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Diesel Electric Wessel for U.S. Public Health Service service tug WALTER WYMAN, re- T= United States public health cently completed by the Spedden “Shipbuilding Co., Inc., Baltimore, is the first diesel electric vessel to be puilt in that port. The vessel is now in commission and is attached to the United States quarantine station at Rose bank, Saten Island, N. Yy ..- Her dimensions are 100 feet in length over all; 23 feet 1% inches in beam over all; 14 feet 2% inches in depth, and draft to bottom of keel at stern is 11 feet % inch when all tanks are full. The load displacement is 270 tons, the gross tonnage is 196 and the net tonnage is 133. A unique feature is the use of By- ers genuine wrought iron plates and Ulster wrought iron rivets for the en- tire hull below the water line. This material is used to insure maximum resistance to corrosion of the vessel’s underbody. Above the water all con- struction is of steel. This vessel was designed in the office of the surgeon general, public health service, by P. W. Clark, naval architect. - The pilot house, located on the up- per deck forward is fitted with dupli- cate pedestals permitting pilot house control of the main propulsion motor from either side of the pilot house. Steering can be done electrically or by hand at will. Windows in the rear of the pilot house make possible a practically unobstructed view of the entire horizon. Interior Arrangements Convenient A spacious saloon is located aft of the pilot house for the use of public health service doctors and inspectors in the line of duty in meeting ships, entering New York harbor from for- eign ports which require quarantine inspection prior to entering United States ports, to prevent the possible introduction of dangerous, contagious and exotic pestilential diseases. On the main deck forward there is a roomy and comfortable saloon for the use of passengers detained at quarantine in cases where quarantin- able disease has broken out on an in- coming ship. Aft of this space are located two toilets and a hospital for six injured or sick persons who may be brought in on an incoming ship. Directly aft of the hospital is the ma- chinery casing. At the stern is a space for transporting freight and supplies or for steerage passengers ordered detained at quarantine due to conditions found on board. Below the main deck, the hull ex- clusive of peak tanks, is devoted to machinery space with ample room, light and air. The machinery con- 20 sists of two 5-cylinder, 12 by 15 inches Fairbanks-Morse diesel en- gines operating at 300 revolutions per minute with a total of 650 horse- power. The exhaust from the diesel engines passes through individual mufflers. Each diesel engine is con- nected by a flexible coupling to a 205 kilowatts, direct current Westing- house generator. , Hach generator de- velops 820 amperes at 250 volts full load and 300 revolutions per minute. Forward of the generators are locat- ed individual 125-volt Westinghouse exciters of 25 kilowatts capacity each at 300 revolutions per minute. Main Propulsion Motor The main propulsion motor sup- plied by Westinghouse is of double armature type with each armature developing 250 horsepower. This mo- tor takes a full load amperage of 818 at 175 revolutions per minute and can be controlled either from the pilot house or from the engine room merely by throwing a switch. The propeller is a three-bladed bronze wheel supplied by. the Columbian Bronze Corp. with 96 inches pitch and 96 inches diameter. Trial re- sults demonstrated the correctness of the characteristics of the propel- ler. Full power was absorbed with the motor turning at 180 revolutions per minute and developing 557 horse- power. With a speed of 11.7 knots under these conditions, the maximum apparent propeller slip was 17.7 per cent. The official acceptance trials were run on the measured mile course Fy off Kent island in Chesapeake bay. During the trials the machinery was operated from practically no load up to 100 per cent load with the results mentioned above. It was calculated that the efficiency of the main pro- pulsion motor is 92.4 per cent, giy- ing a loss from all causes of 45.6 horsepower. On the delivery trip to New York, with only one diesel electric unit working for a short period, it was found that sufficient current could be generated to turn the main motor at 140 revolutions per minute. In other words, when working under overload conditions, one diesel gen- erating set was able to supply suffi- — cient current to operate the main propulsion motor within 20 per cent of its normal rated speed for full power with both generators in com- mission. From this it is apparent that working both generating units at overload an appreciable increase in propeller revolutions might be an- ticipated. A Kingsbury thrust bear- ing, size 17, is fitted on the main propeller shaft just aft of .the propul- sion motor. Among the auxiliaries are a com- bination Fairbanks-Morse diesel driv- en generator and compressor set of 20 kilowatts capacity at 125 volts and 800 revolutions per minute. This set furnishes electricity for auxiliary purposes as required, or the 50 cubic foot compressor will furnish ample supply of starting air for the main engines. This air is stored in a bat- tery of six large air tanks. The fire and bilge pump is an electric motor driven Fairbanks-Morse reciprocating pump, 3% by 6 inches. The same company also supplied an electrically driven emergency oil and water pump for transferring oil or water, or for gradual cooling of the main engines after a long run, by circulating water and oil through the cooling system of éach motor. Walter Wyman-Diesel Electric Tug Built by Spedden Shipbuilding Co. for United States Public Health Service, Foreign Quarantine Division MARINE REVIEwW—May, 1932 Fey an Se grate: