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November, 1909 THE Marine REVIEW 437 Self-Discharging Cargo Steamers N SOME trades and with certain classes of cargo the ship fitted with self-discharging gear has de- cided advantages over permanent shore equipment. For material which moves freely and without much _ tend- ency to bridge and which may be de- ship, the Topeka, was similarly fitted, the conveying apparatus embodying, be- sides greatly increased capacity, many. improvements of detail. Besides crushed stone, both these ships handled slack and anthracite coal and grain very suc- cessfully. The latter they were able Shes Fic. 1--STEAMER WYANDOTTE, livered within short distances of the dock face either into cars or stock pile, or to a shore conveyor, and in trades where runs are comparatively short and the disadvantage of the extra weight aboard the ship is there- fore minimized, the self discharging type is exceedingly economical, It also makes possible the rapid handling of bulk cargoes in ports where shore equipment is entirely wanting and do- ing so at very low cost. As will ap- pear however, the design of ship here presented presupposes cargo of fairly heavy nature, as the design of the hoppers and the space required by the conveying apparatus make light cargo unprofitable, since the ratio of hull weights would be altogether disproportionate. The first ship fitted with conveying apparatus, so far as known, was the Hennepin, a wooden ship, which about 1903 was fitted with conveying machinery for handling crushed stone. A longitudinal hopper, the full length of cargo hold, was formed each side of the center line with rubber belt conveyors beneath, delivering to short cross conveyors at the after end, which passed the material to an inclined cen- tral conveyor extending forward and up- ward through the deck, and delivering to another which carried the material Overboard. Later another continuous and larger wooden Burtt By Great LAKES ENGINEERING Works. to deal with by reason of the construc- tion of the hopper discharge gates which were close-fitting plates sliding transversely to open: and.-close, A ship similarly fitted is also in opera- o tion on the Pacific coast. The stone handled by the ships re- ferred to was of a size known as 2-in. from the quarries at Alpena to De- troit. (See Marine Review Feb. 20, 1908.) The material is known as 4-in. stone, but as is well known, in some dimensions frequently exceeds _ that figure. The size of material and the size and type of gate necessary to handle and control it at the rate de- cided upon, 600 tons per hour, practi- cally eliminated rubber belts- under the hoppers as, if the material should jam the belts would be destroyed, and a steel pan conveyor was decided upon. Cross conveyors were discarded and the pan conveyors are carried upward at the forward end and discharge through a combining spout as seen in Fig. 4, on to the heel of an inclined rubber belt conveyor which delivers to a boom belt conveyor pivoted as shown in Figs. 3 and 4 and which may "be topped up to any desired angle and swung over either side, the total angle of swing being about 200 degrees. This boom has an effective radius of about 75 ft. All conveyors are electri- cally driven, the two longitudinal hop- per conveyors and the first inclined conveyor by a 100 horsepower motor and the boom conveyor by a 30 horse- power motor mounted on the boom. Either side conveyor may be driven in- dependently of the other. Current is furnished by a direct con- nected engine and generator in the engine room. The apparatus has prov- en highly successful not only in hand- Fic. 2--STEAMER ALPENA. BuILt and the opening in the hopper bottoms, which was continuous, was about 6 in. wide. The material was handled at a maximum rate of about 300 tons per pee 1907 the steamer Wyandotte was designed by Babcock & Penton, Cleve- land and New York, for the Michigan Alkali Co. to carry broken lime-stone py AMERICAN SHIP BuILpING Co. ling stone but also both slack and run- of-mine bituminous coal. The Wyandotte is 306 ft. in length and 24 ft. deep. Her midship section is identical with that of the Alpena shown in Fig. 7 except that the latter is 47 ft. beam and 26 ft. deep. As will be seen water ballast is carried clear to the spar deck and the side tanks extend