to order, remembering that this adds a few days to delivery. The mouldings are produced by a firm local to us, Wavecrest Boats, 18 Alexandra Road, Hemel Hempstead, and orders can be sent to them direct. If sent to us, we will simply pass them over. As mentioned last month, the design avoids casting lead, and sufficient sheet lead from a builders’ chant will cost around 75p. Deck ply and other ber, say, another 75p, adhesives the same again. minium tube for mast and booms about mertimAlu45p 18 WRAP ER LEADFOR i HALF FIN PORT 47 ieAlfaBGt W&1BE43Tl2/bsN DE8CKMA“ST,4BIOL SMTARIUiN iOth WRALPED= a | 1|\-} STRU MAIN t= (MPINECUS TE|MPLATE > \| STRUT VERTICAL rfe=pS eea SHleES 7.— |I t Hempsteade,HemlSt,mBeridge13-5 MOULDSIHNEGST.IN&F FIHUTL GNLGASH—UFILBRE |WIRNASPDE 0 2 BEAMS DECK | WIDTH HARDWO DOR 1/4″PLY STRU MAIN H3RAOS/6ETD”WPULY SLHIODWWN/TBOWXITFHO DBOXTWRIANDCIOO STRUEAPD.|) 34″16|I ae 4 FIT NGS 8 4 7J | FIT 10 INWALES OBECHI wet HOLPERSALDIMBERTFWOERNFISLPEATC ULEAV&H SPREADER HERE FITS BE MUST GWEEAIRGHTRIMCOODFELWETIOGHATL LEATDAOIWRISTPHACFIEL) oz bs —i HUL FIN,SKEG, LEADS -I POWLIYTSHTYFRRIENEMNOAFEINTAOXIPPRGASNPFADICELE BOX R/C SUIT TO CARUNE 3/8″ * 3/16″ MB81AS”TE ty ‘a W”STAR—C” ITH USE FOR 1HALEFINSTBD| byS| TAPE’GLS ates 4 PAINT 15 SGETCFR/AOPNMLY6B”ESASRUDCCEKFefebp?—83BA2SrGaRlUBSmsyHae on i= f j\1! i1|I}| BEAMSDBECAKMSRDCIKVETOTONWALS CH :N KaOzEae oes e1spoi0tSa = a-— S e sLTD,PUBICSAMEONDSVILCEDby&dMOignCSopTyArRige-hCtts al: ¢* . HemlStr,Bidg13-5PINLv|STRUPEApfnre.Mepf,okst45dicalm‘12@p,4| oMst45requcdifavl|b1ME2Bh8RSA,FT&tMOeJoINfinSsFulC-zHr.egmpoxtad,l JANUARY \ rt 1972 Dec1971 MODEL BOATS slide in the after strut, and fit the sheet of lead snugly in place. Then check the main strut for fit inside the lead. If everything is O.K., untape the halves and epoxy a strip of 1 in glass tape down the front edge of one half, leaving half the tape width projecting. Epoxy the rear strut to this half, then epoxy the lead in place; although lead is greasy, epoxy resin will adhere to it if it is clean and slightly scratched with glasspaper. Now epoxy the main strut in place, then apply resin to the appropriate areas of the second half shell (especially the trailing edge), lower it in place, and tape the whole unit firmly together. Poke down through the open top to ensure good contact of the l.e. glass tape and the lead. Leave to cure. We now come to (d) and (e) of our introduction, and a simple sum for you. Any radio of up to 1} lb. weight can be used, the lighter the better, of course, and the completed model should weigh—and this is suggested as a firm one-design rule — between 11} and 123 lb. Let us work on the mean figure of 12 1b, and subtract from it the weights we know or can estimate rebates made in the inwales to accept the ends of the beams. The beams can be traced and cut (3/16 in. obeche or spruce) and glued in place, checking by eye from ahead and astern that they form continuous curves to make seating the deck straightforward. Trace and cut two skeg shapes from 3/16 in. timber, angling the grain of the wood differently for each. Excellent timber for this purpose can often be found in the wood backing in old picture frames, which can closely. Hull, with fin mouldings, skeg, 2 1b. 10 02. 14 8 4 4 4 rudder, deck beams Mast, booms, sails Deck Fittings Paint (mostly deck varnish, etc.) Radio Box be picked up for next to nothing in auction sales or junk shops. This wood is thin, knot-free, and could hardly be better seasoned; sometimes it is mahogany but is more often one of the pine or fir family. Cut the two skegs and chamfer the after edges as drawn, then epoxy them together, leaving to cure on a flat surface under a flat weight. Cut a length of 4 in. brass Total 41b. 12 oz. Subtracted from 121b., this leaves 741b. for lead and radio (or lead and vane gear, if you want to sail that way). The radio we expect to fit weighs 14 0z., so if we allow a couple of ounces for a trimming weight, we are left with 64 1b. of lead, or, if we go for the top tube (the thinner the wall the better) and carefully cut away the bottom section to leave a half or a little less integral, as drawn. Epoxy this in the V left by limit of 124 1b., 64 1b. of lead. With the average 36R yacht of a year or two ago, a similar waterline length to Star-C was usual and a 12 ib. boat (the limit in this class) would expect to the chamfers in the aft edge of the skeg. Sand the exterior wood to section, leaving the little curved fillet for the moment; this could be omitted or added as a separate scrap later. Mark the hull carefully and drill a 4 in. hole in the centre of the rudder post position. Enlarge by drilling or filing to accept the tube, then mark and saw and file out a slot to pass the skeg. Slide the skeg into the hull and locate the top step in the deck beam. Check carefully that the skeg is absolutely vertical and in line fore and aft, then epoxy in place. Finish the exterior shape, remembering that the bottom pintle plate has yet to be fitted. The fin comes in two halves, ready trimmed, and the hull at the fin root is stepped to make a nice fit. Fin section is designed to have two lines of constant thickness, and on these lines are positioned the main and rear struts, the latter also doing duty as a limit to the rearward position of the lead. ‘Dry run’ assembly by taping the fin halves together with plastic insulation tape. What we have to do is fit a sheet of lead inside the bottom of the fin (see sketch), fit the main strut inside this, fit the rear strut between the glass fibre halves, and insert a length of tape, if possible, up inside the fin leading edge. The thickness of the lead sheet is immaterial, except that it will affect the width of the main strut at its lower end; the idea of using the sheet in this way is so that it takes any strain from the remaining lead carry 7lb. of ballast on a draught of about 8} in. Thus, our 6-64 1b. carried on an 11 in. draught gives us a slightly higher degree of stiffness. If anything, we have erred on the heavy side for weights above, since it is easier to add an ounce or two into the fin than to try to reduce weight. Incidentally, if you do fancy vane sailing, a 4.0z. vane 15 in. from the C.B. is the same as a 15 oz. radio 4in. from the C.B., so trim should be no problem. There is bound to be slight variation in individual model weights, so weigh your equipment and work out the right amount of lead. Add 5 oz. to the total (the weight of the g.r.p. fin halves) and cut up lead sheet and pack it solidly into the fin, ahead of and abaft the main strut, until the fin weighs the required amount. Run some epoxy in to secure the lead pieces in place, then cut up a polystyrene tile and fill all vacant spaces inside the fin. Two ways of attaching the fin suggest themselves. The first is to cut slots in the fin base on the hull to pass the struts. Smear epoxy round the base, slide the fin in place, and glue (and screw, if you wish) the struts to their respective hull members, the main to the deck beam and the rear to the spreader glued in the hull. Make sure the fin is absolutely vertical. The second, while basically the same, means leav- ing the top of the fin empty and cutting away the flat area of the fin base. Now when the fin is in place, a glass cloth or tape strip can be wetted all round the inside, firmly bonding the fin to the hull. This should commend itself to the belt and braces brigade! packed inside it, rather than putting the strain on the leading edge. joint. If the boat was dropped a few inches, even put down heavily, it would be an embarrassment if the fin split! Step one is therefore to tape the halves together, 20
