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Furthermore, the builder of the ves- sels, Swan, Hunter & Wigham Rich- ardson Co. Ltd. has had a long and successful experience in building ferry steamers. The machinery is also of high quality, consisting of two sets of Par- sons’ steam turbines and single re- duction gears. Hach set drives a four bladed solid manganese bronze pro- peller of aerofoil section. The main propelling engines and other ma- chinery were installed by the _ ship- builder. Another interesting feature, for vessels of this type, is the choice of coal as fuel. And in this connec- tion a striking innovation is the in- stallation of Taylor mechanical stoker of underfeed type to serve the four Yarrow watertube boilers. In this particular case one of the ad- vantages of coal is that it can be run on board direct in railroad freight cars and tipped into the ship’s bunk- ers without handling after leaving the coal mines. Principal particulars of the Twick- ENHAM FrrRRy and sister vessels are noted in the table on the opposite page. Four lines of rails are provided over the greater part of the train space. At the stern these rails converge into two tracks by which the trains pass on to the shore across a draw-bridge at the end of the deck. Trains can be run on and off the vessels without the slightest inconvenience to the passengers. Special attention has been given SNOW to safety and fire prevention. Life- saving appliances have been installed to take care of a total of 550 people. Watertight bulkheads are so ar- ranged that the vessels will remain afloat with any two adjacent com- partments flooded. Furthermore the lifeboats are instantly available. Passenger accommodations on the upper deck are set off by fireproof bulkheads and boundary walls of steel plating. In this way separate sections can be isolated at will. Elaborate fire fighting appliances are provided throughout the vessels. Successful Sea Trials Sea trials of the TwickENHAM Ferry, on June 18 were carried out as nearly as possible to correspond to service conditions. For the trials the vessel was fully loaded with freight cars of coal. During the trials the vessel more than fulfilled expectations. A marked steadiness at all speeds and the absence of smoke or any other indications that coal fuel was being used were especially noticeable. Un- der favorable weather conditions a speed of over 17% knots was ob- tained. Coal consumption and the steam performance of the turbines were carefully noted during the six-hour trial, The results showed that the coal used, which came from a mine near Dover, was being burned under the most efficient conditions. Opportunity was taken during the [eee Ss —- - WEEE si eT i js we eS ty Y Se: Meh. * oy? sn Pig 2 OP) Ak a pg lll MMMM hl ee z ea i SPUN AC fea IE CEE trials to test the maneuvering of the vessel when turning, going ahead and astern, and when starting and stopping. In addition the vessel was kept running for a period of about one and a half hours at full speed astern during which an avy- erage speed of nearly 12 knots was attained. The trials were attended by rep- resentatives of the Southern Railway company: Swan, Hunter & Wigham Richardson Co, Ltd.; Yarrow & Co. Ltd.; Parsons Marine Steam Co.; and Taylor Stoker Co. Ltd. Sir Westcott Abell, consulting naval architect for the owner, and G. S. Baker, superintendent of the William Froude laboratory, were also pres- ent. During the dinner on board R. P. Biddle, assistant docks and marine manager of the Southern Railway, said he had never been on a more successful sea trial, and con- gratulated the shipbuilder and all the other firms participating for their splendid co-operation in pro- ducing such a _ highly satisfactory vessel. Main Propelling Machinery The vessels are propelled by twin screws, each of which is driven by two steam turbines of the latest Parsons’ type, one high pressure and one low pressure, driving separate pinions gearing into a single gear wheel. The shaft on which the gear wheel is mounted is in turn coupled [=} = [ A 6D =", {S ey ein Y ccietittiiede SS (ER ee aes S é le SSSSSSS AF Witthe ty > | eee ee — a er nr oer — por Taylor marine stoker as installed on the cross-channel train ferry steamer, Twickenham Ferry 1. The stoker has our retorts, a bank of tuyeres or air nozzles occurs in the form of porous coke, the volatile having been released gradually during between any pair of retorts and between each end retort and the furnace side wall. 2. The diagram shows a longitudinal section through a retort. A portion of the fuel bed has been omitted from the retort (about one-quarter of the grate length from the front wall) revealing the adjacent tuyere bank and the extent to which this is buried below the fire. 3. The progress of the fuel from the hopper to the ash dump is visualized by the tracks of four fuel-particles A.B.C. an hese are ‘‘underfed and enter the fire from below at points along 75 per cent of the grate length. 4. When the fuel particles reach the level of the tuyere banks they are their progress down the retort. 5. Combustion occurs above the tuyere bank level. The crust of porous coke is thoroughly oxygenated by air from the tuyeres below and acts as a “scrubber” which brings the oxygen into intimate contact with the volatile rising from the retorts. Oxygenation of the coke crust is such that com- bustion is “‘slice free’’. 6. As the “‘rise”’ of volatile occurs along 75 per cent of the grate length the combustion chamber is relatively ‘‘flame free”? resulting in an increased rate of fuel consumption within smoke limits and intense radiation from the in- candescent fuel bed surface. MARINE REVIEW—September, 1934 13