- Description of contents
© Gas MODEL ENGINEER EXHIBITION REPORT r; oats MARCH 1970 THREE SHILLINGS ae U.S.A. & CANADA [uis> HOBBY MAGAZINE MODEL BOATS FIG.1 Triple LAMINATING BACKBONE TO PROFI 6 LAMINATIONS OF VIG” MARINE PLY | fag the” NAILS , DIAGONAL PLANKING of a round-bilge hull PROFILE OF BACKBONE CUT FROM 1/2″ PLANK Part one By G. Keeley be more uniform, with less wastage, and I should imagine that approx. 20 sq. ft. would be adequate to build a Marblehead. Any flexible, long grained veneer is suitable, and the price from D.I.Y. Shops somewhere in the region of 1/3d. per sq. ft. I first perused ‘Boat Modelling’ (August 1964 edition), Vic Smeed’s invaluable ‘Bible’, reference KEEL SLOT to which will be made from time to time during this article, and I would underline that this little book is a must for a marine modeller of any description. Information on diagonal planking was limited, however, | HAVE been interested in model yachting for many years, but having really been bitten by the bug in 1966, I decided after studying the M.A.P. Plans Handbook to build the popular China Boy Marblehead, a hard chine design by D. A. MacDonald. This is an ideal first model, as the plans contain a reasonable amount of construction detail and there is also a separate sheet of fittings and rigging details available especially suitable for the design. The design is, however, now 10 years old and although excellent as a first model, it is not really competitive in top class club competition. I was, therefore, persuaded by fellow members of the Newcastle M.Y.C. to tackle a round bilge hull, and the Caller Herring 10 Rater design by J. Lewis was chosen. It had been my intention to build the hull by the orthodox rib and plank method, but several factors changed my thoughts. In 1967 I spent a couple of days at the ‘A’ Class Championships at Fleetwood, and was fascinated by a beautiful example of diagonal planking with veneer on a yacht called, I think, Trilby. A conversation with the skipper indicated that an extremely strong and light hull was produced by this method. There seemed some comparison with model aeroplane construction in that formers and stringers were used, and as I had dabbled in aero- modelling in my youth, I felt that this experience would be useful. About this time I had reason to visit the warehouse of a local dealer and importer of plywood, and was delighted to see large quantities of scrap veneer which is used as a protective exterior wrapping to the crates of plywood. This was quite literally scrap, and as such, burned or otherwise disposed of, and I had no difficulty in obtaining suitable quantities. Exactly what wood it is as it was in ‘Model Sailing Craft’, by W. J. Daniels and H. B. Tucker, which, although, some years out of print, can often be obtained through the local lending library service. With some trepidation I decided to press on, and the following is intended as a description of the methods I used and the snags I encountered. It is not intended to be a definitive statement of exactly how and how not, merely a résumé of methods I have used and found satisfactory. (1) The setting up of the building board and shadows are described in Boat Modelling Chapter (4) (fig. 37), but it should be remembered that with diagonal planking no ribs are required, and the shadows should make allowance only for the finished thickness of the hull (approx + inch). They should be slotted to allow for the backbone, inwales and stringers, and to facilitate their eventual removal from the hull, the edges should be protected by candle-grease, Sellotape or some other parting agent. Stringers and inwales were of spruce, 3/16 in. and % in. respectively. The stringers should be placed not more than } in. apart and with this spacing at the midsection, several will run only part of the hull length. (2) The backbone was laminated from 1/16 in. ply to a profile cut from a thick plank. An old builders’ scaffold board, well seasoned and at least 14 in. thick, was ideal. This was cut with a coping saw and was very hard work. Access to a band saw would save a lot of sweat on this operation and ensure an n DECK BEAM |S) HATCH OPENING u nn. U I am not too sure, but it resembles gaboon mahogany and as such is ideal for the job. The fact that the veneer is imperfect and varies in quality is not important, as only small strips are required and these can be cut from the most OPENING CUT —FOR HANDLE BACKBONE suitable portions of the sheets. The thickness varies slightly but most seems to have a nominal thickness of approximately 3/64 in. If thinner veneers are he | : available, these would probably be even more satisfactory, as the finished hull would be lighter still. It seemed to me that here was a building method which above all would be cheap, and as time for modelling See “oe is limited, would enable work to be undertaken at any convenient time, and in small doses. If one buys veneer, the quality and thickness would, of course, 104 es FIG.3 SHOWING EXTENSION OF C.6 KEEL PLATE TO FORM CARRYING HANDLE @ ATTACHMENT TO DECK BEAMS MARCH 1970 — BACKBONE FIG.4 SHOWING TIE ATTACHED TO INWALES WOOD SCREW | STABILISING STRUT SCREWED y | |‘ \ UNDERNEATH TO INWALES BEFORE PLANKING BEGINS BUILDING BOARD \ accurate cut. I laminated 6 ply laths, which with the glue lines came out at a convenient thickness of approx 3 in. I did not have a supply of clamps available but found that glueing the laths, nailing them to the profile and removing the nails when dry was quite satisfactory (Fig. No. 1). The width and thickness of the backbone will govern the size of the slot in the shadows, usually } in. to 1 in. at the stem and stern and widening to 14 in. at the keel and midsections (Fig. No. 2). For adhesive I used Aerolite 306, which has proved most satisfactory, although any good waterproof glue, such as Cascamite, can be equally recommended. Aerolite is a two part resin glue consisting of powder and liquid hardener and is obtainable from most good ironmongers or Do It Yourself shops. Diagonal planking is rather heavy on glue and I would recommend buying the powder and hardener in bulk if obtainable rather than in the Handy Packs which are usually to be seen, but which are more expensive. One pound of powder and an 8 oz. bottle of G.P.B.X. Hardener should be plenty. A word of warning concerning Aerolite. The hardener, which is a solution of formic acid, reacts with ferrous metals to produce an unsightly stain and it should therefore be applied by means of a piece of cloth or felt wrapped around a small stick of wood, and not with a brush with a ferrous metal band. VENEER PLANK “DIVIDED FG 5 A & VENEER PLANK a FLAT | | | The backbone can, of course, be cut from the solid, and this may be necessary for a design with a full garboard, but all my efforts have concerned models with plate and bulb keels, when it is merely necessary to cut slots for the keel and skeg on the marked centre line, and to set these items accurately and vertically before planking begins. (Fig. No. 2). The keel should come through to the deck beams and incorporate a handle either below deck in a hatch, or above deck if no hatch is required. Try to ensure that the handle is directly above the centre of gravity of the lead in the keel, otherwise the boat will be uncomfortable to carry. The basic arrangement is shown in figure No. 3 and it must be emphasised that the extension of the keel plate and incorporated handle through the hull must be securely 105 braced or attached to the deck beams. Modern designs tend to have the keel and bulb configuration shown, and this puts a considerable strain on the back-bone and garboard not only at the root of the keel but behind the trailing edge and above the lead bulb (Area A-B on drawing). An important reason for laminating the backbone will be mentioned later when the removal of the hull from the shadows and building board is discussed. (3) Planking. The tendency of diagonal planking is to exert an upward pull on the backbone and an outward pull on the inwales, although this will depend on the grain and thickness of the veneer used. The backbone is sufficiently rigid because of the thickness allowed (Paragraph 2), but to stabilise the inwales they FIG.6 SHOWING CURVE OF PLANK | | | PL ANK AROUND AWKWARD SECTION (EXAGGERATED) Z should be braced with ties or struts as shown in Figure No. 4. These should be of the same material as the inwales (} in. spruce) and should be screwed to the inwales from underneath to facilitate removal later on. Flush off the ends of the ties so that they do not interfere where the planking will overlap the inwales. Before planking begins, the backbone and inwales will need to be chamfered and shaped to conform to the outline of the shadows. The length of plank required will depend on the size of the hull and the position of the plank on the hull (long at the midsection, shorter at the bow and stern). One inch width has proved suitable in almost all cases except where very sharp curves are encountered. A Stanley trimming knife and a steel rule are the tools for cutting. Cut them at your leisure as several hundred will be required, and remember that even thin wood like veneer has a natural bend, and always cut the planks slightly across the grain. This will facilitate a snug fitting around the stringers as planking progresses. Skin No. 1 (1) Fit a plank of veneer as a rebate along the centre line of the keel, flat as in Figure 5(a) or divided as in Figure 5(b), depending on the sections. (2) Take a plank (No. 1) and at the midsection fit (continued on page 113) PLANKS NO.3 N01 NO.2 w, = 2 i ra) x, a” m i] rs) ral FORWARD FIG.7 ———__________ MIDSECTION i oiacrawuaric (77 + PORTION OF PLANK OVERLAPPED, MARKED & SHAPED OT MARCH 1970 PXHE Monitor and similar vessels belong to the mainstream of naval Ironclad of the development, and even if they had never fired a shot in anger, would have had a profound effect upon the thinking in naval circles. The Mississippi Flotilla of ironclad gunboats was Mississippi Flotilla a very different matter, however. They were of simple design, fulfilled the task required of them, and when the war ended, were quickly disposed of. They had, however, played a very important part in the planning of the North. The chief figure associated with the building of the gunboats was J. B. Eads, who in April 1861 expressed his views on how to crush the ‘rebellion’, urging that a base should be established at Cairo, Illinois, with a strong river force supported by shore batteries. This would control the passage of vessels on the Mississippi and Ohio Rivers. This closing of the waterways to the Confederacy would, he predicted, block the main channel through which the South cbtained its food supplies. The only routes which would still be available, west of the Appalachians, would be the Tennessee and Cumberland rivers and the Louisville and Nashville Railroad. The latter could be sabotaged and the rivers, except in flood, could only pass small steamers, and_ their mouths could easily be controlled by gunboats. Captain John Rodgers worked with Eads to design the boats, but the association was not always a success. Eads, a self-made man with a flair for engineering, had once been a riverboat pilot and had experience of salvage operations, and had retired in 1855. He proposed to convert a salvage boat, the Benton, into a gunboat, but authorities objected. Later, the conversion was carried out and she became the most powerful warship on the river. Eads won a contract, with penalty clauses for failure to deliver on time, for the building of several boats, to draw 6 ft. of water, to be plated with iron and carry 13 guns, and to be delivered at Cairo. Shipbuilding in St. Louis had stopped, so that there Period Ships No. 44 The City Class shown in the drawing were built on a standard riverboat hull 175 ft. long and 51 ft. 2 in. wide. On top of this was a casemate with sides sloping at 45 deg. at the front and rear, and 35 deg. at the sides. They were 888 tons, had a flat bottom with three keels, and a speed of 6 knots. The armour, which consisted of charcoal iron, was 23 in. thick and was in plates 13 in. wide by 84 to 11 DIAGONAL PLANKING (continued from page 105) ft. long. The casemate had a timber backing 26 in. thick and the pilot house 194-12 in. The design weight of the armour creased was 75 tons, but subsequent additions inthis to 122 tons. There were two engines, which were of the reciprocating non-condensing type. The crew consisted of 17 officers, 27 petty officers, 111 seamen and 3 landsmen. In addition, there were 12 firemen, 4 coal heavers, and 1 apprentice. The armament was placed in two stern ports, three bow ports, and eight beam ports, four on each side. The guns were three 7 in. bore 42-pounder rifles, three 8 in. bore 64-pounder Navy smoothbore, six 32-pounder smoothbore, and one 30-pounder Parrott. The Confederacy was without the means to build an effective fleet, and consequently, used the methods traditionally used by a weaker naval power. They designed ‘infernal machines’ such as mines, and the ironclad gunboat Cairo had the somewhat dubious distinction of being one of the first victims in the Yazoo River. This boat was located a few years ago and raised, together with numerous artifacts which have provided valuable information regarding the running of these gunboats. A full account of the life and sinking, followed by its discovery and subsequent raising, has been given by one of the prime movers in this, Edwin C. Bearss, who has written a book entitled ‘Hardluck Ironclad’. was plenty of material available initially, though a shortage of iron held up the work in the later stages and he had a network of sub-contractors in the Ohio valley. The shortage of iron and a certain tardiness in payment of instalments by the Government were the reasons Eads gave for his failure to deliver on time. at approximately 45 degrees to the rebate plank (Figure 8(a)) and pin. Lay snugly around the bilge and pin temporarily at the inwale, allowing 4 in. overlap. (3) The next plank (No. 2) should also be fitted at the rebate, aft of No. 1 and on being drawn down around the stringers will be found to overlap plank No. 1. This overlap should be marked with a hard, sharp pencil (Grade 4.H). (4) Plank No. 2 is removed and the same procedure is followed with Plank No. 3 on the forward side of Plank No. 1, which, of course, is now marked on both edges (Fig. No.7). (5) The position of Plank No. 1 is marked on the backbone and inwale and the plank removed and shaped. (6) Plank No. 1 is then replaced and glued permanently in position only at the backbone and inwale, the stringers merely providing the contour which the plank follows. Only the midsection plank is shaped on both edges, and the procedure outlined above is now repeated, moving forward and aft, each plank being temporarily fitted, marked, removed, cut and then per- By P. E. King manently glued in position. I apply glue to the backbone and inwale and hardener to the plank. The fixing of the plank while the glue sets can be done with glass headed pins, obtainable from model shops. These are ideal, but as large numbers are required when the second and third skins are laid, I used plated dressmakers’ pins purchased in +} Ib. boxes. At each session of planking, one should try to glue equal numbers of planks, port and starboard, to balance any stress on the shadows or stringers. It is vitally important that this first skin should conform exactly to contours of the hull, this being more important than having a perfect fit between the planks. If a plank shows a tendency to lift slightly owing to the shape of the section at that point, as indicated in Fig. No. 6, it should be pinned and glued to the appropriate stringer. This is the only occasion on which planks should be glued to the stringers, as the stringers themselves will be removed when the hull is completed. Planks should, of course, be permanently glued to the bow block and transom. When all the temporary pins have been removed, the surface is sanded smooth with a medium grade glasspaper ready for skin No. 2. (to be continued) 113 MARCH 1970 17th RC 24th RC 31st SR RC 31st JUNE 7th RC 7th RC 7th RC 13th SR 14th SR SP 14th 21st SP RC 28th RC JULY 5th RC & P.B.C. Fleetwood M.Y. Lake. 11a.m. 2/6 per event. RCMULTI. Model Yachting RCSP, RCSTG & Leeds M.B.C. Roundhay Park, Leeds. 11 a.m. Fee 2/6 per boat. NORTHERN AREA SPEED ELIMINATORS & NORTHERN SPEED FINALS. 2/6 Noon. Park. Coronation M.C. Crosby covers all events. SR & RCSTG. Scarborough M.P.B.C. Full details later. Sunderland M.E.S. Roker Park Fee 2/6. RCSTG & RCSP. Liverpool M.P.B.C. Walton Hall 2/6 per boat per event. RC p.m. Park. 11 a.m. PAIRS NOM, RCSTG, RCSP & Concours & D.M.E.S. Tarn. Park. Park. RC ENGINE CHAMPIONSHIPS. Manchester R.C.M.C. Heaton 9th SR RC 16th RC 16th SR RC 30th 31st RC RC RC 13th RC 20th SR RC 27th RC OCTOBER 4th SR Fee 2/6 per boat. RCSP NATIONAL PETROL 4th RC 11th RC 11 Fee 2/6 per boat. RCSTG. NATIONAL PILOT CHAMPIONSHIPS FINAL. Crosby M.C. Coronation Park. Noon. covers all events. SR, NOM & RCSTG. 2/6 Liverpool M.P.B.C. Walton Hall Park, 11 2/6 per boat, Pe event. RCSP. a.m. Oldham R.C.M.C. Alexander Park. 11 a.m. 2/6 per boat. RCSTG, RCSP & RCMULTI. Sheffield S.M.S. Millhouses Park. 11 a.m. 1/6 per boat, per event. RCSTG, RCMULTI & STRAIGHT RUNNING. Manchester R.C.M.C. Heaton Park. 11 a.m. Fee 2/6 per boat. RCSTG & RCSP. Glasgow M.B.C. Sak aa Park. Noon. Fee 2/6. RCSTG, RCSPSTG & SR Ossett & Horbury M.M.S. Crow Nest Park. SEPTEMBER RC 6th SR Fee 2/6 PRE-ENTRY. NORTHERN AREA. MULTI: 19th RC 30th SR d’Elegance. Redcar RC 23rd ENDUR- Manchester R.C.M.C. Heaton Park. 11 a.m. Fee 2/6 per boat. RCSTG. NORTHERN AREA STEERING CHAMPIONSHIPS & PILOT ELIMINATORS. Keighley 2nd 2nd 23rd Roses Regatta. Featherstone M.P.BC Purston Park, 11 a.m. Fee 2/- one event, 4/- two or more. SR & RC RC 1 Tynemouth. Straight running and Hydroplanes. Leeds M.B.S. Roundhay Park. No fee. Annual 12th SP Lake. ANCE & RC SNOOKER. Sheffield S.M.S. Crooks Valley Dam. 11 a.m. Fee 2/6. 24 min. RCMULTI & Endurance. Heaton & District. SR Nomination. Maghull Trophy for Scale. RACING CHAMPIONSHIPS. Manchester R.C.M.C. Heaton 26th AUGUST 11 a.m. No fee. Wiest. Riding Annual Regatta. Fleetwood M.Y. & P.B.C. Model Yachting Lake. 11 a.m. 2/6 per boat. Fleetwood International Multi-Racing Championships. Sunderland M.E.S. Roker Park Lake. 1.30 p.m. No fee. Keighley & D.M.E.S. Redcar Tarn. 11 a.m. RCMULTI 1 hr. ENDURANCE. Fee details later. Pre-entry by the 5th July Leeds M.B.S. Roultthen ‘Park. 11 a.m. Fee 2/- per boat. RCSTG, RCSP, RCMULTI. Huddersfield S.M.E. Highfields. per event. SR, NOM & RCSTG. 1/- a.m. 11 Warrington M.C. Heath Park, Runcorn. 11 a.m. Fee details later. RCSTG & RCS. Crosby M.C. Coronation Park. 2/6 Noon. covers all events. SR, NOM, RCSTG. Nelson & D.M.P.B.C. Victoria Park. Fee details later, RCSTG & RCS. 11 a.m. Bradford & Shipley M.E.S. Moor Park. 11 a.m. Fee 2/- one event, 4/- for two or more. SR, RCSTG, RCSP & RCMULTI. Model Yachting & P.B.C. M.Y. Fleetwood Lake. 11 a.m. Fee 2/6 per class. RCSP & RCMULTI (including the L. FISH Trophy event). Hull M.C. East Park. 11 a.m. event, 4/6 two or more. RCSTG Fee 2/- one & RCSP. AUSTRALIAN MARBLEHEAD CHAMPIONSHIPS The Australian Model Yachting Association held their ‘M’ Class Champioceipa at the Nerang Lake in Canberra, on 5-6th April, owing to the weeding up of the’ Albert Park Lake in Victoria, the original intended place for the Championships. On Saturday, racing started at 11.30 a.m. with a very slight breeze coming from the N.W. After lunch the breeze strengthened slightly but only 6 heats were run all day. On Sunday, in more favourable conditions, the racing got off to a prompt start. After the 14th heat, the first two boats were pulling further ahead of the field and it was decided that racing would stop at 5 p.m. Third and fourth places were decided on the results of the resails. Photographs; «show, right, the winning and left, Colin Bell sponging out. Several yachtsmen_ have emigrated and are now ‘down under’. Final scores when racing ended were: 1. R. Dunster Sara Jane model, British active KA40 KS42 2. 3. C. Bell B. Hazeldine Black Magic Merrymac 4. M. Smith Thea KA1 5. 6. D. Middleton R. Hart Nautilus II Apple KA20 KA44 9. 10. 11. 12. 13. 14. 14. R. N. T. A. J. G. A. Jade Playtime Irion Inferno Shandar Steve Chris Sea U KA46 KA14 KS161 KA48 KA28 KA30 KA37 16. 17. 18. N. Lockhart P. O’Brien S. Crews Spray Lady Helen Legend KA21 KA47 KA31 7. 8. 15. M. O’Neil G. Langdown Gamlin Romeril Hemmings Brewer Pollnity Gibich Thompson G. Middleton Sybil Jeanie ‘ Nautilus 19. M. Ragot Bluey 20. H. Bennett Storm KA12 KS100 KA45 KA2 KA29 127 C. Adams Foxtrot Priest Witchcraft after Daniels Mosquito Littlejohn Elusive Witty Bosun Priest Witchcraft Witty Norma Own design Stollery Daredevil APMYC Hard Chine R. Dunstan Trison Own design Hollom Flamenco CMYC BMYC APMYC BMYC MSPBC OF SA CMYC For PT. OF GLASGOW CMYC BMYC APMYC Greenwich APMYC MSPBC OF SA 60 points SS 49 =C«z, 44 73 eee 403 ,, 40 _,, tS eon S025, Soo Sas} S255, ies Daniels Festive China Boy after Adams Pahie China Boy China Boy China Boy MSPBC OF SA BMYC CMYC SMYC CMYC FMBC 29-7 273 ,, 7 eee Dew: 25); 1003 MSPBC OF SA APMYC 30) 30 43
