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Bryan
Dixon-Ward - 'Hunan' |
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“MS HUNAN” of London. “Hunan” was
one of the last examples built of the long line of cargo liners built to
run scheduled break bulk cargo services. Some of these carried passengers,
and some of those a lot of passengers. These latter are what most people
refer to as “Liners”. In fact a “Liner” is a ship running a regular
service. The concept of shipping “Lines” was unheard of with the uncertain
arrival dates of sailing ships, and came about with the advent of steam
for ocean voyages. The cargo liners as we know them lasted until the
carrying of general cargo was taken over by container ships, though
technically most container ships still operate as cargo liners. |
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In all, in her day, Hunan might be considered the ultimate general cargo liner for her trade and time. She was designed and built for the trade between East coast Australian ports and Japan, Taiwan and Hong Kong. The main cargo Northbound was wool and frozen food, and Southbound manufactured goods. “Hunan” was built at Taikoo Dockyard in Hong Kong, being commissioned in 1966. She was the largest ship ever built in Hong Kong. Her owners were the China Navigation Company, a British company with it’s head office in London and Its managing office in Hong Kong. As a member of what is now called the Swire Group, China Navigation is a sister company of Cathay Pacific Airways. China Navigation Company, “China Nav” or “CNCo” was founded in 1870 originally to consolidate cargo at Shanghai from Yangtze river ports for loading on ocean going ships. As a modeller and a practicing sailor, it had always been my ambition to make a model of a ship in which I had served. This is not practical when you live out of a suitcase, so the idea was looked forward to as a post retirement project. As it happens, with the advancing container revolution, Hunan was sold after only two years service with China Navigation Company, which, since I happened to be the commissioning Captain of the ship meant that I was Master of her during most of her life with CNCo. In the light of this slim claim to fame, I decided that “Hunan” was the ship I would like to model. When the time came, in 1998, I let this be known in the right circles, and was most fortunate to receive a full copy of the real world “Hunan’s” As Fitted General Arrangement plans. These were in the traditional scale of 1/8 inch to one foot, that is 1:96… a bit tight for the detail I had in mind. I had spent my hobby time at sea building 4mm/onefoot military models (A hobby in an ice cream container). I also had a Plastic Matchbox Flower Class Corvette which is 1/72nd scale. I wanted to stay close to that for compatibility reasons, so in mid1999 commenced converting the hull dimensions to my chosen scale, 4mm to one foot. A scale of 4mm/Foot is 1/76.2. It sounds an awkward ratio, but in practice while building, dividing the measurements in feet from the 1/96 plan by four by gives the model dimension in (model) feet and 3” fractions in 1/76.2. Later, when building the superstructure in particular, converting in this way, and using a scale of 1mm = 3 inches for the work of marking out parts for cutting is easy. One hardly ever uses the calculator. (I had learned all this while a military modeller) It was therefore not necessary to re-draw the superstructure plans For her day, “Hunan” had a very highly developed hull shape. This was one of the reasons that she had such a high economic speed. I was therefore keen to reproduce the shape accurately. The one thing I lacked was the hull lines. However, the plans on hand included drawings of the internal decks and double bottom tank tops. None of these are straight or level of course, and had to be converted to conventional hull lines. So I spent three months projecting the three dimensional shapes of the decks on to the drawing board to enable the hull shape to be defined in two dimensions. This entailed measuring the dimensions and height of the four internal decks and the tank tops at each of 24 stations along the length of the hull and entering the dimensions into my computer. (Microsoft XL). One click converted the whole lot into the new scale, and using the results the hull form, (from the decks), was drawn full (model) size on parchment paper. (One length of strong dimensionally stable drawing surface). A grid, representing the conventional navel architects hull sections was then drawn over the plan and from these the dimensions for conventional Water Plane, Body Plans and Sheer Section drawings (full size for the model) picked off, re-entered in the computer, and at the same time used to construct the final working drawings. The actual drawings I produced are rather rough (I‘m not a trained draftsman), but smooth enough to give confidence in fairing the dimensions between drawings to avoid “Bumps” in the shape when building. However, after two or three successive “Fairing Runs” over the drawings I had a Table Of Offsets which “worked”. As in full size practice, these offsets were used to mark out the frames and other parts when building commenced. By this time, I was fed up with T squares and dividers, (not to mention pencil sharpeners), and turned my mind to the computer. largely as a fun exercise!! Calculations were made to establish things like the displacement at various drafts and more important the likely behaviour of the hull I had come up with as a floating object. This related in particular to stability and trim. I had no wish build a large complicated model that would fall over or sink by the stern when placed in the water. The “fun” element lay in the fact that back in the 1940s I had been taught to make these calculations manually, (perhaps using a slide rule), a very tedious process. It was a fantastic revelation to do it all with Microsoft XL. It is perhaps to be noted that the usual model makers test tank, the bath, was too small for a model like “Hunan”. As it happened, and I emphasize that my methods as a navel architect guarantee that it is largely co-incidence, or a case of errors cancelling each other out, the calculated full displacement (the total weight) of the model at full load (summer) draft from my own drawings is 37.51 kilos. The actual (bathroom scale) weight of the model when loaded to her marks is 37.5 Kilos. The builders calculated displacement for the hull as designed by them is 16,255 (Long Tones) which scales down to 37.403 kilos. I am satisfied with that result, but (dare I ask?) wonder where the builders made their mistake!! With an accustomed eye, one is able to match the hull as shown on Hull Lines drawings with photographs and recollection. So I was able to eventually start work with confidence, backed up by confirmation from my calculations. The hull was built very conventionally, inverted on a stout building board, with 6mm marine ply for the frames and keel. The keel is doubled for the midships one third of the hull length and in addition the hull bottom was strengthened by side keels over the midships one third length. Planking was 2mm clear pinus radiata cut from 19mm x 155 mm flooring stock. The planks were pinned and glued for approximately one third of the length fore and aft. The remainder of the glue points being held with masking tale while drying. The whole hull is coated with one coat of fibreglass and two of resin, and painted with spray on car paint purchased in cans. The decks and all superstructures are built with 2mm aircraft grade plywood. Window glazing is from cut up CD disks, shiny side out. Which gives a pleasing effect from reflected light. Detail fittings are mostly made to fit. The anchors were purchased. The working windlass was designed and built by myself and the stud link chains purchased. The (non working) cargo winches are cast in room temperature moulding resin. Patterns were made for the six individual parts of the winch from brass and plastic. Moulds being made in RTV rubber and the 18 identical cargo winches assembled from the parts. ( Winches are in fact “Handed” Port and Starboard, but the parts were designed adaptable.) Similarly, the mooring bits were patterned in brass and cast in plastic from RTV moulds. Hand rail stanchions and the rails are assembled from purchased catalogue items, as were fittings like telegraphs, steering wheels and compasses. These look far better than anything I could make myself. |
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The full sized ship… Model Official Number 317715 Call sign GSXA Port of registry London Gross tonnage. (Volume) 8,965Tons (@100cu/foot per ton) LOA 488.5 feet 1.954 meters LBP 450.5 feet Breadth 66.6 feet 266.4mm Service speed 18knots True scale speed 3.04 knots Trial speed (recalled as) 20.6 Knots Full model speed (about) 6knots Summer draft 29’ 10” Light draft 12’ 6.5” Cargo space 475,679 cubic feet (dry cargo) Refrigerated cargo space 925,543 cubic feet Liquid cargo (bulk) 25,705 Cubic feet |
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Main motor is a 7.5 volt electric screw driver motor (and integral gear box) re-rated to12 volts. Main battery supply is 2 off 12volt 7 amp/hour gel cell batteries wired in parallel The batteries remain in situ in service, being recharged through a charging point in the main power control board built below the (removable) Engine Room sky light. There is a volt meter mounted in the control board, together with radio and power switches and a test button for the independent auxiliary battery circuit (which is buried in the hull… if the whistle blows it works!) Main engine control is by r/c in the common way through an Electronize HSX speed control unit. The drill motor pulls 3.2 amps at full speed (in water), for an operating time of four and a half hours, but this consumption is considerably modified if the speed is reduced. I have had the model underway for 7 hours continuously at near scale speed, (and walked miles doing it!) without exhausting the batteries. The remote controlled anchor windlass is driven by a geared motor mounted vertically on a bulkhead below the forecastle deck with the output spindle projecting vertically through the deck and driving a pinion on the windlass main shaft with a worm gear. Control is by radio control using a four relay r/c switch and power comes from a separate 12 volt “Auxiliary” battery. The anchors can be “walked out” and recovered in the appropriate way, but cannot be “run out” (as with full size ships) by radio control. (doing this by r/c was beyond me), though the windlass brakes and clutch can be operated manually to work the windlass and “let go” the anchors. It would be necessary to have four more radio channels available and “watchmaker” class workmanship. The fog horn consists of two electronic sound generators (Robbe) each outputting individual notes through it own speaker and tuned so that the output consists two clashing “diaphonic” sounds. Very typical of ships whistles of the period. The speakers were salvaged from an old computer. The fog horn is radio controlled being switched with a (ex computer mouse) mini switch operated by a mini r/c servo. The speakers and auxiliary circuits occupy the whole of the hull foreword of the bridge. The main engine, speed control, radio and other electrics are all situated in the “Engine room space” and the accommodation above it. The whole accommodation lifts off to give access for maintenance, but in normal operation access to controls is under the removable engine room skylight abaft the funnel. It is a pleasing indulgence that the main engine batteries are situated either side of the main engine… the same position as the Daily Service oil fuel tanks in the full sized ship. The hull abaft the engine room is empty, but can be used as storage for a couple of cans of soft drink, and a sandwich if required. The model is controlled by a four channel FM radio, channels being allotted to speed, steering, whistle and windlass. The radio receiver and it’s dedicated batteries are situated beneath the bridge and funnel decks which lift off for access. Receiver batteries can be readily changed. To service the main power and electrical installation, the whole of the superstructure can be lifted off, leaving the control panel connected. The Control panel can then be removed from the model and bench mounted while still fully connected to the electrical installation by a permanently installed umbilical cord. This gives ready access to the components. In it’s current mode, if ballasted to full draft, the model weighs 37.5Kilos, a bit too much for me to lift with ease for transport. There is plenty of help at the lake, but only me at home, so taking advantage of the fact that general cargo often filled a ship on space without reaching maximum weight, it was admissible to “show a bit of red” along the water line and still look authentic by removing sufficient ballast to make the model more manageable. It would be extremely awkward to move this model unaided, so a “trailer” come loading aid is used. The tray of the trailer is built as a floating pontoon wharf of a length suitable for the model. Fitted with golf trolly running gear it carries the model conveniently and can be used to launch it. With the main wheels removed the whole is readily positioned with the model on board and loaded into my station wagon by running it on mounted dolly wheels along aluminium tracks improvised from old aluminium shower cubicle frames. The whole thing works rather like a MICA ambulance system for loading stretchers. At the lake, the tray of the trailer is used as a floating wharf. This is NOT a model you lift out on to the bank while you get a cup of coffee. A final comment on the naval architecture that originally went into “Hunan”. She displaces far more water than most model speed boats, and goes almost as fast as most of them, yet the waves (i.e. unproductive power expended) she creates when underway are far less spectacular than those produced by her smaller cousins. |
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THE TUG. This is a far less ambitious project than “Hunan” and a far less accurate representation of anything real. In fact The Tug was only built after Hunan, and it’s pontoon trailer, were completed, and someone remarked that the setting needed a tug to make it look right. Eventually this became a challenge. I cast around for suitable tug drawings without success, but in the process gained a general knowledge of typical harbour tug appearance. The real problem was to find a design that wouldn’t take too long to build, and which would work well enough while still being the same scale as “Hunan”. The whole tug project was a rather light hearted support effort to “Hunan” and took about three weeks from start to finish Eventually, and fortuitously, I came across the Revell “Diesel Tug” plastic kit. The vendor was good enough to open the box and let me “measure up”, and I came away with the kit for a static model which I judged suitable for conversion to r/c. In scale the hull is about 90 feet long. A bit small for the task, but large enough internally for conversion from a static model to r/c, and large enough to look convincing in comparison with “Hunan” in photographs. As so often with plastic kits, my accustomed eye made me a bit hesitant about the stability the hull form would provide, particularly since it wasn’t a model designed to float. The overall length of the model is 345mm. I was right. The first attempt failed during the first test sailing. The small motor purchased at a swap meet failed to respond to command, and made so much electrical noise that the r/c lost it’s grip. The model, out of control, drifted into rough water, capsized all too easily and was lost. Good experience. Rather wiser, I purchased another kit, and brand new “R/C compatible” motor and built a replacement. This is the model in service today. The only parts of the original kit retained are the hull, gunwales and deck moulding. Everything else was scratch built as the building progressed. The model represents a typical small steam harbour tug that might have been in service in the 1960s. Virtually no accommodation, tow hook amidships, a high bridge well foreword for visibility, and a low freeboard. She is not modelled after any particular tug. Space within the model is TIGHT, originally the project was powered with 6 volts from 4 AA cells through a speed controller, and the same battery was used for power and radio. This was found unsuitable on several counts. The battery had insufficient capacity, and also insufficient power to give the model a suitable speed. I was also aware that the centre of gravity of the battery pack was higher than desirable, and the completed model, as expected, close to unstable. Somewhere I discovered that the radio receiver incorporated a step down to 5 volts internally, and this allowed me to replace the 6 volt battery pack with a single 9 volt battery. Being more compact, this had a lower centre of gravity, and due to it’s shape there was room in the curve of the hull to put a ballast weight of lead sheet beneath it. Thus, in one stroke, I had more power, better stability… and the running expense of a non rechargeable battery system!!! The propeller is home made, I could not find a suitably sized propeller commercially. However, this enabled me to make a propeller with pronounced pitch developed along relatively short blades. This is desirable to provide powerful transverse thrust when going astern. The secret of a small harbour tugs manoeuvrability. The propeller shaft has bushes as either end so as to leave a cavity for grease. The coupling to the motor is achieved with a short length of rubber tubing. The rudder is also home made… from 6mm marine ply and with a pronounced “airfoil” section; also designed to enhance manoeuvrability. Rudder control is through a micro servo. A measure of the small stability of this model is that the radio switch on one side and the micro servo on the other balance each other! Radio Control is by a conventional AM 2 channel system. The superstructure is made from plastic card, with an emphasis on lightness, (stability again).The boats are cast in resin from the mould made for “Hunan’s” jollyboat. The superstructure lifts off in once piece giving access to the whole of the hull. The superstructure is held in place by a high internal combing as a water resistant measure. This is a small model, and could easily be swamped by large models passing by. Swires operated a number of tugs in Hong Kong, all with Chinese names, under the flag of their dockyard there… Taikoo Dockyard and Engineering. This model is painted to represent a typical example. It was a pure whimsy of mine to call it “Poo Ling”. |
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Bryan
Dixon-Ward The first lot of the Hunan is a well detailed model about 6 feet in length, built, skippered and owned by the Master of the real size ship bearing the same name. With all that work in details and superb finish it’s a credit to Brian (all of the above) can’t blame him for being so cautious when launching and retrieving this boat, he did tell me a sorry about getting some help wetting the hull with some disastrous results, once bitten twice shy I think!! - Steve |
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Footnote: I noticed in the Hunan article that the author was not terribly happy with the hull of the Lindberg tub for RC use. Do you readers know of this product? - http://www.microglass.net/products/p1036.html It is specifically made deeper so that the Linberg tug can be made into a better RC boat. Love the site, hope this helps somebody. Jason Mummery - Canada |
