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Finally, I've got some time to start the post on my next scratch build, a 1:48th scale Denny SGB, actually S304 Grey Fox, IWM picture below, at 145ft, the model will be ~36 inches long in old money. Warning, I expect this build to take a year or so. This time I really will try to make everything (apart from the split-pin stanchions), but some complex components will be 3d printed, though to my own drawings. I'm also going to have a go at the propellers, printed in wax and then cast, may as well go for it... My aim is to produce full drawings, components and etchings so others could build the same model if they wish. I will document it all here, mistakes and all I have two professional plans, one available on line by G Stone in 1:48th scale and one from model shipwright no 87 (March 1994) But as I do with all major builds, I also contacted the maritime Museum in Greenwich (actually the old brass foundry in Woolwich) who have the archive of all naval vessels since the 18th century. They claim to have an example of every type that served in the navy and they have a number of drawings of SGB's. I chose three drawings of SGB303 (the sister of S304), which include the GA and the shell expansion, a vital piece of the puzzle for plated models. At 36 inches long, the model is too large for my block infill so I'm going to plank it on frames and then plate the outside with aluminium sheet to the shell expansion drawing, rivets included. Shell expansions show stuff other drawings omit, like the water intake and outlet for instance. A section of the drawing is shown below and on it you can see the inlet is rectangular and on the centre line, I've not seen that detail before. This section also shows the layout of the outlet with the doubler plate etc. In other parts of the drawing is it clear that the portholes on port and starboard where not in the same place, again, where else could you find that sort of detail? From a scan of the lines (actually from the model shipwright drawing which looks a higher quality piece of work) I prepared a cutting drawing of the keel and frames. The frames have been set back by 2mm to allow for the planking. The keel is 5mm ply but the stem and the docking keel will be made of brass, inset in the ply as the former is sharp and the latter much thinner than the ply (poor quality copy below I started yesterday by cutting out the keel and setting in the brass, seen below on a temporary building board to keep everything straight. Keeping hulls straight is a real challenge as the planking can frames can easily end up twisted (I know this from experience) so I make a lot of fuss at this stage, sometimes it pays off... The hull will have a large slot in the deck for the deck-house. I'm not going to build a working model, but this could easily be done and then the slot would allow access to the motors battery etc. For me is helps to keep the deck house separate until very late in the build, then is will just slot in The frames were printed and mounted to 3 mm ply for cutting out Much later today... More timber to keep things straight. I've had to slot the build board as the boat does not have an exposed keel apart from the small docking keel at the back. I'll be planking it upside down, more detail later. The platform at the back holds the alignment holes for the rudders, you can also see the holes for the prop shafts (5" dia) After much fettling, I glued it up, tape is holding everything straight (I have a phobia about straightness....) So, we're off and running, sheer strakes going in tomorrow
While I continue my research and drawings on the SGB I'm about to build, I thought I'd share some information on Turbinia, a model I completed ~6 years ago and entered into the 2014 Model Engineering Exhibition where it won a bronze metal and a cup for the best dispplayed ship model Below are the complete judging notes I prepared for the show: Ship details Turbinia was built by Charles Parsons in 1894 as a demonstration steam yacht to prove the feasibility of using stream turbines to power ships. When she was launched, she was the fastest vessel ever built, eventually achieving almost 35 knots, an amazing speed for a vessel only 100 feet long. Most famously, she gate crashed the 1897 Spithead review where the entire home fleet was drawn up for the Queen’s inspection. Sailing between the lines of battleships, she comfortably outpaced the torpedo boat chasers used as guard ships. I believe that from that point on, all new British warships were fitted with turbines, the propulsion unit that paved the way for the Dreadnought revolution. Her statistics are: Length: 103’ 9” Beam: 9’ Draught: 3’ Turbinia is preserved today in a museum in Newcastle. The model shows the yacht after a funnel rebuild as she was around 1900, generally as she is preserved. Sources The model was built using three plans: A John Haynes plan @ 1:48 scale: contains a number inaccuracies on the lines and the deck-house locations but useful for some details A model Shipwright plan set by Charles Sells @ 1:24 scale: much better, the lines are based on this plan A small plan reproduced in a booklet produced by Ken Smith in 1996, reproduced below, seems to be from original drawings and so taken as very accurate, albeit small Many current photographs of the preserved ship in the Newcastle museum and various contemporary pictures found on-line As with all plan sets drawn by others, once you get into the detail, discrepancies arise. However, the basics start with the frame centres. In Turbinia is was simple to work out that the frames are at 18 inch centres. The enables the deck houses to be positioned exactly as their ends have to rest on frames. It also positions the stanchions (also on frames) and a good guess at the longitudinal breaks in the shell plating. After a lot of thought, as no shell expansion drawing was available, it was decided to use 5 plates at the mid-ships point, giving a maximum plate width just less that 4’. As the keel strake has to be an inner, the bilge strake is an outer and the sheer strake an inner again. This seems to agree with the pictures of her in dry dock following a collision that nearly sunk her. I’m guessing that rivet lines are weaknesses and flush riveting expensive so minimising rivet lines makes sense. The shell plates all meet between frames (often forgotten that they cannot be joined on a frame line) and no two joins are in the same frame space. It may not be exactly as she was built, but it makes sense to construct it in the way. The bilge strake runs smoothly into the top of the flared stern, this can be seen clearly on one of the dry dock pictures. The deck plating is interesting. Three strakes were used as can be seen from the pictures, with a mixture of flush and raised riveting. I’ve followed this pattern from the photographs. The raised riveting makes sense where the jolly boat is as it provides more purchase when handling the boat. I’m not sure why they went to the trouble of flush rivets elsewhere though. Hull construction The basic hull is solid wood constructed around 1/16” ply frames as shown in the drawing below: The frames were drawn on a CAD package with keel slots, printed and stuck to ply with spray mount before cutting out. The keel, also from 1/16” ply was held straight with 2 x ¼” timber sections. After this was sanded to the downward curve of the rear deck, the whole frame was locked together with a flat deck plate from 1/32” ply. The forward deck house was originally designed to be visible and so this section of the hull was planked. In the event, so little could be seen through the desk house windows that extra interior detail here as omitted. Obeche blocks were cut to slide between the frames, glued and then sanded back to the ply frames. This made a very strong and straight hull with the fine stern deck slope correctly featured. The hull was then painted in a clear liquid epoxy to harden it, allowing for further shape refinement and to act as a firm base for the Aluminium hull plating. The cambered deck was added as a superimposed additional 1/32” ply section on top of a central strip of wood sanded fore and aft to simulate the complex compound curve of the deck. The superimposed deck section contained cut-outs for the funnel and deck houses, allowing them to have flat bases. The three propeller shaft tubes (in brass) were set into the frames before the blocks were added. The hull plating lines were marked out on the hull, with the plate butt lines marked to ensure stagger. Each plate was then cut from Aluminium sheet (4 thou for inner strakes, 8 thou for outer) and bonded to the hull with contact adhesive. With the exception of the stern, all plates are single curvature. The stern plates were heated and beaten to shape. The deck plates were similarly marked and cut out, however, on the deck, the frame lines had been drawn so that the rivet detail could be worked out where non-flush riveting is used. The rivets here are made with a wheel from the back of the plate, again remembering that deck plates do not join on frame lines. Deck houses and fittings The deck houses are made in wood and then plated in Aluminium with rivet detail marked out on the reverse as with the deck plating. The wheel house is made from sheet Copper over a wooden buck, silver-soldered as are the wheel house sliding doors. The funnel is made from sheet brass (for strength) and mounted on a wooden Aluminium lined buck. I included the two smoke stacks inside the funnel casing, the boiler is double ended and I assumed two stacks were used. The fittings are built up from custom etched parts (produced by 4D Model Suppliers) from my artwork (shown below) This contains: Deckhouse rivet flanges & rivet strips Steering quadrant pieces Window frames (2 parts each) Stanchion bases Hatches Deck lights Coal scuttles Wheelhouse portholes Propeller blades The 9 left and right hand propellers are a key feature on the vessel. They were made by turning the hubs in brass and then silver-soldering the blades on in a jig. The outer circle holds the blades, which have been turned through 45 deg, for soldering. After which it is cut away. The window frames were soldered together over an Aluminium jig which held them centred. The Perspex glazing was then snapped in. Using relief etching provides the opportunity for including all rivet detail, quite distinctive on some of the hatches and of course the deck-house flanges. The sheet illustrated was etched in 22 thou brass and produced ~300 pieces from an A5 sheet. The colour code means; Red is half etch from face and; Cyan is half etch from rear. The 10’ ships boat was made with tissue paper and dilute PVA over a wooden buck containing the planking lines. This was then lined on the outside in card when dry and then fitted out in the normal manner. The mast and flag yard are scratch made in brass as are the other minor fittings. I’ve fitted her with an Admiralty pattern anchor, not the Hall’s anchor she has today. This type of anchor is shown on some contemporary photographs and looked interesting to me. I’m guessing she could have carried either. Studying the photographs, the life rings were stored on the outside of the handrails, which seems unusual practice, but is probably due to the limited width on deck. Colours and display The colours follow the pattern of the preserved vessel with the exception of the hull below the water line. This has now been painted black, but contemporary references talk about dark green. Early models also show the hull in green and this colour was used on the vessel before it was moved to Newcastle. This illustration shows a model from the Science Museum. The hull is dark green below the water-line (which is set too low on this model, see contemporary pictures showing a much higher water line). I decided to use this colour for the model, there is plenty of evidence of a green hull and it lifts the model as it would have the actual vessel. The name on her side was a custom water slide made based on a drawing of the ship as preserved. Display is always a difficult problem. For this model, I decided to display it in a simulated dry dock to set it off and add scale to the model. Turbinia is a strange model to scale in your mind as there are no natural scale clues that really help. Adding the dry dock and the figure touching up the paint anchors the scale well. I took some hints from pictures of her in dry dock after a collision but the actual dry dock is not a true model, more a complex stand. She is shown finished and ready to re-float with all her paintwork bright, though age on the deck houses show she is not new. The bright paintwork is set-off by the dull grey dock. No flags are flown as she is not yet floating. The next post shows the completed model