Mark Pearse Posted November 3, 2014 Share #1 Posted November 3, 2014 (edited) I plan to build a 1:12 model of a 28 foot yacht. This design has never been built, but is a variant of a 24 foot yacht design usually called ‘a Ranger’ (see Wooden Boat magazine issue 227). The first of the type was called Ranger, launched in 1933. They are popular & loved because the design fits the purpose so well: day use on Sydney Harbour, with short coastal trips & overnighting capacity. The design was adapted by the designer to a 32’ ocean-going variant, & also a 28’ ocean-going variant. The 28 footer came 8th on IRC handicap in the 2006 Sydney Hobart Race (see youtube video of her in 2012 in 30-35 knots http://www.youtube.com/watch?v=Dd9LqrDP510). The design I will build is slimmer & with less buoyancy in the bow than the ocean-going 28 footer. The ‘Ranger’ yachts are generally 24 foot (7.3m) waterline & on deck, with bowsprit, gaff rig & a raised deck. They are very beamy at around 9’6” (2.9m), or a beam/length proportion of about 40%. This version is 28’ & 9’6” beam, so it’s basically stretched, not scaled up. This design is of interest generally because: the smaller ones are admired & loved, at least locally; this 28’ design has never been built; the designer (Cliff Gale) was a self-taught boat designer & in his day was considered one of Sydney’s best yachtsman. But it’s also personal: I’m lucky enough to have one of the 24 footers. I love the design, that they can be so beamy yet look good & sail so well, & they are a terrific motor boat as well. They sail well in 5 knots & can also sail unreefed in 40 knots. These photos show well the nuggety shape: This is the existing ocean going 28 footer, she's the most similar boat to the design I'm building, but much fuller. It's a big little boat: Cliff Gale was a self-taught designer, who learned by towing carved models behind a dinghy. Ranger was designed by carving a bread & butter half model, which was taken apart & measured. Cliff’s son Bill recently wrote this about his father: "Cliff Gale left school in 1898 aged twelve, & knew arithmetic but had insufficient mathematics to be useful in boat design. As a boy he lived at Woolwich & the family owned a rowing skiff for transport & pleasure. From thirteen to nineteen he made in excess of one hundred rough sailing models, each one progressively different, which he tested from the skiff. At nineteen he felt he had completed his design self-education.” I would like to build the model plank on ribs, & possibly make it RC sailing - although plain sailing is an alternative as well. But I’ll leave that alternative open until I get to that point, I will also be happy if a nice display model is the result. The issue that needs to be resolved is actually what to build... I do have the original drawings as done by a naval architect to Cliff’s design, but having looked carefully at them, they do not relate accurately between the different drawings. The history of the Ranger design makes this even worse: for Ranger herself we have Cliff’s original half model, we have the original drawings done from the half model, & we have lines drawing of Ranger meticulously done by 2 local shipwrights … & they don’t match up. If you compare station 4 on the drawings below, the design drawing shows more tumblehome, & much less buoyancy - the volume below the waterline was increased while being built, to increase her load-carrying capacity: Bill Gale tells me that his father went to the boatbuilder often to supervise the construction, & that he made a number of modifications to the lines while she was being built. For the model, I will have to adapt the lines drawing, trying to do it in a similar way that the lines drawing of Ranger was adapted to the built design. Because of the uncertainty, the model building method needs to help resolve thoughtfully these differences between the various possible shapes, & not be a way of getting caught up in plotting lines on a screen that fit but might be going away from the design. Initially I spent some hours trying to resolve a set of lines that is consistent, as they do not quite match up on the original drawing. My CAD skills are fair but you can’t really see a subtle 3D curved object in a drawing, so making changes to a curve on screen seems risky in this case. So I’ve concluded that I must see the shape in the flesh, & so carve the solid hull shape, based on a set of lines I adapted from the original lines drawing. The shape will be fair, so then I know the molds will work. If the method is too difficult I will be reluctant to make corrections, so it needs to be fairly simple & easy to make & to change. In putting this up early, I hope to benefit from the knowledge & experience of this forum. So I’ve done some sketches below that show the idea for my construction method, & hope that I can get some constructive criticism & help to iron out any issues now. In a few weeks I’ll get back to the computer & finalise the lines drawings; but for now I’ll describe the idea for the building method - as I see it now. 1 Work up a set of lines in CAD, from the original drawings. 2 Cut plywood molds from the station lines. 20141103145702436.pdf 3 Assemble the molds with solid balsa blocking between them, the balsa blocking is to be removable. Possibly brass rods inserted at angles through the balsa & molds. 20141103145708075.pdf 20141103145720688.pdf 4 Carve the hull shape out of the solid, using the molds as indicators. If I need to add to the molds, glue strips of timber on the mold edges. 5 Make the stem, forefoot, keelson, keel, transom etc, to sit neatly over the hull shape. 20141103145726052.pdf 6 Remove some of the solid blocking, where the ribs can sit directly on the molds; leave the blocking where the ribs want to lie at angles, I’ll probably need to put in temporary spacers to help hold the model together. By keeping blocking in the bow area, the ribs can follow their natural line rather be pushed into being straight across the hull. It's not so bad for the aft 2/3s of the hull shape, I think they'll be able to sit on the plywood ribs. 7 Cut the rabbet, rib the hull. 8 Plank the hull. 9 Remove molds & remaining blocking, progressively putting in some deck beams as it goes. 10 Have a cup of tea thanks for reading this, I hope to learn a bit more before starting, & maybe revise the method if needed MP Edited July 26, 2021 by Mark Pearse IgorSky, flying_dutchman2, hexnut and 9 others 12 Quote Link to comment Share on other sites More sharing options...
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