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Twin Screw Diesels in River Towboat Each Engine Connected to Propeller in Tunnel of Unusual Design—Excellent Performance on Trials—For Towing Self Unloading Bulk Cement Barges HE diesel, twin screw, river tug Witu1am Dickinson, built for the Marquette Cement Mfg. Co., Chi- cago, by the Marietta Mfg Co., Point Pleasant, W. Va., from designs pre- pared by T. R. Tarn, naval architect, Pittsburgh, has been delivered to her owner at Cape Girardeau, Mo., after having given a good performance dur- ing her acceptance trials at the yard of the builder. Principal dimensions of the vessel are as follows: Length on deck, feet ........ 124 Beam molded, feet: ............006 26 Depth molded, feet ................ 7 “Crown of deck, inches .......... 6 Mean draft, in service, feet 5 This vessel was designated for tow- ing bulk cement barges on the Missis- sippi river and will operate out of the Cape Girardeau plant of her owner to St. Louis and Memphis where ex- tensive river terminals have been built. The construction of the tug in- cludes the most modern equipment available with special provision for the comfort of the operating person- nel in good living quarters. Some Unusual Characteristics The steel hull is of the open tunnel type with modified scow bow, square transom stern, round bilges and is framed transversely. The deck is faired forward and aft and terminates in rounded corners at the transoms. At the forward transom, knees are fitted for towing. The under water portion of the stern is arranged to facilitate the easy entrance of water to the pro- pellers and also for easy discharge in order to obtain maximum effective- ness in propulsion, greater ability to steer and handle, to simplify the hull — construction and the attachment of the stern bearings, struts and rudder bearings. Unlike the usual curved and round- ed tunnels, the tunnels in this vessel are flat topped and straight sided to more definitely direct and deliver a solid column of water to the propel- lers. The effectiveness of the propel- lers is improved due to the elimina- tion of the revolving or swirling ac- tion imparted to the water in the case of rounded tunnels. Complete Auxiliary Equipment Fuel capacity of forty tons has been provided in the wing tanks abreast the engine space in three fore and aft tanks, port and starboard. The forepeak provides ample space for the special Marietta built duplex air engines for the deck capstans, air storage tanks for the main and auxil- iary diesel engines, the “Lux” fire pre- vention system, and stowage of deck tackle. After hull compartments contain the hydro-pneumatic twin steering gears with pumps and tanks associ- ated with the independent steering and handling system. The steering and handling system is similar to the system installed aboard the NATCHEZ, BIRMINGHAM and Corpova type tunnel boats operated by the Inland Water- ways Corp., and provides for operat- ing the starboard rudders or the port rudders independently of each other to conform to the direction of rota- tion of each associated propeller. The main deck house is built of steel and houses the deck room for- ward, the engine room, and _ the crew’s quarters aft of the engine room. The portion of the deck house containing the crew’s quarters is ceiled with Celotex insulation and panelled. The pilot house is built of steel and ceiled with beaded yellow pine finished bright. The usual pilot wheel for the manual operation of the rudders is not included as part of the pilot house equipment. Instead, steer- ing lever controls synchronized with the helm angles are used with a sav- ing of space and less complication. The exhaust stack is built of steel six feet long by four feet wide and houses the Maxim silencers for the main and auxiliary engines. Sides of the stack are portable for gaining access to the silencers. Deck equipment consists of two combination manual or power Operat- ed capstans on the forecastle, a man. ual operated capstan on the after deck and the usual outfit of cast steel bitts, chocks and cavels. In contrast with the usual “low-down,” elliptical shap- ed cavel with its flat top and bottom and small radii of sides which has survived since wooden steamboat days, the barrels of the cavels are of uniform diameter throughout to give less wear with greater contacting sur- face to the tow lines and with less likelihood of rupturing the rope strands. The chocks are also a depar- ture from the conventional type in that they are entirely pin bearing and each may be used for pulls from either a forward or from an astern direction, thereby eliminating the usual installation of double-chocks to answer the same purpose. On the after deck, seatings are pro- vided for cranes to serve the trunk ‘hatches over the propellers. A single portable crane is provided to serve these hatches and is stowed below — deck when not in use. ee All fuel and water hull tanks, deck doublers and fittings, and weather — decks are electrically welded in addi- — tion to being riveted. Ps Diesel Propelling Machinery The main propelling machinery — consists of two, six cylinder, vertical, © four cycle, solid injection, directly Te versible, full diesel engines manufac: tured by the Atlas-Imperial Diesel Engine Co. = The engine cylinders are 14 inches © in diameter and 18 inches stroke — They develop 350 horsepower each at 225 revolution per minute and are Twin screw diesel river towboat William Dickinson built by Marietta Mfg. Co., Point Pleasant, W. V4. MARINE REVIEw—J anuary, 1931