- Laminated Hull Construction Part II. By F. A. Boardman.
VOLUME 3 NUMBER 36 NOVEMBER 1953 IN THIS ISSUE : Model Transporter Truck for 0 Gauge : Freelance Sentinel Shunter for 00 Gauge : The Dean Magneto : A Model Volkswagen for Electric Drive : One Piece Metal Hulls : Battery Capacitator Flashgun : Improvements to an Old Lathe : Indexing Attachment : Bodiam Castle Modelled : 24cc. Racing Hydroplane : Simple Radio Control for Boats : European Car Meeting Photofeature : “Gerry” 0 Gauge Steam Loco : Pédstead Railway at Grimsby : Laminated Hull Construction : Water Mill : Signal Box in 24 mm. Scale : Test Bench : Prototype Parade—Jaguar Mk. VII ————— — _ November 1953 Laminated Hull Construction PART TWO: BY F. A. BOARDMAN ‘pee next step is to fit and lay on the ribs. Take a piece of 1mm. Aircraft Plywood offcut about 18in. square and cut off in 3 in. strips with the grain. It may be cut with a marking gauge leaving a clean edge with no waste. Com- mencing with the centre section, let into the backbone down to the level of the shadows on the side you are working, cement and pin, using Lin. x 22s brass fretwork pins. Make sure that the rib is sitting on the shadow then cement and pin to the inwhale. Complete this for all shadows Above: Interior view of canoe body. Deck beams are just being fitted, and the centre pair have crosspieces, which will ultimately take hatch. Finished canoe body. Note then recheck with a trial plank. The backbone has now to be cleaned down to the level of all the ribs (see photo). At this stage, before commencing the actual planking, take a piece of mahogany or similar wood, the thickness of the finished planking and } in. wide (in this case it will be 2; in. by { in.), cement and pin this on the after section of the backbone. This is to form the rebate for the planks at the after section only, whereas on the forward section the planks run past the backbone. This rebate may be added at a later stage of planking, use of protective cloth to prevent bruising Below: Close up of method of fitting ribs. Below centre: Details of skeg fitting in the interior. Below bottom: Hull, with moulds fitted and ribs in place on one side completely as mentioned below. With the body section drawing before you, set out the planking using the diagonal lines wherever possible as a guide. This is in order to give you an idea of the various widths of the planking as it passes over each section. All planking should be planed on one face and both edges. The planed face will be on the inside; as the outside has still to be cleaned off there is no point in planing it beforehand. If the planking has been planed off all round when purchased so much the better. The first plank which we will call the strake plank (this may be of mahogany or cedar as a contrast in a varnished hull), is checked with the body section drawing, Fig. 1, from which you will obtain a fair idea of the required widths of the plank as it passes over the sections. Shape one edge of the plank to these sizes in a true curve, the edge being square off the face of the plank. Prepare another plank in a similar manner for the opposite strake. At this point you must decide what method you shall employ for fitting your deck, whether it be let inside the planking or laid on top (Fig. 5). The latter method makes for easier removal if the need arises. In this case we shall assume that you are going to lay the deck on. 643 SPREADER FITTED KEEL LEAD KEEL BOLT TRANSOM OF FASHION sharp “‘lumps.” Then, using a wet cloth, moisten the whole of the hull and when dry, sandpaper once more using a fine grade of paper (M2). Repeat this process using a finer grade of paper each time (No. 1 or 14). The reason for using the water application is to “‘lift” the softwood fibres of the planking which will result in a harder surface and smoother finish for painting. The fitting of the skeg is carried out in the SECTION ALA PIECE a A OETAIL OF SKEG, following manner (Fig. 6). Shape a piece of mahogany or pine, which must be the whole length of the rudder tube, from the profile drawing. Through mortice the backbone to receive it, fit the rudder tube and screw it home hia RUDDER & TRANSOM The two planks which have been prepared may now be cemented and fitted, with the edge that has been shaped facing downwards to the deck line to the skeg. Check the alignment carefully and cement into position. This will give a stronger in order to give a good machined edge for fitting the next plank. This method is adopted with all the planks to the garboard (Fig. 1). When the planking has been carried out to a point where the after portion of the backbone occurs, to a point where the dead wood sits amidships, the rebate strip of mahogany should be laid on the after section of the backbone, if this has not already been carried out as described previously. skeg, capable of withstanding many knocks without fear of it being damaged. Finally, clean up the whole of the hull and prepare to take away the shadows. Unscrew the building board or “stick” from the shadows, leaving these still to be released. In order to make the hull more rigid whilst working, fasten it to the bench by using the keel bolt holes. Cut all the ribs at the deck line and commencing fore and aft release the shadows by knocking them inboard. By taking out all the shadows the hull will not “‘spring” in any direction and you may proceed to clean the inside of the open shell, or to take some weight off the backbone, etc. The glue which remains in the joints will probably be too hard to remove but may be left in as it will increase the strength of the hull. The processes of fitting beams and deck fittings have been well described by other writers and I do not think that they can be improved upon. Before finally fastening the deck, however, three coats of varnish should be applied in the following manner. Dilute the first coat with Turpentine three parts to one, the second coat diluted two parts to one, and finally the third coat of varnish only. A coat of cream enamel will give the interior a clean appearance. When the deck is finally fitted, give it a rubbing down with White Spirit and sandpaper down with very fine paper (No. 0). (To be concluded) In dealing with the planks at the forward portion, I usually fasten about six planks on one side and then the same on the opposite side. Those planks which are fastened first are trimmed off at an angle in line with the other side. ‘ Eventually you will find with the overlapping of the planks in this manner, that you have greater strength where it is required. When all the planking is finished and roughly cleaned off, flatten the point of the planking forward to about 3 in., then cement. Lay on a piece of mahogany 3in. x 3in. | from deadwood to peak of the hull, bending to shape of the profile. This is to give a final locking to the planking. When fitting the garboard piece great care is necessary as this may make or mar good sailing. The portion of the hull should be “jacked off” to accommodate the garboard piece. As a guide, I usually drill the backbone for the keel bolts, which have been determined beforehand, and the garboard is drilled likewise in dressing off. Check 644 ee LEVERAGE OF i ee OF ARE SUPPORT — 2 TO Ts DETAIL the fore and aft level from the datum and check the midship section in a similar manner. Cement the garboard piece to the hull, making use of the Keel bolt holes for cramping to the hull. Fair in the garboard to the canoe body and proceed to clean up the outside. To clean the outside of the hull, scrape off all waste cement and draw out all metal pins as they will not be necessary when using the cement described. Take a “light” or “fine” shaving off all the planking. Using a coarse sandpaper (82), cross paper the hull in order to take down any
