The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

March, 1910 ing to $6,000, makin& ine total esti- mated cost of the béat $129,112. The actual contracts let totalled $117,586,62, "TAE MarRINE REVIEW but including the extra amount fe- quired to harmonize the various separ- ate contracts involved and the com- 93 pensation of the architects, the total cost of the boat to the city reached $128,400. The Largest Commercial Gas Power Boats in the United States nothing looms larger today than the possibilities of the internal combus- tion motor applied to boats engaged in commercial service. From an inauspici- ous beginning less than 20 years ago, the marine. gas engine has risen rapidly from the purely experimental stage to a point where it is not only a recognized, standard motor for pleasure craft of all descriptions, but is also a strong com- petitor of the "steam engine in many lines of commercial service. It is only in very recent years, how- ever, that' the internal combustion motor has been tested to any serious extent in boats) of over 50 gross tons register in. classes of service where the steam engine would be met in direct competi- tion. In 1906, the Standard Oijl Co. L THE world of marine engineering ' launched on San Francisco bay the steel © Cla twin-screw gas propelled oil barge Beni- The Benicia is 140 ft. in length and has a draught displacement of 500 tons. In 1907, the same company launched another oil barge similar to, but larger than the Benicia. This boat, which is said to be the. largest gas- driven vessel in the United States, was named Contra Costa, and has a. load draught displacement of 1,580 Very little has been published concern- ing these two boats, but they have been quietly and steadily at work nearly ev- ery day during the past two years. They have' now been in commission such a length of time that their performance is of value in demonstrating the prac- ticability of gas-powered boats of large size, engaged in continuous commercial service, A study of the hull and engine details of these boats and of their serv- ice record is well worth while. Deck plans and an inboard profile of the Contra Costa are shown in Fig. 1. The huil, which is constructed of steel, was built by the Union Iron Works Co., San Francisco, and the entire en- gine equipment' was furnished by 'the Union Gas Engine Co., East Oakland, Cal. +i nae The boat is 189 ft. in length between perpendiculars, 37 ft. molded beam and 13 ft. 6 in. molded depth. The vessel _was designed for bay. service and to have a maximum carrying capacity on the given dimensions. For this reason the model is made very full, with a bluff bow, parallel sides and rounded stern; .and propelling machinery. tons. . the bottom is flat and the midship cross sections are practically rectangular. The liquid cargo is carried in six oil tanks formed by four transverse and one longitudinal bulkhead. Each tank is about 25 ft. in length and holds trom 1,150 to 1,200 barrels (42 gallons per barrel), the total capacity being 300,000 gallons of oil, weighing 1,058 gross tons. To protect the tanks from external in- jury and the ship from foundering in case of accident, collision bulkheads are fitted at the forward and aft ends of the tank compartments. Accommodations for the crew are pro- vided in the steel deck-house located forward, there being one room for the chief engineer, one room for the assist- ant engineer and oil, one room for the cook, one large room for the four deck hands, one toilet, one mess room and galley. The pilot house is situated above the deck house. It is equipped with the usual navigating equipment, including a standard engine room telegraph. In the texas behind the pilot house are situated rooms for the captain and the mate. Fig. 1 also shows in plan and eleva- tion the arrangement of the pumping The engines are located in a compartment aft of the cargo tanks. On account of the absence of boilers the saving in space occupied by machinery is about 50 per cent; and the saving in weight adds materially to the cargo capacity of the boat without increasing her dimensions or the power required. All power used on board for all purposes is generated by internal combustion engines, : Main Engines. The propelling equipment consists of two engines of 250 brake horsepower each, having six single-acting, four-cycle cylinders, 1214 in. diameter, 14 in. stroke. Each engine is coupled through a self- contained clutch and reverse gear to a three-bladed bronze propeller, 6 ft. diam- eter, 3 ft. 8 in. pitch. It will be noted that the pitch ratio is only 0.61, which is unusually low for reciprocating en- gines, but which is, of course, due to the relatively high rotative speed. The tail shafts are of steel, 6 in. diameter, cased with brass, and run in the usual lignum vitae bearings. With engines making from 240 to 260 R. P. M., the , cargo. 6 in, in diameter and have one coupling: speed of the boat is about eight knots, loaded. The fuel used is No. 1 engine distil- late and is stowed in two steel tanks built into the after corners of the engine room. The fuel is handled by two' small pumps attached to the main engines and is sent through retorts in which it is _ volatilized by the heat of the exhaust. The: effect of the retort action is very marked when the boat is started; the exhaust is quite smoky until the retort becomes heated, about 10 or 15 minutes, when the exhaust becomes clear and smokeless. Gasoline-Driven Pumping Equipment. The cargo is handled by a specially designed pumping system. One 85-H. P., three-cylinder vertical gas engine drives two 8-in. Krogh rotary pumps by means of a Renold silent chain. Each pump can deliver about 21,000 gallons of oil per hour under ordinary condi- tions of temperature and lift. With cold oil, long pipe lines and high lift, this capacity is somewhat reduced. There are two suction mains, each 8 in. in diameter, extending the full length of the tank compartment. Branches, 6 in. diameter, lead from these mains to each tank. All valves are of straight way gate type, which are not easily ob-: structed by dirt, chips or other debris. The valve stems are carried to the upper -- deck through oil tight stuffing boxes, so that all pumping may be controlled from the deck. By-pass connections are pro- vided so that the suction pipes can be used for loading as well as discharging © The regular discharge mains are on each side of the vessel forward and one on each side aft for hose connec- tion with the wharves, One 25-B. H. P., two-cylinder vertical engine is directly connected to a 10- k. w. generator, which furnishes elec- tricity for lighting and also power to operate an electric windlass forward, an electric capstan aft and electric bilge -and fire pumps in the engine room, Small Crew Necessary. In bay Service, Contra " Costa carries one captain, four deck hands, two. en-. gineers, one oiler and one cook, The boat, however, has a United States cer- tificate for coasting service and in that case would carry an additional deck