Ships and Ship Models: Issue 78 – June 1954

TWO SHILLINGS JUNE —-1954 _% — , | The “A” Class Sharpie x and how to build her Ware the moulds are ready, but we may as well make the inner transom first and then erect the whole thing. The inner transom is made in one piece from $-in. pine. It will be seen from the drawing of its forward face (Fig. 11, page 138, April issue) that only a very small piece of wood separates the lower chine from the keel. If this should break off, it can be filled in with plastic wood or stopping when we come to fixing the chines. To erect the moulds, start with Section 6 and work forward to Section 1. Start again at Section 7 and work aft to the transom. When you come to the latter, you will find that owing to its rake, only the forward edge takes on the building board. As it is firmly held by the screws, this can be ignored. In erecting the moulds, align them carefully on the centre-line, and fix with two screws to the crosspieces. In setting up the moulds, remember that those in the forward part of the boat have their after faces on the station lines (i.e. against the cross-pieces), while those in the after part (including the inner transom) have their forward faces on the lines. One small caution should have been given about the ties on the moulds. These must be kept well clear of the edges of the moulds and also of the slots for the longitudinal members of the frame. Having erected the moulds, we can now turn our attention to the stem and keel. These are all made from 14-in. wood excepting the centre portion of the keel, which will be dealt with separately a little later. If wood 14 in. thick is not available, it will make an even better job if this is built up by gluing a } in. layer on either side of a 1 in. centre layer. I have mentioned pine as being a suitable wood, and by this I mean selected yellow pine, but kauri pine, obechi, or Canadian redwood will do just as well. In any case wood should be carefully selected, as light as possible, free from knots, bends and shakes, and with not too prominent a grain. It must be dry and well seasoned. The construction at the bow (see Fig. 6) page 103 March issue shows how the keel is rebated into the stem foot. This can be improved on, however, if the stem and forward section of the keel are being laminated as suggested. In my description I am assuming the latter to be the case, but the builder will easily be able to see the differences in procedure if making of wood 14 in. thick. (Continued from May issue page 185) =a 226 Make a full-size drawing of the stem, but continue the stem right down to the bottom of the keel. At the top continue right up to the datum line and include the ear for fastening to the building board. It may be as well to explain how the laminated stem is joined to the laminated keel. The inside members (the 1 in. thick layers) will be joined with the keel rebated into the forefoot as shown in our diagram while the outer members of the stem come straight down as we have just drawn and lap the inner member of the keel, thus making a sort of mortice, The outer members of the keel butt against the after edges of the stem outer members. Screw the laminations for the stem temporarily together, putting the screws abaft the bearding line so that the screw holes will not show. These screws will be taken out presently, so iron screws can be used. Square up the wood and plane the back dead true. As all our measurements will be based on this, it is important to get this absolutely accurate. a paper template from the drawing through on to one side of the wood. Make and_ prick The lines must be repeated on the other side of the stem. The rabbet and bearding lines are quite easy, but the angle at the top presents a little more difficulty. The after end can be squared across the back with a set square, and if you happen to have an adjustable cabinet maker’s bevel, this can be used. This tool is like a set square but the angle is adjustable. The angle at the top governs the way in which the stem sits on the building board. Not only must the angle be correct, but also it must be square across the wood so that the stem is at right angles thwartships to the building board. Otherwise our hull will be out of truth and could never sail straight. There is no need to clean up the sawcut on the stemhead as it all comes off later. Check this angel carefully with your drawing and also sideways with a set square. This should be done before cutting JUNE, 1954 SHIPS AND SHIP MODELS the stem profile, as at this point it can be re-cut if om “= necessary. Assuming this is all in order the stem can be cut out. Always saw outside the lines and finish down to the lines. Lay the stem aside for a while, and make the forward part of the keel in a rather similar fashion. Screw your laminations together temporarily and mark out your shape for cutting. This should be as in the diagram. The spare wood on the outer layers can be sawn off later. The joint between stem and keel should be made before anything more is done. In this way you will have flat surfaces for cramping up. Take out the screws that hold keel and stem laminations together. The holes will enable you to replace them when you are ready. Cut the notch in the centre layer of the stem to accommodate the fore end of the keel, and fit carefully. Cut off the ends of the two outside layers of the keel to butt against the stem. In cutting do not forget what has been said about cutting outside lines and trimming down to the lines. Get two dead flat pieces of wood and, using G-cramps, cramp your joint up tightly after gluing. The gluing is done with resin glue as previously described, and do not forget to put newspaper between the joint and the bits of wood. One + in. side and the centre pieces should be glued first, and when these have set. the other side can be glued on. The temporary screws have been taken out while you were cutting the joint, but can be re-inserted immediately after gluing and before you cramp up. This will ensure the parts being aligned correctly. When the whole has been glued together, these screws are finally taken out. If the positions for chines and inwales have not already been marked on the stem, this must now be done. Next we can attend to the keel section. Measure up on your drawing of No. 3 Section the height from the top of the keel to the outside of the skin planking on the side of the keel. This distance is the same for all sections. Set your marking gauge to this distance, and run a line along each side of the keel. Reset your marking gauge to # in. and, starting at the stemhead, run a line down the stem and along the keel. This is your centre-line. Next run lines down the stem, and along the keel } in. on each side of the centre-line. This gives you the $ in. width of the stem and cutwater. To shape the keel, plane off the corner from this 4 in width line to the line you put along its side. The joints between the 4 in. side layers of the keel and the centre member give the rebate lines along the keel if the keel is laminated, but otherwise these must be marked. The rabbet along the keel had better be left until later cn, but you can with advantage put a chisel cut along the rabbet line to the approximate depth of the skin planking (3 mm.) as this will help when it is actually cut. Carry this cut forward as far as the junction with the stem, but leave the rest until the boat is set up. The fore corners of the stem have now to be chamfered off from the rabbet lines to the lines down the foreside that mark the 4 in. wide flat cutwater. This can be finished off down to the bottom of the topsides (i.e., the upper chine, but across the bilge plank and round the forefoot had better be left until later. It is extremely difficult to describe the shaping in the region of the forefoot, but once the boat is set up and the planking on, it is obvious what has to be done and presents no difficulty whatsoever. The rabbet down the stem for the topsides can now be cut. This is the full depth of the 3 mm. planking at the rabbet line and runs out to the surface at the bearding line. Cut a small slip of the planking material and use as a gauge during this operation. Lay the stem/keel forepart assembly aside and make the after part of the keel. Mark out and cut as before, starting with the angle of the foot. Incidentally it may be mentioned that using a resin glue, there is no need to clean up saw cuts before gluing. Before proceeding with our keel, two points in connection with resin glues may be mentioned. The first is that to ensure a good joint, only sufficient pressure need be used to bring the surfaces of the joint in contact, but the greater the pressure, the more glue will be squeezed out and the thinner the joint will be. The joint will be equally strong either way. Any superfluous glue squeezed from a joint should be cleaned off with a rag damped with warm water. When a thin glue joint is needed, as in the bread-and-butter fin construction, the glue should be diluted to the Aerolite 301 consistency as already explained. It makes an equally strong joint. (To be continued) next month The July edition of SHIPS & SHIP MODELS will feature . . DRAWING BY LAURENCE DUNN This is another of the popular series by this well known marine artist and shows the general construction and special features of H.M.S. Vidal, the new Admiralty survey ship. NEW FEATURE BY ALAN VILLIERS The story of the Grand Banks Schooners of the present day on one of which the author spent a whole fishing season. This is the first of three instalments. THAMES STEAMERS This is the story of the General Steam Navigation Company of London which employed some of the earliest steamships and which later owned the famous line of Eagle Paddle Steamers which were so popular with Londoners and visitors from all over the world. PHOTOS OF BRITANNIA These were specially taken by the editor pective builder of a model of this ship interesting deck detail which is not easily The boats and davits are also shown in to provide the proswith the wealth of shown on a drawing. considerable detail. You will not want to. miss this issue so we advise you to . 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